ACUS01 KWNS 161247
SWODY1
SPC AC 161246

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0746 AM CDT Fri May 16 2025

Valid 161300Z - 171200Z

...THERE IS A MODERATE RISK OF SEVERE THUNDERSTORMS OVER PORTIONS OF EAST-CENTRAL AND SOUTHEAST MISSOURI...WESTERN AND CENTRAL
KENTUCKY...SOUTHERN ILLINOIS AND INDIANA...SOUTHWEST
OHIO...NORTHWEST TENNESSEE...AND NORTHEAST ARKANSAS...

...SUMMARY...
A regional outbreak of severe thunderstorms is likely this afternoon
into tonight across parts of the mid Mississippi, Ohio and Tennessee
Valleys. This will include intense supercells associated with
tornadoes, large hail and wind damage. Several strong tornadoes are
expected, and a long-track high-end tornado will be possible. From
the evening into the overnight, a bowing line segment is expected to
form with potential for tornadoes and damaging winds, some possibly
greater than 75 mph.

...Mid Mississippi and Ohio Valley/Tennessee Valley Region...
As an upper-level low near the MN/ND border shifts east today, a
mid-level jet streak will move from the Plains into the
mid-Mississippi Valley. A surface cold front will move east across
the Great Lakes, Midwest and OH/TN Valley region this afternoon and
tonight. An expansive warm/moist sector will destabilize during the
day, setting the stage for a regional severe weather outbreak this
afternoon and tonight.

Scattered severe thunderstorms, with a history of large hail, were
ongoing at 13z from northeast AR into eastern KY. Clusters of severe
storms, including supercells, will continue moving northeast within
this corridor through at least early afternoon. The eventual
longevity of these storms remains uncertain, however downstream
diurnal destabilization could allow storms with a severe hail/wind
threat to move into WV/western VA this afternoon.

In the wake of these morning storms, destabilization will occur as a
warm front lifts north, with strong instability (MLCAPE in excess of
2500 J/kg) developing from portions of eastern MO east into the
OH/TN Valley region, and south in advance of the front into eastern
TX. The presence of strong mid-level flow will contribute to
deep-layer shear averaging 50 kts or higher across a large area.

Vigorous redevelopment of severe storms is expected by early
afternoon across southern/eastern MO as height falls overspread the
area. More isolated development is expected southward along the cold
front towards 00Z. Initial storm development will strongly favor
supercell storm mode with all severe hazards possible, including the
potential for strong tornadoes across the Moderate/Enhanced Risk
areas where low-level shear will be strongest. Large to very large
hail will also be possible with mature supercells this afternoon
through early evening. As storms continue moving east across the
OH/TN Valley region, eventual upscale growth into multiple bowing
segments is expected. The tornado threat will continue, especially
with QLCS circulations, and significant severe gusts will also be possible.

...Ark-La-Tex/Lower Mississippi Valley...
Warm mid-level temperatures will tend to delay thunderstorm
initiation along the southward-trailing cold front into northeast TX
until later in the day, however at least isolated development is
expected towards 22z-00z. MLCAPE in excess of 3000 J/kg and 45-55
kts of deep-layer shear oriented favorably relative to the front
suggests a supercell mode with large to very large hail, along with
damaging gusts. Although weaker low-level shear will be present in
this area, some potential for a tornado will exist with any mature
supercell. With time, storms may increase in coverage and begin to
cluster in an environment favorable for a continued severe wind/hail threat.

...Portions of the Mid-Atlantic/northern DelMarVa Peninsula...
As the southern portion of the long-lived MCS over PA/NY continues
moving east/southeast today, the potential will exist for
re-development of organized storms, including supercells, over
portions of southeast PA/southern NJ and the northern DelMarVa
peninsula. With moderate west/northwest flow in place to the east of
the upper level ridge, RAP/HRRR forecast soundings depict sufficient
deep shear and moderate instability for a severe hail and wind risk.
Some consideration was given for higher severe probabilities in this
area, however uncertainty remains on the location of a corridor of
greater risk.

..Bunting/Marsh.. 05/16/2025

$$
--- SBBSecho 3.20-Linux
* Origin: capitolcityonline.net * Telnet/SSH:2022/HTTP (618:250/1)

ACUS01 KWNS 191253
SWODY1
SPC AC 191251

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0751 AM CDT Mon May 19 2025

Valid 191300Z - 201200Z

...THERE IS A MODERATE RISK OF SEVERE THUNDERSTORMS FAR NORTH
TEXAS...MUCH OF CENTRAL AND EASTERN OKLAHOMA...SOUTHEAST
KANSAS...AND THE OZARKS...

...SUMMARY...
Significant severe weather is likely from the central/southern
Plains into the the Ozarks today into tonight. All severe weather
hazards are expected, to include tornadoes (some potentially strong
to intense), very large hail, and severe winds.

... Synopsis ...

A large, amplified trough over the Rockies will shift slowly
eastward into the Plains today. Embedded within this longwave
trough, a complex evolution is expected. Downstream of the trough, a
negatively tilted shortwave trough will deepen and close off across
the northern Plains. Meanwhile, upstream, a closed low currently
over Idaho will dig southeastward, open up, and eject into the
central Plains.

As this evolution occurs, strong midlevel flow (in excess of 50
knots) will remain across much of the central and southern Plains
through the forecast period. By late in the afternoon, midlevel flow
will strengthen to perhaps 70 knots in response to the ejecting low
into the central Plains.

At the surface, the main synoptic low will be somewhat
diffuse/elongated over northwest Kansas into southwest Nebraska this
morning. Extending southward from this low, a dryline will stretch
through western Kansas into the Oklahoma and Texas Panhandles,
continuing into west Texas. A warm front will extend eastward near
the Kansas-Nebraska border before curving southeastward into
Missouri into the southern Appalachians.

The surface low is expected to gradually fill today as it slowly
moves east/northeast into south-central Nebraska, Despite this, rich
Gulf moisture will be maintained across the central and southern
Plains. Dewpoint temperatures at or above 70F will advect northward
from Texas through Oklahoma perhaps to as far north as northeast Kansas.

During the afternoon, strong diurnal heating along the dryline may
result in a sub-synoptic low developing across northwest Oklahoma.
This low will slowly progress east along the Oklahoma-Kansas border
during the afternoon, weakening with time.

... Southern and Central Plains into the Ozarks ...

A strongly sheared atmosphere will already be in place at the start
of the forecast period. As diurnal heating commences and 70F
dewpoints advect northward, the atmosphere across much of the
central and southern Plains will become strongly to extremely
unstable as well, with surface-based CAPE values between 3000-5000
J/kg across the region.

Multiple rounds of storms are expected across the region today. One
such initiating mechanism looks to be a subtle shortwave trough
embedded in the larger scale flow currently across eastern New
Mexico. This wave should initiate thunderstorms across eastern
Oklahoma northward into eastern Kansas by midday. It is unclear if
these storms will initially be elevated, but as they move east and
the atmosphere destabilizes further ahead of the line, a transition
to more surface-based convection should occur. At the same time, the
low-level jet is forecast to strengthen/reorganize across eastern Oklahoma/western Arkansas into western Missouri. This will yield
ample low-level curvature to the hodograph. Thus, given the strongly
sheared environment in place, supercells capable of producing all
severe hazards, including strong tornadoes, will be possible with
this first round of storms.

By mid-to-late afternoon, 30-60 meter mid-level height falls should
overspread the dryline as it mixes east into central Kansas
southward into western north Texas. Rapid thunderstorm development
is expected along the dryline given the forecast extreme
instability. These thunderstorms should develop west of the better
low-level jet/flow, where the low-level flow is expected to be a
little more veered than across eastern Kansas/Oklahoma. This veered
low-level flow still will result in a strongly sheered environment,
but with more straight hodographs and less low-level curvature. The
result should be another round of supercells, albeit with a tendency
to split. These supercells will be capable of producing very large
hail and tornadoes. The number of supercells across the dryline
combined with a propensity to split, may result in destructive
interference and result in a more episodic hail and tornado threat.

In addition to the hail and tornado threat, the number of expected thunderstorms in the presence of a very moist and unstable
atmosphere with steep lapse rates may result in strong downdraft
winds. The most likely region for this will be across portions of
northeast Oklahoma, northwest Arkansas, southeast Kansas, and
southwest Missouri. A 45% wind area was included in this outlook.

... Southern Illinois into Southern Appalachians ...

Along the northern periphery of shortwave ridging over the
Southeast, a midlevel jet streak will cross the southern
Appalachians during the afternoon. Here, an influx of steep midlevel
lapse rates atop rich boundary-layer moisture will yield strong
surface-based instability along/south of a warm front draped across
the region. Scattered thunderstorms will spread east-southeastward
along/south of the front from TN into the southern Appalachians,
where the favorable buoyancy and around 40-50 kt of effective shear
will promote organization into clusters and a couple splitting
supercell structures. Damaging winds and large hail will be possible
with the strongest storms.

Overnight, additional thunderstorms may develop across southern
Illinois and western Kentucky in association with warm-air advection
ahead of the main area of thunderstorms to the west. These
thunderstorms will also pose the potential for small hail and
isolated wind damage.

..Marsh/Smith.. 05/19/2025

$$
--- SBBSecho 3.20-Linux
* Origin: capitolcityonline.net * Telnet/SSH:2022/HTTP (618:250/1)