Area Forecast Discussion
Issued by NWS Milwaukee/Sullivan, WI

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FXUS63 KMKX 020830
AFDMKX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MILWAUKEE/SULLIVAN WI
330 AM CDT SUN AUG 2 2015

.TODAY AND TONIGHT - CONFIDENCE...MEDIUM.

RIGHT ENTRANCE REGION OF UPPER JET DRIVING CONVECTION OVER NORTHERN
WI EARLY THIS MRNG.  THIS SYNOPTIC FORCING SLIDES EAST INTO NORTHERN
LOWER MI THIS MRNG.  FARTHER SOUTH...LOW LEVEL WARM ADVECTION
CONTINUING BUT ELEVATED CIN LAYER HAS BEEN SUPPRESSING CONVECTION
EXCEPT FOR A FEW SHOWERS.  HOWEVER SPC MESOSCALE ANALYSIS SHOWS
ELEVATED CIN LAYER WEAKENING A BIT WHILE THIS WARM AIR ADVECTION
RELATED TO INCREASING LOW LEVEL JET SPREADS ACROSS SRN WI.  IN
ADDITION...WEAK LOW LEVEL SHORT WAVE NOTED ON WIND PROFILERS MOST
LIKELY CONTRIBUTING TO ISOLD CONVECTION ACROSS SRN WI.  HENCE NEED
TO CONTINUE SMALL POPS THIS MRNG.  DEBRIS AND WARM AIR ADVECTION
CLOUDS THIS MRNG SHOULD THIN IN TIME FOR THE AFTERNOON AS 925H TEMPS
WARM TO AROUND 27-28C.  STRONG LOW LEVEL MIXING WILL CARRY THIS WARM
AIR TO SURFACE RESULTING IN AFTERNOON TEMPS PEAKING IN THE UPPER 80S
TO LOWER 90S.  HEAT INDEX READINGS WILL REACH THE 92 TO 97 DEGREE
RANGE THIS AFTN DUE TO THE WARM TEMPS AND 60S DEWPOINTS.

ENOUGH INSOLATION IS EXPECTED THIS AFTERNOON TO RESULT IN WINDY
CONDITIONS WITH SOUTHWEST WINDS GUSTING AS HIGH AS 35 TO 40 MPH.
MAY REACH WIND ADVISORY SUSTAINED WIND THRESHOLD OF 26KTS OR HIGHER
AT SOME SOUTHERN LOCATIONS FOR AN HOUR...BUT NOT ENOUGH CONFIDENCE
AT THIS POINT TO ISSUE HEADLINE.  ALREADY ISSUED SPS FOCUSING ON
STRONG WINDS THIS AFTN ACROSS SRN CWA AND WILL HIGHLIGHT IN HWO.

SHORT TERM GUIDANCE IN REASONABLE AGREEMENT ON UPSTREAM STRONG SFC
COLD FRONT OVER WRN MN SAGGING SOUTH ACROSS CENTRAL AND SOUTHERN WI
THIS AFTN AND EARLY EVENING.  STRONG MORNING CAPPING INVERSION
SHOULD ALLOW BUILD-UP OF INSTABILITY WITH DEWPOINTS LIKELY TO POOL
ALONG FRONT THIS AFTN.  DEWPTS MAY INCREASE TO AROUND 70.  CAPE
EXPECTD TO INCREASE TO 3 TO 4K J/KG AHEAD OF FRONT.  0-6KM BULK
SHEAR TO INCREASE TO 30 TO 40KTS WITH IMPRESSIVE 1KM SHEAR OF 20 TO
30KTS.  IN ADDITION...MID-LEVEL LAPSE RATES TO RISE EVEN FURTHER TO
AROUND 8C.  SPC STORM SCALE ENSEMBLE OF OPPORTUNITY HAS MOST
MESOSCALE MODELS SHOWING UPDRAFT HELICITY VALUES LIKELY TO BE
GREATER THAN 25 M2/S2 JUST TO THE NORTH OF CWA THIS AFTN.  3 HOUR
PROBABILITY OF UPDRAFT SPEED EXCEEDING 20KTS LIKELY IN NRN CWA THIS
AFTN.  WITH STRONG COLD FRONT SAGGING INTO THE NORTHERN CWA...BEEFED
UP POPS TO LIKELY LATE AFTN IN THE NORTH AND EAST CARRYING OVER INTO
THE EARLY EVE.  OUTFLOW BOUNDARY FROM EARLY MORNING NRN WI
CONVECTION SHOULD GET NUDGED BACK TO THE NORTH AS WELL.  NOT
EXPECTING DEBRIS CLOUDS THIS AFTN INTO THE EVENING SO THINKING MUCH
OF THE INSTABILITY AND SHEAR WILL BE REALIZED AHEAD OF FRONT.  AGREE
WITH SPC UPGRADE TO ENHANCED THIS AFTN.

CDFNT QUICKLY SWEEPS THRU SRN WI DURING THE EVENING ALLOWING
DRIER...MORE STABLE CONDITIONS TO RAPIDLY RETURN OVERNIGHT.

.MONDAY AND TUESDAY...FORECAST CONFIDENCE...HIGH

EXPECT DRY WEATHER MONDAY AS HIGH PRESSURE BEGINS TO BUILD IN FROM
THE NORTHWEST AND MODEL PRECIPITABLE WATER VALUES DROP TO AROUND
HALF OF AN INCH. SHOULD REMAIN DRY TUESDAY UNDER THE HIGH.

HIGH TEMPS MON/TUE SHOULD BE RIGHT NEAR NORMAL VALUES.

.WEDNESDAY THROUGH SATURDAY...FORECAST CONFIDENCE...MEDIUM

HIGH PRESSURE WILL BEGIN TO SLIDE NORTHEASTWARD
WEDNESDAY...ALLOWING FOR A RETURN OF DEEPER MOISTURE TO THE AREA.
THE GFS IS QUICKEST WITH THE MOISTURE RETURN...BRINGING A CHANCE
FOR SHOWERS/STORMS THROUGH THE DAY WEDNESDAY. ECMWF/CANADIAN
SOLUTIONS ARE SLOWER AND DRY WED. FIGURED IT WAS AT LEAST SOME
LOW POPS GIVEN THE GFS.

POPS THEN A LITTLE HIGHER FOR WED NIGHT AND THURSDAY AS GFS AND
ECMWF BOTH SLIDE A SHORTWAVE THROUGH THE AREA.

SHOULD TURN DRIER FOR FRI/SAT AS HIGH PRESSURE BUILDS BACK INTO
THE AREA.

TEMPS EXPECTED TO GENERALLY BE A FEW DEGREES BELOW NORMAL FOR THE
SECOND HALF OF THE WEEK INTO THE WEEKEND UNDER PERSISTENT
NORTHWEST FLOW ALOFT.

&&

.AVIATION/12Z TAFS/...ISOLD CONVECTION IS EXPECTED TO DEVELOP LATER
THIS MRNG ACROSS SRN WI.  HOWEVER VFR CONDITIONS WILL CONTINUE INTO
THE AFTN.  A WINDY DAY IS EXPECTED WITH GUSTS PERHAPS REACHING 35
KTS THIS AFTN PENDING SKY COVER AND AMOUNT OF LOW LEVEL MIXING.  A
PERIOD OF SCT CONVECTION IS EXPECTED THIS AFTN AND EVENING.  SOME OF
THE CONVECTION MAY PRODUCE STRONG WINDS AND LARGE HAIL.  NEED TO
INCLUDE LOW LEVEL WIND SHEAR REMARK IN KMSN TAF FOR A FEW HOURS
UNTIL WINDS INCREASE.  FARTHER EAST...MORE BORDERLINE LLWS SITUATION
WHILE SFC WINDS REMAIN LIGHTER THIS MRNG.

&&

.MARINE...TIGHTENING PRESSURE GRADIENT AHEAD OF APPROACHING COLD
FRONT AND INSOLATION WILL ALLOW STRONG WIND TO MIX DOWN TO SHORE
SURFACE AND AFFECT NEARSHORE WATERS LATER TODAY.  WIND GUSTS COULD
GET AS HIGH AS 38 KNOTS ACROSS SOUTHERN MARINE ZONES.  HENCE
UPGRADED SMALL CRAFT ADVISORY SOUTH OF NORTH POINT LIGHT TO GALE
WARNING FOR THE AFTERNOON.  ALSO EXTENDED SMALL CRAFT ADVISORY FOR
NORTHERN ZONES UNTIL 00Z.  MARINERS NEED TO BE AWARE OF THE
POTENTIAL FOR STRONG STORMS AFFECTING THE NEARSHORE WATERS THIS
AFTERNOON AND EVENING AND BE READY TO SEEK SAFE HARBOR.

&&

.BEACHES...STRONG OFFSHORE WINDS ARE EXPECTED AT THE BEACHES TODAY.
DUE TO THE OFFSHORE NATURE...WAVE HEIGHTS AT LAKE MICHIGAN BEACHES
ARE EXPECTED TO BE LOWER...MAINLY BETWEEN 1 AND 3 FEET RESULTING IN
LOW TO MODERATE SWIM RISK CONDITIONS.  SWIMMERS WILL NEED TO BE
CAUTIOUS OF THE POTENTIAL FOR STRONG TSTORMS AFFECTING THE BEACHES
THIS AFTERNOON AND EVE AND BE READY TO SEEK SHELTER QUICKLY.

&&

.MKX WATCHES/WARNINGS/ADVISORIES...
WI...NONE.
LM...SMALL CRAFT ADVISORY FROM 9 AM THIS MORNING TO 2 PM CDT THIS
     AFTERNOON FOR LMZ645-646.

     GALE WARNING FROM 2 PM THIS AFTERNOON TO 7 PM CDT THIS EVENING
     FOR LMZ645-646.

     SMALL CRAFT ADVISORY FROM 9 AM THIS MORNING TO 7 PM CDT THIS
     EVENING FOR LMZ643-644.

&&

$$

TODAY/TONIGHT AND AVIATION/MARINE/BEACHES...MBK
MONDAY THROUGH SATURDAY...DDV



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