Area Forecast Discussion
Issued by NWS Milwaukee/Sullivan, WI

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FXUS63 KMKX 190907
AFDMKX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MILWAUKEE/SULLIVAN WI
307 AM CST WED NOV 19 2014

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

A BROAD 250 MB UPPER TROUGH EXTENDS ACROSS THE WESTERN GREAT LAKES.
LITTLE IN THE WAY OF UPPER DIVERGENCE. A WEAK MID LEVEL 500 MB
SHORTWAVE WILL DROP SOUTHEAST ACROSS SOUTHERN WISCONSIN THIS MORNING
WITH A STRONGER SHORTWAVE MOVING ACROSS THE LAKE SUPERIOR REGION
THIS AFTERNOON. THE 700 MB UPWARD MOTION INCREASES EARLY THIS
MORNING WITH DOWNWARD MOTION OVER SOUTH CENTRAL WISCONSIN BEFORE
NOON...AND OVER THE SOUTHEAST DURING THE AFTERNOON.  ISENTROPIC
ANALYSIS SHOWS CONDENSATION PRESSURE DEFICITS FALL TO LESS THAN 10
MB IN THE 780 TO 620 MB LAYER...BUT ONLY FOR A BRIEF TIME...
ESPECIALLY AROUND SUNRISE.

A WEAK SURFACE TROUGH IS EXPECTED TO MOVE EAST ACROSS THE AREA THIS
MORNING.

THE MESOSCALE MODELS BRING LIGHT REFLECTIVITY/QPF ACROSS THE
AREA...AND KEEP THE BEST VALUES EAST OF THE AREA. NAM FORECAST
SOUNDINGS ARE STILL SHOWING ABOUT A 5 TO 6 HOUR WINDOW OF DECENT AIR
COLUMN SATURATION WITHIN A 7 THOUSAND FOOT DENDRITE SNOW GROWTH ZONE
THIS MORNING.

THUS...KEPT THE LIKELY/CATEGORICAL POPS GOING FOR THIS
PERIOD...WITH A CHANCE IN THE FAR SOUTHWEST. FLUFFY SNOW
ACCUMULATIONS OF MAINLY UP TO 1 INCH ARE EXPECTED IN MOST
AREAS...BUT A LITTLE LESS SOUTHWEST OF MADISON.

COLD HIGHS IN THE 20S ARE EXPECTED TODAY...WITH BRISK WEST WINDS
DEVELOPING IN THE AFTERNOON BEHIND THE TROUGH. THIS WILL BRING
SINGLE DIGIT ABOVE ZERO WIND CHILLS LATER IN THE AFTERNOON.

WINDS WILL DIMINISH OVER SOUTH CENTRAL WISCONSIN LATE AS A RIDGE OF
HIGH PRESSURE APPROACHES FROM THE PLAINS.

.THURSDAY - CONFIDENCE...MEDIUM
UPPER FLOW REMAINS BROADLY CYCLONIC WITH ELONGATED/SHEARED VORT
ACROSS THE STATE. MAIN UPPER TROUGH AXIS DOES SHIFT TO THE EASTERN
LAKES. LOW LEVEL COLD POOL WILL BE WELL ENTRENCHED WITH 925 TEMPS
-13 TO -15C WITH 20-25 KNOTS AT THAT LEVEL AS WELL. MOST HIGHS
WILL REMAIN IN THE TEENS. SO EXPECTING A BLUSTERY DAY WITH TEMPS
CONTINUING WAY BELOW NORMAL. SURFACE RIDGE AXIS MOVES TO IA
THROUGH SRN IL BY DAYS END.

.THURSDAY NIGHT THROUGH FRIDAY EVENING - CONFIDENCE...HIGH
SURFACE HIGH EXPECTED TO DOMINATE THIS PERIOD WITH QUIET WEATHER
BUT COLD CONDITIONS PERSISTING. WITH THE RIDGE AXIS BECOMING
SITUATED ACROSS THE CWA THURSDAY NIGHT EXPECTING WIDESPREAD SINGLE
DIGIT LOWS. THE HIGH SHIFTS INTO THE OHIO VALLEY FRIDAY WITH
PRONOUNCED 925/850 WAA RETURN FLOW SETTING UP. 925 TEMPS MODERATE
TO -3C TO -6C. SO EXPECT TEMPS TO NUDGE INTO THE MID 20S. THE WAA
REGIME CONTINUES INTO FRIDAY EVENING WITH MODELS DELAYING PRECIP
ARRIVAL.

.LATER FRIDAY NIGHT AND SATURDAY MORNING - CONFIDENCE...MEDIUM
THIS PERIOD WILL HAVE POTENTIAL FOR MIXY PRECIP DUE THE WARMING
ALOFT AND COLDER SURFACE TEMPS SLOWER TO MODERATE. SO AFTER 6Z
THROUGH ABOUT 15Z WILL BE THE WINDOW OF CONCERN AS ALL PRECIP
TYPES WILL BE POSSIBLE THOUGH GREATEST CONCERN WILL BE THE
ELEVATED WARM LAYER AND LACK OF SUSTAINED SATURATION IN THE
DENDRIDIC GROWTH ZONE BEARING SOME CONCERN FOR FREEZING RAIN
POTENTIAL. QPF AMOUNTS ARE FORECAST TO BE ON THE LOW SIDE.

.SATURDAY AFTERNOON THROUGH SATURDAY NIGHT - CONFIDENCE...MEDIUM
MILDER AIRMASS PROGGD TO BE IN PLACE WITH 850/925 TEMPS WELL
ABOVE ZERO CELSIUS. BROAD WAA/MOIST ADVECTION PERSISTS THOUGH
BETTER FORCING/BAROCLINICITY LIFTS NORTH AND INTERACTS WITH A
NORTHERN STREAM WAVE LIFTING NORTHEAST. QPF AMOUNTS ONLY A FEW
HUNDREDTHS. WITH THE SUSTAINED SOUTHWEST LOW LEVEL FLOW MILD TEMPS
WILL BE IN PLACE WITH SOME AREAS...ESP IN THE SOUTH POTENTIALLY
EXCEEDING 40.

.SUNDAY AND MONDAY - CONFIDENCE...MEDIUM
PRIMARY SURGE OF RAIN ARRIVES WITH POTENT SHORTWAVE LIFTING
NORTHEAST FROM THE SOUTHERN PLAINS. STRENGTHENING SURFACE LOW
REACHES EITHER NRN IL OR SE WI BY 00Z MON. THE SURFACE LOW LIFTS
NORTHEAST WITH COLDER AIR WRAPING IN AROUND THE LOW SUNDAY NIGHT
INTO MONDAY. SO EXPECT SOME CHANGEOVER TO OCCUR AS THE
PROFILE/COLUMN COOLS. LOW LEVEL TROUGH AND UPPER CYCLONIC FLOW
WILL KEEP SNOW SHOWER CHANCES GOING MONDAY WITH SOME LIGHT
ACCUMULATION POSSIBLE.

.TUESDAY - CONFIDENCE...MEDIUM
LINGERING CYCLONIC FLOW AND LOW LEVEL TROUGHINESSS SUGGESTS
KEEPING SMALL POPS GOING IN THE EAST FOR NOW...PER SUPERBLEND
POPS. GFS SHOWS DRY WX WHILE THE ECMWF LINGERS JUST A SMIDGE OF
QPF AROUND.

&&

.AVIATION/12Z TAFS/...AN AREA OF LIGHT SNOW SHOULD SPREAD EAST
ACROSS TAF SITES THROUGH 15Z AT MADISON...AND 17Z AT THE EASTERN
SITES. VISIBILITIES SHOULD DROP TO NEAR 1 MILE OR NEAR ALTERNATE
MINIMUMS DURING THIS TIME...WITH CEILINGS MVFR TO PERHAPS IFR
CATEGORY. FLUFFY SNOW ACCUMULATIONS OF 1/2 TO 1 INCH ARE
POSSIBLE...WITH 0.1 TO 0.2 INCH RATES PER HOUR.

SHOULD SEE VFR CONDITIONS RETURN BY THE AFTERNOON HOURS ON
WEDNESDAY...WITH GUSTY WEST WINDS AS WELL. MAY SEE A LITTLE BLOWING
AND DRIFTING SNOW...BUT VISIBILITIES SHOULD REMAIN VFR CATEGORY.

&&

.MARINE...THE PRESSURE GRADIENT AND SUBSEQUENT WINDS WILL WEAKEN THIS
MORNING...AS A TROUGH OF LOW PRESSURE MOVES THROUGH THE AREA.

GUSTY WEST WINDS ARE EXPECTED AGAIN THIS AFTERNOON AND INTO
THURSDAY...AS ANOTHER TIGHT PRESSURE GRADIENT DEVELOPS BEHIND THE
DEPARTING LOW. COULD SEE GUSTS TO 30 KNOTS AT TIMES. HIGH WAVES
WOULD BE TOWARD AND OVER THE OPEN WATERS WITH THE OFFSHORE FLOW. A
SMALL CRAFT ADVISORY IS IN EFFECT DURING THIS PERIOD.

&&

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

&&

$$
TODAY/TONIGHT AND AVIATION/MARINE...HENTZ
THURSDAY THROUGH TUESDAY...COLLAR



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