Subj : MESO: Nws Weather Prediction Center College Park Md
To   : wx-storm@lists.illinois.edu
From : COD Weather Processor
Date : Wed Sep 06 2023 16:21:48

AWUS01 KWNH 061621
FFGMPD
MIZ000-062040-

Mesoscale Precipitation Discussion 1041
NWS Weather Prediction Center College Park MD
1220 PM EDT Wed Sep 06 2023

Areas affected...Northern Michigan

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

Valid 061620Z - 062040Z

SUMMARY...Two approaching thunderstorm complexes look to merge
over northern Michigan within the hour. Rainfall rates around
2"/hr are possible within the more vigorous thunderstorm activity
and may result in flash flooding.

DISCUSSION...A stationary front oriented SW to NE from northern
Wisconsin to the U.P. of Michigan was acting as the trigger for
storms tracking into northern Michigan this morning. Farther
south, a complex of storms that originated in northern Illinois
has raced northeast ahead of the cold front. The atmosphere that
lies at the top Michigan's mitten is primed to support excessive
rainfall rates. SPC mesoanalysis showed PWs that were between
1.7-1.9" and MLCAPE >1,000 J/kg. The listed PWs by 18Z will be at
or above the 97.5 climatological percentile according to NAEFS.
The RRFS has had a fairly good handle of the ongoing thunderstorm
activity, and by 18Z, model soundings show low-mid level RH values
average >80% and warm cloud layers as deep as 10,000ft.

The approaching clusters of storms could produce 2"/hr rainfall
rates given the available moisture aloft and instability. There is
also the potential for redevelopment of thunderstorms closer to
the surface low later this afternoon. MRMS 15-minute radar totals
showed amounts as high as 0.8" in the most intense storms west of
Houghton Lake. 1-hr FFGs are as low as 1.5" in some spots. It has
been rather dry over the past two week (AHPS shows rainfall
amounts as low as 10% of normal) and this should limit flash
flooding potential from becoming a larger threat throughout the
region. Still, given the rainfall rates within these storms, flood
prone locations such as poor drainage areas and within urbanized
communities are most at-risk for possible flash flooding this
afternoon.

Mullinax

....Please see https://urldefense.com/v3/__http://www.wpc.ncep.noaa.gov__;!!=
DZ3fjg!-YiiAj6cQty4d8VC4LufOT5eHGN2ic_MnqRovgD73S0V_Lk9kWidVRtEKe0zUGfvY-DN=
jBAG8_XNoa7Bp4YoKRjPuVU$  for graphic product...

ATTN...WFO...APX...

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

LAT...LON   46248397 45388318 44538336 44238430 44208496=20
            44348570 45018597 45968499=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)

.