Subj : MESO: Nws Weather Prediction Center College Park Md
To   : wx-storm@lists.illinois.edu
From : COD Weather Processor
Date : Tue Jul 11 2023 16:15:23

AWUS01 KWNH 111615
FFGMPD
ALZ000-MSZ000-LAZ000-ARZ000-112116-

Mesoscale Precipitation Discussion 0699
NWS Weather Prediction Center College Park MD
1214 PM EDT Tue Jul 11 2023

Areas affected...Southern AR...Northeast LA...Southern MS...Far
Southwest AL

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

Valid 111614Z - 112116Z

Summary...Showers and thunderstorms continue to develop across
portions of southern AR, northeast LA, and west-central MS ahead
of a decaying MCS and associated MCV. Repeat rounds of storms
containing rates up to 2"/hr could support flash flooding.

Discussion...Showers and thunderstorms are proliferating this
morning across portions of the Lower MS Valley, along and ahead of
a remnant MCS from overnight. The more recent activity ahead of
the old complex remains tied to a focused area of 925-850 mb
moisture transport impinging upon a NW-SE oriented warm front,
while new activity was also noted along a southward translating
outflow boundary. Single-source and multi-sensor hourly rainfall
estimates depicted 1-1.5" per hour rates within the most intense
cores, leading to a modest uptick in CREST unit flows earlier
across southwest AR.

The mesoscale environment for heavy rainfall continues to improve
across the region. Earlier upper-air data from SHV sampled PWATs
of 2.05" (above the 90th percentile) with a warm cloud layer
~11,000 feet, while trends in the low-level advected LPW suggest
considerable moistening across the region since 12z. Meanwhile, at
the surface, strong warm sector insolation coupled with upper-70's
dewpoints continues to remove lingering CIN, with 1500-2000 J/kg
MLCAPE estimated across LA into MS. Mean wind within the steering
column remains weak east of the MCV, around 10-15 kts according to
SPC mesoanalysis, while oriented parallel to the surface front.

Over the next several hours, the expectation is for more
convection to develop along the front within the increasingly
moist and unstable environment. While the weak flow aloft will
limit individual cell organization and longevity, it also should
lengthen residence times of heavy rainfall. As storms congeal,
forecast 5-10 kt Corfidi vectors roughly orthogonal to the mean
flow suggest reduced forward propagation potential of the
activity. Within the main axis of training, the 12z HREF suggests
2-4" of rainfall is possible through 21z, which could breach the
3-4" 6 hour FFGs across the region. Some areas across the region
have seen 3-400% of normal precipitation over the last two weeks,
which could exasperate flash flooding effects.

Asherman

....Please see https://urldefense.com/v3/__http://www.wpc.ncep.noaa.gov__;!!=
DZ3fjg!7Sw0g1DUnyOVv9KeCBiA8vneiXcY_ow-EEoj0l18MhZVc0XV3y4LYS-mvVJnkWz41kls=
VCWdBV6-Ne0MzgNuEi5iOGI$  for graphic product...

ATTN...WFO...JAN...LIX...LZK...MOB...SHV...

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

LAT...LON   34219267 33899183 32969064 31578803 30398820=20
            30829062 31509183 32159303 32929378 33569374=20
            34129326=20

=3D =3D =3D
To unsubscribe from WX-STORM and you already have a login, go to
https://lists.illinois.edu and use the "Unsubscribe" link.  Otherwise email
Chris Novy at cnovy@cox.net and ask to be removed from WX-STORM.

--- SBBSecho 3.14-Linux
 * Origin: capitolcityonline.net * Telnet/SSH:2022/HTTP (1:2320/105)

.