Graphic for MPD #0105

Mesoscale Precipitation Discussion 0105
NWS Weather Prediction Center College Park MD
1057 AM EDT Sat Mar 16 2024

Areas affected...a small portion of south Texas

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

Valid 161456Z - 161730Z

Summary...A cluster of mostly nearly surface-based convection
located just south of San Antonio is producing a quick 1-2 inch
rainfall totals amid localized training/repeating.  This cluster
could persist eastward toward areas that received heavier rain
totals (near/west of Houston) over the next few hours, posing an
isolated flash flood risk.

Discussion...A cluster of cells just south of San Antonio has
gained modest organization over the past hour or so, and is
establishing a cold pool and associated gust front over Karnes
County.  The orientation of the cold pool was generally
perpendicular to 20-30 knot southerly flow at 850mb, and surface
temps/point forecast soundings suggest that this activity could be
only slightly elevated while benefiting from appreciable (7-7.5
C/km) mid-level lapse rates.

The longevity of this activity is a bit unclear, although
satellite/radar presentation suggest potential eastward
persistence of the complex along with some degree of upstream
backbuilding.  This would result in a few areas of 1-2 inch/hr
rain rates continuing for at least a couple of hours, posing an
isolated flash flood risk especially in sensitive or urban areas.
The rates generally fall below FFG thresholds in most of the area,
further suggesting only an isolated threat in the near-term. 
Farther east (closer to the Houston Metro area), heavy rainfall
from last night's convection (exceeding 3-4 inches) has resulted
in reduced FFGs and wet soils, so a slightly higher flash flood
risk could exist in this area.  A few spots of urban runoff could
also occur if the upstream flank of the cluster happens to drift
into the San Antonio area through 17Z or so.

Cook

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

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

LAT...LON   30369633 30109541 29699494 29029518 28439647
            28359808 28869967 29449970 30019899 30269791
           
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Last Updated: 1057 AM EDT Sat Mar 16 2024