Subj : MESO: Nws Weather Prediction Center College Park Md
To   : wx-storm@lists.illinois.edu
From : COD Weather Processor
Date : Wed Jul 12 2023 07:37:33

AWUS01 KWNH 120737
FFGMPD
INZ000-ILZ000-IAZ000-121230-

Mesoscale Precipitation Discussion 0704
NWS Weather Prediction Center College Park MD
337 AM EDT Wed Jul 12 2023

Areas affected...Eastern Iowa...Northern Illinois...Far Northwest
Indiana...

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

Valid 120735Z - 121230Z

SUMMARY...Possible repeating thunderstorms along/south of I-80
where recent thunderstorms may have decreased soil capacity and
increase potential for enhanced runoff pose low-end localized
flash flooding risk, especially in urban locations.

DISCUSSION...07z Surface analysis depicts a well defined west to
east stationary front from OTM to PIA to RZL where pooled surface
moisture exists with nearly 90 degrees of convergent surface flow.
 Slightly aloft the nose of a 700-500 mb moisture slug is arriving
across N IL upstream of a trailing line of enhanced moisture aloft
of a broader enhanced 850-700 moisture layer.  This is combining
for overall totals to 1.75, nearing 2" of total PWats.  The area
is also at the eastern edge of broader but strengthening LLJ with
flow of 15-20kts becoming increasingly confluent across N IL,
supporting some upstream moisture flux convergence and modest
mid-level unstable air to advect into the area.  RAP MUCAPE of
1000-1500 J/kg with the convergence is sparking scattered
thunderstorms across E IA into central northern IL. The overlap
with best moisture supports deeper warm cloud environment for
increased rainfall production with 1.5-2"/hr rates within the
cores.=20

Deep unidirectional flow support repeating, which is key given
fairly fast forward propagation of the cells which would limit
overall rainfall totals in the short-term.  Given upstream
strengthening WAA, backbuilding or scattered redevelopment is
expected over E IA into NW IL increasing the potential for
repeating cells.  Satellite imagery suggests some cores will come
in fairly quick succession increasing heavy rainfall potential
within short enough duration to result in isolated low-end flash
flooding.  To increase potential for this, FFG values have been
reduced in proximity to I-80 and south due to recent above average
rainfall.  As such spots of 2"+ are possible over the next few
hours with a spot 3" not out of the realm of possibility if
clustering continues increase with time.   Cells will cross over
into NW IND, but it has been drier and the area has naturally
higher FFG, so have limited the extension of the MPD area in NW
Indiana.

Gallina

....Please see https://urldefense.com/v3/__http://www.wpc.ncep.noaa.gov__;!!=
DZ3fjg!_Pw4SmKKdRwU65BdjMYMi24LAKY1VmmmC4ohUT83tq-ficGvDpC23q1p6_xi4zt3TNo3=
EUZzhP95WpMpj4CTP_UsQ8k$  for graphic product...

ATTN...WFO...DVN...ILX...IWX...LOT...

ATTN...RFC...NCRFC...OHRFC...NWC...

LAT...LON   42599144 42489065 42398830 42198772 41768737=20
            41748681 41588660 41128660 40778695 40598749=20
            40588884 40739104 41089200 41809222 42469191=20
=20=20=20=20=20=20=20=20=20=20=20=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)

.