Dense Fog in Wisconsin, March 7 to 8, 2009

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MILWAUKEE/SULLIVAN WI
300 PM CST SAT MAR 7 2009

.SHORT TERM /TNGT THROUGH TUESDAY/...
FORECAST CONCERN IS INCREASING THREAT FOR BURST OF HEAVY SNOW ACROSS
SOUTHERN WISCONSIN ON SUNDAY.  CURRENT RAIN AREA ACROSS EASTERN IOWA
INTO SOUTHERN WISCONSIN LINING UP WELL WITH LOW CONDENSATION
PRESSURE DEFICITS AND NET ISENTROPIC OMEGA FROM 295 THETA SURFACE
FROM NAM AT 21Z.  CDP REMAINS LOW IN SOUTH TONIGHT BUT OMEGA SHIFTS
OFF TO THE EAST...HENCE EXPECTING RAIN TO DIMINISH TO PATCHY LIGHT
RAIN AND DRIZZLE IN THE SOUTH FOR A TIME.  COLDER...DRIER AIR OVER
CENTRAL/NORTHERN WI SHOULD OOZE INTO SOUTHERN WISCONSIN AS WELL
OVERNIGHT ALLOWING TEMPERATURES TO DROP INTO THE UPPER 20S TO LOWER
30S.

VIGOROUS SHORT WAVE TROF UPSTREAM OVER COLORADO WILL BE AFFECTED BY
UPSTREAM KICKER APPROACHING PACIFIC NORTHWEST AND RACE NORTHEAST
TONIGHT AND SUNDAY.  LAST SEVERAL RUNS OF THE GFS...CANADIAN...NAM
AND UKMT TAKING THIS SHORT WAVE FARTHER SOUTH ACROSS NORTHERN IL AND
SRN LAKE MI BY LATE SUN.  700H CIRCULATION PASSES RIGHT ACROSS SRN
WI BETWEEN 18Z/08 AND 00Z/09.  HI RES ECMWF TRENDING SLIGHTLY
SOUTHWARD AS WELL...BUT ABOUT 60MILES FARTHER NORTH.  WL FOLLOW
COLDER TREND TO THE SOUTH.  SHORT WAVE HAS ABUNDANT DYNAMICS AS ITS
BEEN GENERATING THUNDER WITH LIGHTNING IN ERN CO/NM BEHIND THE DRY
LINE TODAY.  EXPECT PRECIP TO OVERSPREAD SOUTHERN WISCONSIN LATE
TONIGHT AND SUNDAY MORNING.  FORECAST SOUNDINGS SHOW PRECIP SHOULD
BE MIXTURE OF MOSTLY SLEET AND RAIN INITIALLY...AND WITH
TEMPERATURES INITIALLY BELOW FREEZING IN NORTHERN CWA...MAY BE A
PERIOD OF MIXED SLEET/ZR.  OTHERWISE...DYNAMIC COOLING ASSOCIATED
WITH SIGGY SHORT WAVE CAUSES CRITICAL THICKNESSES TO CRASH DURING
THE LATE MORNING IN THE WEST AND ACROSS THE REST OF THE CWA DURING
THE AFTERNOON.  EXPECT MIXTURE OF PRECIPITATION TO CHANGE RAPIDLY
OVER TO SNOW DURING THIS TIME.  IMPRESSIVE LAYER Q-VECTOR
CONVERGENCE THROUGH THE MID LEVELS WITH A PERIOD OF COUPLED JETS
OVER SOUTHERN WI.  850H TEMPERATURES FALL RAPIDLY BELOW FREEZING
DURING THIS TIME.  IMPRESSIVE CROSS HAIR SIGNATURE WITH SLOPING FN
VECTOR RESPONSE TO 2-D FULL WIND FRONTOGENESIS.  CROSS SECTION ALSO
REVEALS PERIOD OF STRONG AGEOSTROPHIC VERTICAL CIRCULATION FROM THE
SURFACE TO THE MID LEVELS WITH LARGE LAYER OF NEGATIVE EPV
INDICATING CONVECTIVE POTENTIAL.  WHAT ALL THIS MEANS...IS THAT MAY
BE A 2 TO 5 HOUR PERIOD OF SLEET AND SNOW...POSSIBLY HEAVY...MOVING
ACROSS THE NORTH AND WEST SUNDAY AFTERNOON.  SOME OF THE SNOW WILL
MELT ON THE PAVEMENT BUT STILL LOOKING AT POSSIBLE 4 TO 8 INCH
ACCUMULATIONS WHERE THIS CHANGEOVER TAKES PLACE.  ROEBBER AND COBB
FAVORING WET 10 TO 1 RATIOS.  HENCE WENT WITH A WINTER STORM WATCH
FOR THE WEST AND SOUTH...AND WILL LET EVENING OR MIDNIGHT SHIFT
RESOLVE AFFECT OF SNOW BURST FOR SUNDAY.

HEAVIEST RAINS TODAY REMAINED OVER CENTRAL SECTIONS OF CWA WITH 0.50
TO 1.0 RESULTING IN SOME PONDING.  GROUND REMAINS FROZEN ACROSS MOST
OF THE AREA AND EXPECTING ANOTHER BURST OF HEAVY RAIN PRIOR TO
CHANGE ON SUNDAY.  BEST LOW LEVEL CONVERGENCE IN SOUTHERN AREAS
WHERE RAIN HAS BEEN LESS TODAY.  HENCE WL FOREGO FLOOD WATCH FOR
SOUTHEAST AT THIS POINT BUT WILL ALSO NEED TO BE REEVALUATED
TONIGHT.

MODELS IN GENERAL AGREEMENT ON ANOTHER VIGOROUS SHORT WAVE MOVING
THROUGH THE UPPER MIDWEST ON TUESDAY.  DEEP MOISTURE AVAILABLE AND
ENOUGH WARM AIR ADVECTION AHEAD OF THIS SYSTEM TO KEEP THE
PRECIPITATION AS RAIN LATER MONDAY NIGHT AND TUESDAY.

.LONG TERM /TUESDAY NIGHT THROUGH SATURDAY/...
LONG TERM GUIDANCE REMAINS IN GOOD AGREEMENT ON STRONG SHORT WAVE
TROUGH MOVING THROUGH WISCONSIN LATER TUESDAY AND TUESDAY EVENING.
MAY BE A TOUCH SLOWER THAN EARLIER THINKING...SO WL CONTINUE MAINLY
RAIN IN THE EVENING IN THE EASTERN CWA ON TUESDAY BEFORE ENDING OR
CHANGING OVER TO LIGHT SNOW.  ELEVATED CAPE IN THE EVENING OVER 500
J/KG IN EAST.  CONSIDERING STRENGTH OF SHORT WAVE AND
MOISTURE...WILL ADD THUNDER THREAT TO EVENING AS WELL.

STRONG PUSH OF COLD AIR ADVECTION IMMEDIATELY BEHIND FRONT TUESDAY
NIGHT WITH PERHAPS SOME LIGHT SNOW SPREADING BACK INTO SOUTHERN
WISCONSIN BEFORE SYSTEM RAPIDLY EXITS TO THE NORTHEAST.  TYPICAL GFS
COLD BIAS FOR MIDDLE OF NEXT WEEK.  THINKING UPPER FLOW WILL NOT BE
QUITE AS NORTHWEST AS INDICATED BY GFS...SO WL KEEP TEMPERATURES A
FEW DEGREES WARMER THAN MOS GUIDANCE.  A QUIET AND COOL PERIOD WITH
DEEP MOISTURE GETTING SUPPRESSED WELL TO THE SOUTH AS SPRAWLING HIGH
PRESSURE SETTLES OVER THE REGION.  WEAK SHORT WAVE TROUGH BETWEEN
HIGH PRESSURE SYSTEMS MAY BRING SOME CLOUDS TO THE REGION THURSDAY
NIGHT THROUGH FRIDAY BUT MOISTURE APPEARS SPARSE.

&&

.AVIATION...PREVAILING MVFR CONDITIONS EXPECTED WITH THE LIGHT TO
MODERATE RAIN AT TAF SITES THROUGH THE EARLY EVENING HOURS. SOME IFR
CEILINGS AND VISIBILITIES ARE POSSIBLE AT TIMES. BEST UPWARD MOTION
WITH RAIN MOVES OFF TO THE EAST BY MID EVENING...WITH LINGERING MVFR
CEILINGS AND VISIBILITIES THROUGH THE REST OF THE NIGHT.

EAST TO NORTHEAST WINDS STRENGTHEN WITH APPROACH OF STRONG LOW
PRESSURE LATE TONIGHT AND SUNDAY. DEEP LAYER UPWARD VERTICAL MOTION
STRENGTHENS DURING SUNDAY MORNING...WITH FORECAST SOUNDINGS SHOWING
POTENTIAL FOR A MIXTURE OF RAIN...FREEZING RAIN...SLEET AND SNOW.
FOR NOW...WILL JUST MENTION A MIX OF RAIN AND SNOW WITH MVFR
CONDITIONS UNTIL FREEZING RAIN AND SLEET POTENTIAL BECOMES MORE
CLEAR.

AS COLDER AIR QUICKLY MOVES INTO THE AREA DURING THE AFTERNOON...A
QUICK CHANGEOVER TO SNOW FROM WEST TO EAST CAN BE EXPECTED. IFR TO
LIFR CONDITIONS ARE POSSIBLE WITH THE SNOW. SNOW COULD BE MODERATE
TO HEAVY AT KMSN GIVEN STRONG DEEP LAYER ASCENT AND POSSIBLE
CONVECTION. KMKE AND KENW WOULD SEE THE CHANGEOVER BY LATE
AFTERNOON.

&&

.MARINE...PASSAGE OF STRONG LOW PRESSURE MENTIONED ABOVE WILL LEAD
TO BRISK NORTHEAST WINDS OF 15 TO 25 KNOTS ALONG THE NEARSHORE
WATERS ON SUNDAY. WAVES OF 3 TO 6 FEET ARE EXPECTED WITH THESE
WINDS...GIVEN THE FAVORABLE NORTHEAST FETCH AND ICE FREE SHORELINE.
THUS...A SMALL CRAFT ADVISORY WILL BE ISSUED FOR SUNDAY.

SMALL CRAFT ADVISORY CONDITIONS ARE POSSIBLE AGAIN TUESDAY THROUGH
WEDNESDAY...WITH ANOTHER POTENT LOW PRESSURE SYSTEM MOVING NORTHEAST
THROUGH THE REGION.

&&

.MKX WATCHES/WARNINGS/ADVISORIES...
WI...WINTER STORM WATCH 15Z/08 TO 23Z/08 WIZ056-062-067.
     WINTER STORM WATCH 17Z/08 TO 23Z/09 WIZ046-047-051-052
     057>059-063-068. /CDT/
LM...SMALL CRAFT ADVISY 12Z/08 TO 00Z/09 LMZ643>646.

SHORT/LONG TERM...MBK
AVIATION/MARINE...WOOD

HAZARDOUS WEATHER OUTLOOK...UPDATED
NATIONAL WEATHER SERVICE MILWAUKEE/SULLIVAN WI
342 PM CST SAT MAR 7 2009

WIZ046-047-051-052-056>060-062>072-081045-
MARQUETTE-GREEN LAKE-FOND DU LAC-SHEBOYGAN-SAUK-COLUMBIA-DODGE-
WASHINGTON-OZAUKEE-IOWA-DANE-JEFFERSON-WAUKESHA-MILWAUKEE-
LAFAYETTE-GREEN-ROCK-WALWORTH-RACINE-KENOSHA-
342 PM CST SAT MAR 7 2009

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

.DAY ONE...TONIGHT

RAINFALL TOTALS RANGING FROM ONE QUARTER UP TO ONE INCH ARE EXPECTED
THROUGH TONIGHT. THE COMBINATION OF THE RAINFALL...ALONG WITH RUNOFF
FROM THE RECENT SNOW MELT AND THE FROZEN GROUND...MAY CAUSE
LOCALIZED LOWLAND FLOODING. THE BEST CHANCE WOULD BE ACROSS AREAS
NEAR THE ILLINOIS BORDER.

THE FOX RIVER NEAR NEW MUNSTER IS EXPECTED TO REACH MINOR FLOOD
STAGE THIS EVENING.

THE WISCONSIN DEPARTMENT OF NATURAL RESOURCES HAS ISSUED AN AIR
QUALITY ADVISORY FOR PARTICLE POLLUTION FOR MILWAUKEE...WAUKESHA AND
OZAUKEE COUNTIES UNTIL 11 PM TONIGHT.

.DAYS TWO THROUGH SEVEN...SUNDAY THROUGH FRIDAY

A WINTER STORM WATCH IS IN EFFECT LATE SUNDAY MORNING THROUGH SUNDAY
AFTERNOON...MAINLY NORTHWEST OF A MONROE...TO COLUMBUS...TO
SHEBOYGAN LINE. SNOW ACCUMULATIONS OF 4 TO 8 INCHES ARE POSSIBLE IN
THE WATCH AREA...WITH LIGHTER AMOUNTS TO THE EAST. SEE THE WINTER
WEATHER MESSAGE PRODUCT FOR MORE INFORMATION.

THERE IS A CHANCE OF THUNDERSTORMS ON SUNDAY.

ANY ADDITIONAL RAINFALL EARLY SUNDAY WILL CAUSE SOME RIVERS ACROSS
SOUTHERN WISCONSIN TO EXCEED BANKFULL AND FLOOD STAGE DURING THIS
PERIOD.

ANOTHER STRONG LOW WILL PASS NORTHEAST THROUGH WISCONSIN ON
TUESDAY...BRINGING MORE RAINFALL...AND AGGRAVATING ANY FLOODING THAT
IS ONGOING.

.SPOTTER INFORMATION STATEMENT...

SPOTTER ACTIVATION WILL NOT BE NEEDED...BUT RAINFALL REPORTS WILL BE
APPRECIATED.

LMZ643>646-081045-
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-
342 PM CST SAT MAR 7 2009

THIS HAZARDOUS WEATHER OUTLOOK IS FOR PORTIONS OF LAKE MICHIGAN.

.DAY ONE...TONIGHT

NO HAZARDOUS WEATHER IS EXPECTED AT THIS TIME.

.DAYS TWO THROUGH SEVEN...SUNDAY THROUGH FRIDAY

A SMALL CRAFT ADVISORY IS IN EFFECT SUNDAY...FOR BRISK NORTHEAST
WINDS AND HIGH WAVES.

WINDS AND WAVES MAY REACH SMALL CRAFT ADVISORY LEVELS AGAIN TUESDAY
THROUGH WEDNESDAY.

THERE IS A CHANCE OF THUNDERSTORMS ON SUNDAY.

WOOD
WWW.WEATHER.GOV/MKX