Area Forecast Discussion
Issued by NWS Milwaukee/Sullivan, WI

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FXUS63 KMKX 171745 AAA
AFDMKX

AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE MILWAUKEE/SULLIVAN WI
1145 AM CST WED DEC 17 2014

.UPDATE...
SCATTERED FLURRIES POSSIBLE THROUGH EARLY AFTERNOON AHEAD OF UPPER
LEVEL SHORTWAVE DROPPING SOUTH THROUGH THE REGION. SHOULD BE IN A
REGION OF GREATER LOW LEVEL SUBSIDENCE THIS AFTERNOON BEHIND THE
SHORTWAVE. UPPER LEVEL CONVERGENCE ASSOCIATED WITH LEFT ENTRANCE
REGION OF UPPER JET MOVING ACROSS S WI SHOULD ALSO HELP END
FLURRIES LATER THIS AFTERNOON. HIGH TEMPERATURES LOOK ON TRACK TO
REACH THE UPPER 20S WITH CLOUD CLEARING LINE VERY SLOW TO MOVE
EASTWARD. AREAS WEST OF MADISON SHOULD SEE SOME BREAK UP OF CLOUDS
BY THE EVENING. CLOUDS SHOULD BECOME MORE SCATTERED OVER SOUTH-
CENTRAL WI OVERNIGHT.

&&

.AVIATION/18Z TAFS/...
EXPECT SCATTERED FLURRIES THROUGH THE EARLY AFTERNOON. CLEARING LINE
ALONG THE MISSISSIPPI RIVER IS SLOW TO PROGRESS EASTWARD. MSN SHOULD
SEE SOME REDUCTION IN CLOUD COVER BY EVENING AND EASTERN TAF SITES
MAY SEE A REDUCTION IN CLOUD COVER LATER IN THE EVENING BUT
CONFIDENCE IS NOT HIGH. MORE CLOUDS ARE EXPECTED TO MOVE IN FROM THE
NORTH OVERNIGHT. SOME UNCERTAINTY ABOUT WHETHER CEILINGS WILL BE
MVFR OR VFR THIS EVENING AND WHETHER IT WOULD BE SCATTERED OR
BROKEN COVERAGE. THESE CLOUDS ARE MORE LIKELY TO IMPACT EASTERN
TAF SITES THAN MSN. MORE CONFIDENCE WITH CEILINGS RISING TO VFR
AFTER MIDNIGHT.

&&

.PREV DISCUSSION... /ISSUED 315 AM CST WED DEC 17 2014/

TODAY AND TONIGHT...FORECAST CONFIDENCE - MEDIUM.

WESTERLY LOW LEVEL WINDS HAVE NUDGED LOW CLOUDS BACK INTO NORTHEAST
CWA LAST HOUR OR SO.  IR IMAGERY SHOWING POTENTIAL THIN SPOTS IN
OVERCAST VCNTY OF KDLL AND KLNR WHICH HAVE RESULTED IN BRIEFLY
HIGHER CIGS.  HOWEVER THIN SPOTS NOT INCREASING.  FARTHER
NORTHWEST...BACK EDGE OF STRATUS FIELD HAS BEEN PROGRESSING SLOWLY
SOUTHEAST ACROSS SE MN.  THIS BACK EDGE WOULD REACH PARTS OF WRN CWA
IN THE EARLY AFTN.

RECENT TAMDAR ASCENT KMKE SOUNDING SHOWED A STRONG INVERSION ABV
3.8K. 00Z KGRB SOUNDING MEASURED CONSIDERABLE COLUMN RH UP TO 500MB.
WEAK FORCING ASSOCD WITH MID-LEVEL SHORT WAVE TROUGH THAT WILL BE
SWINGING THRU SRN WI INTO THE EARLY AFTN WL BE TEMPERED BY WEAK
UPPER LEVEL SUBSIDENCE WITH LEFT ENTRANCE REGION OF UPPER LEVEL JET
PASSING TO THE SOUTH. WL GO MORE PESSIMISTIC WITH CLOUD COVER THIS
MRNG WITH AFTN CLEARING IN THE WEST.  CLOUDS MAY ALSO BREAK UP FOR A
TIME IN THE EAST DUE TO NORTHWEST WINDS AND SUBSIDENCE BUT THINKING
THIS WOULD MOST LIKELY OCCUR LATER TODAY AS CORE OF LOW LEVEL COLD
AIR ADVECTION SLIDES OFF TO THE EAST.  KMKX VCP-31 CONTINUES TO SHOW
VERY WEAK RETURNS INDICATING FEW FLURRIES GETTING SHAKEN OUT OF LOW
CLOUDS.  WL KEEP FLURRY MENTION THRU THE MRNG AS MID-LEVEL LOW
PRESSURE TROF SWINGS THRU.

WL KEEP MORE CLOUDS OVER ERN CWA TNGT AS WEAK LOW LEVEL TROF FINALLY
EXITS AREA LATE TONIGHT.  EXPC AT LEAST PARTIAL CLEARING IN THE
WEST. LACK OF SNOW COVER WL PREVENT OVERNIGHT TEMPS FROM FALLING TO
FAR DUE TO PARTIAL CLEARING AND LIGHTER LOW LEVEL WINDS.  HOWEVER IF
MORE CLEARING IS EXPECTED...TEMPS MAY NEED TO BE LOWERED A FEW
DEGREES.

THURSDAY THROUGH SUNDAY - CONFIDENCE...MEDIUM
QUIET WEATHER PATTERN AS HIGH PRESSURE DOMINATES. WITH 850 TROUGH
DRAWING CLOSER A WEAK WAA PATTERN DEVELOPS THOUGH BEST FORCING
FROM THIS IS STILL TO OUR WEST SO WILL STICK WITH THE DRY
FORECAST. 925 TEMPS SHOW AROUND -8C THURSDAY MODIFYING A BIT TO
-4C BY SATURDAY. THE SOUTHERLY FLOW MODIFIES THE AIRMASS FURTHER
FOR SUNDAY WITH 925 TEMPS TO -1 TO -3C. ECMWF AND GFS BOTH SHOW
PRECIP ASSOCIATED WITH SURFACE/850 TROUGH INDUCED FORCING STILL
REMAINING TO OUR WEST ACROSS IA/MN AND INTO NW WI. SO WILL LEAVE
SUNDAY FORECAST DRY AS WELL.

MONDAY AND TUESDAY - CONFIDENCE...LOW
UPPER JET WILL BE CARVING OUT AND AMPLIFYING A TROUGH ACROSS THE
MIDDLE OF THE COUNTRY THIS PERIOD. ON MONDAY THE MODELS HAVE SOME
AGREEMENT ON HAVING THE EVOLVING SURFACE/850 LOWS TO OUR WEST. A
CONVEYOR OF WARM AND MOIST ADVECTION INTO SRN WI IS EXPECTED. THE
ECMWF IS SLOWER ON PRECIP ARRIVAL AND ALSO SHOWS A COOLER 850 TEMP
REGIME. MEANWHILE THE GFS IS ABOUT 3-4 WARMER AND WOULD BE
SUPPORTIVE OF MORE OF A MIX RATHER THAN SNOW AT THE OUTSET. ON
MONDAY NIGHT AND TUESDAY THE GFS TAKES A WEAK LOW ACROSS NORTHERN
WI WHILE THE ECMWF SHOWS MORE OF AN INVERTED TROUGH FEATURE.
POTENTIAL FOR TRICKY THERMAL PROFILES SO WILL KEEP THE MIXY NATURE
IN THE GRIDS AT THIS TIME...THOUGH SOME EASTERN AND SOUTHERN AREAS
MAY SEE ALL RAIN FOR MUCH OF THIS WITH ANY LIGHT SNOW
ACCUMULATIONS MORE LIKELY IN THE NW CWA. 2 METER TEMPS FROM THE
GFS AND ECMWF SHOW TEMPS ABOVE FREEZING SO LIKELY TO SEE A GOOD
DEAL OF MELTING OF ANY SNOW THAT OCCURS WITH THIS PERIOD. BY
TUESDAY NIGHT MODELS SHOW A SECONDARY AND STRONGER SURFACE/850 LOW
DEVELOPING ON EASTERN SIDE OF INCREASING NEGATIVELY TILTED TROUGH.
BY THIS TIME COLDER AIR WILL LIKELY BE DRAWN INTO ALL OF SRN WI AS
THIS LOW WINDS UP TO OUR EAST PER GFS OR SOUTHEAST PER ECMWF. WILL
BE INTERESTING TO WATCH HOW MODELS HANDLE THIS SECONDARY LOW OVER
THE NEXT SEVERAL MODEL RUNS.

AVIATION/12Z TAFS/...FOR NOW WL REMAIN MORE PESSIMISTIC WITH REGARDS
TO MVFR CLOUD COVER FOR MOST OF TODAY. RECENT ASCENT TAMDAR SOUNDING
FROM KMKE INDICATES STRONG INVERSION ABV 3.5K. ELEVATED INVERSION
ONLY VERY SLOWLY WEAKENS AS LOW LEVEL MOISTURE SLOWLY THINS INTO
TNGT. POSSIBLE THAT WESTERLY WINDS AND SUBSIDENCE IN ERN CWA MAY
CAUSE CIGS TO INCREASE TO VFR LATER TODAY BUT WL LIKELY CARRY MVFR
OR LOW VFR CIGS INTO TNGT FOR NOW. EXPC LGT FLURRIES TO CONTINUE
THIS MRNG AS MID-LEVEL SHORT WAVE SWINGS THRU BUT NO VSBY RESTRICTION
EXPECTED.

MARINE...WILL CONTINUE SMALL CRAFT ADVY THROUGH MID-MORNING. RECENT
SHIP REPORTS INCLUDING TUG NEAR THE EDGE OF THE NEARSHORE WATERS
REPORTING SUSTAINED WINDS IN THE LOW 20 KT RANGE. STEEP LOW LEVEL
LAPSE RATES WL CONTINUE THIS MRNG AS COLD AIR CONTINUES TO MOVE
ACROSS WARMER LAKE MI WATERS. EXPC WINDS TO DIMINISH LATER THIS
MRNG AND AFTN FOLLOWED BY HIGHER WAVE HEIGHTS TOWARDS THE OPEN
WATER.

&&

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

$$

UPDATE...MARQUARDT
TODAY/TONIGHT AND AVIATION/MARINE...MBK
THURSDAY THROUGH TUESDAY...COLLAR


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