Ice Storm Warning 1, NWS Milwaukee, WI

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MILWAUKEE/SULLIVAN WI
313 PM CST WED FEB 25 2009

.FORECAST FOCUS ON WINTER STORM FOR THURSDAY...FOLLOWED BY MAINLY
COLD AND DRY CONDITIONS FOR THE EXTENDED.

.SHORT TERM...TONIGHT THROUGH FRIDAY.

WAVE NUMBER ONE THAT BROUGHT RAIN ACROSS THE CWA HAS PUSHED QUICKLY
EAST OF THE STATE THIS MORNING. HIGH PRESSURE BUILDING ACROSS
SOUTHERN CANADA WILL FUNNEL COLDER AIR SOUTH AT THE SURFACE ON
EAST OR NORTHEAST WINDS THIS EVENING. MEANWHILE...STRENGTHENING
LOW PRESSURE OVER THE CENTRAL PLAINS WILL CAUSE STRONG WARM AIR
ADVECTION BETWEEN 900 AND 700 MB. AS A RESULT...A VERY PRONOUNCED
INVERSION IS EXPECTED WITH STEEP LAPSE RATES ABOVE. THIS WILL
SET UP A VERY DIFFICULT FORECAST SITUATION BY THURSDAY AFTERNOON.

MODEL CONSENSUS HAS BEEN IMPROVING WITH EACH MODEL RUN...WITH THE
EXCEPTION OF THE ECMWF WHICH IS A BIT WARMER THAN THE NAM/GFS. THE
GFS REMAINS THE COLDER MODEL. REGARDLESS OF THE MODEL...CONFIDENCE
IS INCREASING FOR AN ICE STORM TO OCCUR ROUGHLY FROM SAUK COUNTY
EASTWARD TO WASHINGTON AND NORTH TO FOND DU LAC AND SHEBOYGAN.
THIS IS THE REGION WITH COLD SURFACE TEMPS /BELOW FREEZING ON THE
SREF AND THE NAM/GFS 2 METER TEMPS/...AND WARM 850 MB AIR /+4 TO
+6C/ THURSDAY AFTERNOON. ROAD TEMPERATURES ARE STILL WELL BELOW
FREEZING...BUT WITH AIR TEMPS IN THE LOWER 30S..SALT SHOULD DO
THE JOB PRETTY WELL. THE BIGGEST CONCERN HERE IS ICING ON TREES
AND POWER LINES WITH POTENTIAL FOR POWER OUTAGES. QPF IS RATHER
IMPRESSIVE AND ICE ACCUMULATIONS OF A HALF INCH ARE POSSIBLE IF
PRECIPITATION REMAINS MOSTLY FREEZING RAIN AS EXPECTED. OF COURSE
IF TEMPERATURES RISE EVEN ONE DEGREE ABOVE FREEZING...THIS WILL BE
A MAJOR BUST. SNOW WILL LIKELY FALL THURSDAY EVENING...PERHAPS
LEAVING 1-3 INCHES...BUT THE ICING IS THE MAIN CONCERN. A LENGTHY
IN-HOUSE DISCUSSION CONCLUDED SINCE THE ICING THREAT HAS THE
HIGHEST PRIORITY AND IMPACT...WILL ISSUE AN ICE STORM WARNING FOR
THESE AREAS. THE IC.W WILL LIKELY BE REPLACED WITH A WINTER
WEATHER ADVISORY THURSDAY EVENING AS PRECIP TURNS TO SNOW.

FARTHER NORTH ACROSS MARQUETTE AND GREEN LAKE COUNTY...850 MB
TEMPS AREN/T QUITE AS WARM AND THE SUBFREEZING LAYER NEAR THE
SURFACE IS DEEP ENOUGH TO SUPPORT A MIX OF SLEET AND FREEZING
RAIN...PERHAPS MIXED WITH SNOW AT TIMES. GIVEN THE POTENTIAL FOR A
FEW INCHES OF SNOW...IN ADDITION TO AROUND 1/4 INCH OF ICE...WILL
ISSUE A WINTER STORM WARNING FOR THESE AREAS.

FURTHER SOUTH ALONG A LINE FROM DODGEVILLE TO PORT WASHINGTON...
MAINLY RAIN IS EXPECTED THURSDAY...WITH RAIN CHANGING TO
SLEET...FREEZING RAIN AND SNOW LATE THURSDAY AFTERNOON AND
EVENING. GIVEN THIS CHANGE OCCURS DURING RUSH HOUR...FEEL A WINTER
WEATHER ADVISORY IS NECESSARY.

FURTHER SOUTH YET NEAR THE IL BORDER...MAINLY RAIN IS EXPECTED
FOR MUCH OF THE EVENT WITH AN HOUR OR TWO OF SNOW OR SLEET. NO
HEADLINES PLANNED FOR THIS AREA...YET.

ALSO ADDED A CHANCE OF THUNDERSTORMS TO THE FAR SOUTHEAST GIVEN
700-800 J/KG OF ELEVATED CAPE THURSDAY AFTERNOON AND THE STRONG
DYNAMICS OF THE SYSTEM.

WINDY AND COLD CONDITIONS ARE EXPECTED BEHIND THE SYSTEM INTO
FRIDAY.

.LONG TERM...FRIDAY NIGHT THROUGH NEXT WEDNESDAY.

HIGH PRESSURE SLIDES EAST TO THE EASTERN GREAT LAKES FRIDAY NIGHT.
MEANWHILE...LOW PRESSURE WILL DEVELOP ALONG THE TRAILING COLD
FRONT FROM THE DEPARTING WINTER STORM FRIDAY EVENING OVER THE SERN
US. A SECOND UPPER AIR IMPULSE WILL TRACK SOUTHEAST FROM THE
CENTRAL PLAINS TO THE MID MISSISSIPPI RIVER VALLEY SATURDAY. THIS
ENERGY IS EXPECTED TO ALMOST COMPLETELY BYPASS THE CWA...HOWEVER A
THIRD VIGOROUS IMPULSE WILL DROP SOUTHEAST INTO THE UPPER GREAT
LAKES FROM ONTARIO SATURDAY NIGHT. WITH BOTH IMPULSES FAIRLY CLOSE
BY...FELT OBLIGATED TO INCLUDE SCHC -SN DURING THIS PERIOD. DUE TO
THE GULF BEING CUT OFF FROM THE STORM IN THE SOUTHEAST...LITTLE
MOISTURE WILL BE AVAILABLE SO ANY SNOW ACCUMULATIONS WOULD REMAIN
VERY LIGHT.

ANOTHER SHOT OF COLD AIR WILL FOLLOW THE NORTHEASTERN IMPULSE...
BRINGING HIGHS ONLY NEAR 20 SUNDAY...WITH NEAR ZERO READINGS
SUNDAY NIGHT. HIGH PRESSURE SETTLING NORTH AND NORTHEAST OF THE
CWA MAY TURN WINDS NORTHEASTERLY FOR A TIME...PUSHING BANDS OF
LIGHT LAKE EFFECT SNOW SHOWERS WESTWARD. HOWEVER WITH LIGHT WINDS
AND MARGINAL DELTA T/S...IT SHOULDN/T AMOUNT TO MUCH...IF ANY.

INTO THE MIDDLE OF NEXT WEEK...HPC FAVORED HI-RES ECMWF OVER THE
GFS. LOOKS LIKE A NORTHWEST FLOW...WITH BELOW AVERAGE TEMPS. 12Z
GFS CAME IN WITH A WEAK CLIPPER SYSTEM TUESDAY...WITH HI-RES ECMWF
EVEN WEAKER. WILL HOLD OFF ON INTRODUCING POPS AND SNOW YET. MAIN
STORY FOR THE EXTENDED IS WINTER CONTINUES UNTIL FURTHER NOTICE...

&&

&&

.AVIATION...JUST SCT CLOUDS LEFT OVER WESTERN WI WITH BKN TO OVC
CONDITIONS LINGERING OVER EASTERN PARTS OF THE STATE. EXPECT
CONTINUED CLEARING FROM WEST TO EAST INTO THE EVENING WITH SKC
CONDITIONS BY LATE THIS EVENING AND INTO TONIGHT. CLEAR CONDITIONS
WILL BE SHORT LIVED AS CLOUDS MOVE BACK IN TOMORROW MORNING AHEAD OF
NEXT SYSTEM. EXPECT LOWERING CLOUDS DURING THE MORNING AND INTO THE
AFTERNOON AS PRECIP MOVES INTO THE AREA. EXPECT MVFR CONDITIONS BY
LATE MORNING WITH IFR CONDITIONS POSSIBLE IN THE HEAVIER SHOWERS.
PRECIP SHOULD BE ALL RAIN DURING THE DAY SOUTH OF A LINE FROM PORT
WASHINGTON TO DODGEVILLE...WITH A CHANCE FOR THUNDERSTORMS ACROSS
FAR SOUTHEAST WI. NORTH OF THAT LINE...EXPECT A MIX OF
RAIN...SNOW...FREEZING RAIN...AND SLEET.

&&

.MARINE...A STRONG LOW WILL APPROACH ON THURSDAY AND MAY REQUIRE
SMALL CRAFT ADVISORY THURSDAY AFTERNOON. AS LOW PASSES EAST...VERY
STRONG NORTHERLY WINDS KICK IN FOR THURSDAY NIGHT AND FRIDAY. WAVES
SHOULD EVENTUALLY BUILD TO 6 TO 9 FEET OVERNIGHT.

&&

.MKX WATCHES/WARNINGS/ADVISORIES...
WI...WINTER WEATHER ADVISORY FROM 5 PM THURSDAY TO MIDNIGHT CST
     THURSDAY NIGHT FOR WIZ060-064-065.

     WINTER WEATHER ADVISORY FROM 3 PM THURSDAY TO MIDNIGHT CST
     THURSDAY NIGHT FOR WIZ062-063.

     WINTER STORM WARNING FROM NOON THURSDAY TO MIDNIGHT CST THURSDAY
     NIGHT FOR WIZ046-047.

     ICE STORM WARNING FROM NOON THURSDAY TO MIDNIGHT CST THURSDAY
     NIGHT FOR WIZ051-052-056>059.

LM...NONE.

&&

SHORT/LONG TERM...BORGHOFF
AVIATION/MARINE...VANCLEVE

HAZARDOUS WEATHER OUTLOOK...UPDATED
NATIONAL WEATHER SERVICE MILWAUKEE/SULLIVAN WI
1154 AM CST WED FEB 25 2009

WIZ046-047-051-052-056>060-062>072-261045-
MARQUETTE-GREEN LAKE-FOND DU LAC-SHEBOYGAN-SAUK-COLUMBIA-DODGE-
WASHINGTON-OZAUKEE-IOWA-DANE-JEFFERSON-WAUKESHA-MILWAUKEE-
LAFAYETTE-GREEN-ROCK-WALWORTH-RACINE-KENOSHA-
1154 AM CST WED FEB 25 2009

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

.DAY ONE...TODAY AND TONIGHT

NO HAZARDOUS WEATHER IS EXPECTED AT THIS TIME.

.DAYS TWO THROUGH SEVEN...THURSDAY THROUGH TUESDAY

A WINTER STORM WATCH IS IN EFFECT FROM NOON ON THURSDAY THROUGH
THURSDAY NIGHT FOR THE AREA ROUGHLY NORTH OF A LIVINGSTON TO PORT
WASHINGTON LINE. A WINTRY MIX OF RAIN AND SNOW THURSDAY WILL
CHANGE OVER TO ALL SNOW BY THURSDAY NIGHT WITH 5 TO 8 INCHES OF
TOTAL SNOW ACCUMULATION POSSIBLE. THERE COULD BE A PERIOD OF
FREEZING RAIN AND SLEET LATE THURSDAY MORNING AND INTO THE AFTERNOON
ACROSS AREAS OF SOUTH CENTRAL WISCONSIN. IN ADDITION...BRISK NORTH
WINDS DEVELOPING THURSDAY NIGHT AND FRIDAY WILL CAUSE BLOWING AND
DRIFTING SNOW.

UNCERTAINTY EXISTS IN THE EXACT PLACEMENT OF THE HEAVIER SNOW
ACCUMULATIONS AND WINTRY MIX DUE TO THE POTENTIAL VARIABILITY IN
THE FINAL STORM TRACK. STAY TUNED FOR LATER UPDATES.

.SPOTTER INFORMATION STATEMENT...

SPOTTER ACTIVATION WILL NOT BE NEEDED TONIGHT.

LMZ643>646-261045-
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-
1154 AM CST WED FEB 25 2009

THIS HAZARDOUS WEATHER OUTLOOK IS FOR PORTIONS OF LAKE MICHIGAN.

.DAY ONE...TODAY AND TONIGHT

NO HAZARDOUS WEATHER IS EXPECTED AT THIS TIME.

.DAYS TWO THROUGH SEVEN...THURSDAY THROUGH TUESDAY

WINDS AND WAVES WILL LIKELY REACH SMALL CRAFT ADVISORY LEVELS
THURSDAY AFTERNOON AND REMAIN ELEVATED THROUGH FRIDAY NIGHT.

DDV
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