Lake Effect Snow Warning 1, NWS Milwaukee, WI

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MILWAUKEE/SULLIVAN WI
323 AM CST WED JAN 14 2009

.DISCUSSION...FORECAST FOCUS ON BRUTAL COLD FOR THE REST OF THE WEEK.

.SYNOPSIS...OMINOUS DIGGING TROUGH CLEARLY EVIDENT ON IR IMAGERY
HAS ITS EYES SQUARE ON SOUTHERN WISCONSIN FOR LATER TODAY. MUCH OF
CENTRAL AND EASTERN CANADA IS ENGULFED WITH VALUES OF -35 TO -40C
ON IR. SNOW WILL TAPER OFF THIS MORNING BEFORE A PERIOD OF BRUTAL
COLD TONIGHT THROUGH FRIDAY MORNING...BRINGING THE COLDEST
TEMPERATURES SINCE 1996.

.TODAY...CLIPPER SYSTEM RACING EAST ACROSS SOUTHERN IOWA EARLY
THIS MORNING. WIDESPREAD LIGHT SNOW HAS OVERSPREAD SRN WI.
VISIBILITIES REMAIN RATHER DECENT...AVERAGING BETWEEN 1 AND 2
MILES. MOISTURE IS MINIMAL AS ONE WOULD EXPECT LOOKING AT
TEMPERATURES HOVERING NEAR ZERO. MID LEVEL FRONTOGENESIS IS REALLY
THE ONLY FACTOR SUSTAINING THE SNOW AND THIS WILL SLIDE EAST
DURING THE AFTERNOON. THE BEST FORCING IS SLIDING SOUTHEAST ACROSS
WESTERN ILLINOIS. EXPECT THE SNOW TO GRADUALLY TAPER OFF FROM
WEST TO EAST THIS MORNING...WITH SOME SNOW HANGING AROUND IN THE
SOUTHEAST INTO EARLY AFTERNOON DUE TO A COMBO OF POSSIBLE LAKE
EFFECT AND SYNOPTIC CONTRIBUTIONS. INTERESTINGLY...THE LOCAL WRF4G
MODEL SHOWS A MESO LOW DEVELOPING OVER SOUTHERN LAKE MICHIGAN THIS
MORNING...WHICH CAUSES A SPIRAL BAND OF SNOW TO BRUSH THE
LAKESHORE COUNTIES THIS AFTERNOON. WILL LEAVE A CHANCE OF SNOW
NEAR THE LAKESHORE GOING THROUGH AFTERNOON. TOTAL ACCUMULATIONS
COULD REACH 2 INCHES NEAR THE ILLINOIS BORDER.

.TONIGHT THROUGH FRIDAY MORNING...THE REAL COLD WILL BEGIN TO
ARRIVE EARLY THIS EVENING. 08Z OBS INDICATE WIDESPREAD -20 TO -30F
TEMPS ACROSS CANADA. UNFORTUNATELY...THIS AIR WILL NOT MODIFY
MUCH AS IT BLEEDS INTO THE GREAT LAKES. IT SEEMS 925 MB TEMPS GET
COLDER AND COLDER WITH EACH MODEL RUN...AND THEY NOW AVERAGE
-24C...WITH THE NEW NAM SHOWING ALMOST -27C LATE TONIGHT. THIS
WILL YIELD LOWS NEAR -20F MOST PLACES WITH MODIFICATION ALONG THE
LAKESHORE...ALTHOUGH A WEST WIND WILL KEEP EVEN THOSE AREAS COLDER
THAN THEY WOULD OTHERWISE BE. WINDS WILL REMAIN ELEVATED AS A
1048 MB HIGH BUILDS INTO THE DAKOTAS. THIS SPELLS DISASTER FOR
WIND CHILLS. WIND CHILLS SHOULD BE ABLE TO DROP TO NEAR -40F
TONIGHT...WITH SOMEWHAT MODIFIED VALUES ON THE LAKESHORE.

THURSDAY...CAA CONTINUES. 2 METER TEMPS REFUSE TO RISE ABOVE
-7F...AND I TEND TO AGREE WITH THIS GIVEN THE TEMPS ALOFT. DESPITE
SUNSHINE...IT WOULD BE HARD TO BELIEVE THE SURFACE LAYER WOULD BE
ABLE TO WARM AS MUCH AS BUFKIT INDICATES WITH FRESH SNOW COVER.
GUSTY WINDS WILL CONTINUE...PRODUCING DANGEROUS WIND CHILLS.

THURSDAY NIGHT WILL PROBABLY BE THE COLDEST NIGHT IN OVER A
DECADE. HIGH PRESSURE WILL SINK SOUTH INTO MISSOURI...BRINGING THE
RIDGE AXIS OVER SC WI BY 12Z FRI. WITH THE ALREADY VERY COLD
START...I DON/T SEE ANY PROBLEM WITH REACHING THE LOW TO MID -20S
FOR LOWS FRIDAY MORNING. LONE ROCK WILL LIKELY REACH THE -30S.
EVEN MET MOS HAS LNR AT -29.

AFTER MUCH COLLABORATION WITH SURROUNDING OFFICES...WILL UPGRADE
THE WIND CHILL ADVISORY TO A WIND CHILL WARNING FOR THE ENTIRE CWA
FROM 00Z THIS EVENING TO 18Z FRIDAY. WIND CHILL WARNING CRITERIA
/-35F/ WILL PROBABLY NOT BE MET FOR A PERIOD THURSDAY AFTERNOON...
BUT IT WILL STILL BE DANGEROUSLY COLD THROUGH THE DAY. IT ISN/T
WORTH DROPPING THE WARNING EARLY THURSDAY AFTERNOON AND REISSUING
ANOTHER WARNING FOR THURSDAY NIGHT.

.THIS WEEKEND INTO EARLY NEXT WEEK...AS QUICKLY AS THE COLD
CAME...THAT/S HOW QUICK IT WILL LEAVE. SOUTHWEST WINDS LATE FRIDAY
NIGHT WILL BRING MUCH MILDER CONDITIONS BY COMPARISON. A CLIPPER
SYSTEM MAY DIVE SOUTHEAST INTO THE GREAT LAKES SATURDAY...SO
RAISED SNOW CHANCES A TAD.

&&

.AVIATION...IFR VISIBILITIES IN SNOW OVER SOUTHERN WISCONSIN THIS
MORNING AS LOW MOVES ACROSS SOUTHERN ILLINOIS TO THE OHIO RIVER
VALLEY THIS AFTERNOON. MAIN FORECAST PROBLEM WILL BE LAKE
ENHANCEMENT POTENTIAL.  LOCAL WRF MESO MODELS BASED ON GFS HAVE BEEN
DEVELOPING A MESO LOW OVER LAKE MICHIGAN.  PLACEMENT WAS OVER
WESTERN LAKE MICHIGAN OFF MILWAUKEE...BUT LATEST RUN PUTS IT MORE
OVER EASTERN LAKE MICHIGAN.  NEW NAM ALSO PRODUCES MESO LOW TO THE
EAST.  MESO LOW DROPS SOUTH.  MAIN DIFFERENCE IS WITH EASTERN
LOCATION...LAKE SNOW BANDS WOULD BE OVER THE LAKE...WHILE A MORE
WESTERLY LOCATION COULD PULL LAKE BAND INTO AREAS SOUTH OF
MILWAUKEE.  VFR CIGS BY TONIGHT WITH STRONG COLD AIR ADVECTION.

&&

.MARINE...ANOTHER CLIPPER SYSTEM WILL MOVES ACROSS SOUTHERN ILLINOIS
TO THE OHIO RIVER VALLEY THIS AFTERNOON. MAIN FORECAST PROBLEM WILL
BE LAKE  ENHANCEMENT POTENTIAL.  A SMALL CRAFT ADVISORY IS IN EFFECT
WED AFTERNOON THROUGH THURSDAY MORNING. HEAVY FREEZING SPRAY WILL
ALSO BE ISSUED FROM WED NIGHT THROUGH FRIDAY MORNING DUE TO VERY
COLD TEMPERATURES AND ELEVATED NORTHWEST WINDS. WAVES HIGHEST TOWARD
OPEN WATER WHERE FREEZING SPRAY WILL BE MOST LIKELY.

&&

&&

.MKX WATCHES/WARNINGS/ADVISORIES...
WI...WIND CHILL WARNING FROM 6 PM THIS EVENING TO 12 PM CST FRIDAY
     FOR WIZ046-047-051-052-056>060-062>072.

LM...SMALL CRAFT ADVISORY FROM 4 PM THIS AFTERNOON TO 10 AM CST
     THURSDAY FOR LMZ643>646.

     HEAVY FREEZING SPRAY WATCH FROM THIS AFTERNOON THROUGH THURSDAY
     MORNING FOR LMZ643>646.

&&

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

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