Area Forecast Discussion
Issued by NWS Twin Cities, MN

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000
FXUS63 KMPX 170955
AFDMPX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TWIN CITIES/CHANHASSEN MN
455 AM CDT WED SEP 17 2014

.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 257 AM CDT WED SEP 17 2014

NO CHGS IN THE SHORT TERM AS A WEAK BACKDOOR COLD FRONT...
CURRENTLY MOVING SOUTHWARD ACROSS SOUTH CENTRAL CANADA...WILL
MOVE INTO MN BY THIS AFTN...AND THRU MOST OF THE STATE BY THIS
EVENING. WINDS WILL SHIFT FROM THE WEST/SW...TO A MORE E/NE
DIRECTION OVERNIGHT. ALTHOUGH TEMPS WILL BE A FEW DEGREES COOLER
TONIGHT/THURSDAY...IT WILL NOT BE AS NOTICEABLE UNLESS YOU LIVE IN
WC WI WHICH HAS MORE INFLUENCE ON THIS TEMPORARY CANADIAN AIR
MASS.

.LONG TERM...(THURSDAY THROUGH TUESDAY)
ISSUED AT 257 AM CDT WED SEP 17 2014

THURSDAY THROUGH SATURDAY...THIS IS WHERE THE FOCUS IS FOR THE
EXTENDED PORTION OF THE FORECAST. SFC HIGH PRES CENTERED OVER THE
GREAT LAKES WILL SHIFT INTO ONTARIO/QUEBEC PROVINCES WHILE SFC
HIGH PRES DRIVES ESE FROM WRN CANADA TO JUST N OF THE DAKOTAS WED
NIGHT INTO THU. ALOFT...A LARGE WRN CONUS RIDGE WILL SHIFT INTO
THE CENTRAL STATES. HOWEVER...AS THIS RIDGE MOVES E...IT WILL
FLATTEN OUT OVER THE N-CENTRAL CONUS THU NIGHT INTO FRI. THE
COMBINATION OF A MORE ZONAL FLOW ALOFT ALONG WITH A MUCH MORE
MOIST RETURN FROM ON THE BACKSIDE OF THE DEPARTING HIGH... WITH A
DEEP PLUME OF MOISTURE COMING UP FROM THE GULF AHEAD OF THIS LOW
PRESSURE SYSTEM...PERIODS OF SHOWERS AND OCCASIONAL THUNDERSTORMS
ARE EXPECTED FOR THE ENTIRE CWFA MAINLY FRIDAY AFTERNOON THROUGH
SATURDAY MORNING. THERE IS STILL SOME TIMING ISSUES WITH THE
PRECIP ALONG WITH EXACT PLACEMENT...BUT THE SCENARIO SETTING UP
LOOKS TO HAVE WARM ADVECTION RAINFALL EARLY INTO MIDDAY FRIDAY
FOLLOWED BY MORE CONVECTIVE SHOWERS AND OCCASIONAL THUNDERSTORMS
FRIDAY EVENING INTO SATURDAY MORNING AHEAD OF THE COLD FRONT...
WITH SOME LINGERING POST-FRONTAL SHOWERS UNDER THE TRAILING COLD
POOL ALOFT BEHIND THE COLD FRONT. NOT LOOKING FOR VERY HEAVY
RAIN...AT LEAST WIDESPREAD...BUT ISOLATED QPF AMOUNTS IN THE ONE
HALF TO ONE INCH RANGE ARE CERTAINLY POSSIBLE WITH MORE WIDESPREAD
AMOUNTS OF ONE QUARTER TO ONE HALF INCH THROUGHOUT THIS EVENT. IN
ADDITION...THE SEVERE POTENTIAL WITH THIS SYSTEM IS RATHER LOW
SINCE PEAK HEATING DOES NOT QUITE LINE UP WITH BEST CAPE POTENTIAL
AND DEEP SHEAR. THAT BEING SAID...THE DYNAMICS OF THE SYSTEM OF
DEEP BULK SHEAR IN THE 40-50 KT RANGE AND WBZ DOWN TO 11-12 KFT
WITH MODEST LAPSE RATES MAY BE ENOUGH TO PRODUCE AN ISOLD SEVERE
WIND/HAIL TSTM. TOO EARLY TO TELL AT THIS POINT BUT IS DOES BEAR
WATCHING. THE CDFNT WILL PUSH THRU LATE MRNG INTO EARLY AFTN ON
SAT...BEING NUDGED ALONG BY A DIGGING LONGWAVE TROUGH THAT WILL
HELP INTENSIFY THE LOW PRES CENTER BY THE TIME IT REACHES THE
CENTRAL GREAT LAKES...AND AWAY FROM THE WFO MPX CWFA. CONDS
GRADUALLY IMPROVE DURG THE DAY ON SAT AS HIGH PRES APPROACHES FROM
THE W. AS FOR TEMPERATURES...A WARMING TREND WILL CERTAINLY BE
UNDERWAY WITH HIGH TEMPS EASILY ECLIPSING CLIMATOLOGICAL NORMS BY
ROUGHLY 10 DEGREES ON BOTH THE LOWS AND HIGHS FOR FRI AND SAT.

SUNDAY THROUGH TUESDAY...MUCH MORE TRANQUIL AND SEASONABLE PORTION
OF THE FCST AS HIGH PRES EXPANDING OVER THE PLAINS INTO THE UPR
MISS RIVER VALLEY WILL BE THE SCENARIO COME SUN. IN ADDITION...
FLOW ALOFT WILL BE DECIDEDLY NW...ALLOWING STABLE CAA TO PREVAIL
WHILE HIGH PRES TO THE W OF THE AREA IS REPLACED BY HIGH PRES
DEVELOPING OVER ONTARIO PROVINCE...DROPS INTO THE GREAT LAKES AND
EXPANDS WWD OVER WI AND MN. THIS WILL KEEP THE AREA COOL WITH
TEMPERATURES NEAR TO SLIGHTLY BELOW NORMAL SUN-TUE WITH PARTLY
CLOUDY SKIES PREVAILING FOR THE EARLY PART OF NEXT WEEK.

&&

.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z THURSDAY MORNING)
ISSUED AT 448 AM CDT WED SEP 17 2014

NO AVIATION CONCERNS WITH VFR CONDS THRU THE 24 HR PERIOD. WINDS
WILL BE LIGHT THIS MORNING...BECOMING N/NE THIS AFTN IN RESPONSE
OF A COLD FRONT MOVING THRU THE AREA.

KMSP...

VFR CONDS THRU THE PERIOD WITH WINDS GENERALLY S/SW UNDER 5 KTS
THIS MORNING...THEN MORE N/NNE THIS AFTN...WITH WINDS VEERING TO
THE E/ESE BY THURSDAY MORNING.

/OUTLOOK FOR KMSP/

FRI...VFR. CHC SHRA/TSRA BEFORE 9 PM. MORE NUMEROUS AFT 9 PM WITH
MVFR/IFR CIGS/VSBYS. WINDS S-SW 15-25 KT.
SAT...VFR. MORNING -SHRA POSSIBLY MVFR CIGS. WINDS NW 10-15 KT.
SUN...VFR. WINDS NW 10-15 KTS.

&&

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

$$

SHORT TERM...JLT
LONG TERM...JPC
AVIATION...JLT




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