Mesoscale Precipitation Discussion 0734
NWS Weather Prediction Center College Park MD
521 PM EDT Thu Jul 17 2025

Areas affected...Louisiana

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

Valid 172120Z - 180320Z

Summary...Flash flood threat continues to expand west through this
evening over central Louisiana from bands ahead of 93L.

Discussion...Banded convection on the leading/western side of 93L
continues to be intense with the main band crossing I-49 around
21Z. The orientation and repeating of these bands are tied to an
axis of deep-layer moisture convergence focused along the western
flank of the circulation, with very moist and unstable inflow
characterized by 2500-3000 J/kg SBCAPE and 2.5" PWATs.

This low-level convergence axis will continue to slowly pivot
ahead of 93L. The extremely moist and unstable environment should
favor continued development along this boundary with
backbuilding/repeating owing to NWly deep layer mean flow oriented
with the heaviest bands which are on the NW side of 93L. Recent
HRRR runs are a little slow with the activity, but are decent with
placement of the heaviest QPF. Further development on the east
side back toward Lake Pontchartrain is indicated by the HRRR and
likely given the instability axis there though the main heavy rain
threat should be west of New Orleans now.  Other vulnerable metro
areas like Baton Rouge and Lafayette are still under threat
through this evening. Scattered instances of flash flooding should
continue through this evening even if further development avoids
the heaviest rainfall areas from this afternoon (2-5") north of
Morgan City as indicated by recent CAMs. Downstream MPDs are
likely to be needed overnight.

Jackson

ATTN...WFO...JAN...LCH...LIX...SHV...

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

LAT...LON   31799232 31739146 31239096 30509030 30279049
            30029081 29799140 29879279 30449342 31369316