Excessive Rainfall Discussion
NWS Weather Prediction Center College Park MD
428 PM EDT Fri May 3 2024
Day 3
Valid 12Z Sun May 05 2024 - 12Z Mon May 06 2024

...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL FROM SOUTHERN
MISSOURI TO NEAR THE UPPER TEXAS COAST...

...2030Z Update...

As the guidance has shifted southward on Saturday, the same has
occurred on Sunday. Storms will likely be ongoing in portions of
east Texas at the start of the period Sunday morning, and will
continue pushing east into the morning. It appears likely that
there will be an east-west-oriented boundary along which storms
will be training on the south end of a more progressive line of
storms. There is inherent and typical uncertainty with where that
line will set up, especially with recent large southward shifts in
the guidance. Thus, to cover the large changes in the guidance, as
well as very recent and ongoing heavy rain across southeast Texas,
the Slight was expanded well south of inherited, and likely will be
upped at least to a higher-end Slight in Texas if the current
shifts in the guidance hold, with a distinct possibility for a
Moderate upgrade with hopefully agreeable CAMs guidance.

For the Ozarks region, significant uncertainty also exists, as the
area will be on the northern side of the strong shortwave trough
driving all of the convective activity. Much like much of the lower
Mississippi and points west, the area also has average to above
average soil moisture, which in turn will support the development
of flash flooding given enough rainfall. The northern side of the
storm complexes often get cut off from the Gulf moisture supporting
them in favor of storms further south and closer to the Gulf. This
increases the uncertainty in the forecast for this area. For now,
guidance spread has led to an expansion of the Slight into
south-central Missouri and north-central Arkansas...as well as the
surrounding Marginal as far east as Alabama. These are likely to
change due to the highly variable forecasts of convection for this
area.

Wegman

...Previous Discussion...

The potential for excessive rainfall makes its way eastward on
Sunday in association with a closed low aloft and a cold front at
the surface. Model QPF was not as heavy as forecast on Day 2 as
shifting low level flow results in weaker low level moisture flux
convergence along the front. Despite model QPF generally being 2
inches or less...opted for a Slight Risk given the wet antecedent
conditions over portions of eastern Texas and eastern Oklahoma.

Bann