Area Forecast Discussion
Issued by NWS Milwaukee/Sullivan, WI

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FXUS63 KMKX 260345 AAA
AFDMKX

AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE MILWAUKEE/SULLIVAN WI
945 PM CST THU DEC 25 2014

.UPDATE...

SURFACE WINDS ARE BRIEFLY GUSTING TO 20-25 MPH AT TIMES AS 30-35
KNOT SW WINDS AROUND 500 FT OCCASIONALLY MIX DOWN. THESE WINDS
WILL EASE AS BAGGY GRADIENT AROUND WEAK SURFACE LOW REACHES THE
AREA EARLY FRIDAY MORNING. LATEST NAM KEEPING CWA DRY THROUGH 00Z
SATURDAY...WITH THE 00Z GFS BRINGING SOME LIGHT QPF TO NRN SECTIONS
BETWEEN 18Z FRI AND 00Z SAT. SOUNDINGS STILL INDICATE MOSTLY
DRIZZLE OR VERY LIGHT RAIN  WITH ANY PRECIP THAT FALLS WITH THIS
FIRST SURFACE WAVE.

BETTER CHANCE OF PRECIP WITH SECOND WAVE FRIDAY NIGHT AND
SATURDAY. A MIX OF RAIN AND SNOW...AND POSSIBLY SOME FREEZING
RAIN UNTIL DENDRITE GROWTH ZONE SATURATES IN THE FAR NW....WITH
MOSTLY RAIN ELSEWHERE INTO SATURDAY AFTERNOON.

&&

.AVIATION/06Z TAFS/...
EXPECT VFR CONDITIONS...WITH SOME OCCASIONAL WIND GUSTS TO 20
KNOTS THROUGH THE OVERNIGHT. WILL HAVE TO WATCH FOR POTENTIAL OF
LOW-LEVEL WIND SHEAR FOR A TIME OVERNIGHT. WINDS EASE IN THE
EARLY TO MID MORNING AS GRADIENT GETS BAGGY WITH APPROACH AND
PASSAGE OF WEAK LOW...WITH MODELS SATURATING THE LOWER LEVELS FROM
WEST TO EAST LATER FRIDAY MORNING INTO THE AFTERNOON. EXPECT MVFR
CIGS TO RETURN. MODELS HINT AT CIGS RISING TO VFR FOR A TIME IN
THE LATE AFTERNOON AND EARLY EVENING BETWEEN THE DEPARTING WEAK
LOW TO THE NORTH AND AHEAD OF NEXT LOW APPROACHING FROM THE
SW...BUT HAVE CIGS GOING BACK DOWN TO BETWEEN 1500 AND 2000 FT BY
EARLY IN THE EVENING AT KMSN AND BY 03Z AT EASTERN TAF SITES.

&&

.MARINE...

ISSUED A SMALL CRAFT ADVISORY UNTIL 9 AM FRIDAY...MAINLY FOR
FREQUENT WIND SWLY GUSTS TO 25 KNOTS...THOUGH WAVES MAY REACH
CRITERIA BETWEEN PORT WASHINGTON AND SHEBOYGAN FOR A TIME
OVERNIGHT. RAP SOUNDINGS HAVE BEEN SHOWING 30-35 KNOT WINDS WITHIN
500 FT LASTING THROUGH MOST OF THE OVERNIGHT...WITH THE CURRENT
VAD WINDS ON THE MKX 88-D RADAR SHOWING 40 KNOTS DOWN TO 2000 FT.

LAKE SHORE OBS HAVE BEEN GUSTING TO 20 KNOTS BUT WITH SLIGHTLY
BETTER MIXING OVER THE WATERS EXPECT GUSTS TO REACH 25 KTS.
CHICAGO CRIB HAS BEEN GUSTING UP TO 28 KNOTS. WINDS NOT EXPECTED
TO BE STRONG FOR AS LONG NORTH OF PORT WASHINGTON...BUT INITIAL
SSW WIND DIRECTION WILL BUILD WAVES OF 3 TO 5 FEET...WITH THE
HIGHER WAVES TOWARD THE OPEN WATER.

WINDS WILL EASE TOWARD 12Z AS GRADIENT BECOMES BAGGY WITH APPROACH
AND PASSAGE OF WEAK SURFACE LOW.

&&

.PREV DISCUSSION... /ISSUED 334 PM CST THU DEC 25 2014/

TONIGHT AND FRIDAY...FORECAST CONFIDENCE IS HIGH.

EXPECTING MAINLY MID AND HIGH LEVEL CLOUDS TONIGHT UNDER SOME
WARM ADVECTION ALOFT. BETWEEN THE WARM ADVECTION...CLOUDS...AND
SOUTHERLY WINDS...SHOULD SEE LOW TEMPS IN THE LOW TO MID 30S.
THESE LOWS WILL BE A FEW DEGREES HIGHER THAN AVERAGE HIGHS FOR
THIS TIME OF YEAR.

MILD SOUTHERLY FLOW LOW LEVEL FLOW WILL CONTINUE FRIDAY. MODELS
SUGGEST THE LOW LEVELS WILL SATURATE WEST TO EAST FROM LATER IN
THE MORNING THROUGH THE AFTERNOON. THUS EXPECTING LOW CLOUDS TO
RETURN TO THE AREA. BETWEEN THE MILD SOUTHERLY FLOW AND MAYBE AT
LEAST MORNING BREAKS IN THE CLOUDS...LOOKS LIKE HIGHS MAY BE EVEN
A COUPLE DEGREES MILDER THAN TODAY.

FRIDAY NIGHT THROUGH SUNDAY...FORECAST CONFIDENCE IS MEDIUM.

MODELS ARE IN DECENT AGREEMENT WITH BRINGING SURFACE LOW NORTHEAST
FROM THE SOUTHERN PLAINS INTO AND THROUGH SOUTHERN WISCONSIN
FRIDAY NIGHT AND SATURDAY. THE NAM/GFS ARE QUICKER WITH THE LOW
TRACK THAN THE ECMWF/CANADIAN MODELS. ALL OF THE MODELS BRING A
SHOT OF WARM AIR ADVECTION AROUND 12Z SATURDAY...FOLLOWED BY THE
PASSAGE OF THE 850 MB TROUGH AT 18Z SATURDAY...THEN THE 500 MB
VORTICITY MAXIMUM SATURDAY AFTERNOON.

NAM/GFS BRING AREA OF LOW LEVEL FRONTOGENESIS RESPONSE THROUGH
THE AREA SATURDAY MORNING...WITH THE MID LEVEL FRONTOGENESIS
CLIPPING AND REMAINING MOSTLY JUST TO THE NORTHWEST OF THE AREA.
THIS IS THE BEST TIME PERIOD FOR UPWARD VERTICAL MOTION WITHIN A
SATURATED AIR COLUMN...PER AREA FORECAST SOUNDINGS.

THE NAM IS SOMEWHAT MILDER THAN THE GFS WITH TEMPERATURE
PROFILES...AND KEEPS MOST OF THE AREA ALL RAIN. THE GFS DOES COOL
THINGS DOWN ENOUGH FOR A MIX AND CHANGE TO LIGHT SNOW IN THE
NORTHWEST PORTIONS OF THE AREA SATURDAY MORNING. BLENDED THESE
SOLUTIONS WITH THE ECMWF AND CANADIAN...WHICH GIVE THIS MIX AND
CHANGE TO LIGHT SNOW IN THE NORTHWEST COUNTIES SATURDAY MORNING.

WENT WITH LIKELY POPS LATER FRIDAY NIGHT IN THE WEST...THEN ACROSS
ALL OF THE AREA SATURDAY MORNING. MIX IN THE NORTHWEST COUNTIES
LATER FRIDAY NIGHT SHOULD BECOME MAINLY LIGHT SNOW SATURDAY
MORNING...WITH ACCUMULATIONS OF UP TO AN INCH. THE REST OF THE
AREA SHOULD BE MILD ENOUGH FOR JUST RAIN OR A LIGHT MIX BEFORE
ENDING.

COLD AIR ADVECTION LATER SATURDAY INTO SATURDAY NIGHT WILL BRING
DRIER AIR INTO THE AREA. THE DRY CONDITIONS WILL LINGER INTO
SUNDAY. TEMPERATURES SHOULD BE MORE SEASONABLE FOR THIS TIME OF
YEAR ON SUNDAY.

SUNDAY NIGHT THROUGH THURSDAY...FORECAST CONFIDENCE IS MEDIUM.

THE GFS AND ECMWF ARE SHOWING THAT THE OVERALL 500 MB PATTERN MAY
SHIFT TO A MORE NORTHWESTERLY FLOW REGIME BY THE MIDDLE OF NEXT
WEEK. THIS SHOULD SIGNAL A TREND TOWARDS COLDER TEMPERATURES
DURING THIS PERIOD.

A PASSING 500 MB VORTICITY MAXIMUM AND SURFACE COLD FRONT MONDAY
INTO MONDAY NIGHT MAY BRING LIGHT SNOW...SO LEFT LOW POPS GOING
FOR NOW. ANOTHER SYSTEM ON NEW YEARS DAY MAY BRING SOME LIGHT
SNOW...AND LEFT POPS GOING THERE. CONSENSUS MODEL TEMPERATURES DO
TREND TO NEAR TO SLIGHTLY BELOW NORMAL BY THE MIDDLE OF THE WEEK.

AVIATION/00Z TAFS/...

VFR CONDITIONS HAVE FINALLY RETURNED TO SOUTHERN WISCONSIN. THINK
THE NAM BRINGS LOW CLOUDS BACK TOO QUICKLY TONIGHT...SO EXPECTING
VFR TO PERSIST THROUGH THE NIGHT.

MOST MODELS DO SHOW THE LOW LEVELS SATURATING WEST TO EAST FROM
LATER FRIDAY MORNING THROUGH THE AFTERNOON. THUS EXPECTING LOW
CLOUDS TO EVENTUALLY RETURN TO THE AREA.

MARINE...

WINDS CONTINUE TO SLOWLY EASE THIS AFTERNOON...WITH LIGHTER WINDS
EXPECTED TONIGHT INTO FRIDAY.

&&

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

&&

$$

UPDATE...REM
TONIGHT/FRIDAY AND AVIATION/MARINE...DDV
FRIDAY NIGHT THROUGH THURSDAY...WOOD



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