Mesoscale Precipitation Discussion 0838
NWS Weather Prediction Center College Park MD
444 PM EDT Fri Sep 14 2018

Areas affected...Portions of the Lower & Middle TX Coast

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

Valid 142044Z - 150244Z

Summary...Rain totals/rates are beginning to increase south of
Matagorda Bay as cell coverage begins to increase.  Hourly rain
totals to 2" with local amounts to 4" are possible.

Discussion...Showers and thunderstorms are slowly increasing in
coverage north and northeast of a surface low just offshore Padre
Island near an associated inverted trough poised to move inland
into South TX.  Precipitable water values are near 2.5" per GPS
data.  ML CAPE values of 500-1500 J/kg exist here.  Inflow at 850
hPa is ~20 kts per VAD wind profiles.

The mesoscale guidance has a scattered signal for heavy rainfall
over the next several hours, though the activity has been a couple
hours delayed so far per the 12z HREF probabilities of 1"+ an
hour.  So far, there have been occasional short convective bands
which have dumped a quick 2" of rain.  Activity with heavy
rainfall is expected to shift southward through the area as the
stronger 850 hPa inflow shifts southward in the wake of the
disturbance's passage inland.  Hourly rain totals to 2" with local
amounts to 4" are possible in this region.  Over saturated soils
and urban areas this is a concern.

Roth

ATTN...WFO...BRO...CRP...HGX...

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

LAT...LON   28759643 28569591 28429614 27819694 27079725
            26229708 25859718 25799779 26179851 27369838
            28259793 28749721