FOUS30 KWBC 261601
QPFERD

Excessive Rainfall Discussion
NWS Weather Prediction Center College Park MD
1101 AM EST Fri Dec 26 2025

Day 1
Valid 16Z Fri Dec 26 2025 - 12Z Sat Dec 27 2025

...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL FOR PORTIONS OF
SOUTHERN CALIFORNIA...

1600Z Update...

The Marginal Risk area has been expanded north to include much of
northern CA, including the coastal ranges, Bay Area, and northern
portions of the Central Valley. The arrival of a fairly strong
500/700 mb low center just offshore will be driving areas of heavy
showers going through the afternoon hours. While this energy will
be generally weakening with time, the addition of at least modest
boundary layer heating along with some steepening of the mid-level
lapse rates should favor some convective elements capable of
producing localized rainfall rates of 0.50" to 0.75"/hour. Some
localized additional rainfall totals of 1 to 2 inches will be
possible, and especially across the northwest CA coastal range.
These additional rains may foster some additional localized runoff
concerns given the wet/saturated soil conditions and elevated
streamflows. No changes have been made to the Slight Risk area
farther south across southern CA as the threat of heavy rain will
continue here into at least the early evening hours.

Orrison

Previous discussion...

Few changes were needed for this morning's update. A positively-
tilted upper level trough will push ashore and inland across the
Pacific Northwest today. This will keep the flow at all levels
unidirectional out of the southwest across Southern California, on
the leading edge of a 140 kt jet. As the trough pushes east, less
and less of it will be over the Pacific, resulting in a diminishing
of the onshore flow with time. Waves of rainfall will push ashore
into southern California through the day. Lingering instability
will support rates that may be heavy at times. This is most likely
as the storms interact with the terrain of the eastern Transverse
Ranges, from L.A. north and east. It is in this area that the
rainfall forecast peaks at around 3 inches at the highest
elevations. Meanwhile most of the L.A. Basin picks up another 1-2
inches. 1-2 inches of rain would be problematic on a normal day,
but following multiple days of multiple inches of rain per day,
making the 1-2 inches expected today lighter by comparison...expect
scattered instances of flash flooding to redevelop again today.
While all areas of coastal Southern California and the Los Angeles
basin will pick up some rain, those highest totals will be north
and east of the downtown area. Thus, from downtown L.A. north and
east, a higher end Slight is in effect. The flooding impacts will
be the result of continued drainage of prior rainfall over
Christmas Eve and Day, as well as urban effects. A Moderate Risk
may need to be considered from Pasadena east through San Bernardino
if rainfall amounts exceed expected totals.

Elsewhere, the Slight remains in place down the coast to about San
Diego, as the eastward moving bands of rain impacting the L.A.
Basin should struggle to continue further south. Meanwhile the
Marginal for limited shower activity and/or lowering snow levels in
the foothills of the Sierra Nevada remains in place unchanged with
this update. For Central and Northern California, it's probable
that there will be more total precipitation in these parts of the
state compared to further south, but because of lowering snow
levels due to cold air influx with the aforementioned trough
moving in, much of it should fall as snow at the higher elevations,
reducing the flooding threat downstream.

By this evening, the flow will flip around to the northwest,
ushering in drier air and finally ending the rainfall threat across
Southern California likely for the rest of 2025.

Wegman


Day 2
Valid 12Z Sat Dec 27 2025 - 12Z Sun Dec 28 2025

The probability of rainfall exceeding flash flood guidance is less
than 5 percent.

Wegman

Day 3
Valid 12Z Sun Dec 28 2025 - 12Z Mon Dec 29 2025

The probability of rainfall exceeding flash flood guidance is less
than 5 percent.

An area of rainfall across much of the Midwest is expected with a
developing low moving into the Great Lakes. The combination of
prior dry soil conditions, rapid movement, poor instability, and
cold air following the rain should all work to keep this event
largely beneficial. There are no flooding concerns in this area at
this time due to these factors.

Wegman
$$
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* Origin: Capitol City Online (618:250/1)

FOUS30 KWBC 270745
QPFERD

Excessive Rainfall Discussion
NWS Weather Prediction Center College Park MD
245 AM EST Sat Dec 27 2025

Day 1
Valid 12Z Sat Dec 27 2025 - 12Z Sun Dec 28 2025

The probability of rainfall exceeding flash flood guidance is less
than 5 percent.

Wegman


Day 2
Valid 12Z Sun Dec 28 2025 - 12Z Mon Dec 29 2025

...THERE IS A MARGINAL RISK OF EXCESSIVE RAINFALL FROM NORTHERN
ILLINOIS THROUGH WESTERN NEW YORK...

A Marginal Risk upgrade was introduced with this morning's forecast
update across a portion of the Great Lakes, in coordination with a
couple of the impacted forecast offices. While the atmospheric
river event in California is long over, the remnant moisture
therefrom has continued east and will be harnessed by a developing
storm system across the Midwest. The low center will track from
near Kansas City Sunday morning to over Lake Huron by Monday
morning. In that time it will deepen from around 1000 mb Sunday
morning to around 974 mb Monday morning. This rapid cyclogenesis
will allow the moisture to the tune of 5 sigma above normal for
this time of year, as well as IVT values over 750 kg/m/s will
support additional dynamic lift along the warm front which extends
east of the low, and along its cold front to the low center's south.

Elevated convection resulting in locally heavy rainfall is
likely, despite the fast movement of any convective cells. Bare
ground is in place across most of the Marginal Risk area. Due to
lack of flora, it should take longer for the rainfall to penetrate
into the ground, resulting in more runoff. Urban areas in the rain
shield, including Chicago, Detroit, and Buffalo could see urban and
small stream flooding. Across upstate New York, at the higher
elevations some snowpack remains, especially east of the lower
lakes. This too could locally contribute to rising stream and creek
levels leading to isolated instances of flash flooding.

Wegman


Day 3
Valid 12Z Mon Dec 29 2025 - 12Z Tue Dec 30 2025

The probability of rainfall exceeding flash flood guidance is less
than 5 percent.

Wegman

$$
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* Origin: Capitol City Online (618:250/1)

FOUS30 KWBC 281008
QPFERD

Excessive Rainfall Discussion
NWS Weather Prediction Center College Park MD
508 AM EST Sun Dec 28 2025

Day 1
Valid 12Z Sun Dec 28 2025 - 12Z Mon Dec 29 2025

...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL FOR PORTIONS OF
WESTERN NEW YORK...

...New York...

The warm front associated with a rapidly deepening low that will
track from the central Plains to the northern mitten of Michigan
today will move into western New York later this morning. This warm
front will advect much warmer air behind it, to its south, which in
turn will change over any wintry precipitation ahead of it to
plain rain. Dynamics associated with the rapidly deepening low,
including well above normal amounts of atmospheric moisture, some
instability, and slow northward movement, will all allow rain,
heavy at times, to persist from when it starts later this morning
through into tonight, when the trailing cold front sweeps across
western New York, ending any warm precipitation, as much colder
Canadian air rushes in behind the cold front. This extended period
of warm rainfall will occur over a below-normal, but still fairly
robust snow pack at the higher elevations of the Southern Tier, to
the amount of 1-4 inches of snow water equivalent. Thus, the
combination of rain and snow melt should rapidly increase stream,
creek, and river levels across western New York. Thus, the flooding
threat has increased and a Slight Risk for portions of western New
York, generally west of Rochester and north of the PA State Line,
remains in place. Urban and small stream flooding look to be the
types of flooding that are most likely, but any flood-prone area
will be susceptible today and especially into tonight.

...Midwest...

A Marginal Risk extends from northern Illinois across much of
southern Michigan. The warm front with embedded elevated convection
will persist through the entire day in the Marginal Risk area. The
cold front will swing west to east from late this afternoon in
Illinois to this evening across Michigan. This will effectively end
the flooding threat as much colder air turns any lingering
precipitation tonight over to snow, and the lakes help with
localized enhancement across western lower Michigan. Urban and
small stream flooding are possible in the Chicago area, Detroit,
and any smaller urbanized areas in between. Due to relatively dry
conditions across the Midwest prior to today, any instances of
flooding should be isolated.

The rain has already started out this early morning to the
southwest of the Marginal Risk area across portions of Missouri,
Iowa, and western Illinois. For these areas, even drier soils prior
to this storm should keep the flooding threat below the 5% Marginal
Risk threshold, but the area will be monitored for overperformance
and any potential need to extend the Marginal Risk south and west
for the morning into these areas.

Wegman


Day 2
Valid 12Z Mon Dec 29 2025 - 12Z Tue Dec 30 2025

The probability of rainfall exceeding flash flood guidance is less
than 5 percent.

Wegman


Day 3
Valid 12Z Tue Dec 30 2025 - 12Z Wed Dec 31 2025

The probability of rainfall exceeding flash flood guidance is less
than 5 percent.

Wegman
$$
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* Origin: Capitol City Online (618:250/1)

FOUS30 KWBC 290806
QPFERD

Excessive Rainfall Discussion
NWS Weather Prediction Center College Park MD
306 AM EST Mon Dec 29 2025

Day 1
Valid 12Z Mon Dec 29 2025 - 12Z Tue Dec 30 2025

The probability of rainfall exceeding flash flood guidance is less
than 5 percent.

Wegman


Day 2
Valid 12Z Tue Dec 30 2025 - 12Z Wed Dec 31 2025

The probability of rainfall exceeding flash flood guidance is less
than 5 percent.

Wegman


Day 3
Valid 12Z Wed Dec 31 2025 - 12Z Thu Jan 01 2026

...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL FOR PORTIONS OF
SOUTHERN CALIFORNIA...

A potent upper level shortwave trough will move east through the
day Wednesday and approach the southern California coast New Year's
night. As it approaches, the attendant surface low will tap into a
large plume of subtropical moisture that will advect north on the
southerly flow ahead of the trough. The trough itself will be
negatively tilted, supporting cyclogenesis. The surface low will
elongate thanks to the negatively tilted trough, allowing the
southerly flow to spread rainfall north along essentially the
entire California coast. However, with southerly flow, the east-
west oriented Transverse Ranges will be particularly well set up to
capture that moisture and wring it out in the form of upslope
rainfall, in much the same way as the Christmas rainfall event a week ago.

The difference between the Christmas and New Year's rainfall events
in California will be the depth of moisture (less of it this time
around), and lack of instability this time. This combined with the
first part of the event having a southeasterly flow in the lower
levels should help to mitigate the total rainfall impacting the
L.A. Basin and the Transverse Ranges relative to the Christmas rainfall
event. Forecasted PWATs will be around 1.25 inches near the coast.
This is still 4 sigma above normal for this time of year, and
therefore still represents a highly unusual amount of available
moisture. The latest forecast has up to an inch of rain
overspreading much of the lower elevations of the L.A. Basin, while
1-3 inches of rain are forecast for the south- facing slopes of
the Transverse Ranges. Full reservoirs from the Christmas event,
some draining still ongoing due to wetter than normal soils for
this time of year, burn scars, and urban effects should all work to
worsen any flooding effects from the expected rainfall. Thus,
while forecasted rainfall amounts are lower, expect that there will
still be widely scattered instances of flash flooding, especially
in and around burn scars.

A Slight Risk upgrade was introduced with this update, in
coordination with LOX/Oxnard, CA forecast office. Fortunately,
unlike the Christmas rainfall event, for the aforementioned
reasons, do not expect to have additional upgrades in this area.
Short of some much larger forecast change that results in much
higher forecasted rainfall amounts into SoCal, a possibility with a
low probability of occurring, this should be the final risk
category upgrade. Nonetheless the forecast should continue to be
monitored for the latest updates.

Wegman
$$
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* Origin: Capitol City Online (618:250/1)

FOUS30 KWBC 300800
QPFERD

Excessive Rainfall Discussion
NWS Weather Prediction Center College Park MD
300 AM EST Tue Dec 30 2025

Day 1
Valid 12Z Tue Dec 30 2025 - 12Z Wed Dec 31 2025

The probability of rainfall exceeding flash flood guidance is less
than 5 percent.

Wegman


Day 2
Valid 12Z Wed Dec 31 2025 - 12Z Thu Jan 01 2026

...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL FOR PORTIONS OF
SOUTHERN CALIFORNIA...

A large upper level Pacific low will track east and approach the
coast of Southern California on New Year's Eve. The low will
gradually weaken with time, and remain under a ridge in the
polar jet, thus keeping the low cut off from the main jet stream.
The low will draw an unusually moist, tropical air mass northward
up the Mexican coast and into Southern California. The predominant
850 flow will be out of the southeast for much of the day
Wednesday, but will turn more out of the south-southwest by New
Year's Night. This pattern will keep rainfall into the Transverse
Ranges, and much of southern California for that matter, rather
light through the day. However, once the flow turns to become more
orthogonal to the coast Wednesday night, rainfall rates will
increase into the Transverse Ranges. The orthogonal turn of the
flow will correlate with the closest approach of both the upper
level trough and corresponding surface low. These will also enhance
rainfall rates into the mountains.

Hydrologically, while Southern California has had some time to
recover from the Christmas rainfall event, it's still too soon
after the event for full drainage to have occurred. Forecast
rainfall has increased in the past 24 hours, due in part to a
closer approach of the surface low to the coast relative to the
forecast last night. As such, a higher end Slight was issued for
much of the Transverse Ranges, where 2-4 inches of rain are
forecast through the period. Much of that rain will fall between
06Z and 12Z Thursday morning. Meanwhile, in the adjacent L.A.
Basin, 1-2 inches of rain are expected. Between burn scars and
urban concerns, this amount of rain should lead to scattered
instances of flash flooding. Thus, the Slight Risk inherited
remains in place. Further increases to the rainfall forecast may
require an additional upgrade to a Moderate Risk with future updates.

Wegman


Day 3
Valid 12Z Thu Jan 01 2026 - 12Z Fri Jan 02 2026

...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL FOR PORTIONS OF
SOUTHERN CALIFORNIA...

A Slight Risk upgrade was introduced with this update, for many of
the same areas as the Day 2 Slight Risk. At the start of the period
New Year's morning, the brunt of the event will be well underway
across Southern California. Heavy rain will continue into the
morning hours as the surface low and upper level trough finally
move ashore during the day Thursday. Thus, the heaviest rains are
expected Thursday morning. Behind the low Thursday afternoon and
into the overnight, the rain should largely end for most, tapering
to a few showers here and there. Thus, this Slight Risk is really
for the first half of the day, and should be able to be dropped
after that. Nonetheless, an additional 1-2 inches of rain on top of
the rains from the overnight will continue to cause flooding
concerns across Southern California. So while amounts in total will
be less Thursday than on Wednesday, the continuation of Wednesday's
rain on into Thursday will keep the commensurate impacts ongoing as well.

Further north, a Marginal Risk remains in place for portions of the
northern California coastal ranges and extending south along the
Sierra Nevada foothills. The rain in these regions Thursday and
Thursday night will be much more evenly spread in time. However,
these areas are much more equipped to handle the expected rain,
especially since full recovery from the Christmas rainfall event
has already occurred. An isolated instance or two of flash flooding
can't be ruled out, hence the Marginal, but overall impacts into
central and northern California should be minimal.

Wegman
$$
--- SBBSecho 3.28-Linux
* Origin: Capitol City Online (618:250/1)

FOUS30 KWBC 310814
QPFERD

Excessive Rainfall Discussion
NWS Weather Prediction Center College Park MD
314 AM EST Wed Dec 31 2025

Day 1
Valid 12Z Wed Dec 31 2025 - 12Z Thu Jan 01 2026

...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL FOR PORTIONS OF
SOUTHERN CALIFORNIA...

A slow-moving upper level low centered well west of the California
coast will move towards California through the Day 1/New Year's
period. The upper low will remain negatively tilted as it
approaches the coast. This will allow a surface low, already formed
at the start of the period, to move north along the coast.
Southerly winds ahead of the low will drive plentiful Pacific
moisture into southern California. Upslope into the Transverse
Ranges will wring out much of that moisture, resulting in multiple
inches of rainfall, especially New Year's night, into the L.A.
Basin and adjacent Transverse Ranges. Once the center of the
surface low moves north of the Bay Area, its trailing cold front
will move into southern California. This will turn the flow to out
of the southwest, which will further enhance the upslope flow into
the Transverse Ranges, causing heavier rainfall Wednesday night.

The inherited Slight Risk for much of the L.A. Basin and higher-end
Slight for the Transverse Ranges themselves was left largely
unchanged with this update. The forecast weather pattern remains
largely unchanged, with more parallel southeasterly flow into the
Ranges supporting mostly light rain through much of New Year's
Eve and into the evening, then the rain turning heavier around the
stroke of midnight for the L.A. Basin. While soils across Southern
California have dried out a fair bit since the Christmas rainfall
event, both soils and rivers are still running above normal even
several days later. Thus, the renewal of heavy rainfall Wednesday
night should quickly refill any rivers, with much of the lighter
rain during the day Wednesday saturating the soils in time for the
heavier rains Wednesday night to largely convert to runoff. Thus,
the Slight Risk looks to be in good shape, with no major changes to
rainfall amounts expected requiring any further major changes to
the excessive rainfall forecast.

Wegman


Day 2
Valid 12Z Thu Jan 01 2026 - 12Z Fri Jan 02 2026

...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL FOR PORTIONS OF
SOUTHERN CALIFORNIA...

Heavy rain will be ongoing at the start of the period Thursday
morning across much of southern California. As the upper level
shortwave moves into the coast, the winds will turn out of the
west-southwest, or exactly orthogonal to the Transverse Ranges.
This will maximize the upslope enhancement of the rainfall just as
the maximum forcing is moving ashore. Through 18Z, this period New
Year's morning will be when the heaviest rain of the event is
expected into southern California. PWATs between 1 and 1.25 inches
will be between 3 and 4 sigma above normal for this time of year, a
sign of how much moisture will be available to convert into
rainfall and runoff from the Transverse and to a lesser extent,
Peninsular Ranges. Once the shortwave moves ashore and inland by
Thursday evening, the combination of weakening of both upper level
and surface lows, as well as rapid weakening of the onshore west-
southwesterly flow behind the low, will lead to rapid diminishing
of the rainfall across Southern California, such that by Thursday
evening, little if any rainfall will be left.

The Slight Risk inherited is largely unchanged both from the
previous forecast and from the Day 1/Wednesday Slight Risk area.
Both days' Slight Risks will be splitting the two halves of the
same event, so little should be different. There is a higher-end
Slight in effect for most of the Transverse Ranges from about
Malibu east through San Bernardino. This will largely be for the
morning hours, as once the rain weakens, the flooding threat
associated with additional rainfall should also rapidly diminish,
likely resulting in an early downgrade of the Slight Risk Thursday
afternoon.

Further north, along the track of the aforementioned upper level
shortwave, rainfall will persist for much longer into the northern
Coastal Ranges and much of the Sierra Nevada foothills, especially
those along the Sacramento Valley. However, this area has more
thoroughly recovered from the Christmas rainfall event and also is
better equipped naturally to handle long duration rainfall. As
such, only an isolated flash flooding threat, consistent with the
unchanged Marginal, is expected.

Wegman


Day 3
Valid 12Z Fri Jan 02 2026 - 12Z Sat Jan 03 2026

...THERE IS A MARGINAL RISK OF EXCESSIVE RAINFALL FOR PORTIONS OF
CALIFORNIA...

Light rain over most of northern California from about 06Z Friday
through 18Z Friday will end as another large upper level low begins
to make its way towards northern California and Oregon. This upper
low, while bigger, will be less amplified/elongated as compared
with the last upper low. That should focus most of the rainfall
into northern California. Further, the surface low will be a
vertically stacked one, whose occluded front has wrapped clear
around the low center. It is this occluded front making its way
ashore that will restart any heavier rain into the southward facing
slopes of the coastal ranges, Klamath, and the northern Sierra
Nevada foothills. Rainfall totals will generally fall in the 2-3
inch range in most of the mountains, with around an inch into the
Sacramento Valley. This amount of rain should be enough to raise
river levels with perhaps an isolated instance or two of flash
flooding in some of the flashier creeks and streams, but overall
impacts should still be minimal, despite some precipitation
occurring prior to this on Day 2. Much of northern California is
well-suited to handle rainfall amounts such as these, so widespread
impacts are not expected. The area's forecast will be monitored
for any potential Slight Risk upgrades needed.

Wegman
$$
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* Origin: Capitol City Online (618:250/1)

FOUS30 KWBC 010803
QPFERD

Excessive Rainfall Discussion
NWS Weather Prediction Center College Park MD
303 AM EST Thu Jan 1 2026

Day 1
Valid 12Z Thu Jan 01 2026 - 12Z Fri Jan 02 2026

...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL FOR PORTIONS OF
SOUTHERN CALIFORNIA...

A 500mb trough with a small, yet potent, closed circulation will
become part of a negatively tilted 200-500mb upper-trough axis
that is partially responsible for the slug of highly anomalous
moisture that will engulf much of the West today. The focus remains
on Southern California where the Transverse Ranges soils remain
quite sensitive in wake of last week's significant flooding. IVT
values are encroaching upon 500 kg/m/s and embedded within SSWrly
flow that is aligned orthogonally to the Transverse Ranges.
Additional forcing will be located along the frontal boundary that
will trigger additional convection over the East Pacific upon
approach. PWATs are forecast to be just over 1.25" off the Southern
California coast through this morning, but around 18Z, a dryslot
in the 700-300mb layer should result in the conclusion of today's
heaviest rainfall. Some lingering heavy rainfall may be possible in
the Peninsular Range east of San Diego beyond 18Z, but most
rainfall around the L.A. region should be just about over (aside
from lingering upslope into the Transverse Ranges).

Latest HREF guidance does show minor instability present (<250
J/kg on average) between 09-18Z, which may be just enough when
taking into account sensitive soils to result in additional flash
flooding in not just the Transverse Ranges, but also the greater
Los Angeles metro area as well. The new 00Z HREF 24-hour QPF
probabilities for surpassing 3" of rainfall peaks around 50% over
the San Bernadino and low chances (15-25) for localized totals
eclipsing 5". Snow levels remain very high, making just about all
of the expected QPF to be in the form of rain. The lack of higher-
end instability is what is keeping the Slight Risk in place, but
make no mistake-- there remains a heightened risk for flash
flooding this morning in Southern CA with rock slides and debris
flows in/around burn scars possible, including urbanized flash flooding.

Farther north, most area have recovered a bit better from last
week's significant rainfall, but the copious amounts of moisture
combined with sufficient synopitc-scale forcing aloft and
supportive upslope flow along the Coastal Range and as far inland
as the Sierra Nevada does suggest a Marginal Risk for flash
flooding is still warranted. The 00Z HREF does show a small area
between Santa Maria and Big Sur where MUCAPE >250 J/kg could
materialize between 15-18Z and foster more potent instantaneous
rainfall rates as convection moves through. Still, the line of
showers and thunderstorms would be progressive and keep the flash
flooding potential to a very localized area.

Mullinax


Day 2
Valid 12Z Fri Jan 02 2026 - 12Z Sat Jan 03 2026

...THERE IS A MARGINAL RISK OF EXCESSIVE RAINFALL FOR PORTIONS OF
CALIFORNIA...

An expansive upper level cutoff low over the Pacific well west of
the northern California coast will approach the northern California
coast Friday night. The occluded front wrapping around a surface
low will be the primary forcing for heavy rainfall into northern
California Friday night. The occluded front will turn the flow a
bit more onshore (southeast before the front to south-southwest
behind it). This will allow the coastal ranges to upslope some of
that moisture, locally enhancing rainfall rates, particularly into
the northern Coastal Ranges and the Klamath Mountains. Some heavy
rain may impact the Bay area and the coastal ranges south from
there in the waning couple hours of the period, assuming the timing
of the front moving into the coast remains unchanged. IVT values
between 500 and 750 kg/ms are far from impressive, and moisture
anomalies rise to around 2 sigma above normal, a common occurrence
in this part of the world, especially the past few weeks. Thus,
with the rainfall event just getting going, coming in in the middle
of the night, and with less-than-impressive dynamics, the Marginal
Risk for much of the central and northern California coast remains
largely unchanged with this update, and the Marginal looks on track.

Wegman


Day 3
Valid 12Z Sat Jan 03 2026 - 12Z Sun Jan 04 2026

...THERE IS A MARGINAL RISK OF EXCESSIVE RAINFALL FOR PORTIONS OF
CALIFORNIA...

A series of upper level disturbances rotating around a large upper
level low will impact much of California and the West Coast this
weekend. With each upper level disturbance, there will be a
commensurate surface front that also makes its way ashore into
northern California. The result will be an almost non-stop rain,
especially for upslope areas on southerly flow, as well as for all
of the coastal ranges. That said, each disturbance will briefly
increase rainfall rates, with those rates decreasing back down in
between disturbances. Thus, Saturday's rain looks to be a long-
duration relatively light (for most areas) rain, rather than there
being big concerns on any one area seeing prolonged heavy rain.
Given the area's good ability to drain rainwater quickly, a
Marginal Risk remains in effect for northern California. The area
will continue to be monitored for a possible Slight Risk upgrade
with future updates.

Wegman
$$
--- SBBSecho 3.28-Linux
* Origin: Capitol City Online (618:250/1)

FOUS30 KWBC 021540
QPFERD

Excessive Rainfall Discussion
NWS Weather Prediction Center College Park MD
1040 AM EST Fri Jan 2 2026

Day 1
Valid 16Z Fri Jan 02 2026 - 12Z Sat Jan 03 2026

...THERE IS A MARGINAL RISK OF EXCESSIVE RAINFALL FOR THE CENTRAL
CALIFORNIA COAST NORTHWARD INTO NORTHERN CALIFORNIA...

1600Z Update...

The 12Z HREF guidance supports no changes to the Marginal Risk area
for the central CA coast northward into northern CA. The offshore
upper trough/front will be moving east later today and tonight and
will bring periods of locally heavy inland. Some localized runoff
issues will be possible overnight and early Saturday morning given
moderate to locally heavy rainfall rates (isolated 0.50+"/hour) and
the moist/wet antecedent conditions.

Orrison

Previous discussion...

No major model disagreements with the eastward push of the strong
mid to upper level low off the northern California coast day 1. The
low level southerly flow will strengthen Friday along and ahead of
the associated frontal boundary pushing toward the central to
northern California coast. While PW values are only 1 to 1.5
standard deviations above the mean, the 850-700 mb moisture flux
values are more anomalous, 2-3+ standard deviations above the mean.
Precip should increase in intensity along the northern CA coast
after 0000 UTC Sat, and spread south into coastal central CA in the
0600-1200 UTC time frame. The frontal boundary is expected to be
fairly progressive, limiting very heavy rainfall totals. HREF and
RRFS neighborhood probabilities for .50"+ hourly amounts are
generally less than 30%, with a few localized 60%+ probabilities
along the central CA coast range to the south of Monterey, and
across the northern Sierra. Areal average 1 to 1.5" amounts
expected along the central to northern CA coast and 1.5-2" in the
northern Sierra with isolated heavier totals of 2.5-3"+ possible.
No significant changes made to the previous marginal risk, with
localized runoff issues possible where soils remain fairly
saturated from recent rains, especially across northern CA.

Oravec


Day 2
Valid 12Z Sat Jan 03 2026 - 12Z Sun Jan 04 2026

...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL FOR PORTIONS OF THE
NORTHERN SIERRA AND SOUTHERN CALIFORNIA...

The axis of anomalous 850-700 mb moisture flux values...2 to 4
standard deviations above the mean...along and ahead of the inland
moving frontal boundary at the end of the day 1 period will impact
the upslope areas of the northern Sierra and spread through the
Transverse Ranges of Southern California day 2. The primary change
from the previous outlook was to add a small slight risk area in
the upslope area of the Northern Sierra. HREF neighborhood
probabilities for .50"+ hourly rainfall amounts are fairly
high...50%+ at the beginning of the day 2 period and again in the
2100 UTC Sat to 0000 UTC Sun period. This will result in day 2
rainfall totals of 2-4"+ in a region of fairly saturated soils from
recent heavy rains. No changes of note made to the previous slight
risk area over Southern CA in the vicinity of the Transverse
Range. The south southwesterly low level flow will have a
significant upslope component into the Transverse Ranges during
the first half of day 2. This is reflected in both the HREF and
RRFS .50"+ hourly probabilities which are high, 50-80%+ during this
period. Localized runoff issues are possible where soils remain
fairly saturated from recent heavy rains.

Oravec


Day 3
Valid 12Z Sun Jan 04 2026 - 12Z Mon Jan 05 2026

...THERE IS A MARGINAL RISK OF EXCESSIVE RAINFALL ALONG THE
CALIFORNIA COAST AND IN THE UPSLOPE OF THE SIERRA...

Additional shortwave energy expected to rotate through the mean
trof position along the West coast and inland across California day
3. This will support a continued wet showery pattern with
additional moderate to locally heavy precip totals along much of
the California coast Ranges and into the upslope of the Sierra. A
broad marginal risk area was maintained from the previous outlook
this period with changes mostly to better fit the latest model and
WPC qpf. The slight risk area over Southern California in the
vicinity of the Transverse Range was removed given consensus of
additional moderate totals.

Oravec
$$
--- SBBSecho 3.28-Linux
* Origin: Capitol City Online (618:250/1)

FOUS30 KWBC 040830
QPFERD

Excessive Rainfall Discussion
NWS Weather Prediction Center College Park MD
330 AM EST Sun Jan 4 2026

Day 1
Valid 12Z Sun Jan 04 2026 - 12Z Mon Jan 05 2026

...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL FOR PORTIONS OF THE
NORTHERN SIERRA...

Precipitation is expected to increase in coverage and intensity
Sunday morning across northern to central California as the next
batch of shortwave energy rotates through the mean west coast trof
and inland across central CA. PW values and 850-700 mb moisture
flux are expected to increase Sunday associated with this next
batch of shortwave energy. This will support locally heavy precip
totals along much of the California coast Ranges and into the
upslope of the Sierra. Hourly rainfall rates in the .25-.50" range
possible along the central CA coast and into the upslope of the
northern Sierra. A small slight risk area was maintained in the
upslope of the northern Sierra where model consensus is for
potential of additional 1 to 2" of rain. The HREF probabilities of
3 hr precip exceeding 3 hr FFG values shows an area of 15-30%
probabilities sinking southward along the upslope of the northern
Sierra Sunday where the slight risk area is drawn. Overall, no
changes of note made to the previous outlook for the upcoming day 1 period.

Oravec


Day 2
Valid 12Z Mon Jan 05 2026 - 12Z Tue Jan 06 2026

...THERE IS A MARGINAL RISK OF EXCESSIVE RAINFALL ALONG THE CENTRAL
TO NORTHERN CALIFORNIA COAST AND NORTHERN CALIFORNIA...

There are large scale differences developing day 2 with the
amplification of a closed low in the base of the mean trof off the
Central to Southern CA coast. The NAM and GFS are showing a more
southwest solution compared to the EC, CMC and UKMET. This farther
southwest solution is resulting in a trend of less precip along
the central CA coast to the south of San Francisco and into the
Northern Sierra in the GFS and NAM as the low level flow has a
much weaker onshore component compared to the EC, CMC and UKMET.
Models often struggle with closed formation downstream of
flattening upper ridges with overall low confidence at the moment.
The latest WPC qpf did trend towards less precip across the central
CA Coast Range and over the Northern Sierra, but not as dry as the
GFS and NAM. Subsequently, the previous marginal risk area was
decreased in size. There may be additional changes needed to the
risk area with future model cycles, depending how the evolution of
the closing off mid to upper level center evolves.

Oravec


Day 3
Valid 12Z Tue Jan 06 2026 - 12Z Wed Jan 07 2026

...THE PROBABILITY OF RAINFALL EXCEEDING FLASH FLOOD GUIDANCE IS
LESS THAN 5 Percent...

Oravec
$$
--- SBBSecho 3.28-Linux
* Origin: Capitol City Online (618:250/1)

FOUS30 KWBC 050745
QPFERD

Excessive Rainfall Discussion
NWS Weather Prediction Center College Park MD
245 AM EST Mon Jan 5 2026

Day 1
Valid 12Z Mon Jan 05 2026 - 12Z Tue Jan 06 2026

...THERE IS A MARGINAL RISK OF EXCESSIVE RAINFALL ALONG THE CENTRAL
TO NORTHERN CALIFORNIA COAST AND NORTHERN CALIFORNIA...

Upper disturbance off the California coast will meander to the
southeast closer to the coastal plain, eventually pinching off the
mean trough centered to the north and closing off into an ULL as it
migrates down near the latitude of the Bay area. Proximity of the
disturbance and prevailing flow will send a modest IVT pulse
(300-400 kg/ms) crashing into the northern CA coastal plain with
some minor protrusion of the IVT signature inland with a secondary
QPF maxima forecast around the Trinity Mountains over into Shasta
National Forest domain. Hi-res deterministic output is pretty
consistent with the axis of heaviest precip focused from the King
Range down towards Santa Rosa, north of the Bay area with the
latest HREF EAS probs for 1" running between 60-90% for much of
that location with another prob max focused near Mount Shasta.

The main threat for this setup is easily over any urbanized zones
and remnant burn scars across northern CA leading to mainly a
lower-end flash flood concern in the grand scheme of the setup. IVT
signature is one that historically yields more isolated flash flood
threats with the primary focus typically aimed at that coastal
urban centered from the Bay area up towards Eureka, and over the
northern valley locations like Redding. This is where the MRGL
risk was maintained during the forecast as the trend for the
southern edge of any heavy rain prospects south of San Jose has all
but disappeared on guidance. It's still something we'll monitor
for any last minute trends back, but guidance favors mainly the
area north of the Bay at this time. Total QPF for the impacted
areas will be between 1.5-3" with a max between 4-5" for the
coastal ranges north of the Bay area, and over the Shasta National Forest.

Kleebauer


Day 2
Valid 12Z Tue Jan 06 2026 - 12Z Wed Jan 07 2026

...The probability of rainfall exceeding flash flood guidance is
less than 5 percent.

Kleebauer


Day 3
Valid 12Z Wed Jan 07 2026 - 12Z Thu Jan 08 2026

...The probability of rainfall exceeding flash flood guidance is
less than 5 percent.

Kleebauer
$$
--- SBBSecho 3.28-Linux
* Origin: Capitol City Online (618:250/1)

FOUS30 KWBC 061455
QPFERD

Excessive Rainfall Discussion
NWS Weather Prediction Center College Park MD
955 AM EST Tue Jan 6 2026

Day 1
Valid 16Z Tue Jan 06 2026 - 12Z Wed Jan 07 2026

The probability of rainfall exceeding flash flood guidance is
less than 5 percent.

Cook/Kleebauer


Day 2
Valid 12Z Wed Jan 07 2026 - 12Z Thu Jan 08 2026

The probability of rainfall exceeding flash flood guidance is
less than 5 percent.

Kleebauer


Day 3
Valid 12Z Thu Jan 08 2026 - 12Z Fri Jan 09 2026

...THERE IS A MARGINAL RISK OF EXCESSIVE RAINFALL ACROSS NORTHERN ILLINOIS...

Surface low over the Southern Plains will spawn and move northeast
through the period with an established meridional flow projected to
usher elevated moisture poleward, even as far north as the Great
Lakes. Instability will be limited, but non-zero across the Mississippi
Valley with relatively modest MUCAPE on the eastern periphery of
the cyclone. PWAT anomalies approaching record territory would
normally spur greater emphasis on heavy precipitation, but the
relative nature of the PWAT anomaly being in January stunts the
maximum potential limiting more widespread nature of flash flood prospects.

That said, north of I-70, grounds are mostly frozen from the long
stretch of sub-freezing temperatures maintaining a lower prospect
for rainfall absorption and a higher propensity for run off. Areas
along and north of I-80 across northern IL has the deeper sub-soil
layers frozen with grounds likely to encounter majority run off
during the period as moderate to locally heavy rainfall spreads
north. In collaboration with the local Chicago WFO, a small MRGL
was maintained across northern IL to account for the local flooding
threat given the parameters of elevated PWATs and higher risk for
run off. Urbanization in this area is also very prevalent, so heavy
rains could even spur some flooding risks due to poor drainage in spots.

Kleebauer
$$
--- SBBSecho 3.28-Linux
* Origin: Capitol City Online (618:250/1)

FOUS30 KWBC 070740
QPFERD

Excessive Rainfall Discussion
NWS Weather Prediction Center College Park MD
240 AM EST Wed Jan 7 2026

Day 1
Valid 12Z Wed Jan 07 2026 - 12Z Thu Jan 08 2026

The probability of rainfall exceeding flash flood guidance is
less than 5 percent.

Kleebauer


Day 2
Valid 12Z Thu Jan 08 2026 - 12Z Fri Jan 09 2026

The probability of rainfall exceeding flash flood guidance is
less than 5 percent.

Kleebauer


Day 3
Valid 12Z Fri Jan 09 2026 - 12Z Sat Jan 10 2026

...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL ACROSS PORTIONS OF
THE SOUTHERN OHIO VALLEY INTO THE SOUTHEASTERN U.S...

Large scale amplification of a trough over the Central Rockies into
the Central Plains will generate a broad axis of ascent from the
Mississippi Valley to points eastward with a cold frontal
progression slowly migrating east across the aforementioned areas.
Meridional component of the pattern evolution will benefit from the strengthening mean trough with multiple shortwave ejections
rounding the trough base across the Lower Mississippi Valley,
advancing northeast through the Southeastern U.S. before migrating
into the Tennessee Valley by the end of the D3. Deep moisture plume
ahead of the trough will usher anomalous PWATs on the order of +2
to +4 sigma spanning east TX through much of the Southeast into
the Southern Ohio Valley. Ample shear and deep moist axis will
maintain a prevalent fixture for much of the period with flow
running close to, if not parallel to the frontal axis that will
bisect southwest to northeast across the Lower Mississippi Valley
through Central and Northern MS/AL into TN. Current ensemble trends
favor a rather broad axis of 2-3" precip totals just within the
means with the deterministic output pushing closer to 4-5" with the
maxima focused over central MS up through northern AL to south-
central TN. This aligns well with the pattern evolution progressing
the front into those confines with a multi-wave ejection riding
into the front as they eject out of the broad deep-layer
southwesterly flow situated across the region.

This setup is classic for a winter time flash flood prospect across
this area of the CONUS as broad ascent coupled with ample deep-
layer shear and highly anomalous moisture tends to amplify the
threat for heavy rainfall repeating over the same areas. This is
being forecast within the Southeast and far southern edge of the
Ohio Valley with the ensemble overlap generally in that corridor
from east-central MS to points north and east with a maxima
oriented over northern AL into southern TN. This is likely the area
to watch, however don't be surprised if areas south across the
southern half of MS into parts of LA see a greater heavy convective
signature that tends to crop up in the short range as the
instability maximum tends to verify a bit further south compared
to what global deterministic output has at this lead. For now,
maintained general continuity in the grand scheme, but adjusted the
SLGT and MRGL risks based on QPF trends and alignment with the
greatest potential for training, and elevated theta_E placement.

Kleebauer
$$
--- SBBSecho 3.28-Linux
* Origin: Capitol City Online (618:250/1)

FOUS30 KWBC 080715
QPFERD

Excessive Rainfall Discussion
NWS Weather Prediction Center College Park MD
215 AM EST Thu Jan 8 2026

Day 1
Valid 12Z Thu Jan 08 2026 - 12Z Fri Jan 09 2026

...THERE ARE MARGINAL RISKS FOR EXCESSIVE RAINFALL ACROSS PORTIONS
OF THE MIDWEST & LOWER MISSISSIPPI VALLEY...

Midwest/Lower Mississippi Valley...
A strong shortwave preceding the incoming upper level trough is
expected to bring 500+ J/kg of MU CAPE into portions of the region
during the day on Thursday. The 00z NAM's 2000+ J/kg bulls eye in
KS/MO right at the beginning of the period appears unrealistic/too
high based on recent SPC mesoanalysis MU CAPE trends, though its
trailing instability appears more reasonable, reinforced by the 03z
RAP. The mesoscale guidance advertises small areas of a low risk
of 3"+ across portions of KS, MO, IL, IN, and eventually LA and MS
Thursday night/early Friday morning. While precipitable water
values are in the 1-1.25" range for northern areas and 1.5"+ range
for southern areas, the atmosphere should be well saturated. There
appears to be enough instability to realize local hourly amounts of
1.5"+ where a sufficient number of organized thunderstorms are
able to materialize. Right now, that appears to be the biggest
issue. While it has been dry lately, flash flood guidance values
are modest across much of the area, with 3 hour guidance closer to
3" for the Lower Mississippi Valley, 2.5" for portions of KS/MO,
and 2" for IL/IN. The guidance indicates that the heavy rainfall
should move through quickly, so local amounts of 2-3" within a
couple hours could be enough for isolated to widely scattered
issues, particularly in urban areas. This led to the introduction
of Marginal Risk areas for the areas mentioned above.

Roth


Day 2
Valid 12Z Fri Jan 09 2026 - 12Z Sat Jan 10 2026

..THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL ACROSS PORTIONS OF
THE TENNESSEE VALLEY AND DEEP SOUTH...

Lower Mississippi Valley/Southern Appalachians...
A positively tilted trough with minimal eastward progression due to
the parent cyclone's progression northeast will generate a broad
axis of ascent from the Mississippi Valley to points eastward with
a cold frontal progression slowly migrating east. An anomalously
moisture plume ahead of the trough, noteworthy for January and near
summer averages with a range of 1.50-1.75", will be accompanied by
500-1500 J/kg of MU CAPE. Ample shear for convective organization
is expected, with low- level convergence more or less fixed from
the Atchafalya Basin in LA into the southern Appalachians. The
guidance is wet, with local 4-7" totals forecast locally. The
guidance has shifted southwest,. which caused a southwest shift in
the risk areas.

This synoptic setup is classic for a flash flood prospect across
this region. Deep layer southwest flow should lead to cell
training, and enough effective bulk shear exists for mesocyclone
formation. Hourly rain amounts up to 2.5" are possible here, which
would overwhelm urban environments. The 00z HREF for the first half
of the period advertised a 30-35% of 5"+ near Laurel MS, which if
it occurred within a few hours would overwhelm non-urban
environments as well. At the moment, this appears to be a high end
Slight Risk, but it wouldn't be surprising if a Moderate Risk
was considered as we get further inside the mesoscale guidance
window. The eastern bounds of the Marginal Risk area were
coordinated with the RNK/Blacksburg VA, GSP/Greer SC, and
FFC/Peachtree City GA forecast offices.

Roth


Day 3
Valid 12Z Sat Jan 10 2026 - 12Z Sun Jan 11 2026

...THERE IS A MARGINAL RISK OF EXCESSIVE RAINFALL ACROSS PORTIONS
OF THE SOUTHERN APPALACHIANS...

Heavy rainfall early in the period is expected over what should be
at least partially saturated ground across portions of the
Southern Appalachians before heavy rainfall ejects into the
southern Mid- Atlantic States. Added a Marginal Risk as a
precaution for this reason; the threat not expected to persist past
18z Saturday.

Roth
$$
d
--- SBBSecho 3.28-Linux
* Origin: Capitol City Online (618:250/1)

FOUS30 KWBC 090754
QPFERD

Excessive Rainfall Discussion
NWS Weather Prediction Center College Park MD
254 AM EST Fri Jan 9 2026

Day 1
Valid 12Z Fri Jan 09 2026 - 12Z Sat Jan 10 2026

..THERE IS A MODERATE RISK OF EXCESSIVE RAINFALL ACROSS PORTIONS
OF SOUTHERN MISSISSIPPI AND ADJACENT LOUISIANA...

The classic synoptic setup for a winter flash flooding event
continues to slowly adjust to the timing/orientation of the
upstream shortwave over the Southwest U.S. The very strong leading
cyclone across the Great Lakes will continue to zip along to the
east-northeast with well above normal (4 Standard Anomaly/99th
percentile) moisture and flux still streaming across the Ohio and
Tennessee Valley. Ongoing thunderstorms are expected across the
Lower MS Valley as morning surge of Gulf air streams northward
becoming increasingly confluent/convergent well ahead of the
upstream synoptic front in the Plains.

The strong upstream base of the positive tilt trof will be
advancing throughout the day into the Plains, though the upper-
level jet streak also be expanding and strengthening across the
Ozark Plateau into the Ohio River Valley from 110kts to over 150kts
by the end of the forecast period. The trough will also be shearing
into the confluent, increasingly unidirectional low to mid-level
flow allowing for a deep southwest to northeast atmospheric river
from the western Gulf up the Lower Mississippi and through the
Tennessee River Valley into the southern Appalachians/Cumberland
Plateau through the majority of the day. While the low level flow
will be weaker than Thursday, 850-700mb 40-45kts and 1.5-1.75"
total PWat values will allow for high moisture flux convergence and
support efficient rainfall production.

As the trends have slowed the upstream shortwave, this allows for
greater flux of unstable air northward and forcing to
overlap/intersect with 1000-1500 J/kg of MLCAPE across the Coastal
Plain reducing toward 500 J/kg near the southern TN border, pulsing
with northward surges as the shortwave lifts out. This will provide
enough ascent and low level shear for organized bands of
convection that will likely have training elements throughout the
day. Rain-rates of 1.5"/hr are probable though 00z Hi-Res CAMs
support occasional up-ticks to 2"+/hr locally. Combined with the
training profiles, 00z HREF shows solid 15-25% 3"/3hr probability
across Southern MS into far northeast LA, with nearly 50%
neighborhood probability of 5". As such, and in coordination with
local forecast offices, WPC is introducing a small Moderate Risk of
Excessive Rainfall for S MS and adjacent NE LA. It should be
noted, there is solid agreement within the guidance suite of 5-8"
total streaks but there is limited agreement in the placement
particularly west or east.

Thunderstorms will train, but as they move northeast into Middle to
eastern TN and northern and central AL, intensity and rainfall
totals are likely to diminish, given instability will be limited
to 200-300 J/kg. Yet, prolonged duration and sizable totals of 2-4"
are still possible and so the Slight Risk continues to be in place
downstream across much of AL, northern GA, and southeast TN.

Upstream, as the main forcing exits, a secondary axis of
convergence along instability/moisture gradient across eastern
Texas will produce additional, slightly more elevated
thunderstorms. Similar rates of 1.5" to 2"/hr are possible with
some repeating/training tracks across NW LA, though overall
duration and coverage should limit rainfall totals to 2-4" relative
to the Moderate Risk area further southeast. As such, the Slight
Risk was also expanded westward along the axis of best overall
model agreement.

Gallina


Day 2
Valid 12Z Sat Jan 10 2026 - 12Z Sun Jan 11 2026

...THERE IS A MARGINAL RISK OF EXCESSIVE RAINFALL ACROSS PORTIONS
OF THE SOUTHERN APPALACHIANS...

Heavy rainfall early in the period is expected over what should be
at least partially saturated ground across portions of the
Southern Appalachians before heavy rainfall ejects into the
southern Mid-Atlantic States. Added a Marginal Risk as a
precaution for this reason; the threat not expected to persist past
18z Saturday.

Roth/Gallina


Day 3
Valid 12Z Sun Jan 11 2026 - 12Z Mon Jan 12 2026

The probability of rainfall exceeding flash flood guidance is less
than 5 (five) percent.

Gallina
$$
--- SBBSecho 3.28-Linux
* Origin: Capitol City Online (618:250/1)

FOUS30 KWBC 101057 AAA
QPFERD

Excessive Rainfall Discussion...UPDATED
NWS Weather Prediction Center College Park MD
557 AM EST Sat Jan 10 2026

Day 1
Valid 12Z Sat Jan 10 2026 - 12Z Sun Jan 11 2026

...THERE IS A MARGINAL RISK OF EXCESSIVE RAINFALL ACROSS PORTIONS
OF THE SOUTHERN APPALACHIANS TO THE GULF COAST...

Update:

Expanded the Marginal Risk area southwest from the initial issuance
based on radar and satellite trends suggesting the risk of
excessive rainfall will persist beyond 12Z. Confined the expanded
Marginal risk along the axis of highest dew[point ahead of a cold
front moving eastward. Signals still suggest a downward trend
fairly early in the day. For additional details...refer to WPC
Mesoscale Precipitation Discussion 0013.

Bann

Previous Discussion...

Heavy rainfall should be on-goingacross portions of the Southern
Appalachians as the Day 1 period. Some of that rainfall will be
falling on at least partially saturated ground which has the
potential to produce flash flooding. The expectation is that the
threat for excessive rainfall should wane by 18Z today as the area
of rain moves out of the region.

Bann


Day 2
Valid 12Z Sun Jan 11 2026 - 12Z Mon Jan 12 2026

The probability of rainfall exceeding flash flood guidance is less
than 5 percent.

Bann


Day 3
Valid 12Z Mon Jan 12 2026 - 12Z Tue Jan 13 2026

The probability of rainfall exceeding flash flood guidance is less
than 5 percent.

Bann
$$
--- SBBSecho 3.28-Linux
* Origin: Capitol City Online (618:250/1)

FOUS30 KWBC 190746
QPFERD

Excessive Rainfall Discussion
NWS Weather Prediction Center College Park MD
246 AM EST Mon Jan 19 2026

Day 1
Valid 12Z Mon Jan 19 2026 - 12Z Tue Jan 20 2026

The probability of rainfall exceeding flash flood guidance is less
than 5 percent.

Campbell


Day 2
Valid 12Z Tue Jan 20 2026 - 12Z Wed Jan 21 2026

The probability of rainfall exceeding flash flood guidance is less
than 5 percent.

Campbell


Day 3
Valid 12Z Wed Jan 21 2026 - 12Z Thu Jan 22 2026

The probability of rainfall exceeding flash flood guidance is less
than 5 percent.

Gulf Coast... Guidance has hinted at possible QPF of 1-2 inches
for parts of the Southeast Texas and western Louisiana coastline
and points inland inland for this period; however the majority of
the deeper convection will likely remain offshore. There is a non
zero potential for very isolated areas of flash flooding.

Campbell
$$
--- SBBSecho 3.28-Linux
* Origin: Capitol City Online (618:250/1)

FOUS30 KWBC 220738
QPFERD

Excessive Rainfall Discussion
NWS Weather Prediction Center College Park MD
238 AM EST Thu Jan 22 2026

Day 1
Valid 12Z Thu Jan 22 2026 - 12Z Fri Jan 23 2026

The probability of rainfall exceeding flash flood guidance is less
than 5 percent.

A weak surface trough/frontal boundary may spark a few
thunderstorms across southeastern Florida between 15Z and 00Z
today. The airmass along and east of the coast should be plenty
moist and unstable, with weak kinematics below 500mb supporting
slow movement of any cells that may develop. Modest/marginal ascent
aloft and weak lapse rates should keep the overall threat of
heavier rainfall materializing over urban areas of the I-95
corridor fairly isolated. A non-zero threat of flash flooding
exists, but convective coverage and the brevity of the thunderstorm
risk precludes any addition of Marginal areas at this time.

Isolated showers across southern California may also impact
portions of the Transverse Ranges as well, with brief heavy rain
occurring near burn scars across the area. The threat for flash
flooding here is also less than 5% although an isolated instance of
excessive runoff cannot be completely ruled out.

Cook


Day 2
Valid 12Z Fri Jan 23 2026 - 12Z Sat Jan 24 2026

The probability of rainfall exceeding flash flood guidance is less
than 5 percent.

Cook


Day 3
Valid 12Z Sat Jan 24 2026 - 12Z Sun Jan 25 2026

The probability of rainfall exceeding flash flood guidance is less
than 5 percent.

Cook
$$
--- SBBSecho 3.28-Linux
* Origin: Capitol City Online (618:250/1)

FOUS30 KWBC 230810
QPFERD

Excessive Rainfall Discussion
NWS Weather Prediction Center College Park MD
310 AM EST Fri Jan 23 2026

Day 1
Valid 12Z Fri Jan 23 2026 - 12Z Sat Jan 24 2026

...THERE IS A MARGINAL RISK OF EXCESSIVE RAINFALL ACROSS THE TEXAS
HILL COUNTRY...

Maintained low-end/5% probabilities for a conditional flash flood
risk across the Hill Country today and tonight. 00Z models are
suggestive of convection anchoring along an Arctic front - perhaps
becoming slightly elevated while training/repeating across
localized areas. This scenario is conditional on the eventual
location of the Arctic front moving south across the region though,
with some lingering uncertainty present given the tendency for
strong fronts like these to outpace guidance and move farther south
than anticipated. Thus, flash flood potential is conditional as
well. High-res guidance hints at a complex that grows upscale while
migrating east toward the Austin/San Antonio areas late in the
forecast period.

Cook


Day 2
Valid 12Z Sat Jan 24 2026 - 12Z Sun Jan 25 2026

...THERE IS A MARGINAL RISK OF EXCESSIVE RAINFALL ACROSS THE UPPER
TEXAS GULF COAST AND VICINITY...

Maintained 5%/Marginal risk probabilities although with a southward shift/confined to areas near Victoria, Houston, and Lake Charles.
Any chance of deep convection will reside near these areas during
the forecast period and migrate west to east during the first half
of the forecast period (through 00Z Sun). Lingering uncertainty
remains regarding the eventual progress of an Arctic front that
should eventually reach (or even move south of) the I-10 corridor
during the forecast period. If that front moves south faster than
guidance suggests, any deep convective threats will potentially be minimized/shifted toward open Gulf waters. Upstream convective
evolution (storms over the Hill Country and Austin/San Antonio
areas during the Day 1 forecast period) also poses uncertainty
with the forecast. Should storms materialized as currently progged,
1-2 inch/hr rain rates could occur with surface-based or slightly
elevated convection given 1.25-1.75 inch PW values just south of
the front. These rates could pose excessive runoff issues should
they occur in sensitive and/or urban locales.

Cook


Day 3
Valid 12Z Sun Jan 25 2026 - 12Z Mon Jan 26 2026

...THERE IS A MARGINAL RISK OF EXCESSIVE RAINFALL ACROSS NORTHERN
AND CENTRAL ALABAMA...

Models are in pretty good agreement that a linear complex of deep
convection will traverse the area from west to east, with a variety
of solutions providing 1-3 inch rain amounts across the region.
Soil moistures are slightly more moist in portions of central and
northern Alabama compared to surrounding regions, and FFGs are
lower (especially near populated areas). Some concern exists
regarding fast storm motions (derived from point forecast
soundings) and questions about northward extent of moisture
return/60s F dewpoints and subsequent surface-based instability.
Enough of a signal exists across model guidance to introduce low
probabilities (5%) for flash flood potential in these areas, with
spatial refinements to the risk expected in subsequent outlooks.

Cook
$$
--- SBBSecho 3.28-Linux
* Origin: Capitol City Online (618:250/1)

FOUS30 KWBC 250712
QPFERD

Excessive Rainfall Discussion
NWS Weather Prediction Center College Park MD
212 AM EST Sun Jan 25 2026

Day 1
Valid 12Z Sun Jan 25 2026 - 12Z Mon Jan 26 2026

...THERE IS A MARGINAL RISK OF EXCESSIVE RAINFALL ACROSS PORTIONS
OF THE DEEP SOUTH AND ADJACENT SOUTHERN APPALACHIANS...

Latest guidance depicts a gradual uptick in convective coverage in
the first half of the forecast period from eastern Mississippi into western/central Alabama - forced by an approaching mid-level wave
over Texas and dramatic increase in confluent low-level flow across
the Deep South. Though convection will be relatively quickly
moving, cell mergers amid 1.4-1.6 inch PW values will support
areas of heavy rain, with a few locales exceeding 2 inches in 3
hours. FFG thresholds are in that general range (2 in./3 hr.)
across Mississippi through central Alabama, potentially resulting
in areas of excessive runoff. Peak timing of this risk will be in
the 12-21Z timeframe.

Over time, models spread convection eastward into portions of
central/southern Alabama and southwestern Georgia, with a greater
likelihood of surface-based convection. FFGs are substantially
higher across these areas with drier antecedent conditions and low
streamflows. Convective mode (derived by high-res guidance)
depicts a forward-propagating linear complex with rain rates
peaking at around 1-1.5 inch/3 hours on an isolated basis. Any
flash flood threat in this region should be relatively isolated in
nature with less than 5% coverage.

Cook


Day 2
Valid 12Z Mon Jan 26 2026 - 12Z Tue Jan 27 2026

The probability of rainfall exceeding flash flood guidance is less
than 5 percent.

Cook


Day 3
Valid 12Z Tue Jan 27 2026 - 12Z Wed Jan 28 2026

The probability of rainfall exceeding flash flood guidance is less
than 5 percent.

Cook
$$
--- SBBSecho 3.28-Linux
* Origin: Capitol City Online (618:250/1)

FOUS30 KWBC 270803
QPFERD

Excessive Rainfall Discussion
NWS Weather Prediction Center College Park MD
303 AM EST Tue Jan 27 2026

Day 1
Valid 12Z Tue Jan 27 2026 - 12Z Wed Jan 28 2026

The probability of rainfall exceeding flash flood guidance is less
than 5 percent.

Wegman


Day 2
Valid 12Z Wed Jan 28 2026 - 12Z Thu Jan 29 2026

The probability of rainfall exceeding flash flood guidance is less
than 5 percent.

A cold front associated with a low that will track into the Gulf of
Alaska will move into the coast of the Pacific Northwest on
Wednesday. By the time that front moves into the coast, however, it
will be well detached from its parent low in the Gulf of Alaska,
which will be shearing apart in the mountains. The flow out of the
subtropics ahead of the front will provide some additional moisture
to be wrung out in the mountains of the Olympic Peninsula, however,
moisture flux will only ever be modest at best, with IVT values
topping out around 500 kg/ms.

Model guidance suggests total rainfall into Western Washington has
decreased over the last 24 hours, with maximum rainfall amounts in
the Olympic Mountains around 3-4 inches, and lower amounts towards
the coast, around 1-2 inches. This modest rainfall (for this area)
when added to already dry soils and below average river flows,
should preclude any but very isolated flooding. In coordination
with SEW/Seattle, WA forecast office, the inherited Marginal Risk
was downgraded with this update.

Wegman


Day 3
Valid 12Z Thu Jan 29 2026 - 12Z Fri Jan 30 2026

The probability of rainfall exceeding flash flood guidance is less
than 5 percent.

The inherited Marginal Risk across Western Washington was
downgraded to no risk areas with this update. A second wave
traveling northeast along the same front that will bring rainfall
to western Washington from Day 2 will track in similar fashion
roughly parallel to the coast and into British Columbia. This will
leave western Washington with a weaker, shearing apart area of
lighter rain. Rainfall forecast amounts have decreased with this
update. Despite the rivers and streams becoming more elevated,
likely back to normal levels after Wednesday's rains, Thursday's
expected rainfall will be less, and remains unlikely to result in
flash flooding. With the downgrade of the Day 2 Marginal and in
coordination with SEW/Seattle, WA forecast office, the Day 3
Marginal was also downgraded with this update.

Wegman
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