Area Forecast Discussion
Issued by NWS Milwaukee/Sullivan, WI

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FXUS63 KMKX 201639
AFDMKX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MILWAUKEE/SULLIVAN WI
ISSUED BY NATIONAL WEATHER SERVICE GREEN BAY WI
1039 AM CST TUE JAN 20 2015

.AVIATION/18Z TAFS/...
CIGS GENERALLY IN THE IFR CATEGORY LATE THIS MORNING WL EDGE UP
SOME THIS AFTN. ANOTHER ROUND OF IFR/LIFR VSBYS LIKELY OVERNIGHT
AS A BAND OF SNOW MVS THROUGH THE AREA. A LITTLE DZ/FZDZ IS
POSSIBLE AT THE ONSET...BEFORE DEEPER MOISTURE ARRIVES TO SEED THE
LOWER CLDS WITH ICE CRYSTALS.
&&

.PREV DISCUSSION... /ISSUED 332 AM CST TUE JAN 20 2015/

SHORT TERM...

TODAY AND TONIGHT...FORECAST CONFIDENCE - MEDIUM.

EXPECT AREAS OF -SN AND ISOLATED -ZR/-ZL TO DIMINISH THROUGH THE
EARLY MORNING AS WEAK TROF AND LOW LEVEL FRONTOGENETICAL FORCING
SLIDES OFF TO THE EAST.  IR CLOUD ENHANCEMENT SHOWING COLDER CLOUD
TOPS WITH BULK OF PRECIP FALLING ACROSS SRN WI ATTM FAVORING ICE
CRYSTAL INITIATION INTO CLOUD TOP.  HOWEVER SOME MID-LEVEL DRYING
AROUND 5-6K FT RESULTING IN THE PATCHY LIQUID PRECIP.

SOME PATCHY -L OR -ZL MAY LINGER IN THE AREA LATER THIS MORNING INTO
THE EARLY AFTN DUE TO LINGERING WEAK ISENTROPIC LIFT.

OTHERWISE...NEXT SHORT WAVE IN PARADE ALREADY POISED UPSTREAM OVER
CENTRAL DAKOTAS.  THIS WAVE WILL TAKE SIMILAR TRACK TO CURRENT SHORT
WAVE NOW PROGRESSING THRU NRN IL.  DIFFERENCE WITH THIS NEXT SYSTEM
IS THAT COLUMN WILL BE MOISTER AND COLDER THROUGH 10K FEET.  WEAK
MID-LEVEL CIRCULATION PLACEMENT WITH THIS SYSTEM HANDLED WITH BETTER
RUN TO RUN CONSISTENCY FROM NAM GUIDANE.  NAM CARRIES WEAK MID-LEVEL
CIRCULATION ACROSS SRN WI/NRN IL LATE TNGT INTO WED MRNG.  WEAK
FRONTOGENETICAL FORCING AND MODERATE Q-VECTOR CONVERGENCE SHOULD
RESULT IN EXPANDING AREA OF -SN ACROSS SRN WI OVERNIGHT WITH BETTER
CHANCE IN EAST AFT MIDNIGHT.  SHOULD NOT HAVE TO WORRY ABOUT ANY
MIXTURE TNGT WITH DEEPER AND COLDER COLUMN AND PERIOD OF LIFT IN
BETTER DENDRITIC GROWTH ZONE.

SNOW LIQUID RATIOS FROM THICKNESS AND COBB FAVORING AROUND 15 TO 1
TONIGHT.  STRONGEST LOW LEVEL DEFORMATION REMAINS SOUTH OF THE AREA.
HENCE LOOKING AT WIDESPREAD 1 TO 2 INCH SNOWFALL WITH LESSER AMOUNTS
IN THE FAR NORTH AND NORTHEAST.

WEDNESDAY AND WEDNESDAY NIGHT... FORECAST CONFIDENCE MEDIUM.

SNOW WILL BE TAPERING OFF ACROSS SOUTHERN WI DURING THE DAY
WEDNESDAY. THE UPPER LOW WILL BE TRACKING ACROSS SOUTHERN WI IN THE
MORNING WHILE THE WEAK SURFACE LOW SLIDES ALONG THE WI/IL BORDER.
THERE WILL BE DEEP ENOUGH MOISTURE WITHIN THE SNOW GROWTH ZONE TO
SUPPORT LIGHT SNOW... DESPITE THE WEAKENING UPWARD MOTION... Q-
VECTOR CONVERGENCE AND LOW LEVEL FRONTOGENESIS.

THERE IS STILL QUESTION ABOUT HOW LONG THE LIGHT SNOW OR FLURRIES
WILL LINGER INTO WEDNESDAY NIGHT. THE NAM KEEPS DEEP MOISTURE OVER
SOUTHERN WI MUCH LONGER THAN THE GFS AND ECMWF DUE TO IT KEEPING THE
UPPER TROUGH OVERHEAD LONGER. I LEANED TOWARD THE DRIER SOLUTION FOR
NOW.

LONG TERM...

THURSDAY AND FRIDAY... FORECAST CONFIDENCE HIGH.

CLOUDS WILL LIKELY HANG AROUND THROUGH AT LEAST MIDDAY THURSDAY
UNTIL DRY AIR ALOFT CAN MOVE IN WITH WEAK MID LEVEL RIDGING. PLAN ON
QUIET WEATHER WITH RELATIVELY MILD TEMPERATURES THROUGH AT LEAST
EARLY NEXT WEEK.

SATURDAY... FORECAST CONFIDENCE MEDIUM.

A NORTHWEST FLOW PATTERN WILL PERSIST OVER THE UPPER MIDWEST THROUGH
THE WEEKEND. ANOTHER SHORTWAVE DROPPING THROUGH THE UPPER GREAT
LAKES REGION WILL BRING AN ASSOCIATED SURFACE LOW ACROSS ONTARIO AND
A SURFACE TROUGH FROM NORTHWEST TO SOUTHEAST ACROSS WI FRI AFTERNOON
AND NIGHT.

LOOK FOR INCREASING SOUTHWESTERLY WINDS AHEAD OF THE TROUGH LATE THU
NIGHT THROUGH FRI. THE FRONT IS EXPECTED TO COME THROUGH DRY FRI
AFTERNOON/EVENING ALTHOUGH CANNOT RULE OUT A FEW SPRINKLES...
ESPECIALLY TOWARD CENTRAL WI.

THE GFS TEMPORARILY BRINGS COLDER AIR THAN THE ECWMF INTO SOUTHERN
WI BEHIND THE SURFACE TROUGH SATURDAY NIGHT. LOW TEMPS WILL DEPEND
ON WHICH SOLUTION PANS OUT AND ALSO HOW LONG THE LOW CLOUDS
LINGER.

SUNDAY THROUGH MONDAY... FORECAST CONFIDENCE MEDIUM.

ANOTHER SERIES OF SHORTWAVES WILL DROP DOWN FROM THE NORTHERN PLAINS
AND BRING A SWATH OF PRECIP ACROSS MN/IA/IL AND SOUTHERN WI LATE
SATURDAY NIGHT THROUGH SUNDAY NIGHT OR MONDAY MORNING. BOTH THE
ECMWF AND GFS KEEP THE MAIN FRONTOGENETICAL BAND SOUTH OF THE WI
BORDER... BUT THE GFS CLIPS SOUTHERN WI WITH HEAVIER QPF THAN THE
GFS. AT THIS TIME... THE PRECIP TYPE SHOULD BE ALL SNOW. THIS STILL
LOOKS LIKE A LIGHT SNOW ACCUMULATION EVENT... TWO INCHES OR LESS.

AVIATION/12Z TAFS/...AREAS OF -SN AND POSSIBLY BRIEF -ZR WL
DIMINISH THROUGH THE EARLY MORNING...HOWEVER PATCHY -L OR -ZL MAY
REDEVELOP LATER THIS MRNG OR AFTN.  OTRW LOW MVFR OR IFR CIGS SHOULD
LIFT SLIGHTLY TO MVFR LATER TODAY.  -SN WL LIKELY RETURN TONIGHT AS
ANOTHER LOW PRESSURE SYSTEM PASSES BY TO THE SOUTH WITH LOWER CIGS
AND VSBYS.

MARINE...SEVERAL WEAK LOW PRESSURE SYSTEMS WILL PASS BY TO THE
SOUTH OVER THE NEXT 36 HOURS.  PRESSURE GRADIENT WILL TIGHTEN
SLIGHTLY BUT WIND GUSTS ARE NOT EXPECTED TO REACH SMALL CRAFT ADVY
FOR ANY LENGTH OF TIME.  ONSHORE FLOW WL PERSIST UNTIL LATER WED.

&&

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

$$

AVIATION...JS/GRB
TODAY/TONIGHT...MBK
WEDNESDAY THROUGH MONDAY...MRC






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