Excessive Rainfall Discussion
NWS Weather Prediction Center College Park MD
750 PM EDT Thu May 2 2024
Day 1
Valid 01Z Fri May 03 2024 - 12Z Fri May 03 2024

...THERE IS A MODERATE RISK OF EXCESSIVE RAINFALL FOR PORTIONS OF
SOUTHEAST TEXAS & FAR SOUTHWEST LOUISIANA...

...Texas and Louisiana...
The outflow boundary from earlier convection is shifting back
northeast towards Houston, with MU/ML CAPE trends up a bit as the
instability hole caused by the earlier complex recedes northward.
Further northward return as this boundary is possible overnight as
it remains convectively inactive. A couple convective clusters
forming along the dry line across northwest TX are moving east
early this evening and the convection with the higher risk of
heavier rainfall is expected to drop east- southeast as right
movers along the 1000-500 hPa thickness gradient and instability
gradient into southeast TX/southwest LA, with rainfall
rates/totals increasing as it gets into the area around sunrise
just as MU CAPE rises back into the 2000-3000 J/kg range.
Precipitable water values should rise back into the 1.5-1.75"
range. Effective bulk shear of 40-60 kts lies across the area,
which is more than sufficient to allow for convective organization,
including the mesocyclones which have already developed.
Considering rainfall totals and very low flash flood guidance
values in the previous complex's wake, the Moderate Risk area was
maintained in or near Southeast TX. A Slight Risk surrounds this
area, covering both where heavy rain has fallen as of late and
where heavy rain from the expected complex is expected to fall.
Hourly rain totals to 2.5" with additional amounts to 5" are
anticipated over saturated soils/filling rivers and bayous.


...Mississippi Valley/Midwest...
Radar trends and mesoscale guidance shows clusters of showers and
thunderstorms in and near portions of OK this evening into tonight
with less organized, in some cases dying, activity most elsewhere
within the broader Marginal Risk area. A general 1.5-3" of rain,
with locally higher amounts possible, which would fall within
several hours, hence the continuation of the Slight Risk in that
area. The northeast portion of the Slight Risk was removed as the
risk has lowered across much of MO. Flash flood guidance values are
currently running between that 1-2"/hr marker for exceedance, and
soils have some degree of saturation, so it's within the zone of
opportunity to cause some flash flooding potential within the rates
alone.

Roth