Mesoscale Precipitation Discussion 0328
NWS Weather Prediction Center College Park MD
838 PM EDT Wed May 28 2025

Areas affected...Southeast LA

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

Valid 290038Z - 290338Z

SUMMARY...Additional clusters of heavy showers and thunderstorms
will continue to impact southeast LA going through the evening
hours. Areas of urban flash flooding will continue to be possible
and especially around the New Orleans metropolitan area.

DISCUSSION...The early-evening GOES-E IR satellite imagery along
with dual-pol radar shows areas of heavy showers and thunderstorms
moving across southeast LA with some signs of addition
organization taking place within the last 30 to 45 minutes.
Cooling cloud tops are noted with new clusters of convection, and
this activity is generally moving off to the northeast in the
direction of New Orleans and adjacent suburbia.

All of this convection is connected to the persistence of a
long-lived MCS which is less organized than earlier in the day,
but continues to advance downstream while interacting with a very
moist and moderately unstable airmass pooled across the central
Gulf Coast region. The latest RAP analysis shows a well-defined
instability gradient aligned in a southwest to northeast fashion
across southeast LA, with MLCAPE values as high as 1500 to 2000
J/kg. PWs are quite high and on the order of 1.8 to 2 inches, and
this coupled with the instability will support rainfall rates of
as much as 1.5 to 2.5 inches/hour with the stronger convective
cores.

Given the convective trends, this activity is likely to again
impact areas around New Orleans, and some additional rainfall
amounts here may locally reach 3 to 4 inches given some localized
cell-training concerns before the activity advances off to the
east later this evening. Additional concerns for urban flash
flooding will exist over the next few hours as a result.

Orrison

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

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

LAT...LON   30349025 30338956 29848948 29408997 29229072
            29619122 30019098