143
AWUS01 KWNH 040138
FFGMPD
MIZ000-WIZ000-MNZ000-040737-
MESOSCALE PRECIPITATION DISCUSSION 1191
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
937 PM EDT THU SEP 03 2026
AREAS AFFECTED...PORTIONS OF THE UPPER MIDWEST
CONCERNING...HEAVY RAINFALL...FLASH FLOODING POSSIBLE
VALID 040137Z - 040737Z
SUMMARY...NEW THUNDERSTORM ACTIVITY HAS RECENTLY FORMED WHICH HAS
THE POTENTIAL TO GROW UPSCALE AND TRACK EAST-SOUTHEAST WITH TIME.
HOURLY RAIN AMOUNTS TO 2.5" WITH LOCAL TOTALS TO 4" ARE POSSIBLE,
WHICH COULD LEAD TO FLASH FLOODING.
DISCUSSION...ISOLATED TO WIDELY SCATTERED CONVECTION IS FORMING
NEAR AN ML CAPE GRADIENT ACROSS CENTRAL MN AND THE WESTERN UP OF
MI, DESPITE A GREAT DEAL OF CIN REMAINING ACROSS THE REGION.
PRECIPITABLE WATER VALUES ARE ~2". EFFECTIVE BULK SHEAR OF ~50
KTS EXISTS REGIONALLY. MU CAPE OF 1500-4000 J/KG EXISTS NEAR THE
NEW THUNDERSTORM ACTIVITY.
THE MESOSCALE GUIDANCE SHOWS A WIDE VARIETY OF SOLUTIONS...USED
THE 18Z HI-RES NAM WHICH APPEARS TO SHOW A MORE REALISTIC
DEPICTION OF WHAT'S UPCOMING. THUNDERSTORMS ARE EXPECTED TO GROW
IN SCALE AND COULD TRAIN/BACKBUILD WHILE ELEVATED OVER A SURFACE
FRONT IN A REGION OF 850 HPA CONFLUENCE/CONVERGENCE. THE 850 HPA
INFLOW VEERS AND INCREASES WITH TIME, IMPLYING BACKBUILDING AND
EVENTUAL FORWARD PROPAGATION WOULD OCCUR ONCE A COLD POOL DEVELOPS
IN OR NEAR AN EAST-WEST SURFACE TROUGH. GIVEN THE PARAMETERS
AVAILABLE, HOURLY RAIN AMOUNTS TO 2.5" WITH LOCAL TOTALS TO 4" ARE
POSSIBLE. THIS COULD LEAD TO FLASH FLOODING, PARTICULARLY OVER
URBAN AREAS.
ROTH
..PLEASE SEE WWW.WPC.NCEP.NOAA.GOV FOR GRAPHIC PRODUCT
ATTN...WFO...ARX...DLH...FGF...GRB...MKX...MPX...MQT...
ATTN...RFC...MSR...NWC...
LAT...LON 46989242 46679015 46058882 45008725 44238697
43098806 43949111 45509473 46229567 46499398
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