Excessive Rainfall Discussion
NWS Weather Prediction Center College Park MD
345 AM EDT Thu Oct 23 2025
Day 2
Valid 12Z Fri Oct 24 2025 - 12Z Sat Oct 25 2025

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

...Southern Plains...
At the start of the Day 2 period (24.12z), strong LLJ from
overnight will likely have one or more WAA convective clusters
ongoing with a higher based/elevated convection across the KS/OK
border moving toward the Ozark Plateau as left exit ascent region
of a broadening diffluent upper-level jet crosses Oklahoma prior to
the upstream mid-level cyclone exiting the Four Corners into the
southern High Plains on Friday morning. Surface cyclogenesis and
strength of moisture flux convergence within confluent return
moisture stream out of the Western Gulf across central OK will
likely help to maintain a favorable environment for further
upstream redevelopment across portions of central Oklahoma. The
mid-level low is also expected to strengthen slightly with heights
reaching 1-1.5 standard anomalies from bi- weekly means. Strong
DPVA and steepening lapse rates from advection of EML across OK
will allow for quick replenishment of unstable environment with
1000-2000 J/kg of MUCAPE along the upstream environment of the
older WAA induced convection for another bout of stronger
thunderstorms by afternoon/early evening from west-central OK south
into the Permian Basin and perhaps through the Pecos River Valley
with 1.25-1.75"/hr rates possible. Localized streak or two of 2-4"
totals with isolated total of 5"+ through late evening into early
overnight hours.

Toward midday, an upstream kicker shortwave and upper-level jet
speed max rounds the base of the closed low and ejects into the
southern High Plains providing strong mid-level ascent forcing and
strengthening low level winds and therefore, moisture/instability
flux. The stream of warm, moist Western Gulf air will continue to
compile across central TX into the Red River Valley with total
Pwats starting to exceed 1.75" nearing 2". Strong directional and
speed convergence will further expand/strengthen updrafts along
the cold front/dry line, but also quickly advance eastward allowing
for strong scattered thunderstorms with 2"+/hr rates across western
into central TX. Though stronger moisture flux convergence will
allow for higher rates, the faster cell motions will likely limit
overall totals. Yet, scattered incidents of 2-4" in short-duration
is likely to result in scattered incidents of flash flooding, given
limited infiltration even in drier soil conditions/higher FFG
environment.

00z guidance trends suggest a bit greater rainfall at the
beginning of the period toward northeast OK, a slightly higher
alignment of higher QPF maxima across central to northeast OK,
especially with the longer range CAM guidance. However, the general
consensus of QPF maxima also aligns nicely with the core of the
highest FFG values in the region, as well. Given the tendency of
the remaining Hi-Res CAMs to be biased toward the wetter solutions
and alignment with the FFG max, a higher confidence Slight Risk
remains in place, though if trends continue, an upgrade is not out
of the question. Further south, the run to run trends continue to
show a slow southward shift of QPF clusters supporting a small
adjustment of the Slight Risk in that direction as well.


...Pacific Northwest into Northwest California...
Only small localized adjustments were made to the old Day 3
Marginal Risk for the new Day 2 (24.12z-25.12z). The modest
Atmospheric River (AR) will push across the coastal and Cascade
ranges of WA/OR early through the period and relatively quickly the
cold front/AR plume will slide southward with respect to the
coastline into northwest CA by the end of the forecast period.
Strong broad closed low over the northeast Pacific will result in
strong height-falls nearly 2-2.5 standard anomalies from bi-weekly
mean, which is fairly impressive as it is a normal time of year for
the arrival of AR/deep lows. The low's influence provides the
strong draw of the moisture out of the central sub-tropical Pacific
with well over 1" total PWats into the coastal range and up to
.75-1" through the Columbia Valley into central WA; all while
values up to 1.5" remain offshore in the narrowing plume. Winds of
45-50kts through 850-700mb will result in peak IVT values of
700-750 kg/m/s. However, while strong, the duration is going to be
very limited given the strength of the height-falls and forward
propagation of the cold front. QPF signals remain at the 2-4"
range within the favored southwest facing orography with an
occasional rate up to .5" though fleeting; all in line with a broad
Marginal Risk of excessive rainfall.

Gallina

Day 2 threat area: www.wpc.ncep.noaa.gov/qpf/98epoints.txt