Subj : MESO: Heavy rain - floodi
To   : All
From : Mike Powell
Date : Tue May 30 2023 16:39:00

AWUS01 KWNH 302016
FFGMPD
TXZ000-OKZ000-310215-

Mesoscale Precipitation Discussion 0387
NWS Weather Prediction Center College Park MD
415 PM EDT Tue May 30 2023

Areas affected...much of north through southeast Texas

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

Valid 302015Z - 310215Z

Summary...Isolated to scattered thunderstorms should gradually
increase in coverage through the evening hours.  Areas of 1-2.5
inch/hr rain rates could lead to runoff/flash flooding, although
the risk should remain fairly isolated.

Discussion...recent radar/satellite mosaic imagery indicates
deepening convection across a broad part of Texas from just north
of Dallas southward through Waco, with other scattered activity
near a seabreeze across the middle Texas Coast and across
southeast Texas near the Toledo Bend Reservois.  These storms were
moving slowly, with 1-2 inch/hr rates being indicated by MRMS in
the most persistent cores.  Slightly higher values (closer to 2.5
inch/hr) were noted in a cluster just north of Dallas.  The
forcing mechanism for these storms was subtle, but generally
aligned with weak surface convergence along the I-45 corridor,
with easterly winds veering to southeasterly along that axis. 
Additionally, a weak mid-level wave noted over the region via
objective analyses was also supporting updrafts.  1.6 inch PW
values and 1500 J/kg MLCAPE will continue to support deep
convection and efficient rain rates for the next several hours.

Models/CAMs and observations suggest that this activity will be
driven mainly be diurnal forcing, with a gradual weakening of
storms expected after sunset.  Through 02Z, increasing coverage of
convection should allow for a gradual increase in flash flood
potential, although ground conditions are likely not supportive
except for on an isolated basis near urbanized and/or sensitive
areas.  FFG thresholds range from near 1.5 inch/hr across
north-central Texas to over 4 inches/hr across broad portions of
Texas east of I-35 - further supporting the idea of only very
isolated flash flood potential through the early evening.

Cook

ATTN...WFO...CRP...EWX...FWD...HGX...LCH...OUN...SHV...SJT...

ATTN...RFC...ABRFC...LMRFC...WGRFC...NWC...

LAT...LON   33889661 32709497 32059407 31299374 30469391 
            29749509 28549725 28289782 29249841 31129848 
            33719766 

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