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AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MILWAUKEE/SULLIVAN WI
309 AM CST FRI DEC 26 2014

.SHORT TERM...

.TODAY AND TONIGHT...FORECAST CONFIDENCE...HIGH

AN UPPER LEVEL TROUGH WILL EXTEND ACROSS THE NORTHERN AND CENTRAL 
ROCKIES WITH A SOUTHWEST FLOW ACROSS SOUTHERN WISCONSIN. 
 
WEAK UPPER DIVERGENCE MAINLY TONIGHT...ESPECIALLY LATE...ALONG WITH 
WEAK BUT INCREASING 700 MB UPWARD MOTION.  THE 700 MB RH INCREASES 
TONIGHT ESPECIALLY LATE.  850 MB TEMPERATURES INCREASE TODAY...THEN 
COOL...ESPECIALLY NORTH AND NORTHWEST OF MADISON.  AS 500 MB 
CYCLONIC VORTICITY INCREASES AHEAD OF AN APPROACHING MID LEVEL 
SHORTWAVE...A WEAK LOW MOVES NORTHEAST ALONG THE STALLED TROUGH 
AXIS. 850 AND 925 MB LAYERS BECOME SATURATED TONIGHT AS LOW LEVEL  
MOISTURE RETURNS. 
 
THE MODELS BRING AN INCREASE IN LIGHT PRECIPITATION TONIGHT... 
ESPECIALLY LATE. 
 
THICKNESS AND 850 MB TEMPERATURES SUPPORT MAINLY SNOW IN THE FAR 
NORTHWEST TOWARDS THE DELLS AND MARQUETTE COUNTY LATE TONIGHT.  
HOWEVER NAM FORECAST SOUNDINGS SHOW TEMPERATURES JUST ABOVE FREEZING 
EXTENDING FROM 2 TO 5 THSD FT...SO SNOW TURNOVER WOULD BE LATER THAN 
EXPECTED. 

SATURDAY-FORECAST CONFIDENCE HIGH

MODELS IN GOOD AGREEMENT IN MOVING LOW ACROSS SOUTHERN WISCONSIN
EARLY IN THE MORNING...WITH THE WAVE ENDING UP IN NORTHERN LOWER
MICHIGAN BY THE EARLY AFTERNOON. BOUNDARY LAYER TEMPERATURE
PROFILES WILL BE WARM...WITH 40S TO START ACROSS SOUTHEAST HALF.
LOOKS LIKE RAIN SNOW MIX IN NORTHWEST TURNING OVER TO ALL SNOW
WITH A SLUSHY INCH FROM NORTHERN SAUK INTO NORTHERN MARQUETTE
COUNTIES.  

LOOKS LIKE A SCENARIO IN THE SOUTHEAST HALF OF AREA WHERE LIGHT
RAIN ENDS BEFORE COLUMN COOLS ENOUGH TO TURN PRECIPITATION TO
SNOW.  

.LONG TERM...

MONDAY-FORECAST CONFIDENCE MEDIUM

1055+ MB HIGH PUSHES INTO MONTANA WILL POLAR PUSH RUSHING DOWN THE
FRONT RANGE. COLD ADVECTION IN NORTHWEST FLOW SHOULD BRING A
RETURN TO THE REALITY OF WINTER WITH 850 MB TEMPERATURES DROPPING
INTO THE -15C RANGE.  

GFS IS DRY BUT CANADIAN AND ECMWF HAVE A LIGHT BAND OF
FRONTOGENETIC SNOW BUT AT THIS POINT ONLY A SLIGHT CHANCE OF SNOW
IS WARRANTED.  

TUESDAY-FORECAST CONFIDENCE HIGH

POLAR HIGH OF ABOUT 1050 MB SAGS TOWARD NORTHEAST COLORADO WITH
BRISK NORTHWEST FLOW AND 850 MB TEMPS OF -15 TO -20C OVER
SOUTHERN WISCONSIN. LACK OF SNOW COVER WILL PROVIDE SOME
MODERATION... HOWEVER THERE WILL BE SNOWPACK JUST NORTHWEST OF
SOUTHERN WISCONSIN SO THAT MODERATION WILL NOT BE DRASTIC.

WEDNESDAY AND THURSDAY-FORECAST CONFIDENCE MEDIUM

SOME MODERATION WITH WESTERLY LOW LEVEL FLOW BUT LOOKS CONTINUED
DRY AND SEASONAL TEMPERATURES. 

&&

.AVIATION/12Z TAFS/...

EXPECT MAINLY VFR CONDITIONS EARLY...WITH SOME MVFR VSBYS POSSIBLE 
DURING THE EARLY MORNING.  WITH A SOUTHWEST FLOW AROUND 35 TO 40 
KNOTS FROM 15 HUNDRED TO 2 THSD FT...WILL HAVE TO WATCH FOR 
POTENTIAL OF LOW-LEVEL WIND SHEAR FOR A TIME EARLY THIS MORNING. 
WINDS EASE IN THE EARLY TO MID MORNING AS GRADIENT GETS BAGGY WITH 
THE APPROACH OF A WEAK TROUGH. WITH THE SOUTHWEST FLOW BRINGING 
ADDED MOISTURE EXPECT MVFR CIGS TO RETURN BY AFTERNOON...WHICH WOULD 
THEN LOWER TO IFR TONIGHT AND LIFR LATE TONIGHT.  EXPECT LIGHT RAIN 
TO DEVELOP TONIGHT AND POSSIBLY MIX WITH AND CHANGE TO SNOW NORTH 
AND NORTHWEST OF MADISON LATE TONIGHT.  

&&

.MARINE...

A SMALL CRAFT ADVISORY IS IN EFFECT UNTIL 9 AM...FOR FREQUENT 
SOUTHWEST WIND GUSTS TO 25 KNOTS.

WINDS WILL EASE AS GRADIENT BECOMES BAGGY WITH APPROACH OF A 
SURFACE TROUGH.

&&

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

&&

$$

TODAY/TONIGHT AND AVIATION/MARINE...HENTZ
SATURDAY THROUGH THURSDAY...CRAVEN

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