FOUS30 KWBC 231559
QPFERD

Excessive Rainfall Discussion
NWS Weather Prediction Center College Park MD
1059 AM EST Fri Jan 23 2026

Day 1
Valid 16Z Fri Jan 23 2026 - 12Z Sat Jan 24 2026

...THERE IS A MARGINAL RISK OF EXCESSIVE RAINFALL IN AND NEAR THE
TEXAS HILL COUNTRY & IN SOUTH FLORIDA...

South-Central TX/TX Hill Country...
Maintained low-end/5% probabilities for a conditional flash flood
risk across the Hill Country today and tonight. Overrunning showers
have developed north of a front across South-Central TX.  The 12Z
HREF/06z REFS guidance indicates that some convective development
is possible this afternoon, but a bulk of the activity is expected
overnight. The atmosphere becomes increasingly saturated during the
day today, and a pool of 500-1000 J/kg of MU CAPE broadens across
South TX. During the afternoon and evening, the 850 hPa inflow
backs and increases, which led to convective development closer to
the Rio Grande within the HREF ensemble suite. Enough effective
bulk shear is available for convective organization.  Adjustments
to the area used the 06z REFS/12z HREF 3"+ probability footprint.
We still have discordance between the two, with the REFS showing a
much higher chance of 3"+ than the HREF. Activity would be elevated
and has some chance of repeating/training before moving along.
Parts of this area have minimal topsoil, which would allow heavy
rainfall to more readily run off.


...South FL...
Activity moving south-southwest off the Gulf Stream just offshore
Palm Beach County along with attempts at a weak convective band
towards Key Biscayne have led to a new Marginal Risk area. Even
though 850 hPa inflow is weak, the flow enough is strong enough to
lead to ~35 kts of effective bulk shear in an environment with
500-1000 J/kg of ML CAPE and PWs of 1.5". Yesterday, radar
estimates from Key Biscayne were in the 6" range. As a precaution,
will raise a Marginal Risk for populated areas of South FL. Hourly
rain amounts up to 2" with local totals to 4" are possible. Any
heavy rain-related issues in urban areas would be isolated to
widely scattered.


Roth


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

Day 1 threat area: https://www.wpc.ncep.noaa.gov/qpf/94epoints.txt
Day 2 threat area: https://www.wpc.ncep.noaa.gov/qpf/98epoints.txt
Day 3 threat area: https://www.wpc.ncep.noaa.gov/qpf/99epoints.txt