Excessive Rainfall Discussion
NWS Weather Prediction Center College Park MD
1152 AM EDT Fri May 10 2024
Day 3
Valid 12Z Sun May 12 2024 - 12Z Mon May 13 2024

...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL ACROSS PARTS OF
CENTRAL AND EASTERN TEXAS INTO MUCH OF LOUISIANA AND SOUTHWEST
MISSISSIPPI...

...Summary...
Mid-upper level trough traversing the Central-Southern Plains
north of the Red River will lead to a surge of deepening
instability and moisture from the western Gulf of Mexico as a warm
front pushes into eastern TX and southwest LA. Favorable dynamic
and thermodynamic profiles will result in widespread convection
across central-eastern portions of TX into parts of the Lower MS
Valley, where a high-end Slight Risk of excessive rainfall is
anticipated Sunday and Sunday night.

...Central-Southern Plains and Portions of the Lower Mississippi
Valley to the Mid-Upper TX and western LA Gulf Coast...
For now at least, just a modest kinematic response is noted from
the guidance during day 3 ahead of the the approaching shortwave.
850 mb wind anomalies for instance are currently modeled to be
around 1-1.5 standard deviations above normal (while at the same
time 850-700 mb moisture flux anomalies top out between +2-2.5).
The absence of a a more robust subtropical jet streak is the likely
culprit; however, the presence of the 90-100 kt upper jet streak
traversing the Southern Plains and TN Valley will be felt by way of
subtle right-entrance region forcing (focused area of upper
divergence/deep-layer ascent and low-level frontogenesis). This
will enhance the fgen along the leading edge of the surface warm
front, while also retarding it's east-northeastward motion. Largely
elevated, convection will become more widespread downwind of the
warm front in a favorable deep- layer warm/moist advection pattern
off the western Gulf of Mexico. The lingering low-level
frontogenesis/slow progression of the surface front will allow for
some cell training, especially across parts of central-eastern TX
which had received quite a bit of rain over the past week. Over
this region eastward through central LA and southwest MS, feel the
ERO risk will be more of a "high end" Slight (i.e. at least 25%
risk of rainfall exceeding FFG within 25mi of a point). 00Z models
show pockets of 3-5+ inches of rain during day 3 within this area,
with the past 2 ECMWF and UKMET runs consistently wetter than the
other models.

Hurley