Area Forecast Discussion
Issued by NWS Milwaukee/Sullivan, WI

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FXUS63 KMKX 062058
AFDMKX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MILWAUKEE/SULLIVAN WI
358 PM CDT WED MAY 6 2015

.TONIGHT AND THURSDAY... FORECAST CONFIDENCE MEDIUM.

A SURFACE WARM FRONT CURRENTLY IN NORTHERN IL WILL CONTINUE TO TREK
NORTH LATE THIS AFTERNOON. THE LAKE IS CAUSING IT TO STALL... SO IT
IS NOW TAKING ON A NW-SE ORIENTATION. THE FRONT IS APPARENT ON
VISIBLE SATELLITE WITH RELATIVELY CLEAR SKIES AND EAST WINDS ON THE
NORTH SIDE AND CUMULUS CLOUDS ON THE SOUTH SIDE. THE AIR IS WELL-
MIXED AND DRIER BEHIND THIS WARM FRONT.

NORTH OF THE WARM FRONT... ACROSS SOUTHERN WI... DEWPOINT
TEMPERATURES ARE IN THE LOWER 60S INLAND FROM THE LAKE. ELEVATED
CAPE IS AROUND 400 J/KG. I CANNOT RULE OUT A STRAY THUNDERSTORM
ALONG THE WARM FRONT AS IT GETS INTO SOUTH CENTRAL WI LATE THIS
AFTERNOON... BUT CHANCES ARE LOW.

CHANCES FOR SURFACE-BASED THUNDERSTORMS DIMINISH AFTER DARK THIS
EVENING. THERE IS REALLY NOT MUCH CAPE OR MOISTURE AVAILABLE IN THE
UPPER LEVELS FOR THE LOW LEVEL JET TO TRIGGER THUNDERSTORMS ACROSS
SOUTHERN WI LATE TONIGHT... SO KEPT THE FORECAST DRY.

EXPECT DENSE MARINE FOG TO SPREAD INLAND ONCE AGAIN TONIGHT. A DENSE
FOG ADVISORY MAY BE NEEDED FOR THE LAKESHORE COUNTIES. WINDS WILL
BECOME SOUTHERLY BY MID THURSDAY MORNING AND DISSIPATE ANY LINGERING
FOG.

THE SURFACE WARM FRONT WILL BE WELL INTO NORTHERN WISCONSIN ON
THURSDAY. THIS MEANS SOUTHERN WI WILL BE VERY WARM WITH BREEZY SOUTH
WINDS. A WEAK COLD FRONT AND A SHORTWAVE WILL DRIFT INTO WESTERN
WISCONSIN THURSDAY AFTERNOON AND LIKELY TRIGGER THUNDERSTORMS. STORM
MOTION WILL BE WSW SO THERE IS A CHANCE FOR SHOWERS AND
THUNDERSTORMS OVER MAINLY THE WESTERN MKX FORECAST AREA THURSDAY
AFTERNOON. ANY WELL-ORGANIZED STORMS COULD BRING BRIEF DAMAGING
WINDS... SO SPC HIGHLIGHTED THE WESTERN FORECAST AREA IN A MARGINAL
RISK AREA.

.SHORT TERM....SHORT TERM...THURSDAY NIGHT THROUGH SATURDAY

THIS PERIOD MARKED BY MULTIPLE SHORT WAVES CROSSING THE REGION IN SW
FLOW AHEAD OF BROAD POSITIVELY TILTED TROUGH...WITH A COLD FRONT
SLOWLY DROPPING NW TO SE THROUGH THE CWA...EXITING TO THE SOUTHEAST
ON SATURDAY.

THURSDAY NIGHT...FORECAST CONFIDENCE HIGH

SHOWERS AND THUNDERSTORMS SHOULD BE ONGOING AT START OF PERIOD WITH
WARM ADVECTION ON 35-40 KT LOW-LEVEL JET AHEAD OF WEAK LEAD SHORT
WAVE THAT MOVES THROUGH THURSDAY NIGHT INTO FRIDAY MORNING. LOW-
LEVEL WINDS WEAKEN AFTER 06Z AS WAVE LIFTS OFF TO THE NORTHEAST...SO
HAVE TAPERED OFF POPS FROM SOUTH TO NORTH BETWEEN 06Z AND 12Z. BEING
IN THE WARM SECTOR...LOWS WILL ONLY COOL INTO THE LOWER 60S.

FRIDAY AND FRIDAY NIGHT...FORECAST CONFIDENCE MEDIUM

THUNDERSTORM CHANCES REMAIN HIGHEST ALONG AND SOUTHEAST OF THE
SURFACE COLD FRONT AND 850 MB TROUGH THAT BISECT THE STATE FROM
NORTHEAST TO SOUTHWEST...WITH THE FRONT SAGGING INTO THE NW AT 12Z
FRIDAY.  MODELS DIFFERING ON WHETHER OR NOT THE FRONT...PARALLEL TO
THE MID-UPPER LEVEL FLOW...PASSES THROUGH THE CWA BY 12Z SATURDAY.
THE BAROCLINIC ZONE HANGS UP OVER SOUTHERN WISCONSIN AS A SECONDARY
SURFACE WAVE...ASSOCIATED WITH THE NEXT SHORT WAVE IN A SERIES...
MOVES THROUGH LATE FRIDAY AFTERNOON AND EVENING.

WILL BRING LIKELY POPS INTO THE EASTERN HALF OF THE CWA FRIDAY
AFTERNOON AND ALL BUT THE FAR WEST FRIDAY EVENING WITH THE APPROACH
OF THE SHORT WAVE. HIGHER CAPE VALUES ON SLOWER NAM VERSUS GFS BUT
ENOUGH INSTABILITY TO WARRANT THUNDERSTORMS. LINGERING CHANCE POPS
IN THE EAST AFTER 06Z SATURDAY TO ACCOUNT FOR DIFFERING
TIMING/CONFIGURATION OF DEPARTING SURFACE WAVE.

HIGH TEMPERATURES IN THE MID TO UPPER 70S PREDICATED ON BEING IN THE
WARM SECTOR AND SEEING SOME SUNSHINE. WITH THE SLOW MOVING FRONT AND
NO REAL STRONG PUSH OF COLDER AIR...LOWS IN THE 50S EXPECTED.

SATURDAY AND SATURDAY NIGHT...FORECAST CONFIDENCE MEDIUM

HAVE A COLLABORATIVE SLIGHT CHANCE FOR THE ENTIRE DAY SATURDAY...BUT
LOOKING MORE LIKE THE MORNING AND EARLY AFTERNOON MAY BE DRY...WITH
THE COLD FRONT BECOMING STATIONARY TO THE SOUTH OVER ILLINOIS BEFORE
RETURNING AS A WARM FRONT SATURDAY NIGHT. WILL KEEP SATURDAY NIGHT
POPS IN THE CHANCE CATEGORY...WITH THE HIGHEST IN THE SOUTH NEAR THE
ILLINOIS BORDER. A COOLER DAY SATURDAY WITH NORTH WINDS AND HIGHS IN
THE 60S TO AROUND 70...AND LOWS IN THE 40S.

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

THE EXTENDED DOMINATED BY CLOSED SW U.S. 500 MB LOW OPENING UP AS IT
LIFTS NEWD AND CROSSES THE UPPER MIDWEST...MERGING WITH A CANADIAN
TROUGH THAT CLOSES OFF TUESDAY NORTH OF THE UPPER GREAT LAKES.
EXPECT THUNDERSTORMS TO BECOME LIKELY BY SUNDAY NIGHT INTO MONDAY
AS WARM FRONT AND THEN AN OCCLUDED FRONT PASSES THROUGH THE REGION
AS THE SURFACE LOW TRACKS FROM THE CENTRAL PLAINS ACROSS WISCONSIN
REACHING SW QUEBEC BY TUESDAY MORNING. WISCONSIN WILL REMAIN UNDER
THE SOUTHERN FLANK OF CYCLONIC FLOW THROUGH MID-WEEK...WITH PERIODIC
SMALL CHANCES FOR SHOWERS NEAR TO SLIGHTLY BELOW NORMAL TEMPERATURES
THROUGH THE PERIOD.

&&

.AVIATION/00Z TAFS/...

EXPECT MARINE FOG TO SPREAD INLAND ONCE AGAIN THIS EVENING. LOOK FOR
LIFR CIGS/VSBY TO REDEVELOP ALONG THE LAKESHORE. FOG WILL DISSIPATE
BY LATE THU MORNING AS GUSTY SOUTHERLY WINDS BEGIN.

OTHERWISE...THERE IS A SMALL CHANCE FOR SHOWERS AND THUNDERSTORMS
OVER FAR SOUTHERN WI LATER TODAY INTO THIS EVENING ALONG A SURFACE
WARM FRONT.

&&

.MARINE...
 DENSE FOG SHOULD LINGER OVER THE NEARSHORE WATERS THROUGH THURSDAY
MORNING DUE TO WARM AND MOIST AIR OVER THE RELATIVELY COLD WATER.

INCREASING SOUTHWEST WINDS IN THE BOUNDARY LAYER LATER THURSDAY
MORNING SHOULD THIN ANY LINGERING FOG.  SOUTHWEST WIND GUSTS WILL
APPROACH SMALL CRAFT ADVY LEVELS ON THU AS WELL.

&&

.MKX WATCHES/WARNINGS/ADVISORIES...
WI...NONE.
LM...DENSE FOG ADVISORY UNTIL 10 AM CDT THURSDAY FOR LMZ643>646.

&&

$$

TONIGHT/THURSDAY AND AVIATION/MARINE...MRC
THURSDAY NIGHT THROUGH WEDNESDAY...REM


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