Excessive Rainfall Discussion
NWS Weather Prediction Center College Park MD
725 PM EST Thu Nov 5 2026
Day 3
Valid 12Z Sat Nov 07 2026 - 12Z Sun Nov 08 2026

...THERE IS A MARGINAL RISK OF EXCESSIVE RAINFALL ACROSS SOUTH-CENTRAL
AND SOUTH TEXAS...

...2030 UTC Update...

Only minimal adjustments were needed for the Marginal Risk across
south-central/south Texas based on the latest guidance. This
included a northwestward extension into portions of the southern
Hill Country where there remains a concerning signal from the GFS
for heavier rainfall across the more sensitive terrain. As noted
below, a Slight Risk may eventually be needed with more confidence
in the location of the heaviest rainfall, particularly if it were
to focus on portions of the Hill Country or where there would
expectedly be more convergence/forcing along the coast. However,
there remains too much spread in the guidance to have enough
confidence in a risk area for now.

Putnam

...Previous Discussion...

Model guidance is beginning to converge on a synoptic evolution
that would favor areas of heavy rain over southern TX this weekend.
A mid-upper low is forecast to dive southeast out of AZ and into
northern MX late Friday/Fri night, then gradually progress
eastward towards West TX by Sunday. This feature will provide ample
ascent for rainfall, with a strong upper level jet providing
additional lift. Anomalous moisture will advect northward ahead of
this system, and while PWs will likely not be as high as recent
events, it is still forecast to exceed the climatological 90th
percentile. In the low levels we should have east to northeasterly
flow, which will aid in isentropic ascent over the region, but
should also act as a stabilizing factor. Thus the degree of
instability, which will impact rainfall rates and the flash flood
potential, remains a question.

In terms of the latest guidance, the ECMWF AIFS continues to be the
most persistent model showing the heavy rainfall threat, and is
gaining more support from the operational ECMWF, GFS, and CMC.
If/where sufficient destabilization is able to occur to drive
higher rainfall rates, a future Slight risk upgrade may be
necessary. Best chances for this at the moment appear to be along
the south TX coast where instability advecting in off the water and
coastal convergence could focus higher rainfall magnitudes.

B Hurley/Chenard

Day 3 threat area: www.wpc.ncep.noaa.gov/qpf/99epoints.txt