676
AWUS01 KWNH 020157
FFGMPD
TXZ000-020800-

Mesoscale Precipitation Discussion 0206
NWS Weather Prediction Center College Park MD
956 PM EDT Wed May 01 2024

Areas affected...TX Hill Country into the Heart of TX

Concerning...Heavy rainfall...Flash flooding likely

Valid 020200Z - 020800Z

Summary...Scattered to numerous instances of flash flooding likely
with 3-5"+ additional localized totals through the early
overnight. A locally significant to extreme flooding event is also
possible, given the potential for greater than 5" and locally very
wet antecedent conditions.

Discussion...Multiple clusters of convection have organized across
portions of central and eastern TX (from the Hill Country to the
Heart of Texas), resulting in impressive 2-5" localized totals
over the past 3 hours. The mesoscale environment will continue to
support convective development and organization into the overnight
hours, as the air mass is characterized by high instability (SB
CAPE 1500-3000 J/kg) and abundant, anomalously high, moisture
(PWATs 1.7-2.1 inches, between the 90th percentile and max moving
average per SPC sounding climatology).

While the 12z/18z CAMs have really struggled to properly develop
convection through the time of writing, the HRRR has managed to
`catch up` more with reality in depicting convection in the proper
places. This is a bit concerning, however, considering that some
of the latest runs of the HRRR (through 00z) depict additional
5-8" localized totals through 07z. And even though the 18z HREF is
off with the placement of convection relative to reality, there is
still a concerning signal for 5" exceedance (20-30%) across
southern portions of the MPD. This also corresponds to similar
probabilities (20-30%) for the 10 year ARI QPF exceedance, and a
bit higher probabilities (20-40%) for 6-hr FFG exceedance.

Given the concerning meteorological environment and indications
for locally significant rainfall rainfall, scattered to numerous
instances of flash flooding are considered to be likely. A locally
significant to extreme flooding event is also possible, given both
the elevated probability for localized totals greater than 5" and
very wet antecedent conditions across some eastern portions of the
MPD (per NASA SPoRT-LIS 0-100 cm soil moisture percentiles of 90%
or greater, and MRMS imagery indicating locally 6"+ over the prior
48 hours in the vicinity of College Station).

Churchill

...Please see www.wpc.ncep.noaa.gov for graphic product...

ATTN...WFO...EWX...FWD...HGX...SHV...SJT...

ATTN...RFC...WGRFC...NWC...

LAT...LON   32029661 31939557 31399478 30749509 30249557
            29579655 29359802 29459944 30300057 31170028
            31379902 31669776