Area Forecast Discussion
Issued by NWS Twin Cities, MN

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000
FXUS63 KMPX 021023
AFDMPX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TWIN CITIES/CHANHASSEN MN
523 AM CDT WED SEP 2 2015

.UPDATED FOR 12Z AVIATION DISCUSSION...
ISSUED AT 517 AM CDT WED SEP 2 2015

&&

.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 335 AM CDT WED SEP 2 2015

THE COMBINATION OF AN UPPER LEVEL SHORTWAVE TOGETHER WITH A
SEASONABLY MOIST AIRMASS AND 2000 J/KG OF MUCAPE RESULTED IN AN
AREA OF SHOWERS AND THUNDERSTORMS ACROSS SOUTHERN MN THIS
MORNING. 15 MINUTE RAINFALL RATES EQUATED OUT TO AROUND 4 INCHES
PER HOUR UNDER THE HEAVIEST CORES...AND FLASH 3HR PRECIP RETURN
PERIODS WERE 50 TO 100YRS ACROSS WESTERN MN. FORTUNATELY THE
SYSTEM HAS PICKED UP A BIT OF SPEED SO NOT ANTICIPATING ANY HYDRO
PROBLEMS.

THE HIRES MODELS ALL ARE IN AGREEMENT WITH WEAKENING THE SYSTEM
THROUGHOUT THE DAY. THE HRRR/DEVHRRR ARE DOING THE BEST IN TERMS OF
TIMING...SO TRENDED THIS MORNINGS POPS TOWARD THOSE SOLUTIONS.
GIVEN THAT LINE OF THINKING...ALTHOUGH THE TIMING WAS SPED UP
FROM THE PREVIOUS FORECAST...MAY HAVE TO SHIFT POPS NORTHEAST EVEN
QUICKER AND DRY THE REGION BEHIND THIS MORNINGS PRECIP. TODAY WILL
BE ANOTHER MUGGY DAY WITH THE SAME AIRMASS IN PLACE. DEWPOINTS
WILL ONCE AGAIN HOOVER AROUND 70 DEG...AND AFTERNOON HIGHS WILL BE
IN THE 80S FOR MOST LOCATIONS. TONIGHT MAY HAVE TO INTRODUCE FOG
INTO THE FORECAST IF THE SURFACE WINDS DECOUPLE MORE THAN
CURRENTLY FORECAST.

.LONG TERM...(THURSDAY THROUGH TUESDAY)
ISSUED AT 335 AM CDT WED SEP 2 2015

THU-FRI...A SHARP TROUGH/RIDGE PATTERN WILL DEVELOP THU INTO THU
NIGHT OVER THE WRN-CENTRAL CONUS WHICH WILL PREVENT ANY SENSIBLE
WX SYSTEMS FROM IMPACTING THE UPR MISS RIVER VALLEY REGION...
KEEPING RAINFALL OVER THE ACTIVE PAC NW AND NRN ROCKIES ALONG WITH
THE 4-CORNERS REGION. FOR THE MID-UPR MISS RIVER VALLEY...INCRG H5
HEIGHTS ALONG WITH A PROLONGED DEEP PLUME OF MOISTURE FROM THE
GOMEX WILL SPELL WARM/HUMID CONDITIONS FOR THE END OF THE WORKWEEK
AS HIGHS INCRS TO THE UPR 80S TO ARND 90 AND HEAT INDEX VALUES
CLIMB THROUGH THE 90S.

SAT-SUN...THE UPR RIDGE WILL SHIFT E INTO THE GREAT LAKES/OHIO
VALLEY/MID-ATLANTIC REGIONS WHILE A CUTOFF LOW SWINGS INTO THE
NRN CALIFORNIA COAST. WITH ALL LARGE-SCALE FEATURES SHIFTING
EWD...THIS PUTS A TRANSITIONAL MERIDIONAL FLOW OVER THE CENTRAL
CONUS...OPENING THE DOOR TO A PERIOD OF ACTIVE WEATHER FOR THE
WEEKEND. THE CUTOFF LOW WILL HOLD ITS FORM AND JUMP OVER THE NRN
INTERMOUNTAIN REGION AND NRN ROCKIES TO THE NRN PLAINS SAT THRU
SUN...HELPING AID CYCLOGENESIS IN ADVANCE OF ITS PATH. WITH A
DEVELOPING LOW PRES SYSTEM...DEEP SWLY FLOW...PLENTY OF MOISTURE
AND SUPPORT FROM ALOFT...PERIODS OF SHWRS/TSTMS CAN BE EXPECTED
FROM EARLY SATURDAY THRU SUN NIGHT. NOT LOOKING FOR MUCH...IF
ANYTHING...IN THE WAY OF SEVERE WX AS PARAMETERS ARE NOT FAVORABLE
FOR SUCH. HOWEVER...PWATS APPROACHING 2 INCHES WITHIN AN ATMOS
CAPABLE OF PROMOTING HIGH PRECIP EFFICIENCY MAY WELL MAKE FOR
PERIODS OF HEAVY RAIN AND LOCALIZED FLOODING. AS FOR TEMPS...
WARM/HUMID CONDITIONS WILL REMAIN IN PLACE WITH HIGHS STILL IN THE
80S AND HEAT INDEX VALUES INTO THE 90S.

MON-TUE...A MORE VERTICALLY STACKED LOW PRES CENTER FROM BOTH THE
AFOREMENTIONED CUTOFF UPR LOW AND DEVELOPING SFC LOW WILL LOCATE
ITSELF OVER SRN MANITOBA PROVINCE BY MIDDAY MON...WITH ITS
TRAILING CDFNT HAVING BEEN PUSHED THRU THE AREA. THIS WILL ALLOW A
MORE WNW-ESE FLOW ALOFT TO DEVELOP...BRINGING IN COOLER AND MORE
STABLE AIR TO THE REGION WITH SFC HIGH PRES. COOLER/DRIER AIR WILL
THEN TAKE UP RESIDENCE OVER THE AREA FOR THE EARLY PART OF NEXT
WEEK WITH LITTLE TO NO CHANCES FOR PRECIPITATION. HIGHS WILL DROP
BACK INTO THE 70S WITH LOWS IN THE 50S.

&&

.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z THURSDAY MORNING)
ISSUED AT 517 AM CDT WED SEP 2 2015

VFR CONDITIONS TODAY AT THE MINNESOTA SITES...WITH SOME LINGERING
MVFR POSSIBLE AT THE WISCONSIN SITES. PRECIP WILL SHIFT EAST
TODAY...WITH AFTERNOON REDEVELOPMENT POSSIBLE AT KEAU. TONIGHT
WINDS WILL DECREASE...SO THE POTENTIAL IS THERE FOR FOG
DEVELOPMENT AFTER MIDNIGHT.

KMSP...
AREA OF RAIN SHOULD BE OUT THE DOOR BY 12Z...WITH VFR CONDITIONS
THROUGHOUT. NOT ANTICIPATING REDEVELOPMENT THIS AFTERNOON...AND
ALSO NOT EXPECTING FOG TO CAUSE RESTRICTIONS THURSDAY MORNING AT
KMSP.

/OUTLOOK FOR KMSP/
FRI...VFR. WIND S AT 10G20KT.
SAT...VFR WITH MVFR AND SHRA/TSRA POSSIBLE. WIND S AT 10G20KT.
SUN...VFR WITH MVFR/IFR TSRA POSSIBLE EARLY. WIND S AT 15G20KT.

&&

.MPX WATCHES/WARNINGS/ADVISORIES...
MN...NONE.
WI...NONE.
&&

$$

SHORT TERM...JRB
LONG TERM...JPC
AVIATION...JRB


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