Cold in Wisconsin, December 15, 2008

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MILWAUKEE/SULLIVAN WI
347 PM CST SUN DEC 14 2008

.SHORT TERM...992 MB SFC LOW MOVING NEWD THROUGH NW WI WITH ARCTIC
COLD FRONT SURGING EWD TOWARD THE MS RIVER. PCPN WILL CONTINUE TO
DEVELOP AND INTENSIFY ALONG THE COLD FRONT AS UPPER TROUGH AND 140
KT JET STREAK OVER THE ROCKIES SWINGS NEWD TOWARD THE WRN GRTLKS.
PCPN TO BEGIN AS RAIN AND THEN TRANSITION TO SNOW. SOUNDINGS
INDICATE SOME UNDERCUTTING OF COLD AIR BELOW A WARM LAYER BUT WILL
BE BRIEF. THEREFORE INTRODUCED MIXED PCPN INTO THE FCST THIS
EVENING. ONLY MINOR SNOW AND ICE ACCUMULATION EXPECTED BUT SOME
TRAVEL PROBLEMS ARE POSSIBLE ESPECIALLY WITH ABRUPT COOLING. COLD
FRONT TO REACH LAKE MI BY MID EVENING WITH TEMPS NEARING ZERO IN
THE FAR WRN CWA BY SUNRISE WITH UPPER SINGLE DIGITS IN THE FAR
EAST. WLY WINDS OF 20 TO 25 MPH AND VERY COLD TEMPS WILL GENERATE WIND
CHILLS AROUND 20 BELOW ZERO OVER SOUTH CENTRAL WI SO ISSUED AN
ADVISORY LATE TNT THROUGH MON AM.

WLY WINDS AND COLD ADVECTION TO DECREASE THROUGHOUT THE DAY ON
MONDAY BUT ONLY EXPECT TEMPS TO REBOUND 4 TO 6 DEGREES DESPITE
SOME SUNSHINE. A 1036 MB SFC HIGH TO THEN SETTLE OVER WI MON NT.
CLEAR SKIES AND RADIATIONAL COOLING SHOULD ALLOW TEMPS TO DROP
BELOW ZERO FOR MOST LOCATIONS. TRENDED TEMPS TOWARD THE NAM MOS.

MODELS CONTINUE TO SHIFT A 140 KT JET AND 700 MB SHORTWAVE INTO
THE GREAT LAKES TUE AND TUE NT. IT WILL ACT ON A TIGHT TROPOSPHERIC
TEMPERATURE GRADIENT TO PRODUCE DEEP ISENTROPIC LIFT AND Q-VECTOR
CONVERGENCE. MODELS DIFFER ON QPF WITH THE ECMWF AND NAM GENERATING
ABOUT A THIRD OF AN INCH WHILE THE GFS IS STILL AROUND 0.20
INCHES. TOOK A COMPROMISE OF THE QPF AND USED A 19:1 RATIO VIA
COBB TECHNIQUE. TOTAL SNOWFALL WOULD BE 4 TO 6 INCHES. GARCIA
METHOD STILL YIELDS ABOUT 4 INCHES GIVEN MIXING RATIOS OF 2 G/KG
AVAILABLE. WINTER WEATHER ADVISORIES WILL EVENTUALLY BE NEEDED FOR
TUE AFT AND NIGHT.

.LONG TERM...WILL FOLLOW THE ECMWF DURING THIS PERIOD. NWLY WINDS
AND COLD ADVECTION FOR WED AS LOW PRESSURE AREA DEPARTS. HIGH
PRESSURE TO THEN SETTLE OVER WI WED NT INTO THU AM WITH VERY COLD
TEMPS EXPECTED. A SHORTWAVE TROUGH WILL THEN LIFT NEWD OUT OF
THE DESERT SW TO THE GREAT LAKES BY FRI. LATEST ECMWF SFC LOW
MOVES NEWD ACROSS IN AND OHIO. WENT WILL LIKELY SNOW FOR THU AFT
AND NIGHT. HEADLINES WILL PROBABLY BE NEEDED FOR THIS EVENT AS
WELL. COLD ADVECTION TO THEN PREVAIL RIGHT THROUGH THE WEEKEND
WITH A RE-INFORCING SHOT OF COLD AIR BY SUN. 1000-500 MB
THICKNESSES WILL FALL FROM 522 DM ON FRI TO 504 DM BY SUN.

&&

.AVIATION...STRONG COLD FRONT TO MOVE THROUGH KMSN BETWEEN 23Z
SUNDAY AND 00Z MONDAY...AND KMKE AND KENW BETWEEN 01Z AND 02Z
MONDAY. BRISK SOUTH WINDS MAY WEAKEN SOME WITH THE FRONTAL
PASSAGE...BUT SHOULD BECOME BRISK OUT OF THE WEST ONCE AGAIN AFTER
IT...WITH COLD AIR ADVECTION MIXING DOWN WINDS IN THE LOW LEVELS.

STRONG LOW LEVEL FRONTOGENESIS SHOULD ALLOW LIGHT RAIN TO DEVELOP
AND ACCOMPANY THE FRONTAL PASSAGE. A QUICK CHANGE TO LIGHT SNOW IS
EXPECTED IN THE EVENING...BEFORE ENDING AROUND MIDNIGHT. THERE MAY
BE SOME LIGHT FREEZING RAIN AND LIGHT SLEET MIXING IN AT TIMES WITH
THE CHANGEOVER TO SNOW...BUT WILL NOT INCLUDE IN TAFS AT THIS TIME.
SOME MVFR VISIBILITIES ALSO POSSIBLE...BUT WILL LEAVE OUT OF TAFS.

PREVAILING MVFR CEILINGS ARE EXPECTED BOTH BEFORE AND AFTER THE
FRONTAL PASSAGE...LASTING INTO THE EARLY MORNING HOURS. DRY AIRMASS
WITHIN COLD AIR ADVECTION SHOULD HELP MIX OUT CEILINGS IN THE 08Z TO
10Z MONDAY PERIOD. BRISK WEST WINDS EXPECTED TO CONTINUE THROUGH THE
DAY MONDAY.

&&

.MARINE...GALE WARNING TO CONTINUE THROUGH 18Z MONDAY. BRISK SOUTH
WINDS TO 30 KNOTS EXPECTED...WITH FREQUENT 35 KNOT GALES MIXING DOWN
FROM 1000 FEET ALOFT. BRIEF WEAKENING OF WINDS POSSIBLE WITH FRONTAL
PASSAGE AS DESCRIBED ABOVE...BUT WILL REGAIN STRENGTH OUT OF THE
WEST AFTER THE FRONTAL PASSAGE. FREQUENT GALE FORCE GUSTS SHOULD END
BY 18Z MONDAY...AS WINDS ALOFT BEGIN TO WEAKEN. SMALL CRAFT
ADVISORIES WILL BE NEEDED MONDAY AFTERNOON...PERHAPS INTO MONDAY
NIGHT...AS WINDS AND WAVES SLOWLY SUBSIDE.

&&

.MKX WATCHES/WARNINGS/ADVISORIES...
WI...WIND CHILL ADVISORY FROM 3 AM TO 12 PM CST MONDAY FOR WIZ046-047-
     051-056>058-062-063-067-068.

LM...GALE WARNING UNTIL 12 PM CST MONDAY FOR LMZ643>646.

&&

SHORT/LONG TERM...20
AVIATION/MARINE...08

HAZARDOUS WEATHER OUTLOOK...UPDATED
NATIONAL WEATHER SERVICE MILWAUKEE/SULLIVAN WI
339 PM CST SUN DEC 14 2008

WIZ046-047-051-052-056>060-062>072-151100-
MARQUETTE-GREEN LAKE-FOND DU LAC-SHEBOYGAN-SAUK-COLUMBIA-DODGE-
WASHINGTON-OZAUKEE-IOWA-DANE-JEFFERSON-WAUKESHA-MILWAUKEE-
LAFAYETTE-GREEN-ROCK-WALWORTH-RACINE-KENOSHA-
339 PM CST SUN DEC 14 2008

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

.DAY ONE...TONIGHT

RAIN WILL CHANGE TO SNOW WITH PASSAGE OF A STRONG COLD FRONT THIS
EVENING ACROSS SOUTHERN WISCONSIN. LIGHT FREEZING RAIN AND LIGHT
SLEET MAY MIX IN BRIEFLY DURING THE EVENING. ONLY LIGHT SNOW
ACCUMULATIONS ARE EXPECTED.

A SHARP DROP IN TEMPERATURES BEHIND THE FRONT WILL CAUSE ANY
RESIDUAL WATER ON ROADS AND SIDEWALKS TO QUICKLY FREEZE.

.DAYS TWO THROUGH SEVEN...MONDAY THROUGH SATURDAY

SNOW IS LIKELY TUESDAY AFTERNOON AND TUESDAY NIGHT ACROSS ALL OF
SOUTHERN WISCONSIN. SNOW ACCUMULATIONS OF 4 TO 6 INCHES ARE POSSIBLE
BY LATE TUESDAY NIGHT.

SNOW IS LIKELY AGAIN THURSDAY AFTERNOON AND THURSDAY NIGHT...WITH
SNOW ACCUMULATIONS POSSIBLE.

.SPOTTER INFORMATION STATEMENT...

SPOTTER ACTIVATION WILL NOT BE NEEDED.

LMZ643>646-151100-
SHEBOYGAN TO PORT WASHINGTON WI-
PORT WASHINGTON TO NORTH POINT LIGHT WI-
NORTH POINT LIGHT TO WIND POINT WI-
WIND POINT WI TO WINTHROP HARBOR IL-
339 PM CST SUN DEC 14 2008

THIS HAZARDOUS WEATHER OUTLOOK IS FOR PORTIONS OF LAKE MICHIGAN.

.DAY ONE...TONIGHT

A GALE WARNING IS IN EFFECT TONIGHT...FOR STRONG SOUTHWEST WINDS UP
TO 30 KNOTS...WITH FREQUENT GALE FORCE GUSTS TO 35 KNOTS. THE STRONG
WINDS WILL SHIFT TO THE WEST LATER TONIGHT. IN ADDITION...HIGH WAVES
ARE EXPECTED TO CONTINUE.

.DAYS TWO THROUGH SEVEN...MONDAY THROUGH SATURDAY

THE GALE WARNING CONTINUES THROUGH MONDAY MORNING...FOR STRONG WEST
WINDS TO 30 KNOTS...WITH FREQUENT GALE FORCE GUSTS TO 35 KNOTS. THE
STRONG WEST WINDS WILL SLOWLY DECREASE DURING THE DAY.

SMALL CRAFT ADVISORIES WILL BE NEEDED MONDAY AFTERNOON AND PERHAPS
MONDAY EVENING...FOR BRISK WINDS AND HIGH WAVES.

WOOD
WWW.WEATHER.GOV/MKX