Area Forecast Discussion
Issued by NWS Milwaukee/Sullivan, WI

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FXUS63 KMKX 020817
AFDMKX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MILWAUKEE/SULLIVAN WI
317 AM CDT WED SEP 2 2015

.SHORT TERM...

CONVECTION UPSTREAM ACROSS MN SOUTH INTO IOWA ASSOCIATED WITH A LONG
ADVERTISED MID LEVEL SHORT WAVE FORECAST TO PUSH EAST VERY SLOWLY
OVER THE NEXT 24 HOURS. IT WILL LIKELY JUST BE EXITING EASTERN
WISCONSIN AROUND 12Z THU MORNING. A MODERATE LOW LEVEL JET IS
CURRENTLY BRINGING DECENT THETA-E/MOISTURE ADVECTION IN THE 850-
700MB LAYER. THE MODELS HANDLE THE PROGRESSION OF THE ENTIRE SYSTEM
QUITE DIFFERENTLY.  INTERESTINGLY...MOST OF THE HI RES MODELS...
NMM/ARW/HRRR...KEEP THE BULK OF THE CONVECTION NORTH OF THE CWA
THROUGH THE AFTERNOON AND INTO THE EVENING.  THE NAM/GFS/ECMWF...ARE
MUCH MORE BULLISH IN ALLOWING THE CONVECTION TO EVENTUALLY TURN
SOUTHEAST AND PUSH ACROSS MAINLY THE NORTHEAST HALF OF THE FORECAST
AREA. THIS OCCURS ALREADY BY THIS AFTERNOON.  AS SPC MENTIONS IN
THEIR DAY ONE OUTLOOK...WHICH HAS A MARGINAL RISK ACROSS OUR
NORTH...THE OVERALL PATTERN IS...AND I PARAPHRASE WITH A NON-
WORD...MEH. THE SURFACE FEATURES A WEAK...NONDESCRIPT PATTERN AND
THE LOW LEVEL JET WEAKENS WITH TIME. THE MID LEVEL SHORT WAVE
REMAINS THE MAIN DRIVER ALONG WITH AMPLE MOISTURE IN PLACE.  THIS IS
A SITUATION WHERE THE CONVECTION WILL DRIVE THE PATTERN...NOT THE
OTHER WAY AROUND. SO...WOULD EXPECT THE CONVECTIVE COMPLEX TO
CONTINUE TO PUSH INTO NORTHERN/CENTRAL WISCONSIN...THEN TURN
SOUTHEAST WITH TIME DUE TO COLD POOL INFLUENCES.  THIS PUTS OUR NRN
FORECAST AREA UNDER THE HIGHEST POPS LATER THIS AFTERNOON AND
TONIGHT. IF THE CONVECTION IS ROBUST ENOUGH...WE COULD SEE SOME
STRONG/SEVERE WIND GUSTS.  THE AREAS SOUTHWEST OF MADISON COULD MISS
OUT ENTIRELY ON THIS EVENT.

TEMPS ARE TRICKY TODAY AND MAINLY DUE TO THE THREAT OF CLOUD COVER
FROM THE CONVECTION. 925MB TEMPS ARE STILL IN THE MID 20S CELSIUS
RANGE AND WITH FULL SUNSHINE...WE/D HAVE HOT TEMPS LIKE YESTERDAY.
BUT...WILL BACK OFF SLIGHTLY GIVEN THE HIGH/MID LEVEL CLOUDS LIKELY
TO START SPILLING IN HERE LATER THIS MORNING AND AFTERNOON.

.LONG TERM...

THURSDAY THROUGH SATURDAY... FORECAST CONFIDENCE MEDIUM.

THE SHORTWAVE DRIFTING ACROSS THE TOP OF THE EXTENSIVE RIDGE OVER
THE CENTER OF THE COUNTRY IS EXPECTED TO STALL OVER LAKE MICHIGAN ON
THURSDAY AND MIGHT EVEN RETROGRADE BACK INTO WI THU NIGHT. ANY
CONVECTION FROM WEDNESDAY NIGHT MAY LAY OUT A COLD POOL. MODELS ARE
HINTING AT A SITUATION WHERE NEW CONVECTION DEVELOPS ALONG THE COLD
POOL BOUNDARY SOMEWHERE IN CENTRAL/EASTERN WI. THE GFS IS MOST
BULLISH WITH THU NIGHT WHILE OTHER MODELS ARE DRIER. GIVEN A MOIST
ATMOSPHERE WITH PRECIPITABLE WATER VALUES UP TO 1.7 AND DECENT
ELEVATED CAPE... ANY SORT OF WEAK FORCING SUCH AS THE COLD POOL
BOUNDARY OR RETROGRADING SHORTWAVE COULD PRODUCE A FEW
SHOWERS/THUNDERSTORMS. THUS... KEPT THE SLIGHT CHANCE POPS GOING
THROUGH MUCH OF THIS PERIOD.

925MB TEMPS WILL CONTINUE TO BE IN THE 23-25C RANGE... WARMEST
TOWARD WESTERN WI. CLOUDS WILL BE A FACTOR WITH THE MAX TEMPS... BUT
WENT WITH HIGHS AROUND 80 NEAR THE LAKE AND UPPER 80S WELL INLAND.

SUNDAY THROUGH WEDNESDAY... FORECAST CONFIDENCE MEDIUM.

A STRONG UPPER LOW WILL EJECT OUT OF THE PACIFIC NORTHWEST AND
TEMPORARILY BREAK DOWN THE RIDGE OVER THE UPPER MIDWEST EARLY NEXT
WEEK. THIS WILL BRING SHOWER AND THUNDERSTORM CHANCES BACK TO
SOUTHERN WI MAINLY SUNDAY NIGHT INTO MONDAY WITH A WEAK COLD FRONT.

MODELS DIVERGE LATE IN THE PERIOD SO LOW CONFIDENCE BEYOND TUESDAY.
THE GFS STALLS THE FRONT NEAR THE WI/IL BORDER AND THEN DROPS IT
SOUTH ON WEDNESDAY. THE ECMWF MOVES THE FRONT DOWN THROUGH IL
ALREADY ON TUESDAY BUT THEN BRINGS ANOTHER WET SYSTEM THROUGH THE
UPPER MIDWEST ON WEDNESDAY.

&&

.AVIATION/12Z TAFS/...

SOME EARLY MORNING FOG COULD BRING REDUCED VISIBILITIES...BUT THIS
WILL LIKELY BE GONE BY 13Z THIS MORNING. THEN LOOK FOR MAINLY VFR
CONDITIONS THROUGH THE TAF PERIOD.  THERE IS A CHANCE OF SHOWERS AND
THUNDERSTORMS MAINLY TONIGHT.  BRIEF MVFR CONDITIONS ARE ALWAYS
POSSIBLE WITHIN THIS ACTIVITY. THE STRONGEST ACTIVITY SHOULD STAY
NORTH OF THE TAF SITES.

&&

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

$$

TODAY/TONIGHT AND AVIATION/MARINE...DAVIS
THURSDAY THROUGH TUESDAY...MRC



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