Area Forecast Discussion
Issued by NWS Twin Cities, MN

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000
FXUS63 KMPX 211155
AFDMPX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TWIN CITIES/CHANHASSEN MN
655 AM CDT TUE OCT 21 2014

.UPDATE...
ISSUED AT 631 AM CDT TUE OCT 21 2014

UPDATED TO INCLUDE 12Z AVIATION DISCUSSION BELOW.

&&

.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 319 AM CDT TUE OCT 21 2014

TODAY-TONIGHT...SFC ANALYSIS SHOWS AN ELONGATED N-S ORIENTED AREA
OF HIGH PRES ATOP THE AREA WHICH WILL SHIFT OFF TO THE E DURING
THE DAY TODAY...THEN STALL OUT OVER THE GREAT LAKES TONIGHT.
ALOFT...A RIDGE OF HIGH PRES STRADDLING THE BORDER OF MN AND
WESTERN DAKOTAS THIS MORNING WILL SLOWLY SLIDE E ACROSS MN AND WI
DURING THE DAY TODAY...ALSO EXPECTED TO STALL OUT TONIGHT OVER THE
WESTERN GREAT LAKES SOUTHWARD THROUGH THE MID MISSISSIPPI RIVER
VALLEY. THIS DEEP RIDGING COMBINATION WILL KEEP SKIES MOSTLY CLEAR
FOR THE PERIOD THROUGH TONIGHT...ASIDE FROM SOME WRAPAROUND
MOISTURE FROM A DEPARTING UPPER LEVEL LOW PRES CENTER OVER THE
EASTERN GREAT LAKES...BRINGING STRATOCU DOWN OVER MAINLY EASTERN
AND NORTHERN WI...POSSIBLY AS FAR W AS BARRON/RUSK/CHIPPEWA
COUNTIES IN WESTERN WI. THIS CLOUD COVER MAY LINGER FOR MUCH OF
THE DAY IN THE FAR EASTERN PORTION OF THE MPX CWFA WHILE FAIR
WEATHER CU CLOUDS DEVELOP OVER EASTERN INTO CENTRAL MN. COLD AIR
ADVECTION IN ADVANCE OF THE INCOMING RIDGE WILL KEEP HIGHS IN THE
LOW-MID 50S FOR WESTERN WI. IN CONTRAST TO THIS...MODEST WARM AIR
ADVECTION WILL OCCUR FOR CENTRAL-WESTERN MN ON THE BACKSIDE OF THE
UPPER RIDGE WHERE HIGHS WILL RANGE THROUGH THE 60S...AND POSSIBLY
TO NEAR 70 ALONG THE SD BORDER. FOR TONIGHT...THE BEST RADIATIONAL
COOLING CONDITIONS WILL BE OVER WESTERN WI WHERE LOWS WILL DROP TO
NEAR THE FREEZING MARK. THE SPREAD IN LOWS TO CENTRAL-WESTERN MN
WILL BE QUITE LARGE AS WARMER RETURN FLOW WILL HAVE MUCH MORE
INFLUENCE OUT WEST. LOWS TONIGHT IN WESTERN MN WILL ONLY DROP TO
THE MID-UPPER 40S.

.LONG TERM...(WEDNESDAY THROUGH MONDAY)
ISSUED AT 319 AM CDT TUE OCT 21 2014

EARLY MORNING WATER VAPOR IMAGERY SHOWED A PROMINENT CIRCULATION
MOVING EAST ACROSS NORTHERN CALIFORNIA INTO NEVADA. THIS
CIRCULATION IS IN ASSOCIATION WITH AN UPPER LEVEL SHORTWAVE THAT
IS THE MAIN CONCERN FOR THE LONG TERM FORECAST PERIOD. THIS WAVE
IS EXPECTED TO MOVE ENE ACROSS THE WESTERN CONUS AND PRODUCE RAIN
ACROSS THE FA FROM WEDNESDAY THROUGH THURSDAY THAT WILL MOVE WEST
TO EAST ACROSS THE AREA. THERE REMAIN MODEL DIFFERENCES IN TIMING
AND AMOUNTS EXPECTED THAT STILL NEED TO BE SORTED OUT. THE GFS
MOVES THE ENERGY THROUGH THE FASTEST...WHILE THE NAM IS SEVERAL
HOURS SLOWER WITH THE EXPANSION OF ISENTROPIC ASCENT AND
SATURATION ACROSS THE FA. RAINFALL AMOUNTS GENERALLY LOOK TO BE
LESS THAN 0.5".  OVERALL...FORECASTER CONFIDENCE IS BELOW AVERAGE
AT THIS TIME DUE TO THESE DIFFERENCES.

ONCE THIS SYSTEM PASSES...UPPER LEVEL RIDGING WILL ENSUE ACROSS
THE UPPER MIDWEST. LITTLE CHANGE WAS MADE TO THE FORECAST BEYOND
FRIDAY...AS WARM AND DRY CONDITIONS STILL LOOK LIKE A GOOD BET.
WENT WARMER THAN BLENDED GUIDANCE ON FRIDAY AND SUNDAY AS
TEMPERATURES WARM UNDER THE RIDGE. ECMWF AND GFS STILL INDICATE
CYCLOGENESIS ON THE LEE OF THE ROCKIES TOWARD THE END OF THE
WEEKEND WITH SPATIAL AND TEMPORAL DIFFERENCES IN THE EVOLUTION OF
THE SYSTEM. THIS SYSTEM GIVES US OUR NEXT OPPORTUNITY AT
PRECIP...MOST LIKELY AT THE VERY END OF THE WEEKEND INTO EARLY
NEXT WEEK.

&&

.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z WEDNESDAY MORNING)
ISSUED AT 631 AM CDT TUE OCT 21 2014

ASIDE FROM SOME PATCHY GROUND FOG IN WRN WI...AFFECTING MAINLY
KRNH...ALL SITES INITIALIZE AS VFR TDA. HIGH PRES WILL SHIFT OFF
TO THE E...ALLOWING SELY WINDS TO PICK UP AT ALL SITES. A TIGHTER
PRES GRADIENT OVER WRN MN WILL MAKE FOR STRONGER WIND SPEEDS AT
KAXN-KRWF-KSTC SITES...WITH LESSER SPEEDS GOING INTO ERN MN AND
WRN WI. SPEEDS EVENTUALLY ALL SETTLE DOWN TO SE ARND 10 KT THIS
EVE INTO EARLY WED MRNG. NOT MUCH TO SPEAK OF FOR CLOUD COVER...
MAINLY SOME MIDLVL DISSIPATING STRATOCU OVER CENTRAL-WRN WI THIS
MRNG INTO EARLY AFTN THEN HIGH CI CLOUDS MOVING IN FROM THE
DAKOTAS TNGT THRU TMRW.

KMSP...VFR THROUGH THIS TAF PERIOD. E WINDS SLOWLY VEER TO SE TDA
AND TO SSE BY TMRW MRNG WITH SPEEDS ARND 10 KT.

/OUTLOOK FOR KMSP/
WED...VFR. WINDS SSE AT 15G20KTS.
WED NGT...VFR WITH MVFR/SHRA POSSIBLE. WINDS S AT 10KTS.
THU...VFR WITH MVFR/SHRA POSSIBLE. WINDS SSW AT 8KTS.
FRI...VFR. WINDS SSW 5KTS.

&&

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

$$

UPDATE...JPC
SHORT TERM...JPC
LONG TERM...SPD
AVIATION...JPC






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