Area Forecast Discussion
Issued by NWS Twin Cities, MN

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000
FXUS63 KMPX 250357
AFDMPX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TWIN CITIES/CHANHASSEN MN
1057 PM CDT MON AUG 24 2015

.SHORT TERM...(THIS EVENING THROUGH TUESDAY)
ISSUED AT 304 PM CDT MON AUG 24 2015

QUASI-STATIONARY LOW PRESSURE SYSTEM POSITIONED JUST NORTH OF LAKE
SUPERIOR CONTINUES TO CYCLE THE CLOUD COVER SOUTHWARD THROUGH
EASTERN MINNESOTA AND ALL OF WISCONSIN...WITH THE BACK EDGE OF THE
CLOUD LINE DRAPED FROM LONG PRAIRIE...THROUGH ST CLOUD...THE WEST
SIDE OF THE TWIN CITIES...TOWARD ROCHESTER. THE SURFACE LOW WILL
VERY SLOWLY DRIFT EAST THROUGH TOMORROW. THE CLOUD DECK WILL
LIKELY REMAIN IN PLACE THROUGH THE REST OF THE AFTERNOON...AND
BEGIN PUSHING EAST THIS EVENING. THE BLUSTERY WINDS WE ARE
EXPERIENCING THIS AFTERNOON WILL NOTICEABLY WEAKEN AT ABOUT THE
SAME TIME THEY DID LAST EVENING...AROUND 7-8PM. OVERNIGHT...
TEMPERATURES FALLING INTO THE 40S ACROSS WESTERN MN ARE ONCE AGAIN
LIKELY WITH DEW POINTS ALREADY STEADY IN THE MID 40S...AND THE
SURFACE HIGH BEGINNING TO PUSH IN. FURTHER EAST...MORE CLOUD COVER
AND SLIGHTLY MORE WIND WILL KEEP TEMPERATURES JUST A COUPLE
DEGREES WARMER...BUT STILL A COOL MORNING EXPECTED AGAIN TOMORROW
NONETHELESS. THERE WILL STILL BE ENOUGH OF A PRESSURE GRADIENT TO
KEEP WIND SPEEDS AROUND 5 TO 10 MPH. WITH THE HIGH PUSHING INTO
WESTERN MN TOMORROW...THE GRADIENT WILL SLACKEN FURTHER ACROSS
WESTERN MN...SO MOST OF THE AREA CAN EXPECT WIND SPEEDS OF 10-15
MPH WITH MUCH WEAKER GUSTS THAN TODAY. TEMPERATURES WILL REMAIN
BELOW AVERAGE UNDER THE NORTHWEST FLOW REGIME...BUT MORE ABUNDANT
SUNSHINE WILL ALLOW DAYTIME HIGHS TO ECLIPSE 70 DEGREES ACROSS
SOUTHERN MN...BUT COOLER IN WESTERN WI WHERE THE CLOUD COVER MAY
REMAIN THROUGH MUCH OF THE DAY.

.LONG TERM...(TUESDAY NIGHT THROUGH MONDAY)
ISSUED AT 304 PM CDT MON AUG 24 2015

THE MAIN CONCERN IN THE LONG TERM IS A COMPACT UPPER LOW PASSING
ACROSS THE REGION IN THE THURSDAY THROUGH SATURDAY PERIOD. THE GFS
REMAINS THE NORTHERN MOST SOLUTION WITH THIS FEATURE...PASSING
IT ACROSS SD AND FAR SOUTHERN MN/IA. THE CANADIAN AND ECMWF REMAIN
ON A TRACK ACROSS NE AND IA. THE FIM MODEL SPLITS THE DIFFERENCE
BETWEEN THE FOREIGN AND DOMESTIC SOLUTIONS. ALL OF THE SOLUTIONS
WOULD HAVE SHRA/TSRA FOR US...WITH HIGH CHANCE TO LIKELY POPS FROM
LATE THURSDAY NIGHT AND FRIDAY. THE PROBLEM IS THE FACT THAT PW
VALUES ONCE AGAIN ARE PROGGED TO RISE TO THE MAX MOVING AVERAGE
FOR KMPX AT AROUND 1.8 INCHES. THIS COMPACT UPPER FEATURE HAS A
POTENT RIGHT ENTRANCE REGION WITH THE JET ALONG WITH STRONG
DIFFERENTIAL DIVERGENCE. HENCE...PRECIPITATION RUN TOTALS ARE
QUITE HEAVY WITH 3 TO 5 INCHES ACROSS PORTIONS OF EASTERN NE AND
WESTERN IA ON THE CANADIAN AND ECMWF WITH 2 TO 3 INCHES ACROSS
NORTHERN IA AND SOUTHERN MN ON THE GFS. THEREFORE...THE TRACK IS
CRITICAL. DP/DT OVER THE PAST TWO DAYS SHOWS THE ECMWF AND
CANADIAN HAVE HELD THEIR GROUND WITH THE GFS DRIFTING SOUTHWARD
WITH EACH RUN. THE CIPS ANALOGS USING THE GFS AT 84 HOURS SHOWS
THE PERCENTAGE OF THE TOP 15 ANALOGS EXCEEDING THE 48 HOUR UNIFIED
PRECIPITATION DATA SET OF GREATER THAN 1 INCH HIGHEST FROM KOMA
THROUGH KDMX. PERHAPS THE SOUTHERN SOLUTIONS WILL BE MORE CORRECT.

PRECEDING THIS PRECIPITATION EVENT WILL BE A CONTINUATION OF THE
COOL WEATHER PATTERN FOR TUESDAY NIGHT AND WEDNESDAY. A SURFACE
RIDGE AXIS WILL BE OVER US WEDNESDAY MORNING...SO LOWS IN THE 45
TO 50 DEGREE RANGE WILL BE COMMON ALONG WITH MUCH LESS WIND
DURING THE DAY.

IN THE WAKE OF THE LATE WEEK PRECIPITATION EVENT...SOUTHERLY
SURFACE WINDS COMBINED WITH INCREASING HEIGHTS ALOFT WILL BECOME
ENTRENCHED ACROSS THE REGION FOR THE WEEKEND AND NEXT MONDAY. THIS
WILL BRING A RETURN OF HIGH TEMPERATURES CLOSER TO OR EVEN ABOVE
SEASONAL LEVELS. DRY WEATHER IS FORECAST FOR THE WEEKEND AND
MONDAY AS WELL.

&&

.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z TUESDAY NIGHT)
ISSUED AT 1052 PM CDT MON AUG 24 2015

ALL SITES...EXCEPT KEAU...TO REMAIN WITHIN VFR LEVELS THROUGH THE
NEXT 24-30 HRS. MIDLVL DECKS STILL HOLDING STRONG OVER ERN MN THRU
WI AS A LARGE UPR LVL LOW N OF THE GRT LKS SLOWLY ROTATES EWD AWAY
FROM THE AREA. DECKS WILL GRADUALLY ERODE TO THE E OVERNIGHT...
ALLOWING FOR SKC CONDS THRU THE DAY TMRW. ONLY EXCEPTION IS
KEAU...WHICH PER MOS GUIDANCE AND MODEL SOUNDINGS LOOKS TO HAVE
HIGHER-RANGE MVFR CEILINGS OVERNIGHT THRU TMRW MRNG BEFORE LIFTING
TO VFR TMRW AFTN. WINDS TO REMAIN FROM THE NW THROUGH...RANGING
5-10KT OVERNIGHT THEN INCRG TO 10-20 KT TMRW BEFORE SETTLING TO
ARND 5 KT TMRW EVE.

KMSP...VFR THROUGHOUT WITH CLEARING SKIES. GUSTY NW WINDS LATE
MRNG THRU TMRW EVE BUT OTHERWISE NO SIGNIFICANT WX IMPACTS
EXPECTED.

/OUTLOOK FOR KMSP/
WED...VFR. WIND W/SW 5-10KT.
THU...VFR. WIND S AT 10-15KT.
FRI...MVFR PSBL. CHC SHRA. WINDS SE 5-10KTS.

&&

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

$$

SHORT TERM...SPD
LONG TERM...RAH
AVIATION...JPC



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