Area Forecast Discussion
Issued by NWS Milwaukee/Sullivan, WI

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FXUS63 KMKX 021456 AAA
AFDMKX

AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE MILWAUKEE/SULLIVAN WI
956 AM CDT TUE SEP 2 2014

.UPDATE...

SHOWERS THAT WERE TO THE WEST OF THE FORECAST AREA EARLIER THIS
MORNING ALL BUT WIPED OUT AS THEY MOVED EAST. THE MAIN AREA OF
RAIN IS NOW MOSTLY SOUTH OF THE WI/IL BORDER...WITH A FEW SHOWERS
ALSO TO THE NORTH OF THE FORECAST AREA. LATEST MESOSCALE MODELS
STILL SUGGEST SOME ADDITIONAL SHOWER DEVELOPMENT THIS
AFTERNOON...MAINLY IN THE NORTHEAST. COVERAGE IS NOT EXPECTED TO
BE THAT WIDESPREAD AND OVERALL PRECIP AMOUNTS WILL BE ON THE LOW
SIDE. STILL THINKING THERE SHOULD BE ENOUGH SUN AT TIMES TODAY TO
PUSH TEMPS UP TO AROUND 80 THIS AFTERNOON.

&&

.AVIATION/18Z TAFS/...

THERE ARE A COUPLE SMALL SHOWERS ACROSS SOUTHERN WISCONSIN RIGHT
NOW...WITH SOME ADDITIONAL DEVELOPMENT POSSIBLE ACROSS THE
NORTHEAST FORECAST AREA THIS AFTERNOON. ANY SHOWERS THAT DO
DEVELOP WILL LIKELY BE SHORT DURATION...WITH THE AREA EXPECTED TO
BE MAINLY DRY THROUGH THE REST OF THE DAY.

MAIN CONCERN TONIGHT IS THE POTENTIAL FOR SOME FOG DEVELOPMENT.
WINDS WILL BE LIGHT AND SKIES MOSTLY CLEAR AS HIGH PRESSURE SLIDES
BY TO THE SOUTH. WILL LOOK AT 12Z GUIDANCE AS IT COMES IN TO GET A
BETTER FEEL FOR THE FOG POTENTIAL. OTHERWISE...VFR CONDITIONS ARE
EXPECTED THROUGH THE DAY WEDNESDAY.

&&

.PREV DISCUSSION... /ISSUED 349 AM CDT TUE SEP 2 2014/

SHORT TERM...

TODAY - CONFIDENCE...MEDIUM.

VISIBILITY AT SEVERAL LOCATIONS HAVE FALLEN TO ONE QUARTER MILE IN
LAST HOUR AS HIGH CLOUDS HAVE SHIFTED OFF TO THE EAST.  HOWEVER
AVAILABLE WEB CAMS SHOW VSBYS REMAIN GOOD ALL AREAS.  MORE HIGH
CLOUDS STREAMING IN FROM THE SOUTH BUT TEMPS HAVE ALREADY DROPPED
BELOW THE CROSSOVER TEMP ALL LOCATIONS.  THINK THERE WILL BE SOME
LOCALIZED DENSE FOG NEXT SEVERAL HOURS DUE TO DIMINISHING BOUNDARY
LAYER WINDS.  HOWEVER DENSE FOG SHOULD BE BRIEF SO WL HOLD OFF AN
ANY ADVY AND ISSUE NOW/SPS AS NEEDED.

UPSTREAM COMPACT SHORT WAVE SHOWING UP NICELY ON WATER VAPOR IMAGERY
OVER NORTHWEST IA.  APPEARS ECMWF HAS BEST HANDLE ON CURRENT
POSITION BUT ALL SHORT TERM GUIDANCE CARRIES THIS SHORT WAVE ACROSS
SRN WI THIS MRNG AND EARLY AFTN.  WEAK LAYER Q-VECTOR CONVERGENCE
TIED TO LEFT ENTRANCE REGION OF UPPER JET.  EXPECT SFC DWPTS TO
REMAIN IN THE UPPER 50S TO AROUND 60.  LATEST NAM MAY BE OVERDOING
AMOUNT OF ELEVATED INSTABILITY HOWEVER STILL ENOUGH COOL AIR ALOFT
TO GENERATE ELEVATED CAPES OF 300 TO 500 J/KG WITH SHEAR OF 35 TO 45
KTS.  ENOUGH FORCING TO CONTINUE SCHC TO CHANCE POPS EXPANDING WEST
TO EAST ACROSS CWA THIS MRNG AND DECREASING FROM THE WEST THIS AFTN
AS WAVE MOVES EAST OF AREA.  HIGHEST POPS WL BE ACROSS NORTH WHERE
LOWER CONDENSATION PRESSURE DEFICITS ON 305 THETA SFC WILL BE
LOCATED AS WELL AS BETTER SYNOPTIC FORCING FROM UPPER JET.

TONIGHT - CONFIDENCE...HIGH.

MORE FOG LIKELY TONIGHT AS LITTLE CHANGE IN LOW LEVEL HUMIDITY AND
BOUNDARY LAYER WINDS LOOK LIGHTER FOR A GREATER PERIOD OF TIME.
WARM AIR ADVECTION MID/HIGH CLOUDS SHOULD START TO STREAM IN FROM
THE WEST LATE TONIGHT BUT FOG WL HAVE ALREADY FORMED BY THEN.

WEDNESDAY AND WEDNESDAY NIGHT...FORECAST CONFIDENCE MEDIUM.

A WEAK SHORTWAVE TRACKING THROUGH NORTHERN WI WILL COINCIDE WITH THE
RIGHT ENTRANCE REGION OF AN UPPER JET...THE NOSE OF THE 850MB LOW
LEVEL JET AND 850MB WARM AIR ADVECTION WEDNESDAY AFTERNOON AND
EVENING. CONVECTION THAT DEVELOPS IN THIS AREA WILL SLIDE SOUTHEAST
THROUGH EAST CENTRAL WI. THUS...KEPT LIKELY POPS OVER THE NORTHERN
FORECAST AREA WED NIGHT TO HANDLE THIS MAIN AREA OF ELEVATED
THUNDERSTORMS. ELSEWHERE... ONGOING WEAK WARM AIR ADVECTION AND THE
SURFACE WARM FRONT IN THE VICINITY OF SOUTHERN WI COULD LEAD TO
SCATTERED STORMS SO KEPT THE CHANCE FOR THUNDER.

THE NAM AND GFS BOTH SHOW ELEVATED CAPE OF 1500-1700 J/KG OVER SOUTH
CENTRAL WI WED NIGHT. IN ADDITION...BULK SHEAR UP TO 40 KT COULD
SUPPORT SOME STRONG STORMS. SPC HAS MOST OF THE MKX FORECAST AREA IN
A SEE TEXT... OR 5 PERCENT PROBABILITY FOR SEVERE.

LONG TERM...

THURSDAY AND THURSDAY NIGHT...FORECAST CONFIDENCE MEDIUM.

ANY STORMS WILL TAPER OFF OVER SOUTHEAST WI THU MORNING. AFTER
LINGERING CLOUDS CLEAR... THE SURFACE EFFECTIVE WARM FRONT WILL BE
ABLE TO PUSH INTO NORTHERN WI AND KEEP SOUTHERN WI CAPPED DURING THE
DAY. HIGHS ARE EXPECTED IN THE MID TO UPPER 80S. WITH DEWPOINTS
CREEPING INTO THE LOWER 70S... HEAT INDEX VALUES WILL LIKELY TOP OUT
IN THE LOWER 90S. WINDS SHOULD BE FAIRLY GUSTY OUT OF THE SOUTH.

A STRONG SURFACE COLD FRONT WILL TRACK SOUTHEAST THROUGH WI THU
NIGHT. THIS WILL BE THE FOCUS FOR POSSIBLE SEVERE THUNDERSTORMS.
MODERATE SHEAR...HIGH CAPE AND COOLING MID LEVELS COULD ALLOW FOR A
LINE OF SEVERE THUNDERSTORMS TO DEVELOP. SPC HAS MOST OF THE MKX
FORECAST AREA IN A SLIGHT RISK FOR SEVERE WX...15 PERCENT PROB.
DAMAGING WINDS AND LARGE HAIL ARE THE SEVERE THREATS.

FRIDAY AND FRIDAY NIGHT...FORECAST CONFIDENCE MEDIUM.

THE CHANCE FOR SHOWERS AND STORMS MAY LINGER INTO FRI MORNING OVER
SOUTHEAST WI DEPENDING ON THE EXACT TIMING OF THE FRONT AND ANY POST-
FRONTAL STRATIFORM RAIN. THE MAIN UPPER TROUGH WILL TAKE A LITTLE
LONGER TO EXIT...SO EXPECTING A FAIRLY CLOUDY DAY ON FRIDAY. HIGHS
SHOULD ONLY BE IN THE 70S.

A FEW MODELS ARE SHOWING ANOTHER WEAKER SHORTWAVE TRACKING THROUGH
WI FRI NIGHT...SO KEPT THE SMALL CHANCE FOR SHOWERS IN SOUTHEAST WI
OVERNIGHT.

SATURDAY AND SUNDAY...FORECAST CONFIDENCE HIGH.

PLAN ON A QUIET STRETCH OF WEATHER FOR NEXT WEEKEND WITH LOW
HUMIDITY AND COOLER TEMPERATURES. 850MB TEMPS DROP DOWN INTO THE
SINGLE DIGITS THROUGH SUNDAY MORNING. MOSTLY CLEAR SKIES FRI NIGHT
THROUGH SUN NIGHT MEANS TEMPS WILL BE QUITE COOL... WITH LOWS IN THE
LOWER 50S. HIGHS ARE EXPECTED IN THE LOWER 70S. THESE HIGHS ARE
TYPICAL FOR MID SEPTEMBER INSTEAD OF EARLY SEPTEMBER.

MONDAY AND BEYOND...FORECAST CONFIDENCE MEDIUM.

BY MONDAY...WARM AIR ADVECTION WILL RESUME OVER THE MIDWEST AND THE
CHANCE FOR SHOWERS AND THUNDERSTORMS WILL RETURN TO SOUTHERN WI FOR
THE FIRST HALF OF NEXT WEEK.

AVIATION/12Z TAFS/...PATCHY FOG EARLY THIS MRNG SHOULD QUICKLY LIFT
AFTER SUNRISE.  VSBYS IN FOG MAY BRIEFLY DROP TO IFR.  OTRW A VFR
PERIOD WITH MORE FOG LIKELY AGAIN TONIGHT.  WL HAVE TO WATCH OUT FOR
ISOLD TO SCT -SHRA/-TSRA THIS MRNG INTO THE MID-AFTN WITH CLEARING
SKIES LATE THIS AFTN AND EVE.

&&

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

$$

UPDATE...DDV
TODAY/TONIGHT AND AVIATION/MARINE...MBK
WEDNESDAY THROUGH MONDAY...MRC



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