Area Forecast Discussion
Issued by NWS Milwaukee/Sullivan, WI

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FXUS63 KMKX 240829
AFDMKX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MILWAUKEE/SULLIVAN WI
329 AM CDT THU APR 24 2014

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

A RATHER STRONG 250 MB TROUGH EXTENDS ACROSS THE PLAINS EARLY
THIS MORNING AND REACHES THE UPPER MISSISSIPPI VALLEY THIS
EVENING. THE TROUGH SPLITS INTO A NORTHERN TROUGH THAT MOVES
ACROSS THE LAKE SUPERIOR AREA TONIGHT AND A SECOND TROUGH THAT
MOVES ACROSS THE OHIO RIVER VALLEY. THE STRONGER SPEED MAX IS
ASSOCIATED WITH THE NORTHERN SHORTWAVE...WITH SOUTHERN WISCONSIN
IN THE RIGHT ENTRANCE REGION OF THE NORTHERN SPEED MAX...AND CLOSE
TO THE EXIT REGION OF THE WEAK SOUTHERN SPEED MAX. UPPER
DIVERGENCE OCCURS THROUGH TODAY AND SPLITS INTO TWO AREAS
TONIGHT...WITH MODERATE DIVERGENCE ACROSS THE SOUTH AROUND
MIDNIGHT.

WEAK 700 MB WARM AIR ADVECTION TODAY WITH COOLING TONIGHT BEHIND
THE MID LEVEL TROUGH AXIS. ONE AREA OF MODERATE 700 MB UPWARD
MOTION LIFTS NORTH THIS MORNING. OTHERWISE 700 MB UPWARD MOTION IS
FAIRLY WEAK UNTIL IT INCREASES DURING THE LATER AFTERNOON AND
EVENING...WITH DOWNWARD MOTION LATE TONIGHT. 700 MB LAYER IS
SATURATED EARLY...BUT SOME DRYING OCCURS IN THE SOUTHEAST LATER
THIS MORNING AND INTO THE AFTERNOON...BEFORE A BAND OF SATURATION
MOVES EAST THIS EVENING. THEN STRONG DRYING OCCURS FROM THE WEST.
LATE TONIGHT.

A 50 KNOT 700 MB SPEED MAX LIFTS NORTHEAST ACROSS WISCONSIN LATER
THIS MORNING AND AFTERNOON...WITH THE SPEED MAX FROM SOUTHWEST TO
NORTHEAST ACROSS THE STATE. THE MAIN 850 MB 53 KNOT LOW LEVEL JET
MOVES ACROSS WISCONSIN TODAY AS THE JET MAX PUSHES NORTH.

IN GENERAL THE SURFACE TROUGH PASSES FROM WEST TO EAST...BUT BY
EVENING ONE LOW MOVES ACROSS ILLINOIS/INDIANA WITH THEN SOUTHERN
SHORTWAVE AND A SECOND LOW MOVES INTO THE LAKE SUPERIOR REGION. AS
A RESULT SOUTHEAST WISCONSIN DOES NOT GET INTO A TRUE WARM
SECTOR...BUT SOME HEATING DOES OCCUR WITH THE BRIEF DRYING BELOW
800 MB. HELICITY INCREASES TO 425...BUT CAPE IS LIMITED TO AROUND
50 JOULES/KM AND IS ELEVATED...SO THERE IS LIKELY SOME THUNDER
POTENTIAL.

EXPECT THE EARLY MORNING PRECIPITATION TO LIFT NORTH AND LIKELY
END IN THE FAR SOUTH AND PORTIONS OF THE SOUTHEAST BEFORE THE
PRECIPITATION WITH THE MID LEVEL TROUGH AXIS APPROACHES FROM THE
WEST THIS AFTERNOON OVER SOUTH CENTRAL WISCONSIN AND OVER THE EAST
THIS EVENING. PRECIPITATION SHOULD END BY MIDNIGHT OVER SOUTH
CENTRAL WISCONSIN.

.SHORT TERM...FRIDAY THROUGH SATURDAY NIGHT...FORECAST CONFIDENCE
IS MEDIUM.

LOW PRESSURE WILL MOVE EAST OF THE REGION FRIDAY...WITH THE COLD
FRONTAL PASSAGE DELAYED UNTIL AFTER 00Z SATURDAY. DRY AIR MOVING
INTO THE REGION SHOULD BRING A QUIET WEATHER DAY. REMOVED LIGHT
POPS DURING THE AFTERNOON...AS AREA FORECAST SOUNDINGS FROM
NAM/GFS ARE SHOWING LESS MOISTURE THAN IN PREVIOUS MODEL
RUNS...WITH LITTLE IN THE WAY OF UPWARD VERTICAL MOTION.

925 MB TEMPERATURE FIELDS SUGGEST HIGHS SHOULD REACH INTO THE 60S
ACROSS THE AREA...WITH MID TO UPPER 60S IN SOUTHERN PORTIONS OF
THE AREA. BREEZY WEST WINDS SHOULD NEGATE ANY LAKE BREEZE
FORMATION.

COLD FRONT DROPS SOUTHWARD THROUGH THE AREA FRIDAY EVENING...WITH
STRONG COLD AIR ADVECTION LATER FRIDAY NIGHT IN ITS WAKE. NAM
SHOWING QPF WITH STRONG LOW LEVEL FRONTOGENESIS RESPONSE FIELDS
ACROSS THE AREA LATER FRIDAY NIGHT...WITH THE ECMWF AND CANADIAN
MODELS HAVING LIGHT QPF IN THE EASTERN COUNTIES. THE GFS IS DRY.

NAM SOUNDINGS HAVE MORE MOISTURE IN THE LOW TO MID LEVELS THAN THE
GFS DURING THIS TIME. NAM SEEMS OVERDONE SOMEWHAT WITH THE
FRONTOGENESIS. FOR NOW...WILL ADD LOW POPS FOR LIGHT RAIN FRIDAY
NIGHT. MAY END UP DRY FOR THIS PERIOD IF MOISTURE AND
FRONTOGENESIS DO NOT MATERIALIZE. LOWS FRIDAY NIGHT WILL DIP INTO
THE MID 30S NORTH TO AROUND 40 SOUTH.

SATURDAY LOOKS TO BE DRY...WITH ONSHORE WINDS KEEPING CHILLY
TEMPERATURES IN THE 40S NEAR LAKE MICHIGAN...TO MID 50S IN SOUTH
CENTRAL WISCONSIN.

LOW PRESSURE UNDERGOES CYCLOGENESIS IN THE CENTRAL PLAINS
SATURDAY NIGHT. WARM AIR ADVECTION DEVELOPS ACROSS THE REGION
DURING THIS TIME...WITH AN SOUTH TO SOUTHWESTERLY 850 MB LOW
LEVEL JET HELPING BRING MORE MOISTURE INTO THE REGION. THIS SHOULD
BRING CHANCES FOR RAIN INTO THE AREA...AS AIR COLUMN MOISTENS UP.

.LONG TERM...SUNDAY THROUGH WEDNESDAY...FORECAST CONFIDENCE IS
MEDIUM.

ECMWF AND GFS MODELS ARE IN FAIR AGREEMENT WITH FEATURES. LOW
PRESSURE SLOWLY WEAKENS AS IT SHIFTS EAST SOUTHEAST FROM THE
CENTRAL PLAINS INTO THE CENTRAL/SOUTHEAST ILLINOIS AREA SUNDAY
INTO TUESDAY...WITH A CUTOFF 500 MB LOW SLOWLY SHIFTING INTO THE
REGION. GFS SOMEWHAT FURTHER NORTH WITH THE 500 MB LOW THAN THE
ECMWF. THIS BRINGS QPF THROUGH THE AREA DURING THIS PERIOD...ON
THE COOL SIDE OF THE LOW.

THE 500 MB LOW THEN ABSORBS ANOTHER 500 MB LOW RETROGRADING INTO
THE REGION FROM NORTHEASTERN CANADA TUESDAY NIGHT INTO
WEDNESDAY...SLOWING DOWN THE SURFACE LOW TRACK. THIS KEEPS MORE
QPF ACROSS THE AREA. FOR NOW...WILL CONTINUE TO USE CONSENSUS POPS
AND TEMPERATURES FOR THIS PERIOD. LOOKS TO BE COOL AND WET...WITH
A GOOD 1 TO 2 INCHES OF RAINFALL POSSIBLE OVER A LONG DURATION.

&&

.AVIATION/12Z TAFS/...

CONTINUE TO SEE VFR CIGS/VSBYS WITH THE LIGHT RAIN WITH INITIAL
BAND OF RAIN CROSSING SOUTHERN WISCONSIN. FAR SOUTH CENTRAL AND
SOUTHEAST WISCONSIN WILL LIKELY SEE THE RAIN. THEN AS A SURFACE
TROUGH MOVES EAST ACROSS SOUTHERN WISCONSIN WILL BRING IN MVFR
CONDITIONS WITH STEADIER SHOWERS THIS AFTERNOON SOUTH CENTRAL AND
OVER THE EAST THIS EVENING WITH SOME IFR POTENTIAL. SOME CLEARING
ESPECIALLY WEST OF MADISON LATE TONIGHT BEHIND A COLD FRONT.

&&

.MARINE...

GUSTY SOUTHEAST WINDS LOOK TO DEVELOP BY MID-MORNING AND CONTINUE
UNTIL BAGGY GRADIENT AROUND SURFACE LOW REACHES THE NEARSHORE
WATERS AROUND MID-EVENING.

STRONG WEST WINDS WILL REACH SMALL CRAFT CRITERIA SATURDAY.

&&

.MKX WATCHES/WARNINGS/ADVISORIES...
WI...NONE.
LM...SMALL CRAFT ADVISORY FROM 10 AM THIS MORNING TO 10 PM CDT THIS
     EVENING FOR LMZ643>646.

&&

$$

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



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