Subj : MESO: Nws Weather Prediction Center College Park Md
To   : wx-storm@lists.illinois.edu
From : COD Weather Processor
Date : Sun Jun 04 2023 05:21:23

AWUS01 KWNH 040521
FFGMPD
TXZ000-041000-

Mesoscale Precipitation Discussion 0421
NWS Weather Prediction Center College Park MD
120 AM EDT Sun Jun 04 2023

Areas affected...South-central to Southeast Texas...

Concerning...Heavy rainfall...Flash flooding possible

Valid 040520Z - 041000Z

SUMMARY...Colliding clusters/outflow boundaries will result in
broad scale ascent and descent with sub-hourly bursts up to 2",
posing multiple focused incidents of rapid inundation/flash
flooding overnight.

DISCUSSION...Regional RADAR mosaic and GOES-E satellite loops
denote numerous clusters and outflow boundaries starting to
collapse into collisions centered along I-10 and the near the
Coastal Plain where pockets of remaining capped instability still
remains.  Generally values of 1500 J/kg of MLCAPE exist with
impeding 25 J/kg of CINH across the area of concern.  Mature
convective complex outflow boundaries have been and are likely to
continue to be a sufficient catalyst to overcome the minor
inhibition.  Current trends suggest, a convergence near/north of
Houston metro and with over 1.5" total PWats, a broader slab
ascent will likely be limited in movement as the mid to
upper-level flow is weak at the far southeast extent of the NW to
SE trof.  As such, the fast ascent is more prone to a similar
quick downburst over broader areas with 1.5-2" totals likely to
fall in multiple focused areas in less than an hour.

While the area has been in drought per AHPS precip anomalies and
high FFG values, the shear magnitude in short-duration on
initially hard, hydrophobic dry ground may result in increased
run-off and much less absorption; compound that if over
urban/impermeable surfaces.  The broad areal coverage of the
collision may also overwhelm neighboring upper reaches of
watersheds as well, increasing risk of rapid inundation flooding.=20
  This scenario is more likely further east toward the Houston
Metro.  Further west, more direct collision and potential upstream
isentropic ascent from the south/south-southwest may allow for
longer updraft maintenance near/east of San Antonio but this is a
bit less certain and confidence in FF potential is a tad less, but
clearly not zero.

Gallina

....Please see https://urldefense.com/v3/__http://www.wpc.ncep.noaa.gov__;!!=
DZ3fjg!_Ukmm2kixFYp-zrwspZv7GPk9lXouHe1aKOevcT3ARGmVMN0g5X9s-wNZHTJKyB_r7Ed=
dpT-jU3hxkodVH7JS2OTVXE$  for graphic product...

ATTN...WFO...CRP...EWX...HGX...

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

LAT...LON   31039553 30829496 30289468 29559504 28689627=20
            28469720 28499785 28799831 29299880 29709859=20
            29469777 29559722 29899679 30529653 30879612=20
=20=20=20=20=20=20=20=20=20=20=20=20

=3D =3D =3D
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