Area Forecast Discussion
Issued by NWS Milwaukee/Sullivan, WI

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FXUS63 KMKX 241722
AFDMKX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MILWAUKEE/SULLIVAN WI
1122 AM CST TUE FEB 24 2015

.UPDATE...WATER VAPOR/RAP COMBO SHOWS SHORTWAVE AXIS ENTERING SRN
WI. THIS RESULTED IN SEVERAL AREAS OF MAINLY LIGHT SNOW SHOWERS.
FRONTALLY INDUCED BAND OF SCT SHSN SHIFTING SE FROM CNTRL WI. THIS
WILL COME THROUGH THIS AFTERNOON AND THE HRRR HAS A PRETTY GOOD
HANDLE ON THESE TRENDS. POST FRONTAL PRESSURE RISE AREA MOVING
INTO NW WI AND ALL OF MN.

PC

&&

.AVIATION/18Z TAFS/...POCKETS OF SNOW SHOWERS CONTINUE ASSOCIATED
WITH SHORTWAVE TROUGH MOVING THROUGH SRN WI. MORE SCT SHSN ARE
MOVING SE FROM CNTRL WI. EXPECT THESE TO SWING THROUGH THIS
AFTERNOON WITH RAPID CLEARING IN THE WAKE. SO SOME MVFR CIGS/VSBYS
AT TIMES WITH ISOLATED IFR VSBYS IN SOME OF THE HEAVIER SNOW
SHOWERS. THESE WILL BE MOVING ALONG WITH MINOR ACCUMS. NEXT
SHORTWAVE WILL INCREASE MID DECK ON WEDNESDAY THOUGH WILL KEEP ANY
AFTERNOON SNOW CHANCES SW OF KMSN.

PC

&&

.PREV DISCUSSION... /ISSUED 904 AM CST TUE FEB 24 2015/

UPDATE...HAVE MADE A QUICK UPDATE TO BOOST POPS UP EVERYWHERE
WITH AREA RADAR MOSAIC SHOWING INITIAL BAND MOVG THROUGH SE WI AND
SECONDARY AREA SWINGING SE FROM KARX AREA. SOME DECENT RETURNS
WITH KARX VSBY DOWN TO 2SM. STILL LOOKING AT MINOR ACCUMS...FEW
TENTHS.

PC

PREV DISCUSSION... /ISSUED 330 AM CST TUE FEB 24 2015/

TODAY...FORECAST CONFIDENCE IS MEDIUM.

WILL CONTINUE LIKELY WORDING FOR A PERIOD OF -SN THIS MORNING
MAINLY OVER CENTRAL AND EASTERN PORTIONS OF CWA. IMPRESSIVE LAYER
Q-VECTOR CONVERGENCE OF 20 UNITS EXTENDS FROM THROUGH THE LOW TO
MID-LAYERS. Q-VECTOR CONVERGENCE A RESULT OF STRONG WARM AIR
ADVECTION AND STRONG SHORT WAVE TROUGH CURRENTLY ADVANCING INTO
NRN MN...WHICH IS TIED TO LEFT EXIT REGION OF UPPER JET. THIS WAVE
RIDING ON THE HEELS OF FIRST WAVE CURRENTLY MOVING EWD ACROSS NRN
WI.

FIRST WAVE SERVING TO MOISTEN MID-LEVELS WITH PATCHY -SN FALLING
ACROSS NRN WI. SECOND WAVE WL HAVE A BIT MORE LOW TO MID-LEVEL
MOISTURE TO WORK WITH AS COLUMN PWAT INCREASES TO AROUND A QUARTER
INCH THIS MRNG. SHORT RANGE GUIDANCE ALSO SHOWS A BRIEF PERIOD OF
FRONTOGENETICAL FORCING SLIDING ACROSS SRN WI LATER THIS MRNG.
POTENTIAL FOR ONE HALF INCH UP TO ONE INCH OF SNOW IN NORTHEAST
CWA. WL BE LUCKY TO GET MEASUREABLE LIQUID PRECIP ACROSS SOUTHWEST
CWA.

DESPITE LOSS OF MID-LEVEL MOISTURE THIS AFTERNOON...ARCTIC FRONT
EXPECTED TO MOVE ACROSS SRN WI. LINGERING LOW LEVEL RH UP TO 5K
FEET...PARTIALLY IN DENDRITIC GROWTH ZONE...AND STEEP LOW LEVEL
LAPSE RATES AS FRONT SLIDES THRU. HENCE KEPT SOME LOWER POPS FOR
POTENTIAL OF SCT -SHSN ACROSS ERN CWA. RAP SOUNDINGS SHOWS LOW
LEVEL RH DECREASING RAPIDLY IN THE LATE AFTN WHILE NAM HOLDS ONTO
DEEPER MOISTURE INTO THE EVE. FOR NOW KEPT EVENING /AFTER 00Z/
DRY.

925H TEMPS WARM TO -6 TO -8. HOWEVER CLOUDS AND BREEZY SOUTHWEST
TO WEST WINDS WL KEEP DAYTIME HIGHS IN CHECK. EXPECT HIGHS TO PEAK
IN THE MID 20S TO AROUND 30.

TONIGHT...FORECAST CONFIDENCE IS HIGH.

ARCTIC FRONT SLIDES ACROSS SRN WI TNGT ALLOWING COLD AIR TO
RETURN ON NORTHWEST WINDS. LOW LEVEL MIXING OF DRY AIR SHOULD
RESULT IN CLEARING SKIES OVERNIGHT WITH OVERNIGHT TEMPS RETURNING
TO THE SINGLE DIGITS ABV ZERO. MAY HAVE SOME GUSTS TO 25 KTS IN
THE LATE AFTN AND EARLY EVE RESULTING IN PATCHY BLOWING SNOW WITH
BEST CHANCE IN THE NORTHEAST. OTHERWISE...NOT EXPECTING MUCH BS
FROM CURRENT SNOW COVER DUE TO CRUST.

SHORT TERM...WEDNESDAY THROUGH THURSDAY NIGHT...FORECAST
CONFIDENCE IS MEDIUM.

MODELS ARE IN DECENT AGREEMENT WITH SHOWING A GENEARL NORTHWEST
FLOW AT 500 MB ACROSS THE REGION DURING THIS PERIOD. THEY DO SHOW
SOME DIFFERENCES WITH TIMING AND PLACEMENT OF QPF WITH CLIPPER
SYSTEM SLIDING SOUTHEAST THROUGH THE REGION. ALL MODELS SHOW THE
BULK OF THE QPF AND UPWARD VERTICAL MOTION FIELDS MISSING THE AREA
TO THE SOUTHWEST WEDNESDAY NIGHT.

THE CANADIAN MODEL IS THE MOST AGGRESSIVE WITH QPF OVER MOST OF
THE AREA...WITH THE NAM/GFS/ECMWF BRUSHING THE FAR SOUTH. THEY
ALSO SHOW SOME LAKE EFFECT SNOW SHOWER POTENTIAL WEDNESDAY
NIGHT...WITH NORTHEAST WINDS AND MOISTURE BELOW AND ABOVE THE
INVERSION. DELTA T VALUES ARE QUITE FAVORABLE...THOUGH DECENT ICE
COVERAGE ON THE LAKE MAY LIMIT LAKE EFFECT POTENTIAL.

FOR NOW...WILL MAINTAIN LOW POPS IN THE FAR SOUTH AND SOUTHEAST
COUNTIES FOR MAINLY WEDNESDAY NIGHT...HANGING ON IN THE FAR
SOUTHEAST INTO THURSDAY MORNING. LITTLE TO NO SNOW IS EXPECTED AT
THIS TIME.

ANOTHER SHOT OF COLD AIR ADVECTION OCCURS WEDNESDAY NIGHT INTO
THURSDAY...AS ARCTIC HIGH PRESSURE MOVES SOUTHEAST THROUGH THE
NORTHERN PLAINS. THIS WILL BRING REINFORCING SHOT OF ARCTIC AIR
INTO THE AREA. QUIET WEATHER IS EXPECTED BY THURSDAY AFTERNOON AND
NIGHT ACROSS THE AREA.

LONG TERM...FRIDAY THROUGH MONDAY...FORECAST CONFIDENCE IS
MEDIUM.

GFS/ECMWF GENERALLY CHANGE 500 MB FLOW TO A MORE ZONAL LOOK FOR
FRIDAY INTO SATURDAY...LINGERING INTO MONDAY. THEY BRING A SHOT OF
WARM AIR ADVECTION SATURDAY NIGHT WITH DEEP MOISTURE AND GOOD
UPWARD VERTICAL MOTION IN THE DENDRITE SNOW CRYSTAL GROWTH ZONE. COLD
FRONT THEN SLOWLY MOVES EAST SOUTHEAST THROUGH THE AREA
SUNDAY...BEFORE EXITING SUNDAY NIGHT. CONTINUED HIGH POPS FOR
SATURDAY NIGHT INTO SUNDAY...WITH SEVERAL INCHES OF SNOWFALL
POSSIBLE. MORE COLD AIR LOOKS ON TAP FOR MONDAY...WITH ANOTHER
ARCTIC HIGH IN THE REGION.

AVIATION/12Z TAFS/...

ENOUGH FORCING AS DESCRIBED ABOVE TO WARRANT A BRIEF PERIOD OF
LOWER VSBYS AND CIGS AT ERN TAF SITES LATER THIS MRNG. WL DROP TO
MVFR CIGS/VSBYS AS AREAS OF -SN MOVE THRU. MAY BE A FEW LINGERING
-SHSN IN THE AFTN WITH CIGS POSSIBLY LINGERING AROUND MVFR LEVELS.
EXPECT TREND TOWARD VFR IN THE LATE AFTN OR EVE. LOW LEVEL WIND
SHEAR WILL CONTINUE THRU THE LATE MRNG.

MARINE...

HIGH RESOLUTION VISIBLE SATELLITE FROM MONDAY SHOWED WIDESPREAD
ICE COVER FROM THE SHORE EXTENDING OUT TO AROUND 10 MILES INTO
LAKE MI. STRONG SOUTHWEST WINDS DEVELOPED OVERNIGHT DUE TO THE
RAPIDLY TIGHTENING PRESSURE GRADIENT...HOWEVER AIR TEMPS REMAINED
QUITE COLD. TEMPS ONLY WARM INTO THE 20S TODAY WITH WINDS
DIMINISHING SOMEWHAT THIS AFTN BEFORE THE COLD AIR RETURNS
TONIGHT.

THINKING A FEW AREAS OF OPEN WATER MAY FORM BUT NOT EXPECTED TO
BE WIDESPREAD. STRONGEST WINDS ARE EXPECTED THIS MORNING WITH COLD
TEMPS...WITH SOME ABATEMENT THIS AFTN AND EVE AS TEMPS WARM INTO
THE 20S. A FEW GALE GUSTS TO 35 KTS POSSIBLE BUT NOT EXPECTED TO
BE FREQUENT ENOUGH TO WARRANT UPGRADING TO GALE WARNING AT THIS
TIME. WL CONTINUE SMALL CRAFT ADVY INTO TONIGHT.

&&

.MKX WATCHES/WARNINGS/ADVISORIES...
WI...NONE.
LM...SMALL CRAFT ADVISORY UNTIL MIDNIGHT CST TONIGHT FOR LMZ643>646.

&&

$$
TODAY/TONIGHT AND AVIATION/MARINE...MBK
WEDNESDAY THROUGH MONDAY...WOOD


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