Excessive Rainfall Discussion
NWS Weather Prediction Center College Park MD
346 AM EDT Sun Oct 4 2026
Day 2
Valid 12Z Mon Oct 05 2026 - 12Z Tue Oct 06 2026

...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL FOR THE LOWER TEXAS
COAST...

...Texas Coast...
Another day of heavy rainfall is likely across the Lower Texas
Coast and into parts of South Texas, likely increasing or
exacerbating flash flooding impacts anticipated during D1.

A surface front will track southward into the Gulf Sunday and
linger along the Lower Texas Coast Monday. While the accompanying
ribbon of instability may be quite compressed by Monday, PWs as
high as 2.5" and deep warm cloud depths will maintain a favorable
thermodynamic environment for heavy rainfall. Additionally, an axis
of 700-500mb deformation just offshore will arc back towards the
region, resulting in a narrow corridor of enhanced ascent to drive
streaks of convection with heavy rain. The HREF (when available)
and REFS both indicate a 20-30% chance of rainfall rates exceeding
2"/hr, which through training thanks to continued anti-parallel
Corfidi vectors may produce an additional 3-5" with locally higher
amounts (REFS 5"/24hr probabilities above 50%). For this reason a
SLGT risk has been added for a narrow corridor of the BRO CWA.

...Southeast...
A similar environment persists farther east along the Gulf Coast
from the Florida Panhandle and extending northeast into coastal
South Carolina. A cold front will be drifting slowly southeast
across this area as height falls south of an expansive mid-level
trough inexorably work their way south towards the Gulf Coast. Weak
impulses moving through the flow aloft will help generate waves of
low pressure along this front, and where these waves move northeast
they will enhance the rainfall through locally accelerated flow and
stronger ascent. Regardless, efficient rainfall rates of 2-3"/hr
are likely within a plume of exceptional tropical moisture (PWs
above 2.25") and deep warm cloud depths. Considered a SLGT risk
where the guidance supports areas of heavier rainfall, but there
continues to be some uncertainty as to how much instability will
persist north of the front (depending on how far south it
progresses), and anafrontal rainfall may not be heavy enough for a
SLGT risk upgrade. While training is likely along the CAPE
gradient which through these rain rates could lead to 2-4" of rain
atop saturated soils from D1, opted to maintain the MRGL risk at
this time due to this uncertainty. However, a SLGT risk upgrade may
be needed if signals continue to support another day of heavy rain
on Monday.

Weiss


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