Area Forecast Discussion
Issued by NWS Milwaukee/Sullivan, WI

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FXUS63 KMKX 261811 AAA
AFDMKX

AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE MILWAUKEE/SULLIVAN WI
1211 PM CST FRI DEC 26 2014

.UPDATE...

ENJOY THE SUNSHINE WHILE YOU CAN THIS MORNING. HIGH CLOUDS ARE
WORKING THEIR WAY INTO SOUTHERN WI AHEAD OF THE NEXT LOW PRESSURE
SYSTEM TODAY. THEN WE WILL BE STUCK IN LOW CLOUDS OVERNIGHT THROUGH
SATURDAY. GIVEN THE SUNSHINE AND WARM AIR ADVECTION... TEMPERATURES
ARE ALREADY APPROACHING VALUES WE HAD FOR THE FORECAST HIGH...
ESPECIALLY UP TOWARD CENTRAL WI. SOUTHEAST WI COULD SEE UPPER 40S
TODAY. WE ADJUSTED MAX TEMPS ACCORDINGLY.

SURFACE LOW PRESSURE WILL TRACK NORTHEAST ON THE LEADING EDGE OF A
500MB SHORTWAVE EJECTING OUT OF THE PLAINS. LIGHT RAIN WILL LIKELY
HOLD OFF UNTIL AFTER MIDNIGHT AND EVEN AFTER THAT IT SHOULD BE
SPOTTY. THE NAM HAS HIGHER QPF BEHIND THE COLD FRONT THAN THE OTHER
MODELS... SO I WILL GO WITH A LIGHTER BLEND FOR TONIGHT INTO
SATURDAY. IT SHOULD STAY ALL RAIN EXCEPT NORTHWEST OF MADISON WHERE
THERE WILL BE A CHANGEOVER TO SNOW DURING THE MID TO LATE MORNING
SATURDAY... SHORTLY BEFORE ENDING.

&&

.AVIATION/18Z TAFS/...

VFR TODAY WITH A SOUTHWEST FLOW AHEAD OF A LOW PRESSURE TROUGH
SPREADING INTO THE REGION. WITH THE SOUTHWEST FLOW BRINGING ADDED
MOISTURE EXPECT MVFR CIGS TO RETURN BY EVENING...WHICH WILL LOWER TO
IFR TONIGHT AND LIFR LATE TONIGHT.  VSBY WILL BE DOWN TO A MILE OR
TWO IN FOG WITH THE LOW CEILINGS. EXPECT LIGHT RAIN TO DEVELOP AFTER
MIDNIGHT AND POSSIBLY MIX WITH AND CHANGE TO SNOW NORTH AND
NORTHWEST OF MADISON SATURDAY MORNING. PRECIP WILL BE LIGHT AND MAY
BE DRIZZLE INSTEAD OF RAIN AT TIMES.

&&

.MARINE...

WINDS ARE EASING AS THE PRESSURE GRADIENT BECOMES BAGGY WITH
APPROACHING SURFACE TROUGH. ALLOWED THE SMALL CRAFT ADVY TO EXPIRE
AT 9 AM.

WINDS WILL INCREASE SATURDAY AFTERNOON IN THE WAKE OF A COLD FRONT.
GUSTS WILL APPROACH SMALL CRAFT ADVY LEVELS LATE IN THE AFTERNOON
FOR A SHORT PERIOD OF TIME.

&&

.PREV DISCUSSION... /ISSUED 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...NONE.
&&

$$

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


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