Area Forecast Discussion
Issued by NWS Milwaukee/Sullivan, WI

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FXUS63 KMKX 250144
AFDMKX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MILWAUKEE/SULLIVAN WI
844 PM CDT TUE MAR 24 2015

.UPDATE...
AN IMPRESSIVE FRONTOGENETIC BAND OF PRECIP MOVED INTO THE FORECAST
AREA THIS EVENING AND WAS GENERALLY A MIX OF RAIN AND SLEET WITH A
FEW COLD SPOTS REPORTING FREEZING RAIN. FORTUNATELY...ROAD SURFACE
TEMPS ARE STILL HOVERING IN THE MID 30S TO AROUND 40 AND COUNTY
DISPATCHERS SO FAR HAVEN/T REPORTED ANY PROBLEMS. THIS BAND IS
PUSHING INTO A VERY DRY AIRMASS...DEWPOINTS STILL IN THE LOWER
TEENS ACROSS THE EAST...AND IT/S NOW SHOWING THE EXPECTED RESULTS
OF DIMINISHING AS IT MOVES NORTH.

WE SHOULD SEE ANOTHER SURGE OF MOISTURE AND DEEP FORCING AS THE
SHORT WAVE AND ASSOCIATED STACKED LOW PRESSURE SYSTEM LIFT
NORTHEAST TOWARD SOUTHEAST WI. THE LOW LEVEL JET TO THE SOUTH IS
CURRENTLY INTENSIFYING AND EXPECTED TO REACH 40-50KTS JUST TO OUR
SOUTH BY 1 AM. THIS INITIAL BAND OF PRECIP WILL BE FOLLOWED BY
ANOTHER SURGE OF PRECIP BY MIDNIGHT AND IT WILL CONTINUE TO BLOSSOM
AFTER MIDNIGHT...DIMINISHING QUICKLY FROM WEST TO EAST TOWARD
SUNRISE. SURFACE TEMPERATURES ARE CRITICAL AND VERY CLOSE TO
FREEZING. WE SHOULD SEE THOSE TEMPS RISE A BIT AS THE SOUTHERLY
WINDS INCREASE. FOR NOW...I THINK OUR ADVISORY FOR THE NORTHERN
COUNTIES WILL HOLD. BUT...IF THOSE TEMPS CONTINUE TO FALL AND THE
RAIN IS MOVING IN...WE MAY NEED TO EXPAND THE ADVISORY.

&&

.AVIATION/06Z TAFS/...
IFR CONDITIONS WILL OVERSPREAD SOUTHERN WISCONSIN BY OR SHORTLY
AFTER MIDNIGHT AS A STRONG LOW PRESSURE SYSTEM LIFTS NORTHEAST
INTO THE GREAT LAKES. ANOTHER SURGE OF PRECIPITATION WILL HIT THE
AREA TOWARD MIDNIGHT AND CONTINUE THROUGH 10-12Z WED. THE
PRECIPITATION WILL DIMINISH QUICKLY FROM WEST TO EAST AROUND 12Z
WED. CIGS/VSBYS WILL IMPROVE TO VFR LEVELS BY MID MORNING ON
WEDNESDAY.

TEMPERATURES WILL BE HOVERING NEAR THE FREEZING THRESHOLD...SO
THERE IS A CHANCE FOR SOME SLEET AND FREEZING RAIN. PAVEMENT
TEMPERATURES SHOULD REMAIN ABOVE FREEZING HOWEVER...SO ANY ICING
MAY ONLY BE ON ELEVATED SURFACES.

&&

.PREV DISCUSSION... /ISSUED 328 PM CDT TUE MAR 24 2015/

TONIGHT - FORECAST CONFIDENCE...MEDIUM

POTENT SHORTWAVE TROUGH CONTINUES TO SHIFT EAST FROM THE CENTRAL
PLAINS. LOW LEVEL DRY AIR FEED PERSISTS AROUND RETREATING HIGH.
PRECIP SURGING TOWARDS CWA FROM ERN IA. SURFACE TEMPS IN MOST AREAS
HAVE CLIMBED WELL ABOVE FREEZING AND WITH CLOUD COVER AND SE WINDS
TO REMAIN SUSTAINED...THE USUAL DROPOFF IN TEMPS NOT LIKELY. THE NAM
SOLUTION CONTINUES TO SHOW WARNING TYPE ICING ACROSS THE CWA AND PER
COLLAB WITH GRB/ARX WILL NOT GO THIS ROUTE. WITH THE DRY AIR IN
PLACE INITIALLY THINK THERE IS POTENTIAL FOR SOME EVAP COOLING WITH
SOME SNOW MIXED IN BEFORE THE LOW LEVEL WARM SURGE TAKES OVER AND
MAKES PREDOMINANT PRECIP TYPE RAIN. HOWEVER PORTIONS OF THE WRN AND
NRN CWA WILL HAVE MORE VULNERABLE THERMAL PROFILES SO THE CURRENT
LAYOUT OF THE ADVISORY SEEMS OK WITH BEST SNOW ACCUM POTENTIAL IN
THE FAR NORTHERN CWA AND WESTERN PERIPHERY OF THE CWA.

WEDNESDAY - FORECAST CONFIDENCE...MEDIUM

PRIMARY SHORTWAVE AND LOW LEVEL TROUGH WILL SHIFT EAST EARLY IN THE
MORNING QUICKLY BRINGING ANY PRECIPITATION TO AN END. SECONDARY WAVE
AND UPPER SPEED MAX ROTATE IN DURING THE AFTERNOON. SO WILL
ACKNOWLEDGE THE TRENDS OF THE GFS/NAM AND HAVE A SMALL POP FOR THE
AFTERNOON HOURS. SOME QUESTION ON DEGREE OF SATURATION. ALSO ECMWF
KEEPS PRECIP SOUTH AND GFS JUST GRAZES SRN CWA. WITH WESTERLY FLOW
AND SOME POTENTIAL BREAKS IN THE CLOUDS...925 TEMPS SUPPORT HIGHS IN
MID/UPPER 40S.

SHORT TERM...WEDNESDAY NIGHT TO FRIDAY - FORECAST
CONFIDENCE...MEDIUM

SOME LINGERING LIGHT PRECIPITATION SHOULD BRIEFLY DRY UP IN THE
EARLY MORNING HOURS THURSDAY UNTIL A SECOND WAVE OF A RAIN/SNOW MIX
ARRIVES EARLY THURSDAY INTO EARLY FRIDAY ALONG SOME WEAK
FRONTOGENETICAL LIFT AND 500 MB SHORTWAVE ENERGY. MODELS SUGGEST
TRACK OF HIGHEST QPF AMOUNTS TO BE ALONG THE EASTERN HALF OF THE
FORECAST AREA...ALTHOUGH UNCERTAINTY EXISTS REGARDING QPF AMOUNTS
AND PRECIP TYPE. PUT IN A CHC OF LIGHT RAIN/SNOW MIX EARLY...THEN
TRANSITION INTO ALL RAIN AS TEMPERATURES INCREASE. KEPT SMALL CHANCE
OF LIGHT SNOW FOR LATE THURSDAY AND EARLY FRIDAY AS TEMPERATURES
DROP BELOW FREEZING. PRECIPITATION LOOKS TO CEASE BY FRIDAY MORNING.

LONG TERM...FRIDAY NIGHT AND SATURDAY - FORECAST CONFIDENCE...MEDIUM

CHILLY TEMPERATURES LOOK TO RETURN TO THE REGION AS AN AREA OF HIGH
PRESSURE MOVES IN. BUFKIT SOUNDINGS SHOW A DRY AIRMASS MOVING IN
ALONG WITH THIS HIGH PRESSURE SYSTEM. WHILE THE HIGH WILL KEEP
CONDITIONS QUIET...TEMPERATURES WILL DROP WITH HIGHS REACHING ONLY
THE LOWER 30S FOR FRIDAY...WITH LOWS SATURDAY IN THE TEENS.

SATURDAY NIGHT TO WEDNESDAY - FORECAST CONFIDENCE...MEDIUM

THE AREA OF HIGH PRESSURE WILL MOVE OUT OF THE REGION LATE SATURDAY
AS AN AREA OF LOW PRESSURE MOVES THROUGH SOUTHERN PORTIONS OF
CANADA. A COLD FRONT ASSOCIATED WITH THIS LOW PRESSURE SYSTEM WILL
SWING THROUGH WISCONSIN EARLY SUNDAY...BRINGING ANOTHER SHOT OF
PRECIPITATION. MID LEVEL SUPPORT DOES EXIST WITH THE GFS AND
CANADIAN MODELS SHOWING A DECENT 500 MB SHORTWAVE TROUGH AND
ASSOCIATED POSITIVE VORTICITY ADVECTION WITH IT. GFS AND ECMWF
MODELS ARE SHOWING QPF AMOUNTS AOB 0.10 OF AN INCH.

THIS SYSTEM MOVES OFF TO THE EAST LATE SUNDAY. QUIET CONDITIONS
RETURN AS HIGH PRESSURE MOVES INTO THE REGION AND STAYS IN CONTROL
INTO TUESDAY. ANOTHER ROUND OF PRECIPITATION MOVES INTO THE REGION
LATE TUESDAY INTO WEDNESDAY. THERE IS SOME UNCERTAINTY WITH THIS
PARTICULAR SYSTEM WITH REGARDS TO TIMING AND AMOUNTS.

AVIATION/00Z TAFS/...VFR INTO THIS EVENING WITH MID/HIGH CLOUDS ON
THE INCREASE. MAIN MOISTURE SURGE ARRIVES TONIGHT WITH STRENGTHENING
LLJ. PRECIP PROGGED TO ARRIVE 23-02Z...SW-NE ACROSS THE CWA. FOR THE
EASTERN TAF SITES BULK OF PRECIP EXPECTED TO BE RAIN WITH SOME MIX
POTENTIAL DUE TO DYNAMIC COOLING LATER IN THE NIGHT. BEST SNOW
ACCUMS EXPECTED TO THE NORTH OF TAF SITES. WILL BE CAREFULLY
MONITORING BOUNDARY CONDITIONS FOR PRECIP TYPE. WITH TEMPS HAVING
CLIMBED ABOVE FREEZING BELIEVE THE CLOUD COVER AND SUSTAINED SE
WINDS WILL KEEP THEM ABOVE THAT CRITICAL THRESHOLD. ALL IN ALL GOING
FCST ON TRACK. IFR CIGS/LIFR CIGS LIKELY AS THE MAIN PRECIP AREA
MOVES THROUGH OVERNIGHT. DECENT CONSENSUS FROM THE NAM/GFS MOS AND
LLVL RH PROGS. PRECIP WINDS DOWN QUICKLY WEDNESDAY MORNING AS
WESTERLY FLOW AND SUBSIDENCE TAKE HOLD IN THE WAKE OF THE TROUGH.
RENEWED SPEED MAX AND SECONDARY MAY PRODUCE SOME LIGHT RAIN IN THE
AFTERNOON...BUT POPS QUITE LOW AT THIS TIME.

MARINE...A SMALL CRAFT ADVISORY IS IN EFFECT FOR TONIGHT THROUGH
THE DAY WEDNESDAY. LOOKING FOR GUSTY EASTERLY WINDS THIS EVENING AS
STRENGTHENING LOW PRESSURE APPROACHES THE REGION...EASING FOR A TIME
OVERNIGHT AS THE LOW MOVES ACROSS NE IL AND LOWER LAKE
MICHIGAN...WITH WINDS SHIFTING WEST AND INCREASING AS THE LOW MOVES
INTO LOWER MICHIGAN WEDNESDAY. THE TIGHT GRADIENT AROUND THE
DEPARTING LOW WILL KEEP WINDS AT ADVISORY LEVELS UNTIL LATE
AFTERNOON/EARLY EVENING WED.

&&

.MKX WATCHES/WARNINGS/ADVISORIES...
WI...WINTER WEATHER ADVISORY FROM 1 AM TO 10 AM CDT WEDNESDAY FOR
     WIZ046-047-051-052.

LM...SMALL CRAFT ADVISORY UNTIL 7 PM CDT WEDNESDAY FOR LMZ643>646.

&&

$$

UPDATE...DAVIS
TONIGHT/WEDNESDAY AND AVIATION/MARINE...JTS
WEDNESDAY NIGHT THROUGH TUESDAY...COLLAR


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