FOUS30 KWBC 241957
QPFERD

Excessive Rainfall Discussion
NWS Weather Prediction Center College Park MD
257 PM EST Sat Jan 24 2026

Day 1
Valid 16Z Sat Jan 24 2026 - 12Z Sun Jan 25 2026

...THERE IS A MARGINAL RISK OF EXCESSIVE RAINFALL OVER
CENTRAL/SOUTHERN LOUISIANA INTO SOUTHERN MISSISSIPPI...

An Arctic front, analyzed 50-100 miles south of the LA coast at
15Z is expected to slowly lift north today/tonight over
southeastern LA and southern MS with a weak surface wave or two
developing along the front. This will occur ahead of an eastward
advancing southern stream shortwave trough over the Baja Peninsula,
with anomalous moisture out ahead advecting northward from the
Gulf. Earlier this morning (13-14Z), observed hourly rainfall rates
along the upper Texas Coast were in the 2 to 3 inch range with 1
inch in 15 minutes reported in Brazoria County. This same moisture
plume will be advancing downstream across the central Gulf Coast
with precipitable water values increasing into the 1.5 to 1.9 inch range.

Relatively steep 700-500 mb lapse rates of 6.5 to 7.5 C/km will
support elevated instability above a low-level inversion located
between 850 mb and just above the surface to support MUCAPE up to
~1000 J/kg from LA into south-central MS with parcels more surface
based as one moves closer to the Gulf Coast. While CAPE will be
marginal, sufficient shear will exist for quasi-organized cells
with motions similar to the orientation of low level convergence
axes, allowing for training potential. Hourly rainfall of 1 to 2+
inches and 24 hour storm totals of 3 to 5 inches will be possible.
A lower end Marginal Risk was introduced in coordination with the
affected WFOs, with impacts likely remaining focused within any
urban overlap of heavy rain.

Otto


Day 2
Valid 12Z Sun Jan 25 2026 - 12Z Mon Jan 26 2026

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

Showers and thunderstorms are likely to be ongoing at the start of
the period (12Z Sunday) across the Lower MS Valley into central
MS the northern half of GA. Instability across the D2 area of
concern (central MS into the southern Appalachians) is expected to
remain weak and likely reduce from its peak of ~500 J/kg from the
early morning to the late afternoon. Areas of SW to NE training
near a frontal boundary beneath modestly diffluent flow aloft with
hourly rainfall totals of 1 to 2 inches will be possible. By
around 18Z, eastward translation of an upstream shortwave should
coincide with the axis of heavier precipitation moving toward the
east at a steady pace with only brief training possible along and
ahead of the main precipitation axis. As heavier precipitation
reaches the southern Appalachians, hourly rainfall is likely to
peak in the 0.5 to 1.0 inch range but freezing rain for portions
of the area will limit runoff potential. Locally sensitive ground conditions/urban areas will be at greatest risk of runoff concerns,
though the overall threat appears to be fairly isolated in nature.
24 total rainfall totals for the region are expected to range from
1 to 3 inches (perhaps locally in excess of 3 inches) through 12Z Monday.

Otto


Day 3
Valid 12Z Mon Jan 26 2026 - 12Z Tue Jan 27 2026

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

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