Mesoscale Precipitation Discussion 0094...Corrected
NWS Weather Prediction Center College Park MD
414 PM EDT Sat Mar 29 2025

Corrected for Typos in discussion

Areas affected...Southeast LA...Far Southwest MS

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

Valid 292005Z - 300005Z

Summary...Showers and thunderstorms are expanding and intensifying
over south-central LA. While a fair amount of uncertainty remains,
training cells with maximum hourly rainfall rates of 2-3"/hour
will support an increasing flash flood threat (possibly
significant) this afternoon.

Discussion...Radar and Day Cloud Phase imagery this afternoon
continues to depict expanding thunderstorm coverage along the
Central Gulf Coast. As this activity matures, radar estimates
hourly rainfall rates of 1.8-2.8"/hour are occurring within the
most intense cores.

This uptick in coverage and intensity is likely in response to 1)
increasing insolation across the region, 2) the approach of an
offshore MCV, and 3) a broad north-south oriented 850 hPa
convergence axis. Near the convection, mesoanalysis estimates of
1500 J/kg MLCAPE (in a saturated and "skinny" profile), PWAT of
1.6-1.7", and 20 kts of effective bulk shear suggest cells should
maintain enough organization to realize the moist and unstable
environment. Over the next several hours, expect areas downstream
to fill in where cumulus is showing increasing development, and
train as the slow moving forcing aligns with the mean flow.

With all of this said, there remains a fair amount of uncertainty
amongst the CAM suite with how the convection evolves through
tonight. However, through 0z, the 12z HREF suite depits increasing
probabilities of 6 hour QPF exceeding the 10 to 100 year ARI,
generally focused over Southeast LA (45% and 35%, respectively).
This suggests an increasing threat of flash flooding over the next
several hours, some of which could be significant -- particularly
over vulnerable urban areas.

Asherman

ATTN...WFO...LCH...LIX...MOB...

ATTN...RFC...LMRFC...NWC...

LAT...LON   31069021 30728892 29788903 29539047 29699186
            30059252 30619249 30989160