Mesoscale Precipitation Discussion 0908
NWS Weather Prediction Center College Park MD
211 AM EDT Sun Sep 30 2018
Areas affected...TX Gulf Coast
Concerning...Heavy rainfall...Flash flooding possible
Valid 300610Z - 301210Z
Summary...Thunderstorms tracking inland along the mid/upper Texas
Gulf Coast this morning may become more widespread over the next
several hours. With a favorable environment for heavy rainfall in
place, flash flooding may be possible.
Discussion...HGX radar returns show convection developing just
offshore Galveston to the TX/LA border with a slow drift to the
west/northwest. Recent GOES16 cloud tops have cooled quickly and
the latest RAP mesoanalysis puts between 1000-1500 J/kg of MLCAPE
along the coast within a high PWAT zone (2.0-2.1" per GPS data).
Hi-res models are handling this activity poorly and are generally
too slow and displaced from reality. Though most of the guidance
does show some convection blossoming toward 09z or so but lacks
spatial consistency. It's uncertain how much will track inland,
but what does will be working with a highly efficient environment
for heavy rainfall. Main concern is for repeated rounds of storms
over urban sensitive areas but also in locations that picked up
heavy rainfall in the last 24 hours.
With several clusters of storms around, a quick burst of 1-2
inches with totals of 3-4 inches is possible.
Taylor
ATTN...WFO...HGX...LCH...
ATTN...RFC...WGRFC...
LAT...LON 30079430 29799390 29319424 28899511 28699574
28979591 29259590 29469576 29619559 29789540
29999501
Last Updated: 211 AM EDT Sun Sep 30 2018