Area Forecast Discussion
Issued by NWS Milwaukee/Sullivan, WI

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000
FXUS63 KMKX 160829
AFDMKX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MILWAUKEE/SULLIVAN WI
329 AM CDT SAT AUG 16 2014

.SHORT TERM...

TODAY AND TONIGHT...FORECAST CONFIDENCE - MEDIUM.

MAIN CONCERN IS SMALLER THREAT OF PRECIPITATION TODAY AND TONIGHT
WITH SEVERAL PASSING WEATHER SYSTEMS.  MID-LEVEL SHORT WAVE OVER
SW IA CAUSING WIDESPREAD SHRA AND EMBEDDED T OVER SOUTHERN IA INTO
NRN MO.  THIS WAVE IS EXPECTED TO PROGRESS SLOWLY SE OVER NEXT 24
HOURS.  APPEARS BEST LOW LEVEL MOISTURE CONVERGENCE AND Q-VECTORS
REMAIN JUST SOUTH OF SOUTHERN WI WITH THIS FEATURE SO WL REMOVE
SMALL POPS IN FAR SOUTH.  ATTENTION THEN SHIFTS NORTH WHERE STRONG
CDFNT WAS LOCATED OVE LAKE SUPR INTO MN ARROWHEAD.  NORTHWEST FLOW
ALOFT WL CARRY THIS FRONT INTO CENTRAL WI BY LATE AFTN.
IMPRESSIVE LOW LEVEL FRONTOGENETICAL FORCING SPREADS INTO
NORTHEAST CWA BY 00Z.  FRONT IS THEN EXPECTED TO LOSE SOME OF ITS
PUNCH AS IT PROGRESSES FARTHER SOUTH ACROSS SRN WI DURING THE EVE AS
IT RUNS INTO SHORT WAVE RIDGING TO THE NORTH OF CENTRAL MS VLY WAVE.
BEST CHANCE FOR CONVECTION WL BE JUST AHEAD OF THIS FRONT OVER
FDL/SBM AREAS LATE THIS AFTN.  EXPECT DEWPTS TO REACH MID 60S AHEAD
OF THE FRONT WHICH WILL RESULT IN SFC CAPES OVER 1000 J/KG.  BULK
SHEAR WL BE AROUND 30KTS.  MAY HAVE JUST ENOUGH INSTABILITY AND
SHEAR FOR ONE OR TWO STORMS TO TURN VIGOROUS IN THE FDL/SBM AREAS
FOR AN HOUR OR TWO.

OTRW EXPC A DIMINISHING TREND TO THE CONVECTION WITH THE LOSS OF
INSOLATION IN THE EARLY EVENING AS CDFNT REMNANTS SWEEP ACROSS REST
OF SRN WI.

SUNDAY AND SUNDAY NIGHT...FORECAST CONFIDENCE MEDIUM.

DRY SURFACE HIGH PRESSURE OVER ONTARIO WILL WEDGE DOWN INTO SOUTHERN
WI ON SUNDAY. MODELS STILL LINGER A STRATUS DECK OVER SOUTHERN WI
THROUGH MIDDAY SUNDAY. THE NAM TRIES TO HANG ONTO IT LONGER THAN THE
GFS. THE MID LEVEL RIDGE...DRY PROFILE AND LOW LEVEL MIXING WOULD
SUPPORT THE EARLIER SCATTERING OF CLOUDS. SKY COVER AND EAST WINDS
WILL KEEP TEMPS COOL THROUGH THE DAY...IN THE UPPER 60S LAKESHORE
AND MID 70S WELL INLAND.

WARM AIR ADVECTION AND A WEAK SHORTWAVE WILL BRING INCREASING CLOUDS
TO THE REGION SUNDAY NIGHT...BUT EXPECT WEATHER TO REMAIN DRY
THROUGH THE NIGHT IN THE MKX AREA. THE CLOUDS WILL LIMIT THE
COOLING...SO BUMPED UP THE MIN TEMPS INTO THE MID/UPPER 50S.

.LONG TERM...

MONDAY THROUGH WEDNESDAY...FORECAST CONFIDENCE MEDIUM.

THE 00Z ECMWF NOW TRIES TO SPREAD PRECIP INTO SOUTHERN WI EARLIER
THAN THE OTHER MODELS. THIS IS IN ASSOCIATION WITH THAT WEAK
SHORTWAVE AND A LITTLE HIGHER MOISTURE. OPTED TO KEEP THE AREA DRY
ON MONDAY FOR NOW DUE TO THE DRY AIR IN PLACE.

BY MONDAY NIGHT...MODELS ARE CONSISTENT IN SPREADING SHOWERS AND
THUNDERSTORMS INTO SOUTHERN WI AHEAD OF A STRONGER 500MB SHORTWAVE
TROUGH SWINGING DOWN THROUGH THE UPPER MIDWEST. THIS UPPER LOW WILL
STALL OVER THE UPPER GREAT LAKES THROUGH WEDNESDAY. I INCREASED THE
POPS TO LIKELY OVER THE WESTERN FORECAST AREA AND IF THE MODELS
CONTINUE THEIR CONSISTENT TREND IN SPREADING PRECIP ACROSS THE WHOLE
AREA...EXPECT POPS TO INCREASE MORE WITH LATER FORECASTS.

PRECIPITABLE WATER VALUES WILL BE AROUND 1.5 INCHES. WITH MODERATE
INSTABILITY AND FAIRLY WEAK SHEAR...THESE SHOWERS AND THUNDERSTORMS
WILL BE EFFICIENT RAIN PRODUCERS. THIS SLOW-MOVING SYSTEM SHOULD
BRING SOME MUCH-NEEDED RAIN TO SOUTHERN WI.

THE ECWMF AND GFS SOLUTIONS DIFFER WITH THEIR PLACEMENT OF THE
SURFACE FRONTS ON WEDNESDAY... WHICH COULD MEAN LINGERING
SHOWERS/TSTORMS OR DRY WEATHER. BY WED NIGHT...EXPECTING DRY WEATHER.

THURSDAY THROUGH FRIDAY...FORECAST CONFIDENCE LOW.

AN 850MB BAROCLINIC ZONE OVER THE MIDWEST WILL LIFT NORTHWARD INTO
SOUTHERN WI THU AND FRIDAY. THE FRONT WILL EITHER STALL OVER THE
WI/IA/IL BORDER AND KEEP SOUTHERN WI IN THE AVERAGE TEMP RANGE FOR
NEXT WEEKEND...PER THE ECWMF... OR THE FRONT WILL LIFT INTO EAST
CENTRAL WI AND USHER VERY WARM AND HUMID AIR INTO SOUTHERN WI...PER
THE GFS. EITHER WAY...THIS FRONT WILL BE A TRIGGER FOR
THUNDERSTORMS AT TIMES.

MODEL SOLUTIONS DIVERGE SIGNIFICANTLY FOR NEXT WEEKEND.

&&

.AVIATION/12Z TAFS/...

MAY BE A BRIEF PD OF LIGHT FOG AT KENW BUT HOPING THAT BOUNDARY
LAYER MIXING AT AND JUST ABOVE INVERSION PREVENTS MORE SIGNIFICANT
FOG EARLY THIS MRNG.  OTRW VFR CONDITIONS TO CONTINUE TODAY BUT
EXPECT MVFR STRATUS TO FOLLOW IN WAKE OF STRONG BACKDOOR CDFNT THAT
WILL SWEEP ACROSS SRN WI LATE THIS AFTN AND EVE.  WEAK TSTRMS MAY
AFFECT TAF SITES LATE THIS AFTN AND EVE AS CDFNT

&&

.MARINE...

MARINERS SHOULD EXPECT AN ABRUPT WIND SHIFT LATE THIS AFTN AND EVE
OVER THE NEAR SHORE WATERS AS BACK DOOR CDFNT SAGS SWD ACROSS LAKE
MI.  EXPC S TO SW WINDS TO QUICKLY BACK TO THE NORTHEAST.  NAM AND
WRF SHORT TERM GUIDANCE SUGGESTING WIND GUSTS WILL APPROACH SMALL
CRAFT ADVISORY LEVELS FOR A TIME BEGINNING LATE THIS AFTN IN
LMZ643..SPREADING INTO REST OF MARINE ZONES IN THE EARLY EVENING.
WAVE HEIGHTS SHOULD REMAIN JUST BELOW SMALL CRAFT ADVISORY LEVELS.
DUE TO DESCREPANCY IN PERIOD OF TIME OF GUSTY WIND IN SHORT TERM
GUIDANCE...WL HOLD OFF ON ISSUING SMALL CRAFT ADVY AT THIS TIME.
MODIS IMAGERY FROM FRI AFTN SHOWS MOST OF LAKE MI WITH SEA SURFACE
TEMPS IN THE UPPER 50S TO MIDDLE 60S.

&&

.BEACHES...

SOUTHWEST WINDS MAY BACK TO THE SOUTH THIS AFTN AT LAKE MI BEACHES
FROM PORT WASHINGTON SOUTH TO KENOSHA.  A VIGOROUS CDFNT WL SAG
RAPIDLY SOUTH ACROSS THE LAKE SHORE AREA LATE THIS AFTN AND EVENING.
WINDS WL TURN ABRUPTLY TO THE NORTHEAST AFT THIS FRONT PASSES.  THIS
FRONT WL AFFECT SHEBOYGAN BEACHES BETWEEN 3 PM AND 5 PM...WITH REST
OF BEACHES TO KENOSHA SHORTLY AFTER.  A PERIOD OF GUSTY NORTHEAST
WINDS FROM LATE AFTN THRU TONIGHT WILL CAUSE WAVE HEIGHTS TO KICK UP
TO 2 TO 4 FEET CAUSING A MODERATE SWIM RISK.  EVENING SWIMMERS WL
NEED TO USE EXTREME CAUTION DUE TO RAPIDLY BUILDING WAVES
CAUSING STRONG CURRENTS AT THE SHORE.

&&

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

$$

TODAY/TONIGHT AND AVIATION/MARINE...MBK
SUNDAY THROUGH FRIDAY...MRC



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