Excessive Rainfall Discussion
NWS Weather Prediction Center College Park MD
801 PM EST Tue Nov 18 2025

Day 1
Valid 01Z Wed Nov 19 2025 - 12Z Wed Nov 19 2025

...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL ACROSS WESTERN
ARIZONA, FAR SOUTHEASTERN CALIFORNIA, AND FAR SOUTHEASTERN
NEVADA...

...Southwest U.S...
A Slight risk was maintained for portions of western AZ and
immediate adjacent areas of southeast CA and southern NV. A general
decrease in instability is expected to result in a downward trend
in convective coverage overnight. However, the upper low will
remain to the west providing broad synoptic ascent and low level
moisture transport will also persist. A few pockets of instability
should linger as well...which should be enough to allow for
isolated linear convective segments to persist. This convection
will continue to locally train within the deep layer southerly 
flow, with a few instances of 1"/hr rainfall possible. So while 
the overall coverage and magnitude of the flash flood risk should 
be on the decline overnight, localized instances of flash flooding
will remain possible.

...Ohio Valley...
We will maintain a Marginal risk across KY into northern TN.
Scattered convection should continue ahead of a cold front posing 
a very localized flash flood risk. In general cells will either be
quick enough moving or not producing high enough rates to result 
in flash flooding. However some stronger cells, especially on the 
southwest flank of the risk area where instability is greater, 
could locally produce 1-2"/hr rainfall. Rainfall rates are lower 
on the northeast side of the risk area, but more antecedent rain 
and a bit more persistence of the rain here could still pose a very
isolated threat.

Chenard

Day 2
Valid 12Z Wed Nov 19 2025 - 12Z Thu Nov 20 2025

...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL OVER PORTIONS OF
SOUTH-CENTRAL TEXAS, THE CONCHO VALLEY, & THE TEXAS HILL COUNTRY...

The upper level trough moving across the Southwest US continues to
allow for sufficient coverage of scattered showers and embedded
thunderstorms into Wednesday across these areas for a Marginal Risk
threat level.  Localized flash flooding could continue to be a
concern.

Across the Southern Plains, low level-moisture will be drawn
northward with precipitable water values rising into the 1.5-1.75"
range, abnormally high for mid-November. When combined with
500-1500 J/kg of MUCAPE and 850 hPa inflow of ~25 kts, the
development of organized convection late Wednesday night into
early Thursday morning is becoming increasingly likely in and near
South-Central TX. Hourly rain amounts to 2.5" and local totals to
5" are anticipated early Thursday morning. This potential led to a
new Slight Risk which was coordinated with the EWX/New Braunfels
and SJT/San Angelo forecast offices. Its footprint was most in line
with the 06z REFS 30%+ chance of 3"+ amounts.

Roth


Day 3
Valid 12Z Thu Nov 20 2025 - 12Z Fri Nov 21 2025

...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL OVER PORTIONS OF
THE SOUTHERN PLAINS INTO ARKANSAS/MISSOURI...

...Southern Plains...
The flow aloft backs over portions of Texas and Oklahoma and
becomes increasingly diffluent Thursday morning as an upper trough
makes its way from the southern Great Basin into and across the
southern Rockies. This configuration aloft with increasingly moist
flow in the low levels ahead of a surface cold front will foster an
environment producing excessive rainfall by means of intense
rainfall rates by individual storms and by training of cells/repeat
convection. The axis of highest precipitable water values...
1.5-1.75"...sets up over the eastern half of Texas into
southeasternmost Oklahoma and Arkansas, which is well above
average for mid- November. Localized rainfall amounts up to 2.5" in
an hour with additional local totals of 5" possible within this
set up which would result in scattered instances of flash flooding.
Changes to the risk areas were mostly confined with some paring
back of the Slight across OK.


...California...
Maintained a Marginal Risk area from continuity for portions of
coastal Southern California as the next area of low pressure
produces another round of on-shore flow of moisture and associated
rainfall Thursday into early Friday. Rainfall amounts at this point
look to be pretty modest but will be falling on areas where
antecedent conditions have been wet for the better part of 5 days.
That may result in additional localized flooding on Thursday or
Thursday night.

Roth


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