Area Forecast Discussion
Issued by NWS Milwaukee/Sullivan, WI

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FXUS63 KMKX 201611 AAA
AFDMKX

AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE MILWAUKEE/SULLIVAN WI
1111 AM CDT MON APR 20 2015

.UPDATE...

THERE ARE A FEW POCKETS OF LIGHT RAIN AND DRIZZLE HANGING ON ACROSS
SOUTHERN WI LATE THIS MORNING. THIS IS WITHIN THE DEFORMATION ZONE
OF THE DEPARTING SURFACE LOW... AND AN OF STRONGER 700 OMEGA AND
FRONTOGENESIS. LOOK FOR THIS AREA OF PRECIP TO LIFT NORTHEAST
THROUGH EARLY AFTERNOON. DRIER AIR WILL WORK ITS WAY INTO SOUTH
CENTRAL AND EVENTUALLY SOUTHEAST WI LATER THIS AFTERNOON. LOOK FOR
SHOWERS TO END... BUT CLOUDS TO LINGER.

THE STRONGEST PRESSURE RISES OCCURRED MID MORNING OVER SOUTH CENTRAL
AND SOUTHEAST WI. THIS WAS ACCOMPANIED BY STRONG WIND GUSTS UP TO 30
MPH. THE PRESSURE CHANGE MAGNITUDE IS DECREASING... BUT THE
ATMOSPHERE IS MIXING HIGHER... SO EXPECT THESE GUSTS TO CONTINUE
THROUGH THE LATE AFTERNOON.  WINDS AND GUSTS ARE EXPECTED TO REMAIN
JUST BELOW WIND ADVISORY CRITERIA.

&&

.AVIATION/18Z TAFS/...

PERIODS OF LIGHT RAIN AND DRIZZLE WILL DIMINISH THROUGH MID
AFTERNOON AS LOW PRESSURE MOVES OFF TO THE NORTHEAST.  WEST-
NORTHWEST WIND GUSTS WILL BE IN THE 27 TO 30 KNOT RANGE THROUGH LATE
AFTERNOON.

EXPECT MVFR CIGS TO BRIEFLY IMPROVE TO VFR LATE THIS AFTERNOON WITH
DEEPER MIXING AND DRIER AIR WORKING INTO THE REGION. THE CIG SHOULD
FALL BACK TO MVFR LATER TONIGHT INTO TUESDAY MORNING AS ANOTHER
SURGE OF COLD AIR WRAPS AROUND SRN CANADIAN UPPER LOW.

&&

.MARINE...

SMALL CRAFT ADVY CONDITIONS WILL PERSIST THROUGH THIS EVENING DUE TO
A TIGHTENING PRESSURE GRADIENT AND STRONG ISALLOBARIC COMPONENT IN
WAKE OF LOW PRESSURE OVER THE NEAR SHORE WATERS. STRONGEST WINDS
LIKELY TO BE OVER THE SHORE AREAS AS COOLER LAKE WATERS WILL CAUSE
LOW LEVEL INVERSION AWAY FROM THE SHORE...PREVENTING STRONGEST WINDS
GUSTS FROM REACHING LAKE SURFACE.

ANOTHER BREEZY DAY IS ANTICIPATED ON TUESDAY AS LINGERING PRESSURE
GRADIENT OVER THE GTLAKES RESULTS IN WEST WIND GUSTS LIKELY REACHING
SMALL CRAFT ADVY LEVELS.

&&

.PREV DISCUSSION... /ISSUED 325 AM CDT MON APR 20 2015/

TODAY AND TONIGHT... FORECAST CONFIDENCE - MEDIUM.

MORE WIDESPREAD RAIN AFFECTED CWA DURING THE EVENING AS DEEPENING
LOW PRESSURE TOOK MORE NORTHERN AND WESTERN TRACK.  FEW FAR
SOUTHEAST LOCATIONS RECEIVED A BENEFICIAL INCH OF RAINFALL WITH MOST
AREAS FARTHER WEST RECEIVING BETWEEN ONE QUARTER AND ONE HALF INCH.

SYNOPTIC SCALE FORCING ASSOCD WITH DEEPENING LOW HAS PUSHED OFF TO
THE NORTHEAST OVERNIGHT ALLOWING WIDESPREAD RAIN TO DIMINISH OVER
PARTS OF THE SOUTH AND EAST.  HOWEVER LINGERING DEFORMATION AND AREA
OF FRONTOGENETICAL FORCING WILL MOVE ACROSS CENTRAL AND SRN WI THIS
MRNG. LARGE AREA OF RAIN OVER WRN WI INTO SOUTHEAST MN AND NORTHEAST
IA WL SWEEP NORTHEAST ACROSS CWA.  HENCE WL CONTINUE CATEGORICAL
POPS THIS MRNG ACROSS NORTH AND WEST WITH LIKELY IN THE SOUTHEAST.
SOME AREAS MAY RECEIVE AN ADDITIONAL ONE QUARTER INCH THIS MRNG.

STRONG ISALLOBARIC PRESSURE RISES BEHIND DEEPENING LOW PRESSURE
AND STRONG WEST TO NORTHWEST WINDS WILL RESULT IN WINDY DAY WITH
GUSTS REACHING 30 TO 35 MPH. SUSTAINED WINDS WILL REACH THE 20 TO
25 MPH RANGE FOR A TIME AS WELL BUT REMAINING BELOW WIND ADVISORY
CRITERIA. ALSO WL CONTINUE TO MENTION FOG FOR A TIME EARLY THIS
MRNG DUE TO BAGGINESS IN PRESSURE DUE TO BRIEF NEARNESS OF SFC
LOW.

MID-LAYERS START TO DRY OUT AFTER RAIN DIMINISHES THIS
AFTERNOON...BUT A FEW LIGHT SHOWERS OR SPRINKLES MAY LINGER OR
REDEVELOP DURING THE AFTN INTO THE EARLY EVENING AS SECONDARY WEAKER
SHORT WAVE ROTATES AROUND DEEP CANADIAN UPPER LOW AND MOVES ACROSS
CENTRAL WI.

WL CONTINUE SLIGHT CHANCE FOR SOME LIGHT RAIN OR LIGHT SNOW IN
NORTHERN CWA LATE TNGT AS SECONDARY SURGE OF COLD AIR ASSOCD WITH
SHARPENING MID-LEVEL TROF APPROACHES SRN WI.

TUESDAY - CONFIDENCE...MEDIUM
UPPER LOW LIFTS NORTHEAST FROM THE U.P. BUT SRN WI REMAINS WELL
ENTRENCHED WITHIN STRONGLY CYCLONIC FLOW REGIME. EMBEDDED VORT
MAXES WILL ROTATE AROUND THE LOW AND ONE WAVE OF NOTE IS PROGGD TO
WORK INTO SRN WI DURG THE AFTN HRS. 850 TEMPS -3 TO -5C THO 925
TEMPS ABV ZERO AND BUFKIT SOUNDINGS SUPPORT SUFFICIENT WARMING IN
THE LOWEST LAYERS TO KEEP SCT PRECIP IN THE LIQUID FORM. PLENTY OF
CLOUD COVER EXPECTED WITH BREEZY CONDITIONS AND COOL TEMPS IN THE
UPPER 40S/LOW 50S.

WEDNESDAY - CONFIDENCE...MEDIUM
UPPER FLOW REMAINS CYCLONIC WITH MOSTLY SHEARED/ELONGATED VORT
AXIS ACROSS THE AREA. STILL SOME LOW LEVEL TROUGHING TO CONTEND
WITH SO WILL HAVE SOME SMALL POPS IN NE CWA. 925 TEMPS SUBZERO
CELSIUS SO WILL HAVE A LITTLE MENTION OF SNOW MIXING IN EARLY
BEFORE BOUNDARY LAYER MODIFIES.

THURSDAY - CONFIDENCE...MEDIUM
MID LEVEL CYCLONIC SHEAR ZONE GRADUALLY LIFTS NORTHEAST. LOW
LEVEL COLD POOL SLOWLY MODIFIES. SURFACE RIDGING BECOMES MORE OF A
PLAYER SO WILL GO WITH A DRY FORECAST.

THURSDAY NIGHT AND FRIDAY - CONFIDENCE...LOW
THE GEM AND ECMWF SHOW THE UPPER RIDGING AND SURFACE HIGH BEING
DOMINANT WHILE INFLUENCE OF CENTRAL PLAINS ENERGY REMAINS WELL TO
OUR SOUTHWEST. MEANWHILE THE GFS SUGGESTS A MORE PROGRESSIVE AND
OPEN WAVE WITH PRECIP SHIELD FROM SUBSEQUENT SURFACE LOW
DEVELOPMENT BRUSHING SRN WI DURG THIS PERIOD. AT THIS TIME WILL
SIDE WITH THE ECMWF AND GEM AND KEEP THE CWA DRY.

SATURDAY AND SUNDAY - CONFIDENCE...MEDIUM
MODELS IN BETTER AGREEMENT SHOWING SURFACE HIGH IN PLACE. ECMWF
AND GFS SOLUTIONS SHOWED THE CENTRAL PLAINS WAVE WEAKENING AND
BEING SUPPRESSED SOUTH OF THE AREA BY THE MORE DOMINANT NORTHWEST
FLOW ACROSS THE WRN GRT LAKES.

AVIATION/12Z TAFS/...PERIODS OF LIGHT RAIN WILL DIMINISH LATER
THIS MORNING AS SYNOPTIC SCALE FORCING WITH DEEP LOW PRESSURE
MOVES OFF TO THE NORTHEAST. AREAS OF FOG WILL ALSO AFFECT SOUTHEAST
WI EARLY THIS MRNG UNTIL WNDS PICK UP FROM THE WEST IN TIGHTENING
PRESSURE GRADIENT. WIND GUSTS LIKELY TO REACH 30KTS TODAY BEHIND
DEPARTING LOW PRESSURE. EXPECT IFR CIGS TO INCREASE TO MVFR AS
COLDER...DRIER AIR POURS IN THIS MRNG. WL MOST LIKELY INCREASE TO
VFR THIS AFTN BUT MAY FALL BACK TO MVFR LATER TONIGHT AS ANOTHER
SURGE OF COLD AIR WRAPS AROUND SRN CANADIAN UPPER LOW.

MARINE...PUSHED START TIME OF SMALL CRAFT ADVY UP TWO HOURS ACROSS
SOUTHERN ZONES AS TIGHTENING PRESSURE GRADIENT AND STRONG
ISALLOBARICCOMPONENT IN WAKE OF LOW PRESSURE AFFECTS NEAR SHORE
WATERS BY MID TO LATE MORNING. STRONGEST WINDS LIKELY TO BE OVER
THE SHORE AREAS AS COOLER LAKE WATERS WILL CAUSE LOW LEVEL
INVERSION AWAY FROM THE SHORE...PREVENTING STRONGEST WINDS GUSTS
FROM REACHING LAKE SURFACE.

ANOTHER BREEZY DAY IS ANTICIPATED ON TUESDAY AS LINGERING PRESSURE
GRADIENT OVER THE GTLAKES RESULTS IN WEST WIND GUSTS LIKELY REACHING
SMALL CRAFT ADVY LEVELS.

&&

.MKX WATCHES/WARNINGS/ADVISORIES...
WI...NONE.
LM...SMALL CRAFT ADVISORY UNTIL 8 PM CDT THIS EVENING FOR LMZ645-646.

     SMALL CRAFT ADVISORY UNTIL 8 PM CDT THIS EVENING FOR LMZ643-644.

&&

$$

UPDATE...MRC
TODAY/TONIGHT AND AVIATION/MARINE...MBK
TUESDAY THROUGH SUNDAY...COLLAR


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