Mesoscale Precipitation Discussion 0983
NWS Weather Prediction Center College Park MD
1246 AM EDT Tue Oct 16 2018

Areas affected...Southeast Texas

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

Valid 160445Z - 160815Z

Summary...Numerous showers and thunderstorms this evening should
persist into the overnight hours as low level moisture continues
to be drawn over a shallow dome of cold air which will continue to
lead to increasingly saturated soil conditions.  This, in turn,
may lead to additional flash flooding into the overnight hours.

Discussion...The latest radar imagery showed an expansive area of
showers and embedded thunderstorms across the broader area of
southeast TX. Moist deep layer southwest flow overrunning a
surface cold front continues to generate plenty of large scale
isentropic ascent for the convection which is being aided by a
nose of elevated instability and also proximity of favorable
right-entrance region jet dynamics. MUCAPE values over southeast
TX were still in the range of 500 to 1000 j/kg with and the PWATS
have reached 1.75 inches which has been helping to produce heavy
rainfall amounts of as much as 1.5 inches/hr within some of the
stronger convective cores.

The large scale dynamics aloft over the region are courtesy of an
upper trough amplifying into the Southwest U.S. and this should
maintain favorable right-entrance region jet forcing overhead
going through at least 08Z.  The HRRR suggests rainfall rates will
be tapering off here about then while the RAP suggested that the
low level flow will continue to provide a source of moisture and
instability into the early morning hours.

Expect as much as 3 to 4 inches of additional rain going into the
early morning hours where stronger convective cells tend to
concentrate and repeat over the same area. Given the moistening
and saturation of the soil, some increased potential for flash
flooding will continue into the overnight.

Bann

ATTN...WFO...FWD...HGX...SHV...

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

LAT...LON   32629446 32499378 31769366 30699509 29779572
            30029624 31229570