Area Forecast Discussion
Issued by NWS Milwaukee/Sullivan, WI

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000
FXUS63 KMKX 241602 AAA
AFDMKX

AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE MILWAUKEE/SULLIVAN WI
1002 AM CST WED DEC 24 2014

.UPDATE...

LATEST NAM AND HRRR CONTINUE TO SHOW LESS PRECIP FOR SOUTHERN
WISCONSIN TODAY. WITH SATURATION STRUGGLING UP TO AROUND
-10C...ANY PRECIP THAT DOES MOVE THROUGH WILL PROBABLY BE EITHER
LIGHT SNOW OR LIGHT RAIN. SEEING THIS MIX RIGHT NOW TO THE WEST.
AT THIS POINT...NO APPRECIABLE RAIN OR SNOW IS EXPECTED AS
DEEPENING LOW PRESSURE LIFTS NORTH WELL TO THE EAST OF THE
FORECAST AREA. WILL PROBABLY NEED TO CUT BACK ON POPS FOR THE
REMAINDER OF THE DAY. LIGHT PRECIP WILL WIND DOWN BY THE LATE
EVENING HOURS.

VISIBILITIES CONTINUE TO IMPROVE ACROSS THE FORECAST AREA THIS
MORNING...SO WILL ALLOW THE DENSE FOG ADVISORY TO EXPIRE AT 10 AM.

&&

.AVIATION/18Z TAFS/...

LATEST MODELS CONTINUE TO THE DOWNWARD TREND IN PRECIP
CHANCES...WITH NO APPRECIABLE RAIN OR SNOW EXPECTED THROUGH THE
REMAINDER OF THE DAY. STILL MAY SEE A LITTLE LIGHT SNOW OR RAIN AT
TIMES INTO THE EVENING HOURS AS THE UPPER THROUGH SWINGS THROUGH.

VISIBILITIES WILL CONTINUE TO IMPROVE THROUGH LATE
MORNING...THOUGH LOW CLOUDS WILL LIKELY PERSIST INTO TONIGHT.
SHOULD SEE A RETURN TO VFR CONDITIONS BY MID OR LATE THURSDAY
MORNING.

&&

.MARINE...

WILL FURTHER DELAY START OF SMALL CRAFT ADVISORY UNTIL 00Z.
FARTHER EAST TRACK OF LOW PRESSURE MOVING NORTHEAST TOWARD
THE CENTRAL GREAT LAKES DELAYING TIGHTENING PRESSURE GRADIENT OVER
LAKE MICHIGAN.  HENCE NOT EXPECTING GUSTY NORTHWEST WINDS TO DEVELOP
UNTIL TONIGHT.  SHIP REPORT EAST OF RACINE AT EDGE OF NEARSHORE
WATERS HAD SUSTAINED WINDS OF 12 KT.

&&

.PREV DISCUSSION... /ISSUED 342 AM CST WED DEC 24 2014/

SHORT TERM...

THE 00Z NAM/GFS AND ECMWF HAVE TRENDED EAST WITH LOW EXPECTED TO
TRACK ALONG IN/OH BORDER AND INTO SOUTHEAST MICHIGAN. RAPID
DEEPENING PHASE OF ABOUT 1 MB/HOUR EXPECTED TO START IN THE
MORNING IN OHIO VALLEY AND CONTINUES INTO THE EVENING AS STORM
CROSSES SOUTHEAST MICHIGAN AND BOUND FOR GEORGIAN BAY.

WILL CONTINUE THE PREVIOUS IDEA OF LOWERING THE ACCUMULATING SNOW
AND HAVE CANCELLED THE WINTER WEATHER ADVISORIES.  NAM FORECAST
SOUNDINGS SHOW A FAIRLY DRY LAYER FROM 4 TO 13 THSD FT EARLY THIS
MORNING OVER THE FAR SOUTHEAST.  THIS DIMINISHES...BUT DEEP
SATURATION IS RATHER BRIEF LATE THIS MORNING AND EARLY AFTERNOON
BEFORE DRYING OCCURS AROUND 10 THSD FT EARLY THIS EVENING. SNOW
RATIOS ARE RATHER LOW IN THE FAR EAST WHERE THE PRECIPITATION WOULD
BE MORE.  THE 12Z ECMWF HAS LITTLE IF ANY MEASURABLE PRECIPITATION
OVER SOUTHEAST WISCONSIN.  THE HRRR IS THE MOST AGGRESSIVE MESO MODEL
WITH AROUND 0.15 OF PRECIPITATION OVER THE LAKESHORE COUNTIES.
HOWEVER EVEN THIS WOULD BE LIMITED DUE TO THE CONSENSUS 6 TO 1 SNOW
RATIOS.

THE NEW 06Z NAM CONTIUES THE EASTWARD TREND AND NOW AGREES WITH THE
ECMWF WITH LITTLE IN THE WAY OF MEASURABLE PRECIPITATION OVER
EASTERN WISCONSIN.

CHRISTMAS DAY...FORECAST CONFIDENCE HIGH.

HIGH PRESSURE CENTERED OVER THE GULF COASTAL STATES WILL STRETCH ITS
AXIS UP INTO THE GREAT LAKES FOR CHRISTMAS...BRINGING A DRY AND
RATHER PLEASANT DAY WITH HIGHS IN THE MID TO UPPER 30S. WE MIGHT
EVEN SEE A LITTLE SUNSHINE.

LONG TERM...

FRIDAY THROUGH SATURDAY... FORECAST CONFIDENCE MEDIUM.

FRIDAY WEATHER WILL REMAIN QUIET AND MILD OVER SOUTHERN WI. HIGHS
ARE EXPECTED IN THE LOWER 40S WITH A SOUTHERLY BREEZE. THERE WILL
LIKELY BE LOW CLOUDS AROUND DUE TO THE LOW LEVEL MOISTURE SPREADING
BACK INTO THE REGION.

A WEAK SURFACE LOW PRESSURE TROUGH AND COLD FRONT WILL SLIDE THROUGH
SOUTHERN WI FRIDAY NIGHT. MEANWHILE... A 500MB SHORTWAVE WITHIN THE
LEFT EXIT REGION OF A STRENGTHENING UPPER JET WILL BE TRACKING
THROUGH CENTRAL AND NORTHERN WI. MODELS ARE SHOWING TWO AREAS OF
PRECIP ASSOCIATED WITH THIS SYSTEM... ONE MAINLY IN IL THAT CLIPS
SOUTHEAST WI AND THE OTHER OVER THE NORTHWEST HALF OF WI. THE MKX
FORECAST AREA WILL LAND BETWEEN THESE TWO FAVORED AREAS. THE GFS AND
NOW THE 06Z NAM SHOW THESE TWO AREAS CLEARLY IN THE QPF FIELD AND
THE ECMWF DOES TO A LESSER EXTENT.

TEMPERATURE PROFILES SHOW THAT MOST OF THE PRECIP IN SOUTHEAST WI
WILL FALL AS RAIN AND THEN GRADUALLY CHANGE OVER TO SNOW OVERNIGHT
INTO SATURDAY MORNING BEFORE ENDING. IN THE NORTHERN FORECAST
AREA... THE TEMP PROFILE IS COLDER AND WE ARE LOOKING AT A RAIN/SNOW
MIX CHANGING OVER TO SNOW BY MIDNIGHT. PRECIP AMOUNTS WILL BE
LIGHT... LESS THAN A TENTH OF AN INCH. ANY SNOW ACCUMULATION WOULD
BE LESS THAN A HALF INCH.

THE ECWMF HANGS ONTO THE LIGHT PRECIP LONGER IN SOUTHEAST WI THAN
THE GFS ON SATURDAY. COLD AIR ADVECTION AND CLOUDS WILL LEAD TO
STEADY TEMPS AROUND 30 THROUGH THE DAY.

SUNDAY THROUGH TUESDAY... FORECAST CONFIDENCE HIGH.

SURFACE HIGH PRESSURE AND DRY WEATHER WILL DOMINATE FOR SUNDAY AND
MONDAY... BUT TEMPERATURES WILL BE BELOW AVERAGE.

ANOTHER BROAD TROUGH WILL CROSS THE COUNTRY EARLY NEXT WEEK AND MAY
BRING SOME LIGHT SNOW ACROSS WISCONSIN ON A SHORTWAVE MONDAY NIGHT
INTO TUESDAY.

THEN A DEEPER UPPER LEVEL TROUGH IS FORECAST TO DROP DOWN FROM
CANADA THROUGH THE UPPER MIDWEST AND BRING JANUARY-LIKE TEMPERATURES
INTO THE REGION FOR THE NEW YEAR.

AVIATION/12Z TAFS/...

EXPECT IFR/LIFR CIGS OVER MUCH OF SOUTH CENTRAL AND PORTIONS OF
SOUTHEAST WISCONSIN.  LIFR FOG EXPECTED TO PERSIST FOR A FEW HOURS
AFTER SUNRISE OVER PORTIONS OF SOUTH CENTRAL WISCONSIN.

OVER THE FAR SOUTHEAST IFR CIGS POSSIBLE LATER THIS MORNING AND
AFTERNOON.  DUE TO THE EXPECTED MIX OF RAIN AND SNOW FAR EAST
TEMPERATURES IN THE MID TO UPPER 30S AT SURFACE MAY PREVENT
SIGNIFICANT CHANGEOVER AND PAVEMENT MAY REMAIN MAINLY WET THROUGH
THE PRECIPITATION DURATION.  HOWEVER STILL SOME ACCUMULATIONS ARE
POSSIBLE.

MARINE...

RAPID DEEPENING LOW WILL RESULT IN BRISK NORTH AND THEN NORTHWEST
WINDS THIS AFTERNOON INTO EARLY THURSDAY. WITH THE LOW GOING FURTHER
EAST THE THREAT OF GALES IS DIMINISHING ON THE WEST SIDE OF LAKE
MICHIGAN SO CURRENT SMALL CRAFT ADVISORY SHOULD SUFFICE.

&&

.MKX WATCHES/WARNINGS/ADVISORIES...
WI...NONE.
LM...SMALL CRAFT ADVISORY FROM 6 PM THIS EVENING TO NOON CST THURSDAY
     FOR LMZ643>646

&&

$$

UPDATE...DDV/MBK
TODAY/TONIGHT AND AVIATION/MARINE...HENTZ
THURSDAY THROUGH TUESDAY...MRC


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