Area Forecast Discussion
Issued by NWS Milwaukee/Sullivan, WI

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000
FXUS63 KMKX 290221
AFDMKX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MILWAUKEE/SULLIVAN WI
921 PM CDT TUE JUL 28 2015

.UPDATE...TOO MUCH UNCERTAINTY TO CONTINUE WITH LIKELY WORDING
OVERNIGHT. HOWEVER WILL CONTINUE CHANCE POPS AS STILL EXPECT
UPSTREAM AREA OF FRONTOGENETICAL FORCING TO CLIP SOUTHERN
WISCONSIN BETWEEN 06Z AND 12Z. UNIMPRESSIVE LOW LEVEL JET
BEGINNING TO PIVOT MORE WESTERLY WHICH DOES NOT BODE WELL FOR MORE
WIDESPREAD CONVECTION. WIDESPREAD CONVECTION RUMBLING ACROSS
CENTRAL IOWA ALONG OUTFLOW BOUNDARY AND WARM FRONT WILL CONTINUE
TO SUPPRESS MAIN FORCING TO THE SOUTH OVERNIGHT. OVERNIGHT TEMPS
LOOK IN GOOD SHAPE WITH WARM AND MUGGY CONDITIONS EXPECTED UNTIL
LATE.

&&

.AVIATION/06Z TAFS/...STILL EXPECT SCT CONVECTION TO AFFECT TAF
SITES MAINLY BETWEEN 06Z AND 12Z. CIGS SHOULD LOWER BUT MOSTLY
REMAIN VFR WITH RAPID CLEARING EXPECTED WED MRN.

&&

.MARINE...FOR NOW KEPT NORTHERN ZONE IN SMALL CRAFT ADVISORY FOR
LATER WED MRNG THRU THE AFTN. BOTH RAP AND EARLIER GFS WERE
INDICATING STRONGER WINDS GUSTS AFFECTING NEAR SHORE WATERS THAN
CURRENT FORECAST. IF 00Z NAM COMES IN WITH SIMILAR VALUES...THEN
NEXT SHIFT MAY NEED TO EXPAND SMALL CRAFT TO INCLUDE SOUTHERN
ZONES.

&&

.PREV DISCUSSION... /ISSUED 341 PM CDT TUE JUL 28 2015/

TONIGHT AND WEDNESDAY...FORECAST CONFIDENCE IS MEDIUM.

CURRENT CONVECTION IN IOWA SHOULD REMAIN SOUTH OF THE AREA INTO
THE EVENING HOURS...AS BEST UPWARD VERTICAL MOTION FIELDS REMAIN
IN THAT AREA. MAY INCLUDE SOME LOWER END POPS IN THE FAR
SOUTHWEST/SOUTH IN CASE THEY BUILD FURTHER TO THE NORTHEAST.
SHOULD SEE MIDDLE TO HIGH CLOUDS LINGER INTO THE EARLY
EVENING...WITH SOME BREAKS AT TIMES.

A TOUGH FORECAST FOR TONIGHT INTO EARLY WEDNESDAY MORNING WITH
POPS WITH THE PASSING COLD FRONT. THE SYNOPTIC MODELS...AND SOME
OF THE MESOSCALE MODELS...ARE SHOWING A DECENT AMOUNT OF QPF WITH
THE FRONTAL PASSAGE. HOWEVER...SOME OF THE MESOSCALE MODELS ARE
MUCH LESS ROBUST WITH THE QPF.

THE SYNOPTIC UPWARD VERTICAL MOTION IS MODEST AT BEST...WITH SOME
LOW LEVEL FRONTOGENESIS AND A PASSING BUT MODEST 500 MB VORTICITY
MAXIMUM. TALL SKINNY MEAN LAYER CAPES ON AREA FORECAST SOUNDINGS
ARE SHOWN...WITH WEAK DEEP LAYER SHEAR. PRECIPITABLE WATER VALUES
REMAIN QUITE HIGH...AROUND OR OVER 2.00 INCHES.

THE LEVEL OF FREE CONVECTION IS AROUND THE 700 MB LEVEL...SO
THINK ANY PRECIPITATION WILL BE RIGHT ALONG THE FRONT. THE
UNCERTAINTY IS THERE AND THINGS MAY BE MORE WIDELY SCATTERED THAN
CURRENTLY FORECAST. FOR NOW...WILL CONTINUE TO TIME LIKELY POPS
EASTWARD ACROSS THE AREA LATER THIS EVENING AND OVERNIGHT. LOCALLY
HEAVY RAINFALL IS POSSIBLE WITH HIGH MOISTURE CONTENT IN THE AIR.
SMALL HAIL AND BRIEF GUSTY WINDS ARE POSSIBLE AS WELL...WITH THE
BEST SEVERE RISK TO THE SOUTHWEST OF THE AREA.

GUSTY WEST WINDS ARE EXPECTED WEDNESDAY...AS THE PRESSURE
GRADIENT TIGHTENS. THE NORTHERN COUNTIES SHOULD SEE THE HIGHEST
GUSTS...AROUND 25 TO 28 KNOTS OR SO. THE MIXING AND DRIER AIRMASS
SHOULD RESULT IN HIGHS REACHING INTO THE MID 80S ACROSS THE
AREA...PERHAPS A FEW DEGREES WARMER WITH FULL SUNSHINE IN THE
AFTERNOON.

SHORT TERM...WEDNESDAY NIGHT THROUGH FRIDAY NIGHT...FORECAST
CONFIDENCE IS HIGH.

AN OCCLUDED LOW WILL PREVAIL OVER HUDSON BAY CANADA WITH HIGH
PRESSURE FROM THE CENTRAL PLAINS INTO THE OHIO RIVER VALLEY FOR
THIS TIME PERIOD. THIS GIVES A WNWLY FLOW ALOFT AND AT THE SFC.
BREEZY WINDS AND FULL SUNSHINE IN THE AFTERNOON WILL MIX OUT THE
HIGHER DEWPOINTS MAKING FOR LOWER HUMIDITY...AND HIGH TEMPS IN THE
MID TO UPPER 80S FOR THU AND FRI. A WEAK SFC TROUGH WILL PASS FRI
AFT BUT THE MIXING WILL LIMIT THE CAPE...AND SFC CONVERGENCE WILL
BE WEAK SO WILL MAINTAIN THE DRY FORECAST FOR NOW.

LONG TERM...SATURDAY THROUGH TUESDAY...FORECAST CONFIDENCE IS
MEDIUM.

SRN WI WILL BE ON THE SRN PERIPHERY OF THE WESTERLIES FOR THIS
PERIOD. AT THE SFC...A HIGH PRESSURE RIDGE WILL MOVE ACROSS THE
REGION FOR SAT WITH A SFC TROUGH OR WEAK COLD FRONT APPROACHING
FOR SAT NT AND SUN. THUS A RETURN OF HIGH THETAE AIR IS EXPECTED
ALONG WITH CHANCES OF TSTORMS. THE FRONT MAY THEN STALL INTO MON
SO TSTORM CHANCES CONTINUE. THE AREA MAY GET A BREAK FROM TSTORM
CHANCES OF TUE BUT LOW CONFIDENCE AT THIS TIME.

AVIATION/00Z TAFS/...

BROKEN TO OVERCAST MIDDLE TO HIGH CLOUDS SHOULD LINGER ACROSS
MOST OF THE AREA INTO THE EARLY EVENING HOURS. THERE MAY BE SOME
EROSION OF THESE CLOUDS IN PARTS OF THE AREA. LIGHT/MODERATE
SOUTH/SOUTHEAST WINDS ARE EXPECTED INTO EARLY THIS
EVENING...BEFORE WEAKENING SOMEWHAT.

AN AREA OF SHOWERS AND THUNDERSTORMS ARE LIKELY WITH THE COLD
FRONTAL PASSAGE LATER TONIGHT INTO EARLY WEDNESDAY MORNING ACROSS
TAF SITES. MAY SEE MVFR VISIBILITIES AND CEILINGS AT TIMES. THERE
IS SOME UNCERTAINTY IF THESE SHOWERS AND STORMS WILL OCCUR...SO
MAY GO WITH JUST SHOWERS AND VICINITY THUNDER IN TAFS FOR NOW.
THIS WOULD BE FOR A THREE OR FOUR HOUR PERIOD LATER THIS EVENING
AND OVERNIGHT AT EACH SITE.

GUSTY WEST WINDS ARE EXPECTED WEDNESDAY BEHIND THE FRONT...WITH
FREQUENT GUSTS TO AROUND 20 KNOTS. VFR CONDITIONS ARE EXPECTED
WEDNESDAY AT ALL SITES.

MARINE...

ISSUED A SMALL CRAFT ADVISORY FOR THE NORTHERN MOST MARINE
ZONE...PORT WASHINGTON TO SHEBOYGAN...FROM LATE WEDNESDAY MORNING
INTO WEDNESDAY EVENING. GUSTY WEST WINDS ARE EXPECTED TO DEVELOP
DURING THIS TIME...WITH FREQUENT GUSTS TO 25 KNOTS. THE WINDS
SHOULD DIMINISH BY MIDDLE TO LATE WEDNESDAY EVENING. SIMILAR GUSTS
MAY OCCUR ON THURSDAY AS WELL IN THIS AREA.

THE REST OF THE NEARSHORE WATERS SHOULD SEE FREQUENT WEST GUSTS
TO 20 KNOTS WEDNESDAY AND THURSDAY. THIS AREA WILL NEED TO BE
MONITORED AS WELL FOR SMALL CRAFT ADVISORIES...GIVEN THE
BORDERLINE GUSTS EXPECTED.

&&

.MKX WATCHES/WARNINGS/ADVISORIES...
WI...NONE.
LM...SMALL CRAFT ADVISORY FROM 11 AM TO 11 PM CDT WEDNESDAY FOR
     LMZ643.

&&

$$

UPDATE...MBK


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