Excessive Rainfall Discussion
NWS Weather Prediction Center College Park MD
503 AM EDT Mon Jun 15 2026
Day 2
Valid 12Z Tue Jun 16 2026 - 12Z Wed Jun 17 2026

...THERE ARE MODERATE RISKS OF EXCESSIVE RAINFALL FOR THE ENTIRE
TEXAS GULF COAST AS WELL AS FOR WEST-CENTRAL MISSISSIPPI...

...Texas Gulf Coast...

A plume of incredibly deep tropical moisture over the entire Texas
Gulf Coast will be in place at the start of the period Tuesday
morning. Ongoing lee cyclogenesis in advance of a strong upper
level disturbance will support continuous numerous showers and
thunderstorms in the onshore flow up the western coast of the Gulf
and into the Texas Gulf Coast. This disturbance will further
increase the amount of moisture available for the storms, as PWATs
rise to record territory in some areas, possibly exceeding 2.75
inches. Any and all storms that continue to develop ahead of the
low will be capable of multiple inch/hour rainfall rates, despite
the reduced instability in the early morning. When added to
Monday's rains, flash flooding is likely to continue all along the
Texas Gulf Coast until the low itself, which will track
northeastward roughly parallel to the coast passes a given
longitude, switching the wind direction from onshore southward to
offshore northwestward. Since the low will be barely moving, a
steady onshore flow across the middle and upper Texas Gulf Coasts
will continue to favor training storms impacting coastal areas,
with the Houston Metro remaining particularly vulnerable. Meanwhile
for the lower Texas coast, once the low moves offshore, the
northwesterly flow will dramatically decrease storm coverage and
intensity, though not completely shut it off due to the deep
moisture still in place even behind the low, with the front lagging
behind along the Rio Grande.

There is considerable uncertainty as to the northern and western
extent of the rainfall threat on Tuesday. The cold front bringing
much drier air will continue its progress south and east across
South Texas, so the threat will end from west to east during the
day. Meanwhile extensive cloud cover should limit instability well
away from the coast. Thus, the storms will have a progressively
narrowing portion of the Texas Gulf Coast that they will be able to
impact. Regardless, heavy rain will continue to impact the Lower
Texas Coast from the D1 period into Tuesday morning, and the heavy
rains will continue further up the coast throughout the period.
This supports a continuation of the Moderate Risk into the
southwest corner of Louisiana.

...West Central Mississippi...

Heavy rains across western Mississippi are likely to redevelop in
the same area along the I-20 corridor during peak heating Tuesday
afternoon, and perhaps in some areas never completely stop Tuesday
morning from any overnight rainfall. The front driving the heaviest
rainfall with the strongest storms will be completely stationary
over Mississippi, whereas in Louisiana and points west, it will
continue painfully slow south and eastward progress. Thus, when
storms refire Tuesday afternoon, they will be over many of the same
hard hit areas of central Mississippi as on Monday. Further east,
on Monday the storms will align east-southeastward from western
Mississippi to northern Florida. By Tuesday however, northward
progress of the front as a warm front will allow the heaviest
rains to impact further north into Alabama and Georgia. Despite a
lack of rain on Monday, the still wet soils across central Alabama
towards Birmingham and Montgomery may require an eastward
extension of the Moderate Risk area into central Alabama.
Regardless it appears western Mississippi will still be the area
that gets the most rain, especially over the combined 2 day period.
Rains in west central Mississippi should diminish with loss of
daytime heating Tuesday night with lingering storms pressing
southeastward toward southern Alabama and the Florida Panhandle
Tuesday night.

Wegman


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