Subj : MESO: Nws Weather Prediction Center College Park Md
To   : wx-storm@lists.illinois.edu
From : COD Weather Processor
Date : Thu Jul 18 2024 19:27:07

AWUS01 KWNH 181927
FFGMPD
ALZ000-MSZ000-LAZ000-190125-

Mesoscale Precipitation Discussion 0652
NWS Weather Prediction Center College Park MD
326 PM EDT Thu Jul 18 2024

Areas affected...in and near southern & central MS

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

Valid 181925Z - 190125Z

Summary...Thunderstorms are developing along a pre-frontal trough
across MS within a moist and unstable air mass.  Hourly rain
totals to 3" with local amounts to 5" are possible.

Discussion...A mesoscale low appears to have formed on the
northern end of a squall line moving across southeast LA, and in
the warm air advection pattern ahead of it along a pre-frontal
trough, new activity has formed across southwest MS with more
isolated storms noted across central MS and west-central AL.  The
thunderstorms are forming out ahead of a positively-tilted upper
level shortwave stretching from central KS through western TN and
across central AR, as seen on water vapor imagery.  Precipitable
water values of 2"+ are noted in this area per VAD wind profiles
and very short term RAP forecasts.  A pool of 2000-3000 ML CAPE
lies across central MS per SPC mesoanalyses, which is likely to
build another 500 J/kg or so this afternoon.  Effective bulk shear
appears to be under 25 kts, but appears sufficient for some level
of organization per radar imagery.

The mesoscale guidance suggests that the mesoscale low should
build somewhat up in scale and become an MCV with time, which
could increase effective bulk shear regionally up to 25 kts and
increase convective organization further.  The mass of convection
and related mesocyclone should migrate east-northeast to northeast
with time, preferring to propagate into the region of best
instability.  The main causes for heavy rainfall appear to be cell
training and cell mergers.  Given the above, hourly rain totals to
3" and local amounts to 5" are possible, which would be especially
problematic in urban areas.

Roth

....Please see https://urldefense.com/v3/__http://www.wpc.ncep.noaa.gov__;!!=
DZ3fjg!91vKg7046JrG_pbSXM36_a_bW3fb8sFzaKsa54DykHvQhcEW6dIKLFGFS_Kzz2wCvwcK=
PV7IfPg4VR5xIYEM0uFCvK4$  for graphic product...

ATTN...WFO...BMX...JAN...LIX...MOB...

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

LAT...LON   33238865 32838802 31328820 30368922 30289024=20
            30939087 31379130 32758998=20

=3D =3D =3D
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