024
AWUS01 KWNH 040638
FFGMPD
WIZ000-MNZ000-041200-
MESOSCALE PRECIPITATION DISCUSSION 1193
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
237 AM EDT FRI SEP 04 2026
AREAS AFFECTED...WISCONSIN...
CONCERNING...HEAVY RAINFALL...FLASH FLOODING POSSIBLE
VALID 040645Z - 041200Z
SUMMARY...INCREASING ISENTROPIC CONVECTION WITHIN
REPEATING/TRAINING PROFILE SUGGESTS WITH AMPLE MOISTURE AND RATES
UP TO 2"/HR SUPPORTS AND AXIS OF 2-4" TOTALS THROUGH EARLY
MORNING. INCIDENTS OF FLASH FLOODING BECOMING INCREASINGLY
POSSIBLE.
DISCUSSION...GOES-E 10.3UM AND REGIONAL RADAR DEPICT TWO AREAS OF
INCREASING CONVECTION ACROSS THE UPPER GREAT LAKES. THE FURTHER
NORTH ACROSS NE MN WITH A SECONDARY WAA WING ACROSS W U.P OF MI
WITH A BROADENING CLUSTER OF ISENTROPICALLY INDUCED, EXPANDING
CLUSTERS ACROSS CENTRAL WI INTO SE WI. CIRA LPW/LVT ALONG WITH
VWP SHOWS THE MAIN CORE OF THE WARM CONVEYOR BELT (EASTERN BRANCH)
IS OVER-TOPPING THE RIDGE AND CYCLONICALLY CURVING, FURTHER
ENHANCING MOISTURE CONVERGENCE GENERALLY AT A LOWER ALTITUDE ABOUT
850-900MB. THE FORMER IS DRIVEN BY PROXIMITY TO STRONGER DPVA
FROM ADVANCING SHORTWAVE TROUGH OVER N MN WITH EASTWARD EXPANSION
AROUND 700-750MB WHERE THE WESTERN BRANCH OF THE DEVELOPING TROWAL
HAS SUFFICIENT BACKED MID LEVEL FLOW FOR SUFFICIENT CONVERGENCE
FOR INCREASING BUT SLIGHTLY WEAKER WAA DEVELOPMENT.
OVERALL, THE WCB IS STREAMING ALONG AND NORTHWEST OF THE HIGHEST
INSTABILITY AXIS WHICH RESIDES THROUGH THE MISSISSIPPI RIVER
VALLEY WITH NEARLY 4000 J/KG OF CAPE NEAR LACROSSE AND SOUTHWARD,
THOUGH STEADY GRADIENT OF 1000-1500 J/KG EXTENDS AS FAR NORTHEAST
INTO THE SW PORTIONS OF THE U.P. DENOTING THE WEAKER, MORE
SCATTERED NATURE COMPARED TO THOSE DOWNSTREAM IN CENTRAL AND
SOUTHEAST WI WHERE OVERSHOOTING TOPS ARE COOLING BELOW -70C. CIRA
LVT SHOWS CORE OF WCB IS ALSO T-BONED ACROSS CENTRAL WI WITH OVER
75-100 KG/M/S OF FLUX THROUGH 850-700MB RESULTING IN ENHANCED TPW
OVER 2". GIVEN FLOW IS 20-30KTS CONVERGENCE THROUGH 850-700MB AND
STRONG UPDRAFTS WILL SUPPORT 2"/HR RATES WITH STRONGEST CORES
OCCASIONALLY REACHING 2.5".
DEEP LAYER STEERING QUICKLY VEERS OUT OF THE NW TO SUPPORT A
GENERAL NW TO SE ENVIRONMENT FOR REPEATING TRAINING, THOUGH MEAN
FLOW IS STRONG, THE EFFECTIVE BULK SHEAR THROUGH DEPTH SOLID
SUPERCELL COMPOSITES IN LOWER DOUBLE DIGITS DENOTE ROTATING
UPDRAFT CAPABILITY REDUCING FORWARD SPEED, INCREASING RESIDENCY
TIME FOR THE ELEVATED CORES. HOWEVER, THIS ROTATION WILL HELP
SOME RIGHT TURNING DEFLECTION FOR IDEAL REPEATING/TRAINING
EVENTUALLY REACHING SOUTHEAST WI AND POTENTIALLY INTERSECTING MORE
URBAN LOCATIONS THAT CURRENTLY. AS SUCH STREAKS OF 2-4" TOTALS
ARE BECOMING INCREASINGLY POSSIBLE. FFG VALUES OF 1.5-2"/HR AND
<3"/3HRS SUGGEST SCATTERED INCIDENTS OF FLASH FLOODING ARE
BECOMING INCREASINGLY POSSIBLE THROUGH THE EARLY MORNING HOURS.
UPSTREAM, THE FORWARD PROPAGATING COMPLEX AND WARM ADVECTIVE 700MB
WING WILL CONTINUE TO QUICKLY ADVANCE INTO NW WI. GOES-E SWIR
SUGGESTS THERE ARE A FEW CELLS TRYING TO DEVELOP ALONG THE NW TO
SE AXIS BETWEEN THE COMPLEXES AT LOWER ELEVATIONS (AND THEREFORE
FURTHER SOUTHWEST). INTENSE RATES WILL ACCOMPANY, BUT FORWARD
SPEEDS WILL BE HIGHER ALONG WITH BETTER SOUTHEASTERLY INFLOW TO
FURTHER INCREASE FORWARD PROPAGATION. COMBINE THIS WITH NATURALLY
HIGHER FFG VALUES (2-2.5"/HR & 3-4"/3HRS) ACROSS THE NORTHWOODS OF
N WI AND SW UP OF MI AND FLASH FLOODING IS NOT AS LIKELY AS
FURTHER DOWNSTREAM ACROSS CENTRAL AND SE WI. STILL, THIS COMPLEX
IS LIKELY TO BEGIN TO RACE SOUTHEAST TOWARD AREAS ALREADY AFFECTED
BY LEADING CLUSTERS AND MAY RESULT IN REAGGRIVATION OF ANY ONGOING
FLOODING CONDITIONS.
GALLINA
..PLEASE SEE WWW.WPC.NCEP.NOAA.GOV FOR GRAPHIC PRODUCT
ATTN...WFO...ARX...DLH...GRB...MKX...MPX...
ATTN...RFC...MSR...NWC...
LAT...LON 46779245 46219067 45888972 45108773 44698720
43358768 42758768 42658826 43128896 44159011
45529186 46299266
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