Area Forecast Discussion
Issued by NWS Milwaukee/Sullivan, WI

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FXUS63 KMKX 210354
AFDMKX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MILWAUKEE/SULLIVAN WI
954 PM CST TUE JAN 20 2015

.UPDATE...A NARROW BAND OF LOW LEVEL FRONTOGENESIS AND SNOW IS
SLOWLY SHIFTING EWD FROM SW WI INTO SOUTH CENTRAL WI. TO THE
EAST...VERY LIGHT SNOW AND FLURRIES IS OCCURRING OVER SE WI. LIGHT
SNOW WILL DEVELOP AND EXPAND OVER ALL OF SRN WI DURING THE
OVERNIGHT AS THE UPPER LOW MOVES ALONG THE WI AND IL BORDER
THROUGH WED AM. THE LOW LEVEL FRONTOGENESIS AND HEAVIER SNOW BAND
WILL DEVELOP SWD INTO IL TOWARD SUNRISE AND THROUGH WED AM. THUS
THE HEAVIER SNOW TOTALS OF JUST UNDER TWO INCHES IS FORECAST SOUTH
AND WEST OF MADISON WITH LESS THAN ONE HALF INCH TOWARD CENTRAL
WI.


&&

.AVIATION/06Z TAFS/...LIGHT SNOW WILL EXPAND ACROSS ALL OF SRN WI
BY THE EARLY MORNING HOURS OF WED AND END FROM WEST TO EAST DURING
THE MID TO LATE MORNING. CIGS WILL FALL BELOW 1.0 KFT DURING THE
EARLY MORNING HOURS AS THE SNOW INCREASES IN COVERAGE AND
INTENSITY. VSBYS OF 2-3 MILES BUT BRIEF PERIODS OF 1 MILE ARE
EXPECTED WITH THE SNOW. CIGS WILL RISE ABOVE 1 KFT DURING WED
AFTERNOON WITH MVFR VSBYS APPROACHING VFR VSBYS BY LATE AFTERNOON.


&&

.PREV DISCUSSION... /ISSUED 228 PM CST TUE JAN 20 2015/

SHORT TERM...

TONIGHT AND WEDNESDAY...FORECAST CONFIDENCE...HIGH

WIDESPREAD LIGHT SNOWFALL IS EXPECTED ACROSS THE FORECAST AREA THIS
EVENING INTO WEDNESDAY MORNING. A NEARLY STACKED SFC TO MID-LEVEL
LOW PRESSURE SYSTEM WILL SLIDE ACROSS THE SOUTHERN FORECAST AREA
AFTER MIDNIGHT INTO WED MORNING. MOISTURE IS DEEP ENOUGH TO GO ALONG
WITH SOME WEAK LIFT FOR SEVERAL HOURS OF SNOWFALL. SOUNDINGS
INDICATE THAT SATURATION MAY GENERALLY BE CONFINED TO THE LOWER
LEVELS DURING THE ONSET OF PRECIP...POSSIBLY RESULTING IN A LACK OF
ICE CRYSTALS FOR A WHILE. TEMPS SHOULD BE AT OR BELOW FREEZING MOST
PLACES BY EVENING...SO MENTIONED PATCHY FREEZING DRIZZLE ALONG WITH
SNOW CHANCES INITIALLY. EXPECTED SNOW AMOUNTS HAVE NOT CHANGED MUCH
FROM THE PREVIOUS FORECAST...RANGING FROM ABOUT 2 INCHES IN THE
SOUTHWEST TO JUST UNDER AN INCH IN THE FAR NORTHEAST.

MODELS GENERALLY DROP THE QPF OFF PRETTY FAST WEDNESDAY
MORNING...BUT OPTED TO LINGER SNOW CHANCES THROUGH THE DAY GIVEN
SATURATED SOUNDINGS AND VERY WEAK LIFT INTO THE AFTERNOON. CLOUDS
AND PRECIP WILL KEEP TEMPS FROM FALLING MUCH TODAY...OR RISING MUCH
WEDNESDAY...WITH LOWS TONIGHT AND HIGHS TOMORROW GENERALLY WITHIN 5
DEGREES OF EACH OTHER.

WEDNESDAY NIGHT AND THURSDAY...FORECAST CONFIDENCE HIGH.

THE NAM/GFS AND ECMWF BRINGS A 500 MB LEVEL TROUGH AXIS INTO SOUTHERN
WISCONSIN WEDNESDAY NIGHT WITH THE TROUGH AXIS EXITING THE EAST BY
THURSDAY EVENING. WEAK 700 MB UPWARD MOTION WEDNESDAY NIGHT
DIMINISHES THURSDAY MORNING. THE 700 MB RH IS HIGHEST TOWARD
CENTRAL WISCONSIN WEDNESDAY NIGHT...THEN THE 700 MB RH DRIES
THURSDAY. THE 925/850 MB LAYER REMAINS HIGH WEDNESDAY NIGHT THEN
DRIES FROM THE NORTH THURSDAY. THE MODELS DO NOT GENERATE ANY
MEASURABLE PRECIPITATION WEDNESDAY NIGHT.

AT THE SURFACE A SOUTHWEST FLOW BEGINS WITH WARM AIR ADVECTION
OCCURRING LATER THURSDAY.

THURSDAY NIGHT AND FRIDAY...FORECAST CONFIDENCE HIGH.

THE MID AND UPPER LEVEL FLOW IS OUT OF THE NORTHWEST THURSDAY NIGHT
BEFORE A A WEAK SHORTWAVE MOVES ACROSS THE NORTHERN PLAINS TOWARDS
WISCONSIN LATER FRIDAY.

WARM AIR ADVECTION IS OCCURRING AHEAD OF AN APPROACHING
SURFACE TROUGH...WITH LITTLE IF ANY PRECIPITATION ACROSS THE
SOUTH.

LONG TERM...

FRIDAY NIGHT AND SATURDAY...FORECAST CONFIDENCE HIGH.

THE GFS AND 00Z ECMWF ARE IN BETTER AGREEMENT IN BRINGING TWO WEAK
SHORTWAVES ACROSS IN THE NORTHERN STREAM.

THE SURFACE TROUGH MOVES ACROSS THE AREA FRIDAY NIGHT WITH WEAK
COLD AIR ADVECTION...THEN ANOTHER WEAK TROUGH DROPS IN FROM THE
NORTH.

SUNDAY...FORECAST CONFIDENCE HIGH.

YET ANOTHER BUT STRONGER SHORTWAVE DROPS ACROSS THE UPPER
MISSISSIPPI VALLEY FROM THE NORTHWEST ON SUNDAY. THE GFS/ECMWF AND
DGEX ARE IN BETTER AGREEMENT ON THE SHORTWAVE WITH THE ECMWF JUST
A BIT FARTHER NORTH.

A RATHER STRONG CLIPPER MOVES ACROSS IOWA/ILLINOIS SUNDAY.

THE ECMWF AND DGEX BRINGS A MODERATE SNOW ACROSS MUCH OF SOUTHERN
WISCONSIN WITH THE GFS HAVING THE MODERATE BAND SOUTH ACROSS
ILLINOIS. THIS COULD END UP BEING AN ADVISORY TYPE SNOW FOR
SOUTHERN WISCONSIN.

MONDAY AND TUESDAY...FORECAST CONFIDENCE HIGH.

BY MONDAY THE TROUGH SHIFTS EAST WITH A NORTHWEST FLOW ACROSS THE
UPPER MISSISSIPPI VALLEY. COLD AIR ADVECTION OCCURS MONDAY WITH A
SURFACE HIGH OVER WISCONSIN TUESDAY ON THE ECMWF. THE GFS IS A
LITTLE FASTER...ALREADY BRINGING WARM AIR ADVECTION INTO SOUTHERN
WISCONSIN TUESDAY.

AVIATION/00Z TAFS/...

WIDESPREAD LIGHT SNOWFALL IS EXPECTED ACROSS THE FORECAST AREA THIS
EVENING INTO WEDNESDAY MORNING. MAY SEE A LITTLE FREEZING DRIZZLE AT
THE ONSET OF PRECIP THIS EVENING. EXPECTED SNOW AMOUNTS HAVE NOT
CHANGED MUCH FROM THE PREVIOUS FORECAST...RANGING FROM ABOUT 2
INCHES IN THE SOUTHWEST TO JUST UNDER AN INCH IN THE FAR NORTHEAST.
THE SNOW SHOULD BE OF THE DRIER VARIETY...WITH LIQUID TO SNOW RATIOS
PEAKING AT ABOUT 16 TO 1.

MODELS GENERALLY DROP THE QPF OFF PRETTY FAST WEDNESDAY
MORNING...BUT OPTED TO LINGER SNOW CHANCES THROUGH THE DAY GIVEN
SATURATED SOUNDINGS AND VERY WEAK LIFT INTO THE AFTERNOON. NOT
EXPECTING MUCH IF ANY ADDITIONAL ACCUMULATION BY AFTERNOON.

LOW CLOUDS WILL LIKELY PERSIST THROUGH THE DAY WEDNESDAY. GUIDANCE
SUGGESTS VSBYS COULD DROP AS LOW AS A MILE DURING THE HIGHEST
SNOWFALL RATES. WILL KEEP AN EYE ON UPSTREAM OBS AND ADJUST TAFS AS
NEED BE.

&&

.MKX WATCHES/WARNINGS/ADVISORIES...
WI...NONE.
LM...NONE.
&&

$$

UPDATE...GEHRING
TONIGHT/WEDNESDAY AND AVIATION/MARINE...JTS
WEDNESDAY NIGHT THROUGH TUESDAY...HENTZ



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