735
AWUS01 KWNH 040951
FFGMPD
OHZ000-MIZ000-INZ000-041500-
MESOSCALE PRECIPITATION DISCUSSION 1194
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
550 AM EDT FRI SEP 04 2026
AREAS AFFECTED...SOUTHERN LOWER MICHIGAN...NORTHWEST OHIO...EXT.
NORTHEAST INDIANA...
CONCERNING...HEAVY RAINFALL...FLASH FLOODING POSSIBLE
VALID 040950Z - 041500Z
SUMMARY...EXPANDING CONVECTION WITHIN FAVORABLE TRAINING/REPEATING
ENVIRONMENT POSE LOCALIZED 2-3.5" TOTALS AND POSSIBLE INCIDENT(S)
OF FLASH FLOODING THROUGH MORNING.
DISCUSSION...09Z SURFACE ANALYSIS DEPICTS AN ILL/BROADLY DEFINED
STATIONARY FRONT ACROSS NORTHERN OHIO INTO FAR SW MI BEFORE
CROSSING LOWER LAKE MICHIGAN INTO SOUTHERN WI. WEAK SURFACE
SOUTHERLY FLOW WITH ENHANCED LOW 70S TDS IS PROVIDING CONVERGENCE
ALONG THE STATIONARY FRONT, THOUGH QUICK VEERING OF FLOW FROM 925
TO 850MB MORE DUE WESTERLY IS ONLY OBLIQUELY ISENTROPICALLY
ASCENDING THROUGH THE FRONT. GOES-E WV SUITE AND AMVS DENOTE AN
ENHANCED OUTFLOW CHANNEL PERHAPS INFLUENCED/AIDED BY THE UPSTREAM
CONVECTIVE COMPLEX OVER E WI, TO PROVIDE SOME BROADENING
DIVERGENCE ALOFT TO ACCOMPANY THE WEAK SURFACE CONVERGENCE. RAP
ANALYSIS ALSO NOTES, WEAKENING CINH TO BELOW 10-20 J/KG ACROSS THE
FRONTAL ZONE FROM LOWER MI INTO N WV BUT ALSO ALIGNED WITH
GRADIENT OF CONDITIONALLY UNSTABLE AIR WITH UP TO 1250 J/KG OF
CAPE AVAILABLE.
GOES-E 10.3UM AND REGIONAL RADAR DENOTE THESE ELEMENTS HAVE BEEN
SUFFICIENT FOR CONVECTIVE INITIATION WITH OVERSHOOTING TOPS OVER
THE CIRRUS COOLING BELOW -65C OVER EATON/JACKSON COUNTY WITH NEWER
CELLS DOWNSTREAM IN NORTHEAST OH. UPSTREAM ELEVATED WAA
CONVECTION FROM THE LARGER COMPLEX IS STARTING TO PROGRESS ACROSS
THE LAKE TOWARD SW MI AND LIKE THE NEW DEVELOPMENT IS FAVORABLY
ORIENTED TO DEEP LAYER STEERING FLOW WHICH SHOULD PROMOTE A
REPEATING/TRAINING ENVIRONMENT. EFFECTIVE BULK SHEAR OF 25-35KTS
SHOULD FURTHER SUPPORT CELL ORGANIZATION WITH PERHAPS SOME WEAK
ROTATION TO SLOW SOUTHEASTWARD PROPAGATION INCREASING RESIDENCY.
POOLED MOISTURE THROUGH DEPTH PROVIDES AMPLE MOISTURE AND WITH
WEAKLY VEERED/CONVERGENT 925-850MB FLOW AT 20-25KTS, PROVIDES
AMPLE FLUX FOR EFFICIENT RAINFALL PRODUCTION AND RATES OF
1.5-1.75"/HR. HYDROLOGICALLY, SOUTHERN MI IS VERY SANDY AND
NATURALLY HIGH FFG VALUES WILL REQUIRE THE REPEATING AND OR SLOWED
FORWARD PROPAGATION TO RESULT IN 2-3.5" TOTALS IN 3HRS; THOUGH
THIS DOES DECREASE TOWARD SE MI AND INTO NORTHERN OH WHERE HOURLY
FFG VALUES GO FROM 2.5" IN MI AND LESS THAN 1.5" IN SE MI/NW OH
(3HR OVER 3" AND LESS THAN 2" RESPECTIVELY). AS SUCH, FLASH
FLOODING MAY BE MORE ISOLATED TO WIDELY SCATTERED AND MORE LIKELY
IN FEW URBAN LOCATIONS IN PROXIMITY TO THE FRONTAL BOUNDARY. AS
SUCH, FLASH FLOODING IS CONCERNED POSSIBLE THROUGH DAYBREAK ACROSS
THE AREA OF CONCERN.
GALLINA
..PLEASE SEE WWW.WPC.NCEP.NOAA.GOV FOR GRAPHIC PRODUCT
ATTN...WFO...CLE...DTX...GRR...IWX...
ATTN...RFC...MSR...TIR...NWC...
LAT...LON 43898647 42768427 41478190 40878191 40728248
41078375 41548502 42188647 42748631 43208640
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