Excessive Rainfall Discussion
NWS Weather Prediction Center College Park MD
402 AM EDT Wed Apr 29 2026
Day 3
Valid 12Z Fri May 01 2026 - 12Z Sat May 02 2026

...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL IN CENTRAL AND
SOUTHEAST TEXAS AND THE CENTRAL GULF COAST...

Organized heavy rain bands may be ongoing at the start of the
forecast period (Friday morning) across Central Texas, described in
the Day 2 portion of this discussion. The Slight Risk area was
pulled back to the west to account for the possibility of ongoing
impacts; the rainfall may be split between the two forecast
periods, so the QPF for 12Z Friday to 12Z Saturday, viewed in
isolation, would tend to undersell the flash flood risk on Friday
morning in central Texas.

That was the main adjustment made to the outlook at this time. We
continue to see a strong signal for heavy rainfall from Texas into
the central Gulf Coast region. The rainfall forecast has increased
a bit with the major axis shifting south about 80 miles over the
past four forecast cycles. Models show a very strong low-level
convergence signal with a strong frontogenetic circulation shifting
east along the Gulf Coast during the period. This will be situated
in an environment with anomalously high PWs (above the 90th
percentile for late April; generally 1.5 to 1.8 inches) and narrow
CAPE profiles. The strong convergence should help focus efficient
convective rain bands and could lead to training of heavy rain
rates for multiple hours.

We will continue to monitor guidance trends for possible increases
in probabilities (and risk levels) if confidence grows in the
placement of the heaviest rainfall. Training rain bands in that
environment could easily lead to several inches of rain in just a
few hours. While much of the Slight Risk area is experiencing
drought conditions, that can be overcome for flash flooding impacts
if heavy rain rates are prolonged enough in a given location.
Therefore, the key to any increases in ERO probabilities would be
much greater confidence in placement of training rain bands. For
now, the Slight Risk highlights the general area where this is
possible, given available guidance and the overall parameter space.

Lamers

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