Area Forecast Discussion
Issued by NWS Milwaukee/Sullivan, WI

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FXUS63 KMKX 221615 AAA
AFDMKX

AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE MILWAUKEE/SULLIVAN WI
1115 AM CDT FRI APR 22 2016

.UPDATE...

BRISK NORTHEAST WINDS IN THE WAKE OF A COLD FRONT WILL PERSIST
THROUGH THE EARLY AFTERNOON. THE COLD AIR ADVECTION AND LINGERING
LOW LEVEL MOISTURE ARE LEADING TO WIDESPREAD CLOUDS ACROSS SOUTHERN
WI THIS MORNING. DRIER AIR WORKING INTO THE AREA FROM THE NORTH WILL
HELP TO THIN OUT THE CLOUDS LATER THIS AFTERNOON AND ESPECIALLY THIS
EVENING.

TEMPERATURES ARE ON TRACK TO REACH THE MID TO UPPER 50S INLAND
TODAY. LAKESHORE AREAS WILL STAY COOLER. THE CLEARING SKIES AND
LIGHT WINDS OVERNIGHT WILL ALLOW FOR DECENT RADIATIONAL COOLING. MIN
TEMPERATURES ARE EXPECTED IN THE LOWER TO MID 30S TONIGHT THUS A
FROST ADVISORY IS IN EFFECT.

&&

.AVIATION/18Z TAFS/...

MVFR CIGS WILL PERSIST ACROSS SOUTHERN WI INTO EARLY AFTERNOON
BEFORE LIFTING TO VFR AND SCATTERING OUT AS DRIER AIR WORKS INTO THE
AREA. BRISK NORTHEAST WINDS WILL SLOWLY DIMINISH THROUGH THE
AFTERNOON. VFR CONDITIONS EXPECTED THE REST OF THE TAF PERIOD.

&&

.MARINE...

TIGHT PRESSURE GRADIENT WILL KEEP GUSTY NORTH TO NORTHEAST WINDS AT
SMALL CRAFT LEVELS INTO THE AFTERNOON...THEN SLOWLY DIMINISH FROM
NORTH TO SOUTH AS RIDGE OF HIGH PRESSURE MOVES INTO THE WESTERN
GREAT LAKES. EXPECT GUSTS UP TO 30 KTS FROM MILWAUKEE SOUTH UNTIL
LATE MORNING. THESE WINDS WILL BUILD HIGH WAVES THAT WILL TAKE A BIT
LONGER TO SUBSIDE AFTER WINDS EASE. THUS END TIMES FOR THE SMALL
CRAFT ADVISORY LOOK ON TARGET.

&&

.PREV DISCUSSION... /ISSUED 333 AM CDT FRI APR 22 2016/

TODAY AND TONIGHT...FORECAST CONFIDENCE - MEDIUM TO HIGH.

BACK DOOR COLD FRONT CUTTING THROUGH CWA EARLY THIS MRNG...FROM
AROUND KBUU TO KMSN TO KC35.  FRONT WL CONTINUE TO SAG STEADILY
SOUTHWEST THROUGH THE EARLY MORNING DUE TO UPSTREAM PRESSURE RISES
OVER NRN WI.  WINDS TURNED NORTHEAST UPON FRONTAL PASSAGE WHICH
ALLOWED LAKE FOG TO MOVE INLAND LAST SEVERAL HOURS.  KMKE WEBCAM
CONTINUES TO SHOW DENSE FOG OVER THE AIRPORT.  LOW LEVEL MIXING
HOWEVER WILL CONTINUE TO INCREASE NEXT SEVERAL HOURS WHICH WILL
RESULT IN INCREASING VSBYS THROUGH 12Z.  APPEARS NOT ENOUGH LOW
LEVEL CONVERGENCE AND COLUMN MOISTURE TO GENERATE -SHRA ALONG FRONT
SO WL GO WITH DRY SCENARIO EARLY THIS MORNING.  LOW LEVEL COLD AIR
ADVECTION AND BUILDING RIDGING AND SUBSIDENCE WL CONTINUE DRY
CONDITIONS THROUGH THE DAY.  LOW CLOUDS LIKELY TO AFFECT CWA FOR A
TIME THIS MORNING AS COLD AIR SWEEPS IN.  HOWEVER DRIER AIR AND
SUBSIDENCE SHOULD RESULT IN THINNING AND CLEARING OF CLOUDS DURING
THE AFTN AND EVE.

UPSTREAM WARM AIR ADVECTION AND PASSING WEAK SHORT WAVE IN NORTHWEST
FLOW WL RESULT IN SOME MID/HIGH CLOUDS LATER TONIGHT.  HOWEVER MID-
LEVEL ISENTROPIC SURFACES INDICATING BULK OF THESE CLOUDS TO REMAIN
TO THE NORTH OF SRN WI.  HENCE EXPECT GOOD RADIATIONAL COOLING
OVERNIGHT.  925H TEMPS WL FALL INTO THE 4-7C RANGE OVERNIGHT AS LOW
LEVEL MIXING FALLS OFF TO AROUND 5 KTS...SETTING UP MODERATE
INVERSION.  WITH MOSTLY CLEAR SKIES FOR BULK OF THE NIGHT AND DRY
AIR IN PLACE...OVERNIGHT TEMPS WL FALL INTO THE LOW TO MID 30S
ACROSS MOST OF THE AREA LATER TNGT INTO EARLY SAT.  THIS SCENARIO
FAVORS AREAS OF FROST SO PER COORDINATION WITH NEIGHBORING NWS
WFOS...WL POST FROST ADVY FOR MOST OF THE AREA.  FOR NOW...WL KEEP
OUT LAFAYETTE AND IOWA COUNTIES AS MORE BORDERLINE SITUATION FOR
MORE WIDESPREAD LATE NIGHT FROST.  MEDIAN DATE OF LAST 32F IN SPRING
FOR MOST OF THE CWA IS FROM LATE APRIL THROUGH THE FIRST WEEK OF
MAY. ALSO FROST WL BE MORE PREVALENT FARTHER INLAND...AWAY FROM LAKE
MICHIGAN.

SATURDAY - CONFIDENCE...MEDIUM TO HIGH
SURFACE RIDGE AXIS WILL SHIFT EAST OF WI. AFTER A CHILLY/FROSTY
START...925/850 TEMPS WILL MODIFY AND RESULT IN A DECENT REBOUND
WITH A GOOD AMOUNT OF SUNSHINE. ONSHORE FLOW WILL KEEP THE FAR ERN
PORTION OF THE CWA COOLER.

SATURDAY NIGHT AND SUNDAY - CONFIDENCE...MEDIUM
500 MILLIBAR RIDGING WILL BE SLIDING ACROSS SRN WI THIS PERIOD. 850
WAA WILL BE ONGOING WHICH WILL BE THE MAIN DRIVER FOR ANY SHRA/TSRA.
850 BAROCLINIC ZONE GRADUALLY SHIFTS INTO NRN WI. 250 JET ACROSS
SRN CANADA INTO THE EASTERN LAKES SETS UP SOME UPPER DIVERGENCE
ESP SAT NGT INTO SUN MRNG. PRIMARY MID LEVEL FORCING WILL REMAIN
TO OUR WEST WITH 500 MILLIBAR LOW CENTER SHIFTING FROM THE ROCKIES
INTO SOUTH DAKOTA. MODELS IN DECENT AGREEMENT IN KEEPING BEST
FORCING FOR QPF ACROSS NORTHERN/CENTRAL WI CLOSER TO BETTER
BAROCLINICITY AND UPPER JET SUPPORT. SUPERBLEND POPS HAVE A
NORTH/SOUTH GRADIENT AND THIS LOOKS REASONABLE GIVEN THE MORE
LIKELY AREA OF BETTER FORCING. 925 THERMAL GRADIENT TIGHTENS UP
ACROSS CENTRAL WI AS THE DAY WEARS ON BUT SOUTHERLY WINDS ARE
PROGGD TO PULL UP 925 TEMPS TO ALMOST 20C IN PARTS OF THE SOUTH SO
THIS COULD SEND TEMPS DEEP INTO THE 70S DEPENDING ON CLOUDS/PCPN
TRENDS. SO OPTED WITH THE SLIGHTLY WARMER BCCONSALL OVER
SUPERBLEND WHICH ALSO BLENDS BETTER WITH NEIGHBORING OFFICES.

SUNDAY NIGHT THROUGH MONDAY NIGHT - CONFIDENCE...MEDIUM
FORCING FROM APPROACHING 500 MILLIBAR WAVE WILL ENHANCE PRECIP THIS
PERIOD THOUGH STILL SOME TIMING DIFFERENCES WITH THE GFS BEING THE
FASTEST SOLUTION AND THE GEM THE SLOWEST. LOW PRESSURE IS EXPECTED
TO TRACK THROUGH NORTHERN ILLINOIS WITH SURFACE FRONT SAGGING INTO
SRN WI. WILL HAVE THE HIGHEST POPS THIS PERIOD WITH CONSENSUS 500
TIMING SHOWING MONDAY AS THE GREATEST INFLUENCE FROM THE WAVE. WILL
HAVE THUNDER MENTIONED GIVEN DEGREE OF WARMTH/MOISTURE AHEAD OF THE
SOUTHWARD MOVING FRONTAL BOUNDARY WITH THE SURFACE LOW RIDING ALONG
IT. BUFKIT CAPES DO NOT HIT 1000 J/KG BUT CERTAINLY ENOUGH TO KEEP
THE THUNDER MENTION GOING.

TUESDAY - CONFIDENCE...MEDIUM
SURFACE HIGH FROM CANADA RIDGES SOUTH INTO WI BRINGING A BREAK IN
THE ACTION ALONG WITH A COOLER AND DRIER REGIME.

WEDNESDAY AND THURSDAY - CONFIDENCE...LOW TO MEDIUM
ACTIVE PATTERN CONTINUES WITH ANOTHER 500 MILLIBAR WAVE MOVING IN.
TIMING DIFFERENCES AGAIN...THIS TIME WITH THE ECMWF BEING THE FASTER
SOLUTION...AT LEAST IN TERMS OF THE LEADING WAA SLUG OF RAIN
TUESDAY NIGHT. BIG THERMAL DIFFERENCES TOO WITH THE GFS ABOUT
10-12C COOLER ON 925 TEMPS WEDNESDAY. THE ECMWF HAS A SLIGHTLY
NORTHERN TRACK INTO SRN WI WITH THE LOW WITH THE GFS KEEPING IT
FURTHER SOUTH AND RESULTING IN THE COLDER THERMAL PROFILE. BY
THURSDAY SYSTEM STARTS TO PULL OUT WITH BOTH MODELS SHOWING SOME
HANG BACK PRECIP WITH TROUGH EXTENSION INTO WI FROM DEPARTED LOW.
WILL BE SUING SUPERBLEND TEMPS/POPS FOR GUID.

AVIATION/12Z TAFS/...LOW CLOUDS AND VSBY ASSOCD WITH LAKE FOG MOVED
INTO ERN TAF SITES LAST SEVERAL HOURS AS SFC WINDS TURNED NORTHEAST
BEHIND BACK DOOR COLD FRONT. AS WINDS INCREASE BEHIND FRONT NEXT
SEVERAL HOURS...EXPECT FOG TO THIN AND DISSIPATE. VARYING CIGS CAN
BE EXPECTED EARLY THIS MRNG TRANSITIONING TO PERIOD OF MVFR BEFORE
THINNING DURING THE AFTN. VFR CONDITIONS WL SETTLE IN DURING THE
AFTN AND PERSIST TNGT.

MARINE...INCREASING NORTH TO NORTHEAST WINDS BEHIND BACK DOOR COLD
FRONT WHICH WILL BE EXITING LMZ646 SHORTLY WILL CAUSE ENOUGH MIXING
OVER THE LAKE TO THIN AND DISSIPATE THE DENSE FOG. SHEBOYGAN WEBCAM
SHOWS THE DENSE FOG HAS DISSIPATED AT 08Z. HENCE LET MARINE DENSE
FOG ADVY EXPIRE EARLY THIS MORNING. STRONG PUSH OF COLD AIR DELAYED
SEVERAL HOURS BEHIND EXITING COLD FRONT BUT STILL EXPECT FREQUENT
WIND GUSTS OF 25 TO 30 KTS TO DEVELOP EARLY THIS MRNG. THESE WINDS
WILL CAUSE WAVES TO BUILD THIS MORNING. THE HIGHER WAVES AND WINDS
WILL LINGER INTO THE EVENING BEFORE SUBSIDING. HENCE CURRENT SMALL
CRAFT ADVY END TIMES LOOK IN GOOD SHAPE.

&&

.MKX WATCHES/WARNINGS/ADVISORIES...
WI...FROST ADVISORY FROM 1 AM TO 8 AM CDT SATURDAY FOR WIZ046-047-051-
     052-056>060-063>066-068>072.

LM...SMALL CRAFT ADVISORY UNTIL 10 PM CDT THIS EVENING FOR LMZ645-646.

     SMALL CRAFT ADVISORY UNTIL 7 PM CDT THIS EVENING FOR LMZ643-644.

&&

$$

UPDATE...MRC/REM
TODAY/TONIGHT AND AVIATION/MARINE...MBK
SATURDAY THROUGH THURSDAY...COLLAR



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