Area Forecast Discussion
Issued by NWS Milwaukee/Sullivan, WI

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FXUS63 KMKX 270926
AFDMKX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MILWAUKEE/SULLIVAN WI
326 AM CST TUE JAN 27 2015

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

A STRONG 144 KNOT 250 MB NORTH/NORTHWEST JET WILL BE ACROSS
SOUTHERN WISCONSIN ON THE BACK SIDE OF THE STRONG EAST COAST
TROUGH. THE JET WEAKENS TONIGHT AS AN UPPER RIDGE APPROACHES THE
UPPER MISSISSIPPI VALLEY LATE TONIGHT. LITTLE IN THE WAY OF UPPER
DIVERGENCE. THE LAST MID LEVEL CYCLONIC VORTICITY MAX EXITS FAR
SOUTHEAST WISCONSIN BY SUNRISE. DOWNWARD 700 MB MOTION BY SUNRISE
CONTINUES THROUGHOUT THE DAY AND INTO THE EVENING WITH WEAK UPWARD
MOTION MOVING IN FROM THE WEST LATE TONIGHT.

700 MB RH IS DRY OVER SOUTH CENTRAL WISCONSIN AND DRIES OVER THE
FAR EAST THIS MORNING. 700 MB RH INCREASES AGAIN MAINLY AFTER
MIDNIGHT TONIGHT AS WARM AIR ADVECTION OCCURS. WEAK 850 MB WARM
AIR ADVECTION OCCURS TODAY AND INCREASES TONIGHT.

850 MB RH REMAINS HIGH THIS MORNING BUT DRIES THIS AFTERNOON. 925
MB RH REMAINS HIGH THROUGH THE DAY AND ACTUALLY DRIES MORE OVER
THE FAR EAST. THEREFORE THE STRATUS WILL BE SLOW TO ERODE...AND
BREAKS MAY OCCUR EAST INSTEAD OF A WEST TO EAST PROGRESSION.

THE WEAK SURFACE TROUGH WEAKENS FARTHER AS A WEAK HIGH PRESSURE
RIDGE BUILDS ACROSS THE WESTERN GREAT LAKES TODAY AND BEGINS TO
MOVE EAST TONIGHT.

THERE COULD BE A FEW FLURRIES EAST THROUGH SUNRISE THIS MORNING.
PATCHY FREEZING DRIZZLE IS ALSO POSSIBLE THROUGH AROUND 8 AM.

.SHORT TERM...WEDNESDAY THROUGH THURSDAY NIGHT...FORECAST
CONFIDENCE IS MEDIUM.

SYNOPTIC MODELS ARE IN GOOD AGREEMENT WITH WARM AIR ADVECTION
KICKING IN WEDNESDAY ACROSS THE AREA. AREA FORECAST SOUNDINGS
REMAIN FAIRLY DRY DURING THE DAY...WITH SOME MIDDLE TO HIGH CLOUDS
MOVING INTO THE AREA. KEPT DRY FORECAST GOING FOR WEDNESDAY. SOUTH
SOUTHEAST WINDS GRADUALLY INCREASE WITH THE TIGHTENING PRESSURE
GRADIENT. MILD HIGHS IN THE MID 30S ARE ANTICIPATED.

MAIN ISSUE WILL BE CHANCES FOR LIGHT FREEZING RAIN WEDNESDAY NIGHT
INTO EARLY THURSDAY MORNING ACROSS THE AREA. SYNOPTIC MODELS ARE
IN DECENT AGREEMENT WITH GENERAL TRENDS. WARM AIR ADVECTION
CONTINUES IN THE LOW LEVELS UNTIL AROUND 06Z THURSDAY...WITH UPPER
DIVERGENCE FROM LEFT FRONT QUADRANT OF 300 MB JET STREAK. SURFACE
LOW SLIDES EASTWARD ACROSS FAR NORTHERN ILLINOIS LATER WEDNESDAY
NIGHT.

850 MB TROUGH MOVES THROUGH THE AREA LATER WEDNESDAY NIGHT.
DECENT UPWARD VERTICAL MOTION ASSOCIATED MAINLY WITH LOW LEVEL
FRONTOGENESIS RESPONSE FIELDS WEDNESDAY EVENING...WITH MORE MID
LEVEL FRONTOGENESIS/Q VECTOR CONVERGENCE LATER WEDNESDAY NIGHT
INTO EARLY THURSDAY MORNING. LEAD 500 MB SHORTWAVE TROUGH REMAINS
JUST SOUTH OF THE AREA LATER WEDNESDAY NIGHT...WITH ANOTHER
SLIDING SOUTHEAST THROUGH THE AREA THURSDAY MORNING.

AREA FORECAST SOUNDINGS SHOWING SOME DIFFERENCES WITH THERMAL
PROFILES WEDNESDAY NIGHT INTO EARLY THURSDAY MORNING...WITH THE
NAM SHOWING A MORE ELEVATED WARM LAYER THAN THE GFS. THEY DO AGREE
THAT MOISTURE WILL BE CONFINED TO AROUND AND BELOW THE WARM LAYER.
USING THE TOP DOWN APPROACH...GET A DECENT CHANCE FOR LIGHT
FREEZING RAIN ACROSS AREAS THAT ARE AT OR BELOW FREEZING. THIS
WOULD BE MAINLY THE NORTHERN PORTIONS OF THE AREA FROM 00Z TO 09Z
THURSDAY...BEFORE SPREADING ACROSS THE REST OF THE AREA
AFTERWARDS.

SOME SLEET COULD MIX IN AS WELL IN THESE AREAS...BEFORE
TRANSITIONING TO A MORE LIGHT SNOW OR LIGHT RAIN/LIGHT SNOW MIX ON
THURSDAY. KEPT HIGHEST POPS IN THE NORTHEAST...WHERE THE BEST
UPWARD VERTICAL MOTION FIELDS SHOULD BE LOCATED. HIGHER POPS MAY
BE NEEDED FOR WEDNESDAY NIGHT INTO EARLY THURSDAY IN LATER
FORECASTS. A HEADLINE FOR THE LIGHT FREEZING RAIN MAY BE NEEDED
AS WELL.

NORTHWEST WINDS BRING COLD AIR ADVECTION LATER THURSDAY INTO
THURSDAY NIGHT...WITH DRIER AIR ENDING ANY LINGERING
PRECIPITATION.

.LONG TERM...FRIDAY THROUGH MONDAY...FORECAST CONFIDENCE IS
MEDIUM.

GFS/ECMWF SHOWING HIGH PRESSURE SLIDING EAST SOUTHEAST THROUGH THE
REGION FRIDAY...THEN TO THE EAST FRIDAY NIGHT. QUIET WEATHER AND
SLIGHTLY BELOW NORMAL TEMPERATURES ARE EXPECTED.

THESE MODELS ARE THEN TAKING AN INITIAL 500 MB SHORTWAVE TROUGH
INTO THE AREA SATURDAY NIGHT AND SUNDAY...WITH THE MAIN SHORTWAVE
TROUGH MOVING INTO THE AREA LATER SUNDAY INTO SUNDAY NIGHT.
SURFACE LOW MOVES FROM THE ARKLATEX REGION INTO THE OHIO RIVER
VALLEY SUNDAY...BEFORE MOVING NORTHEAST AND STRENGTHENING SUNDAY
NIGHT.

GFS SOUNDINGS SHOWING DEEP COLUMN MOISTURE DEVELOPING ACROSS THE
AREA DURING MOST OF THIS TIME...TAPPING THE DENDRITE SNOW GROWTH
ZONE. THIS WOULD RESULT IN A PROLONGED LIGHT TO MODERATE SNOW
EVENT ACROSS THE AREA...WITH AT LEAST A FEW INCHES OF SNOW
ACCUMULATION POSSIBLE. LEFT CHANCE POPS FOR NOW...BUT MAY NEED TO
BE RAISED IN LATER FORECASTS IF MODELS REMAIN CONSISTENT.

ANOTHER HIGH MOVES INTO THE REGION MONDAY...BRINGING A RETURN TO
QUIET WEATHER. BELOW NORMAL TEMPERATURES ARE EXPECTED LATER IN THE
WEEKEND INTO EARLY NEXT WEEK.

&&

.AVIATION/12Z TAFS/...

850 MB RH REMAINS HIGH THIS MORNING BUT DRIES THIS AFTERNOON. 925
MB RH REMAINS HIGH THROUGH THE DAY AND ACTUALLY DRIES MORE OVER
THE FAR EAST. THEREFORE THE IFR STRATUS WILL BE SLOW TO
ERODE...AND BREAKS MAY OCCUR EAST INSTEAD OF A WEST TO EAST
PROGRESSION. THE WEAK SURFACE TROUGH WEAKENS FARTHER AS A WEAK
HIGH PRESSURE RIDGE BUILDS ACROSS THE WESTERN GREAT LAKES TODAY
AND BEGINS TO MOVE EAST TONIGHT.

THERE COULD BE A FEW FLURRIES EAST THROUGH SUNRISE THIS MORNING.
PATCHY FREEZING DRIZZLE IS ALSO POSSIBLE THROUGH AROUND 8 AM.

&&

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

$$

TODAY/TONIGHT AND AVIATION/MARINE...HENTZ
WEDNESDAY THROUGH MONDAY...WOOD



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