WPC Met Watch

WPC Met Watch


Mesoscale Precipitation Discussion: #0260 (Issued at 614 PM EDT Sun May 12 2024
) MPD Selection


Graphic for MPD #0260

Mesoscale Precipitation Discussion 0260
NWS Weather Prediction Center College Park MD
614 PM EDT Sun May 12 2024

Areas affected...Southern Louisiana...

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

Valid 122215Z - 130230Z

SUMMARY...Strong repeating clusters upstream are
weakening/diminishing but also approach sizable urban centers
posing possible flash flooding concerns over the next few hours.

DISCUSSION...Regional RADAR and 10.3um EIR GOES-E Loop depict a
parade of cold top/stronger intense thunderstorm clusters tracking
from the Piney Woods of E TX across south-central LA toward
Southeast LA.  Cells are tracking along the elevated instability
gradient along/northeast of the warm front that has remain
near/just south of the LA coast, with MUCAPEs of 500-1000 J/kg
along and south of the I-10 corridor.  Instability is reduced
across SE LA, mainly as advection/isentropic ascent is reduced
relative to further west in SE TX/SW LA becoming weaker in the
15kt range while boundary layer to surface is starting to become
more parallel to the boundary reducing necessary influx to
maintain strength.  Still, the cells will have history and take
time to diminish, especially the lead wave that has favorable
inflow from the southeast of high moisture air.  Forward speeds
should increase, but with 1.75-2" total PWATs sub-hourly rates of
1-2" remain possible. 

The greater concern remains, not one particularly slowly weakening
cells, it is the combination of several upstream crossing urban
centers like Baton Rouge to New Orleans and towns/cities along
I-12 north of Lake Pontchartrain.  Given 2-4 repeating stronger
cells (even with diminished instabilty) may result in spots of
2.5-3.5" particularly further west along I-10 into Baton Rouge. 
As such, coverage of potential flash flooding should be limited in
area to these localized urban considerations. However, have
expanded the MPD area of concern back to SE TX border to extend
duration of concern/discussion highlighted in MPD 258. 




LAT...LON   31269255 30979168 30508974 29898958 29489001
            29719127 30009220 30269310 30659373 31219336

Download in GIS format:    Shapefile
 | KML

Last Updated: 614 PM EDT Sun May 12 2024

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