Mesoscale Precipitation Discussion 0427
NWS Weather Prediction Center College Park MD
717 AM EDT Fri Jun 13 2025

Areas affected...southern Louisiana, far southeast Texas

Concerning...Heavy rainfall...Flash flooding likely

Valid 131116Z - 131716Z

Summary...A cluster of slow-moving storms have produced estimated
4-6 inch rainfall totals near Lafayette, Louisiana this morning. 
This cluster is expected to very slowly evolve within a very
unstable airmass, posing a risk for flash flooding through
17Z/noon CDT.

Discussion...Scattered thunderstorms have managed to evolve into a
persistent, slow-moving cluster near Lafayette this morning.  The
storms are embedded in deep south-southwesterly steering flow of
around 20-25 knots, but have managed to backbuild locally due to
1) confluent 850mb wind fields evident via objective analyses, 2)
a weak surface boundary extending from near Galveston, TX
east-northeastward through Lafayette to near Hammond, LA, and 3)
strong instability/weak inhibition along and south of that subtle
boundary.  Impressive moisture/instability content within the
pre-convective airmass (2000 J/kg MLCAPE, 2 inch PW values) were
contributing to impressive local rain rates exceeding 2.5
inches/hr at times.  With 4-6 inches of rain having already
fallen, some impacts are likely with the ongoing activity in the
short term.

Through 17Z/noon CDT, the reinforcement of a surface/outflow
boundary near the convection (due to cold pool formation) will
likely enable continued development and training of cells.  Some
propagation of this cluster is expected, and both westward and
eastward development of storms toward areas near Lake Charles and
near/south of Baton Rouge can be expected.  Another 3-5 inches of
rainfall can be expected beneath the heavier, slower-moving
thunderstorm bands as well.  Locally higher amounts cannot be
ruled out in a few spots.

Cook

ATTN...WFO...HGX...LCH...LIX...

ATTN...RFC...FWR...ORN...NWC...

LAT...LON   30509132 30289060 29989016 29599001 29229034
            29169115 29539237 29659388 29469442 29779450
            30179381 30479252