Subj : MESO: Nws Weather Prediction Center College Park Md
To   : wx-storm@lists.illinois.edu
From : COD Weather Processor
Date : Sun Jun 25 2023 02:03:29

AWUS01 KWNH 250203
FFGMPD
WIZ000-ILZ000-MOZ000-IAZ000-250730-

Mesoscale Precipitation Discussion 0577
NWS Weather Prediction Center College Park MD
1002 PM EDT Sat Jun 24 2023

Areas affected...middle to upper MS Valley

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

Valid 250201Z - 250730Z

Summary...Localized 2-4 inch totals will pose an isolated flash
flood threat from eastern IA/MO into southwestern WI and western
IL through 07Z. Training of cells will have the potential to
generate 2-3 in/hr rain rates.

Discussion...Regional radar imagery at 0130Z showed a small
cluster of thunderstorms stretching from eastern IA into
southwestern WI, with isolated to scattered thunderstorm activity
southward into western IL and northeastern MO. These storms were
occurring within the warm conveyor belt ahead of a closed low over
the Dakotas, out ahead of a surface cold front approaching from
the west, with low level confluence maximized across eastern IA in
the vicinity of a remnant stationary front. Precipitable water
values were 1.5 to 1.7 inches (area 00Z soundings and GPS
measurements) for locations along and west of the remnant
stationary front crossing the mid-MS Valley along with MLCAPE of
1000 to 3000 J/kg. Instability values rapidly decreased with
eastern extent into southeastern WI and eastern IL. While
individual cells were moving progressively toward the ENE at 25-40
kt, upstream development of cells has been noted over the past 1-2
hours.

Dry antecedent conditions and correspondingly high FFG values of
near 3 inches in 3 hours should limit the flash flood threat to
isolated and urban locations across the region but the potential
for short term training and repeating cells could produce 2-3
in/hr rainfall rates. This potential will be greatest where WSW to
ENE alignment of cells sets up, matching the steering flow aloft.
Diffluent flow aloft combined with some modest increase in the low
level jet should help to increase cell coverage over the next
couple of hours while thunderstorms and instability gradually
shift eastward with time. However, the best coverage of additional
thunderstorms should remain tied to the greatest low level
convergence from eastern IA into northern IL.

Otto

....Please see https://urldefense.com/v3/__http://www.wpc.ncep.noaa.gov__;!!=
DZ3fjg!9JGusDcsTbJqDmYz2g8-ambsTU2WaE2gHyohWzzXDbpzMYql_YvR0mrjy36TWdbri6lS=
E-iKaYB8Qgx28c4j42RXZaQ$  for graphic product...

ATTN...WFO...ARX...DMX...DVN...EAX...ILX...LOT...LSX...MKX...

ATTN...RFC...MBRFC...NCRFC...NWC...

LAT...LON   43019099 42739005 41828905 40178931 38918965=20
            38279022 38279126 39209228 41329262 42289205=20
=20=20=20=20=20=20=20=20=20=20=20=20

=3D =3D =3D
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