Area Forecast Discussion
Issued by NWS Milwaukee/Sullivan, WI

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FXUS63 KMKX 161758
AFDMKX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MILWAUKEE/SULLIVAN WI
1158 AM CST TUE DEC 16 2014

.UPDATE...
REDUCED POPS SLIGHTLY AS PRECIPITATION HAS BECOME MORE WIDELY
SCATTERED. WINDS HAVE SHIFTED NORTHWEST AND ARE GUSTING ACROSS THE
REGION BEHIND SURFACE LOW. EXPECT GUSTY NW WINDS TO CONTINUE THROUGH
THE EVENING AND TEMPERATURES WILL CONTINUE TO DROP. SOME LIGHT SNOW
SHOWERS MAY IMPACT AREAS MAINLY NORTH AND WEST OF MADISON THIS
AFTERNOON. NO ACCUMULATION EXPECTED.

&&

.AVIATION/18Z TAFS/...
SNOW SHOWERS NEAR LA CROSSE MAY IMPACT MSN THIS AFTERNOON BUT
CONFIDENCE IS NOT HIGH ENOUGH THAT THEY WILL HOLD TOGETHER. IF THEY
DO MSN COULD SEE AN HOUR OF IFR CONDITIONS BUT NO ACCUMULATION
EXPECTED. GUSTY NORTHWEST WINDS EXPECTED TO CONTINUE THROUGH THE
EVENING. EXPECTING MVFR CONDITIONS AFTER MIDNIGHT AS DRIER AIR WORKS
INTO THE REGION FROM THE NORTHWEST. CLOUDS COULD START TO BECOME
SCATTERED LATE WEDNESDAY AFTERNOON.

&&

.MARINE...
THE DENSE FOG ADVISORY FOR THE NEARSHORE WATERS OF LAKE MICHIGAN
WILL BE ALLOWED TO EXPIRE AT NOON...AS GUSTY NORTHWEST WINDS WILL
HELP MIX OUT THE FOG.

SMALL CRAFT ADVISORY CONTINUES THIS AFTERNOON INTO WEDNESDAY MORNING
ACROSS THE NEARSHORE WATERS. GUSTY NORTHWEST WINDS ARE EXPECTED TO
DEVELOP EARLY THIS AFTERNOON...WITH FREQUENT GUSTS OF 23 TO 28
KNOTS. A TIGHT PRESSURE GRADIENT OVER THE AREA WILL BE RESPONSIBLE
FOR THE GUSTY WINDS. THESE WINDS WILL LINGER TONIGHT INTO EARLY
WEDNESDAY MORNING...GRADUALLY WEAKENING BY MIDDLE MORNING. THESE
WINDS WILL GENERATE HIGH WAVES TOWARD AND OVER THE OPEN WATERS OF
LAKE MICHIGAN.

&&

.PREV DISCUSSION... /ISSUED 333 AM CST TUE DEC 16 2014/

TODAY AND TONIGHT...FORECAST CONFIDENCE - MEDIUM.

EXTENDED ONGOING DENSE FOG ADVY SEVERAL MORE HOURS TO ACCOUNT FOR
BAGGINESS IN PRESSURE PATTERN ASSOCIATED WITH SFC LOW PRESSURE
MOVING ACROSS NRN IL TO OVER LK MI THIS MRNG. OCNL -RA WL CAUSE
VISIBILITIES TO FLUCTUATE SOMEWHAT BUT EXPECING -RA TO REMAIN MORE
PATCHY IN ERN CWA THRU EARLY THIS MRNG.  WEBCAMS AND SFC OBS SHOW
DENSE FOG HAS ADVANCED WWD INTO WASHINGTON AND WAUKESHA COUNTIES SO
INCLUDED THESE IN DENSE FOG ADVY.

LOW PRESSURE WL CONTINUE TO SPEED OFF TO THE NORTHEAST THIS MRNG DUE
TO UPSTREAM KICKER TROF OVER NORTHERN PLAINS.  WATER VAPOR IMAGERY
CLEARLY SHOWS CIRCULATION OVER NW IL MOVING STEADILY ENW.

AREAS OF -RA WL CONTINUE TO AFFECT CWA THROUGH MID-MRNG AS UPPER LOW
AND ASSOCIATED MID-LEVEL DEFORMATION MOVES ACROSS THE AREA.  COLDER
AIR UPSTREAM SPREADING INTO WEST CENTRAL WI WL SPREAD INTO SOUTH
CENTRAL WI THIS MRNG...POSSIBLY RESULTING IN A MIXTURE CHANGING OVER
TO A PERIOD OF -SN.  LAGGING WARMER PAVEMENT TEMPS SHOULD PREVENT
ACCUMULATIONS MORE THAN A COUPLE TENTHS.  ENOUGH MID-LEVEL RH
EXPECTED IN DENDRITIC GROWTH ZONE TO PREVENT ANY SIGNIFICANT
-ZR...HOWEVER BRIEF PD NOT IMPOSSIBLE AS TEMPS FALL BELOW FREEZING
THIS AFN IN WEST.

MUCH DRIER AIR ABV 3K FT SPREADS ACROSS SRN WI THIS AFTN AND EVE AS
BREEZY SFC WINDS CONTINUE TO PULL COLDER AIR ACROSS THE AREA.  925H
TEMPS FALL AROUND 12C IN NEXT 24 HOURS.  WITH LINGERING LOW LEVEL
CYCLONIC CURVATURE AND THERMAL TROF BUILDING IN...WL KEEP MORE
CLOUDS HANGING AROUND THRU TNGT WITH A CHANCE FOR FLURRIES IN THE
NORTH CLOSER TO LOW PRESSURE TROF.

WEDNESDAY - CONFIDENCE...MEDIUM
PRIMARY UPPER LOW CENTER SHIFTS EAST WITH ELONGATED SHEAR AXIS
SLIDING SOUTHWARD INTO SRN WI. LOW LEVEL COLD ADVECTION CONTINUES
WITH 925 TEMPS -8 TO -10C FOR MUCH OF THE DAY. EAST/WEST ORIENTED
SURFACE/850 TROUGH AXES FOCUSED MORE ACROSS NRN/CNTRL WI WITH
HIGHER LLVL RH FOCUSED THERE. THE NAM MOS KEEPS IT OVC ALL DAY
WHILE THE GFS OFFERS MORE HOPE FOR SUNSHINE IN SRN WI.

THURSDAY - CONFIDENCE...MEDIUM
SURFACE/850 RIDGE AXIS BECOMES A BIT MORE CENTERED ACROSS WI.
AXIS OF LLVL RH SHIFTS INTO SRN WI THOUGH GFS/ECMWF SHOW DECREASING
TREND WHILE NAM PERSISTS WITH OVC CONDITIONS. WITH LESS INFLUENCE
OF BOTH THE LOW LEVEL TROUGH AXES AND MID LEVEL CYCLONIC FLOW
CONFIDENCE WOULD BE GREATER THAT THE NAM IS OVERDOING THE LOW
LEVEL RH FIELDS.

FRIDAY - CONFIDENCE...MEDIUM
WEAK SOUTHWEST UPPER FLOW WITH SURFACE/850 HIGH PRESSURE IN CONTROL.

SATURDAY - CONFIDENCE...MEDIUM
MODELS SHOW UPPER CIRCULATION APPROACHING FROM MN/IA AT VARYING
STRENGTHS AND TIMING. THE ECMWF DOES CLOSE A LOW OFF WITH A SMIDGE
OF LIGHT QPF. OTHER MODELS KEEP PRECIP FURTHER WEST. WILL RIDE
WITH THE QUIET BLENDED POPS FOR NOW.

SUNDAY - CONFIDENCE...MEDIUM
GEM/GFS SHOWING A BROAD CYCLONIC FLOW WITH EMBEDDED SHORTWAVES
AHEAD OF A POSITIVE TILT TROUGH DROPPING IN FROM MN. MEANWHILE THE
ECMWF SHOWS A BIT MORE MID LEVEL RIDGING TAKING HOLD. IN THE LOW
LEVELS THERE IS SOME AGREEMENT WITH A WEAK WARM AIR ADVECTION
SIGNAL. SURFACE HIGH STARTS DRIFTING TO THE EAST OF THE AREA WITH
ECMWF A BIT QUICKER WITH A LIGHT SOUTHERLY SURFACE FLOW TAKING
HOLD.

SUNDAY NIGHT AND MONDAY - CONFIDENCE...LOW
APPEARS THAT A SHORTWAVE WITH A BIT MORE OOMPH WILL APPROACH THE
AREA. THE ECMWF DRIVES IN PRECIP QUITE A BIT FASTER SUNDAY NIGHT
WHILE THE GFS HOLDS THINGS OFF UNTIL MONDAY NIGHT. AT THIS POINT
850 TEMPS/THICKNESSES POINT TOWARDS SNOW THOUGH CLOSER CALL IN THE
SOUTH. STILL A WAYS OFF AND STRENGTH OF SOUTHERLY FLOW AHEAD OF
THE LOW WILL DICTATE WHETHER ENOUGH WARMING OCCURS TO NECESSITATE
INCLUSION OF A MIX IN PARTS OF THE AREA.

AVIATION/12Z TAFS/...AREAS OF DENSE FOG WILL CONTINUE EARLY THIS
MORNING HOWEVER WL BE TEMPERED SOMEWHAT BY OCNL -RA. LOW CIGS/VSBYS
WL CONTINUE THRU MID- MRNG. OCCASIONAL -RA AND -DZ WL TAPER OFF
THIS MRNG AS LOW PRESSURE MOVES OFF TO THE EAST. MAY CHANGE OVER
TO A MIXTURE OF -RA AND -SN BEFORE ENDING LATE THIS MRNG OR
AFTN...ESPECIALLY AT KMSN.

INCREASING NW WINDS ON BACKSIDE OF LOW PRESSURE WL CAUSE CIGS
TO INCREASE TO MVFR LATER TODAY.

MARINE...SFC LOW PRESSURE OVER NORTHWEST IL WL CONTINUE TO MOVE ENE
ACROSS SRN LAKE MI EARLY THIS MRNG. WINDS WL REMAIN LIGHT WHILE A
MILD...MOIST AIR MASS REMAINS OVER LAKE MI. EXPECT AREAS OF DENSE
FOG TO CONTINUE UNTIL WINDS INCREASE FROM THE NORTHWEST LATER THIS
MRNG. HENCE EXTENDED DENSE FOG ADVY A FEW HOURS. TIGHTENING PRESSURE
GRADIENT BEHIND DEPARTING LOW PRESSURE WILL RESULT IN NORTHWEST
WIND GUSTS REACH SMALL CRAFT ADVY LEVELS THIS AFTN THRU TNGT.
THESE GUSTY OFFSHORE WINDS WILL CAUSE WAVES TO INCREASE TO 3 TO 5
FEET TOWARD THE OPEN WATER.

&&

.MKX WATCHES/WARNINGS/ADVISORIES...
WI...NONE.
LM...SMALL CRAFT ADVISORY UNTIL 9 AM CST WEDNESDAY FOR LMZ643>646.

&&

$$

UPDATE...SM/WOOD
TODAY/TONIGHT AND AVIATION/MARINE...MBK
WEDNESDAY THROUGH MONDAY...COLLAR



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