Winter Storm in Wisconsin, December 1, 2006

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MILWAUKEE/SULLIVAN WI
836 PM CST THU NOV 30 2006

.UPDATE...UPON EVALUATION OF CURRENT TRENDS IN REAL WORLD AND QUICK
PEEK AT 00Z NGM/RUC PROGS...HAVE DECIDED THAT NO ADJUSTMENTS
NEEDED FOR ONGOING WINTER STORM WARNING AND SNOW ADVISORY ACROSS
CWA AT THIS TIME. SOME CONCERN THAT TEMPERATURES AND LOW DEW POINTS
REFLECT ESTABLISHMENT OF DRY AIRMASS IN PLACE OVER CWA. HOWEVER
THESE COOL TEMPERATURES SEEM TO BE REFLECTED IN COBB NUMBERS FOR
BOTH NAM/GFS SOLUTIONS WHICH START WITH RELATIVELY HIGH 14-18:1
SNOW RATIOS WITH ONSET OF SNOW...THEN RATIOS TREND TOWARD 10:1 BY
END OF SNOW EVENT. IN ADDITION CRAS IR HAS VERY GOOD INITIAL
DEPICTION OF BAROCLINIC LEAF SIGNATURE DEVELOPING OVER KANSAS AND
PROGS SOUTHERN EDGE OF THIS SIGNATURE OVER WARNING AREA BETWEEN
12Z AND 15Z FRIDAY...THE BEST TIME WITH EXPECTED GFS PLACEMENT OF
SURFACE LOW OVER NORTHWEST INDIANA. AT THIS TIME AMOUNTS AND
TIMING OF SNOWFALL EVENT LOOK TO BE ON THE MONEY.

&&

.SHORT TERM...SOME LOW TEMPERATURE FORECAST ADJUSTMENTS WILL BE
MADE IN UPCOMING ZONES.

.LONG TERM...NO CHANGES AT THIS TIME.

&&

.PREV DISCUSSION... /ISSUED 156 PM CST THU NOV 30 2006/

DISCUSSION...FCST FOCUS ON WINTER STORM FOR LATE TONIGHT INTO
FRIDAY AFTERNOON. HEAVIEST SNOWFALL EXPECTED BETWEEN 6 AM AND 11
AM.

WATER VAPOR SHOWS A VERY IMPRESSIVE AND VERY INTENSE H5 LOW
CIRCULATION OVER THE RED RIVER VALLEY OF THE OK/TX BORDER. THIS
SYSTEM HAS HAD THUNDER ASSOCIATED WITH IT ACROSS NCNTRL TX...BUT
THE LIGHTNING TREND HAS BEEN DIMINISHING. DRY...COLD AIR PUMPING
INTO THE FORECAST AREA THIS AFTERNOON...HIGH CLOUDS LINGER ONLY IN
THE EAST.

THE H5 LOW TAKES A TURN NE OVERNIGHT AND ROCKETS INTO THE EASTERN
GREAT LAKES DURING AN 18 HOUR PERIOD BEGINNING AT 06Z TONIGHT. THE
DYNAMICS WITH THIS STORM ARE INTENSE AND THE MOISTURE IS ABUNDANT.
THE 12Z MODEL GUIDANCE HAS RAISED CONFIDENCE THAT THE SOUTHEAST
WILL GET HIT VERY HARD LATE TONIGHT AND FRIDAY MORNING. THE GFS
HAS SHIFTED A BIT FARTHER NORTH. THIS MAY BE IN RESPONSE TO AN
INFLUENTIAL PULL FROM A STRONG LOW DROPPING SOUTH FROM LAKE
WINNIPEG AREA OF CANADA. THE WARM LAKES THIS TIME OF YEAR DO SEEM
TO HAVE A TENDENCY TO PULL THESE SYSTEMS FARTHER NORTH THAN
EXPECTED AS WELL. THE UPR LEVEL JET DOES SHOW SOME COUPLING
POTENTIAL WITH AN UPPER DIVERGENCE BULLSEYE COVERING THE CWA
FRIDAY MORNING. THE AVAILABLE DEEP UVV FROM THE AGEO CIRCULATION
IS TIMED VERY NICELY WITH OTHER FEATURES.

THE NAM IS FAVORED MORE THAN THE GFS AND MOSTLY DUE TO HOW THE GFS
APPEARS TO HAVE TOO MUCH QPF ACROSS THE WRN CWA AFTER 12Z FRI.
THIS DOESN/T SEEM VERY LIKELY GIVEN THE TIGHT GRADIENT OF THE
DYNAMICS AND THE DRY AIR ENTRAINMENT FROM THE NORTH. DWPNTS ARE
CURRENTLY RUNNING IN THE SINGLE DIGITS IN THE WRN CWA. THE BEST
FRONTOGENESIS...Q-VECTOR CONVERGENCE AND ISENTROPIC LIFT/MOISTURE
IS LIMITED TO THE SE WITH A TIGHT GRADIENT TO THE NW. HERE IS THE
CAVEAT...THE GFS CAN/T BE RULED OUT COMPLETELY. THE LOW DROPPING
INTO THE NRN PLAINS DOES APPEAR TO PULL THE H5 DEFORMATION ZONE
FARTHER TO THE NW INTO WI. THERE IS EVIDENCE OF A TROWL AT H6
PUSHING INTO THE WRN CWA FRIDAY MORNING THAT MAY PRODUCE SOME
FOCUSED FRONTOGENESIS DEEPER INTO THE CWA THAN EXPECTED. BUT IN
THE END...THE DRY AIR WILL BE TOUGH TO OVERCOME AND WILL KEEP THE
BEST SNOWS FARTHER TO THE EAST. THIS WILL HAVE TO BE WATCHED
CAREFULLY.

COMING UP WITH SNOW AMOUNTS IS DIFFICULT. THE GARCIA METHOD WOULD
PUT AVERAGE MIXING RATIOS IN THE 2.5 TO 3 G/KG AREA. BUT THERE IS
LIKELY GOING TO BE A LAKE COMPONENT THAT WILL BRING ADDITIONAL
MOISTURE TO THE FAR SOUTHEAST. DELTA-TS ARE ABOUT 12 TO 13 DEG C.
ALSO GIVEN THE STRONG DYNAMICS...THE POTENTIAL FOR SOME CONVECTIVE
SNOW LOOKS VERY REAL. BOTH THE GFS AND THE NAM ARE PAINTING ABOUT
1 TO 1.1 INCHES OF QPF ACROSS SRN MILAUKEE/RACINE/KENOSHA AND ERN
WALWORTH COUNTIES. WITH AN 11 TO 1 RATIO /POSSIBLY BETTER GIVEN
COLD AIR/ THAT WOULD TRANSLATE TO 10 TO 14 INCHES. WE ARE ALSO
LOOKING AT EASTERLY WINDS SHIFTING TO NORTH DURING THE MORNING
BLOWING 20 TO 30 MPH WITH GUSTS TO 35 MAYBE 40 MPH. NEAR WHITEOUT
CONDITIONS ARE POSSIBLE IN THE SOUTHEAST.

WILL TAPER THE SNOW AMOUNTS OFF TO THE NORTH AND WEST PRETTY
QUICKLY. WILL TIER THE WINTER STORM WARNING WITH A SNOW ADVISORY
FOR ABOUT 3 TO 5 INCHES.

EXTENDED FORECAST LOOKS FAIRLY QUIET AND COLDER THAN WE/RE USED
TOO.

MKX WATCHES/WARNINGS/ADVISORIES...
SNOW ADVISORY FROM 3 AM TO 3 PM CST FRIDAY FOR WIZ051-WIZ058-
WIZ063-WIZ068.

WINTER STORM WARNING FROM 3 AM TO 3 PM CST FRIDAY FOR WIZ052-
WIZ059-WIZ060-WIZ064-WIZ065-WIZ066-WIZ069-WIZ070-WIZ071-WIZ072.

&&

.MKX WATCHES/WARNINGS/ADVISORIES...
SNOW ADVISORY FROM 3 AM TO 3 PM CST FRIDAY FOR WIZ051-WIZ058-
WIZ063-WIZ068.

WINTER STORM WARNING FROM 3 AM TO 3 PM CST FRIDAY FOR WIZ052-
WIZ059-WIZ060-WIZ064-WIZ065-WIZ066-WIZ069-WIZ070-WIZ071-WIZ072.

&&

ZAJDEL

HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE MILWAUKEE/SULLIVAN WI
605 PM CST THU NOV 30 2006

WIZ046-047-051-052-056>060-062>072-011030-
MARQUETTE-GREEN LAKE-FOND DU LAC-SHEBOYGAN-SAUK-COLUMBIA-DODGE-
WASHINGTON-OZAUKEE-IOWA-DANE-JEFFERSON-WAUKESHA-MILWAUKEE-
LAFAYETTE-GREEN-ROCK-WALWORTH-RACINE-KENOSHA-
605 PM CST THU NOV 30 2006

THIS HAZARDOUS WEATHER OUTLOOK IS FOR PORTIONS OF EAST CENTRAL
WISCONSIN...SOUTH CENTRAL WISCONSIN AND SOUTHEAST WISCONSIN.

.DAY ONE...TONIGHT

A WINTER STORM WARNING IS IN EFFECT FOR PORTIONS OF SOUTHEASTERN
WISCONSIN LATE TONIGHT...GENERALLY SOUTHEAST OF A LINE FROM
SHEBOYGAN...TO WATERTOWN...TO JANESVILLE. A SNOW ADVISORY IS IN
EFFECT FOR PORTIONS OF SOUTH-CENTRAL WISCONSIN.

.DAYS TWO THROUGH SEVEN...FRIDAY THROUGH WEDNESDAY
A WINTER STORM WARNING IS IN EFFECT FOR PORTIONS OF SOUTHEASTERN
WISCONSIN...GENERALLY SOUTHEAST OF A LINE FROM SHEBOYGAN...TO
WATERTOWN...TO JANESVILLE THROUGH FRIDAY AFTERNOON. A SNOW ADVISORY
IS IN EFFECT FOR PORTIONS OF SOUTH-CENTRAL WISCONSIN THROUGH FRIDAY
AFTERNOON.

.SPOTTER INFORMATION STATEMENT...

SNOWFALL REPORTS ARE REQUESTED LATE TONIGHT THROUGH FRIDAY.

LMZ643>646-665-011030-
SHEBOYGAN TO PORT WASHINGTON-
PORT WASHINGTON TO NORTH POINT LIGHTHOUSE-
NORTH POINT LIGHTHOUSE TO WIND POINT-
WIND POINT TO WINTHROP HARBOR ILLINOIS-
WISCONSIN ADJACENT OPEN WATERS OF LAKE MICHIGAN TO MID LAKE-
605 PM CST THU NOV 30 2006

THIS HAZARDOUS WEATHER OUTLOOK IS FOR PORTIONS OF LAKE MICHIGAN.

.DAY ONE...TONIGHT

A SMALL CRAFT ADVISORY REMAINS IN EFFECT UNTIL LATE TONIGHT. A
GALE WARNING GOES INTO EFFECT LATE TONIGHT.

.DAYS TWO THROUGH SEVEN...FRIDAY THROUGH WEDNESDAY

A GALE WARNING IS IN EFFECT FRIDAY MORNING. A SMALL CRAFT ADVISORY
MAY BE NEEDED FRIDAY NIGHT THROUGH MONDAY.

WWW.WEATHER.GOV/MKX
TZ