000
FXUS63 KMKX 240402
AFDMKX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MILWAUKEE/SULLIVAN WI
1002 PM CST MON FEB 23 2015

.UPDATE...A BRIEF PERIOD OF LIGHT SNOW IS STILL EXPECTED FOR TUE
AM AS A SHORTWAVE TROUGH CURRENTLY OVER MANITOBA CANADA DIGS SEWD
INTO SRN WI. IN ADDITION TO THE PVA...IS LOW LEVEL WARM ADVECTION
AND FRONTOGENESIS. THE ATMOSPHERE IS FAIRLY DRY HOWEVER...THUS
ONLY A COUPLE HOURS OF VERY LIGHT SNOW WITH LITTLE TO NO SNOW
ACCUM.

&&

.AVIATION/06Z TAFS/...BREEZY SWLY WINDS WILL CONTINUE THROUGH TUE
AM...THEN TURN NWLY TUE NIGHT WITH THE PASSAGE OF A COLD FRONT.
LLWS WILL DEVELOP FROM 06Z-15Z TUE AS A 50 KT WSWLY LLJ SHIFTS
ACROSS THE REGION. UP TO A 2 HOUR PERIOD OF LGT SNOW IS EXPECTED
TUE AM WITH THE WARM ADVECTION AND LOW PRESSURE ALOFT. THE SNOW
WILL REMAIN VERY LIGHT WITH ONLY BRIEF PERIODS OF MVFR CIGS AND VSBYS.
SKIES WILL THEN BECOME PARTLY CLOUDY BY LATE TUE AFTERNOON AND
CONTINUE INTO TUE NT WITH VFR CONDITIONS.

&&

.PREV DISCUSSION... /ISSUED 306 PM CST MON FEB 23 2015/

SHORT TERM...

TONIGHT AND TUESDAY... FORECAST CONFIDENCE HIGH.

SURFACE LOW PRESSURE TRACKING ACROSS ONTARIO WILL DRAG A COLD FRONT
THROUGH MN TONIGHT AND WI ON TUESDAY. THE LOW IS SUPPORTED BY A MID
LEVEL SHORTWAVE TROUGH AND ENTRANCE REGION OF A STRONG UPPER JET.
MEANWHILE... SURFACE HIGH PRESSURE WILL REMAIN PARKED OVER THE
CENTER OF THE COUNTRY. THIS WILL LEAD TO A TIGHT PRESSURE GRADIENT
ACROSS SOUTHERN WI TONIGHT INTO TUESDAY MORNING AS THE SURFACE
TROUGH/COLD FRONT APPROACHES.

EXPECT GUSTY SOUTHWEST WINDS FROM THIS EVENING THROUGH TUE MORNING.
WINDS WILL REMAIN ELEVATED AS THEY SHIFT WEST EARLY TUE AFTERNOON IN
THE WAKE OF THE SURFACE TROUGH... AND THEN BREEZY NORTHWEST WINDS
THROUGH LATE TUESDAY EVENING. EXPECT DRY WEATHER TONIGHT WITH
INCREASING HIGH AND MID LEVEL CLOUDS. THERE WILL BE HIGH OMEGA WITH
THE LEADING WEAKER SHORTWAVE OVERNIGHT... BUT THE AIR WILL BE TOO
DRY FOR ANY PRECIP. MIN TEMPS TONIGHT WILL OCCUR THIS EVENING. MAX
TEMPS TUESDAY WILL APPROACH 30.

A POTENT 500MB SHORTWAVE WILL SWING THROUGH CENTRAL WI LATE TUE
MORNING. THIS AND THE WARM AIR ADVECTION SHOULD BE ENOUGH FORCING
AND HAVE ENOUGH LOW LEVEL MOISTURE TO SUPPORT A PERIOD OF LIGHT SNOW
OVER MOST OF SOUTHERN WI TUE MORNING. THUS... INCREASED POPS TO
LIKELY. SNOW ACCUMULATION WILL BE LIGHT... A HALF INCH OR LESS.

TUESDAY NIGHT AND WEDNESDAY...FORECAST CONFIDENCE HIGH.

THE BASE OF THE INITIAL NORTHERN STREAM TROUGH EXITS THE EASTERN
GREAT LAKES AND MOVES INTO SOUTHEAST CANADA WEDNESDAY....WITH A
SECOND TROUGH AXIS MOVING ACROSS THE NORTHERN PLAINS WEDNESDAY.
VERY WEAK UPPER CONVERGENCE WITH WEAK DOWNWARD MOTION AT 700 MB
TUESDAY NIGHT AND VERY WEAK UPWARD MOTION WEDNESDAY. 700 MB RH IS
LOW EXCEPT IN THE FAR SOUTHWEST WEDNESDAY. THE 925/850 MB RH
DRIES TUESDAY NIGHT WITH 925 MB RH INCREASING AGAIN WEDNESDAY
AFTERNOON.

850/700 MB TEMPERATURE ADVECTION IS RATHER NEUTRAL WITH WEAK COLD
AIR ADVECTION WEDNESDAY. MOST OF THE 925 MB COLD AIR ADVECTION
TAKES PLACE TUESDAY EVENING.

ANOTHER COLD SURFACE HIGH NORTH OF MONTANA AND THE DAKOTAS...
BUILDS INTO THE UPPER MISSISSIPPI VALLEY.

WEDNESDAY NIGHT AND THURSDAY...FORECAST CONFIDENCE HIGH.

THE SPLIT FLOW BREAKS DOWN AS THE NORTHERN TROUGH BUILDS BACK
TOWARD THE SOUTHWEST WITH THE 500 MB TROUGH AXIS ACROSS WISCONSIN
TOWARDS NEBRASKA.

THE COLD SURFACE HIGH SAGS ACROSS THE PLAINS AND INTO THE UPPER
MISSISSIPPI VALLEY INTO WISCONSIN. AS THE HIGH MOVES ACROSS...
BELOW NORMAL TEMPERATURES WILL HAVE A FIRM GRIP ON THE REGION.
WITH LIGHT WINDS LOW TEMPERATURES WILL BE VERY COLD WELL INLAND IF
SKIES ARE MOSTLY CLEAR. WINDS CHILLS WILL NOT BE MUCH OF A
FACTOR. THE LOW LEVEL FLOW BECOME NORTHEAST ON THURSDAY. HOWEVER
THE INVERSION LEVEL IS LOW...AROUND 3 THSD FT. SOME FLURRY
POTENTIAL MAY DEVELOP OFF THE LAKE. WITH THE LIGHT NORTHEAST FLOW
TEMPERATURES NEAR LAKE MICHIGAN WILL NOT BE AS COLD.

LONG TERM...

THURSDAY NIGHT AND FRIDAY...FORECAST CONFIDENCE HIGH.

THE NORTHERN STREAM BECOMES A BIT MORE ZONAL AS IT WEAKENS AND A
STRONG SHORTWAVE MOVES SOUTH ACROSS THE WESTERN U.S.

THE CENTER OF THE COLD SURFACE HIGH IS CENTERED ACROSS THE MID
MISSISSIPPI TO SOUTHERN GREAT LAKES REGION...CONTINUING THE COLD
TEMPERATURES. HOWEVER WITH LIGHT WINDS...WINDS CHILLS WILL NOT BE
A FACTOR.

SATURDAY THROUGH MONDAY...FORECAST CONFIDENCE MEDIUM.

THE WESTERN SHORTWAVE REACHES THE SOUTHWEST U.S. WITH A WEST
SOUTHWEST FLOW ACROSS THE SOUTHERN PLAINS TO WISCONSIN.

THE GFS AND ECMWF MODELS ARE NOW FAIRLY SIMILAR.

THE 12Z ECMWF IS A LITTLE FASTER IN BRINGING IN LIGHT TO MODERATE
SNOW INTO SOUTHERN WISCONSIN SATURDAY NIGHT WITH BOTH MODELS
INDICATING A LONG DURATION SNOW WITH WITH SEVERAL INCHES OF
ACCUMULATION. THE HIGHER ACCUMULATIONS WOULD BE SOUTH TOWARD THE
ILLINOIS BORDER.

THE MAIN DIFFERENCE IS THE 12Z GFS AS A MORE NORTH AND SLOWER LOW
TRACK. ACCUMULATING SNOW SHOULD PERSIST INTO SUNDAY EVENING...
WITH THE HEAVIER SNOW TOTALS TO THE SOUTH OVER NORTHERN ILLINOIS.

THE LOW WILL MOVE TO THE NORTHEAST U.S. MONDAY WITH HIGH PRESSURE
BEGINNING TO BUILD INTO THE UPPER MISSISSIPPI VALLEY AND WISCONSIN
LATE MONDAY...WITH MORE COLD TEMPERATURES.

AVIATION/00Z TAFS/...

STRONG LOW PRESSURE WILL BE MOVING ACROSS ONTARIO CANADA TONIGHT AND
TUESDAY. THIS WILL RESULT GUSTY SOUTHWEST WINDS FROM LATE AFTERNOON
THROUGH TUESDAY MORNING... ELEVATED WEST WINDS THROUGH TUESDAY
AFTERNOON... AND BRISK NORTHWEST WINDS TUESDAY EVENING. LOW LEVEL
WIND SHEAR IS EXPECTED OVERNIGHT WITH 2KFT WINDS BLOWING 45-50KTS.

HIGH AND MID LEVEL CLOUDS WILL INCREASE TONIGHT. A LOW PRESSURE
TROUGH AND LEADING WARM ADVECTION SHOULD BRING A PERIOD OF LIGHT
SNOW TO SOUTHERN WISCONSIN LATE TUESDAY MORNING. VERY LIGHT
ACCUMULATIONS FROM MADISON TO MILWAUKEE AND SOUTH... UP TO A HALF
INCH NORTH OF THERE. EXPECT VFR CONDITIONS THROUGH TUESDAY MORNING.
MVFR CIGS AND VSBY WILL BE POSSIBLE DURING SNOW LATE TUE MORNING.

MARINE...

STRONG SOUTHWEST WINDS WILL DEVELOP BY THIS EVENING AND CONTINUE
THROUGH TUESDAY EVENING AS LOW PRESSURE MOVES ACROSS ONTARIO CANADA
WHILE HIGH PRESSURE PASSES TO OUR SOUTH. A SMALL CRAFT ADVISORY IS
IN EFFECT FROM 9 PM THIS EVENING THROUGH MIDNIGHT TUESDAY EVENING
FOR SOUTHWEST WINDS UP TO 30KTS.

&&

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

&&

$$

UPDATE...GEHRING
TONIGHT/TUESDAY AND AVIATION/MARINE...MRC
TUESDAY NIGHT THROUGH MONDAY...HENTZ