Subj : MESO: Nws Weather Prediction Center College Park Md
To   : wx-storm@lists.illinois.edu
From : COD Weather Processor
Date : Fri May 23 2025 15:59:11

AWUS01 KWNH 231559
FFGMPD
FLZ000-232200-

Mesoscale Precipitation Discussion 0306
NWS Weather Prediction Center College Park MD
1158 AM EDT Fri May 23 2025

Areas affected...Southeast Florida...

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

Valid 231600Z - 232200Z

SUMMARY...Slow moving very intense/efficient thunderstorms capable
of 2.5-3"/hr rates and highly localized totals of 4-5"+ across
urban corridor may result in rapid inundation flooding concerns
through this evening.

DISCUSSION...GOES-E Visible imagery, 15z surface observations and
local VWP denote the old surface front/boundary is dissolving
across southern Florida but vestiges of roll clouds and moisture
gradient suggest it remains along/north of Grand Bahama and
intersects with early morning sea-breeze along/just east of
Broward county with the breeze boundary dropping south along the
Keys.  A secondary roll arc can be see SW of Collier
county...suggesting the remaining front exists through the
Everglades, though there is a weak vorticity center/twist in the
cu field over western Palm Beach county which also matches up with
925-850mb VWP and pooled/enhanced moisture pool.  Td in the upper
70s and total PWat values of 2" exist in the vicinity of the low
with expanding cu field that has some suggestion of TCus starting
to form.  Given temps are nearing 90F, MLCAPEs are reaching 2000+
J/kg along the eastern coast near the low/frontal zone.=20

Destabilization is expected  in the next 1-2 hours with this
weakly convergence area and with the ample deep warm layer and
moisture, rapid rainfall efficiency will rapidly increase with
expanding thunderstorms.  Deep layer flow is weak below 700mb but
above, there should be enough westerly wind speed to support
updraft  outflow and some weakly organized cells for a few
updraft/downdraft cycles increasing duration in vicinity of the
urban corridor of SE Florida.  Onshore flow should help to reduce
eastward propagation (relative to similar cells that will develop
along the SW FL coast).  Given this rates of 2.5-3"/hr are
possible, with 12z HREF probs of 3"/hr maximizing around 20-25%
between 20-22z (2"/hr is near 45%); localized spots of 4-5" are
possible in less than 1-3hrs possibly resulting in
focused/localized rapid inundation flooding in the urban centers.

Gallina

....Please see https://urldefense.com/v3/__http://www.wpc.ncep.noaa.gov__;!!=
DZ3fjg!8ap2bN96LpgJxqTt9VvD_OBi_2sr22VHjYzpdG0tjXxAS3HB0wB_U-UCfiiAYOLaBvL8=
iuSVy-P9FyqPtMmzPoyzTuw$  for graphic product...

ATTN...WFO...MFL...MLB...

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

LAT...LON   27648050 27578036 27168019 26857999 26118003=20
            25698012 25468029 25458046 25788052 26118037=20
            26328033 26548043 26598045 27048070 27288078=20
            27538069=20

=3D =3D =3D
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