Subj : MESO: Nws Weather Prediction Center College Park Md
To   : wx-storm@lists.illinois.edu
From : COD Weather Processor
Date : Wed Jun 04 2025 14:46:42

AWUS01 KWNH 041446
FFGMPD
SCZ000-GAZ000-042100-

Mesoscale Precipitation Discussion 0360
NWS Weather Prediction Center College Park MD
1045 AM EDT Wed Jun 04 2025

Areas affected...portions of coastal GA & SC

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

Valid 041500Z - 042100Z

Summary...Narrow convective bands which can train for 1-2 hours
are anticipated to increase in frequency late this morning into
late this afternoon.  Hourly rain amounts to 2.5" with local
totals to 4" are possible, which could lead to issues in urban
areas.

Discussion...Water vapor imagery shows a pair of upper level
circulations across east-central GA and south of Apalachicola FL.=20
Their combined influence has brought a deep moisture plume into
the region, with precipitable water values above 2".  Inflow at
850 hPa is ~20 kts per VAD wind profiles.  Effective bulk shear is
near 25 kts and ML CAPE of 1000-2000 J/kg are available near the
upstream of the GA and southern SC coasts.  Thus far this morning,
a few very narrow, training bands of showers have led to hourly
amounts of 1.5-2.5" and local amounts as high as 4".

The expectation is for some increase in coverage of narrow rain
bands with time as a surface trough sharpens and a surface low
tries to develop near the GA coast this afternoon, which should
amp up the 850 hPa inflow and effective bulk shear a little more.=20
Slight increases in the Galvez-Davison index with time imply
somewhat greater convective coverage with time as well.  The
mesoscale guidance, while it has a signal for heavy rainfall, may
be seeming to underplay amounts per their relatively coarse (when
compared to radar imagery) resolution.  Hourly amounts to 2.5" and
local totals to 4" remain possible where narrow convective bands
can persist for 1-2 hours.  A complicating factor in areas such as
Charleston SC would be the tidal cycle, with high tide expected at
2010z, which would potentially enhance any existing heavy rainfall
issues.  Issues are expected to be mainly constrained to urban
areas.

Roth

....Please see https://urldefense.com/v3/__http://www.wpc.ncep.noaa.gov__;!!=
DZ3fjg!-r5aQ_FAUKQZLTPJ-XZ0VXHitvMNr3fmdEouGD4sVH9UNcLOwScoJI1nQhHzVwJpimDJ=
YGl8I53R6HZR9Q1kH5UDLmM$  for graphic product...

ATTN...WFO...CHS...

ATTN...RFC...ALR...NWC...

LAT...LON   33247996 33087914 32128061 31738110 31858142=20
            32368137 32898076=20

=3D =3D =3D
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