Mesoscale Precipitation Discussion 0167
NWS Weather Prediction Center College Park MD
514 AM EDT Thu Apr 24 2025

Areas affected...south-central LA

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

Valid 240912Z - 241400Z

Summary...Slow moving showers and thunderstorms will pose an
isolated flash flood threat to portions of south-central LA over
the next 3-5 hours. Slow cell movement with potential for 2 to 3+
in/hr rates will exist.

Discussion...Local radar imagery from KPOE and neighboring sites
showed a relatively small and largely warm-topped cluster of
showers and thunderstorms over south-central LA at 09Z. Rainfall
over the past few hours over LA has produced an outflow boundary
which extended 20-30 miles south of and roughly parallel to I-10
from near Lake Charles to near Abbeville. Modest low level flow
atop this boundary and low level speed convergence (seen via VAD
wind plots at 925 mb and 850 mb) appeared to be contributing
factors in the location of the cluster of heavy rain, factors not
being modeled well by recent RAP runs. Enhanced divergence within
the left-exit region of an upper level jet max over south-central
TX into the western Gulf was also possibly aiding with lift across
the region.

While this cluster has been in place for several hours in some
form, there are growing concerns for slowing of cell movement
given recent radar trends. Continued overrunning of the
rain-cooled boundary is expected to continue over the next 3-5
hours with components of slow moving/backbuilding/training
allowing for localized heavy rainfall to continue across
south-central LA. The environment is forecast to remain mostly
unchanged over the next 2-3 hours and additional potential for 2
to 3+ in/hr rainfall rates will remain along with localized storm
totals over 5 inches possible in a relatively short period of
time. These high rainfall rates will be most concerning with any
overlap of urban or other areas with poor drainage.

Otto

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

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

LAT...LON   30999214 30969128 30849089 30459061 29939068
            29779159 29919251 30219280 30699269