Area Forecast Discussion
Issued by NWS Twin Cities, MN

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000
FXUS63 KMPX 301210
AFDMPX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TWIN CITIES/CHANHASSEN MN
710 AM CDT TUE SEP 30 2014

.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 414 AM CDT TUE SEP 30 2014

HIGH PRESSURE WAS CENTERED OVER SOUTHERN ONTARIO EARLY THIS MORNING
WITH AN EXTENSIVE AREA OF STRATUS COVERING THE MUCH OF THE GREAT
LAKES AND THE UPPER MISSISSIPPI VALLEY REGION. THE HIGH WILL DRIFT
SLOWLY EAST TODAY AS A VIGOROUS LOW PRESSURE SYSTEM LIFTS THROUGH
THE NORTHERN PLAINS. THE SURFACE PRESSURE GRADIENT WILL BE
INCREASING THIS MORNING WITH WINDS BECOMING MORE SOUTHEAST WITH
TIME. THIS WILL AID IN SHREDDING OF THE STRATUS DURING THE MORNING.
HOWEVER...AS THE LOW CLOUDS GO...MID/HIGH LEVEL CLOUDINESS WILL BE
ON THE INCREASE FROM THE WEST ENDING UP IN A MOSTLY CLOUDY TO CLOUDY
DAY.

A BAND OF SHOWERS AND THUNDERSTORMS ASSOCIATED WITH THE LOW PRESSURE
SYSTEM TO OUR WEST WILL DRIVE INTO WEST CENTRAL AND SOUTHWEST MN BY
EARLY THIS AFTERNOON. THE VARIOUS CAMS ARE IN REALLY GOOD AGREEMENT
WITH THE TIMING AND LOCATION...WITH THE ACTIVITY SPREADING INTO
EASTERN MN BY THIS EVENING AND ACROSS WESTERN WI TONIGHT. AT THIS
POINT...THE TWIN CITIES SHOULD REMAIN DRY UNTIL SUNSET. THE ONE
ASPECT NOTED WITH THIS SYSTEM IS THAT DUE TO THE SHORT WAVE LIFTING
ALMOST DUE NORTH THROUGH THE NORTHERN PLAINS...THERE IS A CONTINUED
SLOWING TO THE EASTWARD PROGRESSION OF THE SHOWERS AND THUNDERSTORMS
TONIGHT. THIS MAY RESULT IN THE RAIN NOT REACHING LADYSMITH AND EAU
CLAIRE UNTIL LATE IN THE NIGHT/DAYBREAK WEDNESDAY. RAIN AMOUNTS
THROUGH TONIGHT WILL BE GREATEST OVER SOUTH CENTRAL MN WITH AMOUNTS
UP TO A HALF INCH. NO SEVERE WEATHER IS EXPECTED IN OUR FA
WITH THE STORMS.

HIGH TEMPERATURES WILL REMAIN A LITTLE BELOW NORMAL TODAY IN MOST
AREAS. THE EXCEPTION IS IN THE MN RIVER VALLEY WHERE MIDDLE TO UPPER
60S ARE FORECAST NEAR THE LOW LEVEL THERMAL RIDGE. THERE WILL BE
QUITE THE CONTRAST IN LOW TEMPERATURES TONIGHT FROM WEST TO EAST DUE
TO THE WET/DRY SCENARIO. LOWS FROM NEAR 60 IN SOUTHWEST MN TO THE
LOWER 40S NEAR LADYSMITH.

.LONG TERM...(WEDNESDAY THROUGH MONDAY)
ISSUED AT 414 AM CDT TUE SEP 30 2014

SEVERAL CHANGES WERE MADE DURING THE LONG TERM TO REFLECT CHANGES
SEEN WITH THE 30.00 MODELS...WILL SEPARATE THEM OUT INTO THE
SIGNIFICANT AND MINOR CATEGORIES. THE SIGNIFICANT CHANGES WERE MADE
TO THURSDAY AND FRIDAY. THURSDAY...POPS WERE INCREASED
SIGNIFICANTLY...ESPECIALLY EAST OF I-35...WHERE THE 30.00 GUIDANCE
IS IN GOOD AGREEMENT ON ANOTHER RAINY DAY UNFOLDING. FRIDAY CHANGES
INCLUDED CUTTING BACK ON HIGHS...SIGNIFICANTLY INCREASING CLOUD
COVER AND WIND SPEEDS...AND INCREASING/EXPANDING POPS. MORE MINOR
TWEAKS WERE NEEDED FOR WEDNESDAY AND SUNDAY. FOR WEDNESDAY...SIMPLY
INCREASED EXISTING LIKELY POPS EAST OF I-35 INTO THE CATEGORICAL
RANGE. FOR SUNDAY...EXPANDED LOW POPS TO ACCOUNT FOR THE THREAT OF
SHOWERS WITH A CLIPPER THAT WILL BE DROPPING ACROSS THE AREA THEN.

WHAT CHANGED WITH THE MODELS? THE BIGGEST THING THAT CHANGED IS THEY
ARE ALL PHASING SRN STREAM ENERGY COMING OUT OF THE CENTRAL PLAINS
AND A POWERFUL NRN STREAM WAVE COMING OUT OF CENTRAL CANADA A DAY
EARLIER. THIS HAS TAKEN THE LOW RIDING UP THE COLD FRONT ON THURSDAY
FROM HEADING FOR LAKE MICHIGAN TO GOING UP THROUGH CENTRAL WI
INSTEAD...WHICH PULLS PRECIP CHANCES QUITE A BIT WEST ON
THURSDAY...WITH A STRONG DEFORMATION BAND OF PRECIP CURRENTLY
PROGGED TO COME ACROSS SE MN AND WRN WI. ONLY CHANGES TO GUIDANCE ON
WEDNESDAY IS THAT EVERYTHING HAS COME IN LINE WITH WHAT THE ECMWF
HAS BEEN SHOWING FOR DAYS WITH A WAVE AND ASSOCIATED PRECIP WORKING
UP THE FRONT DURING THE DAY ON WEDNESDAY...IMPACTING MAINLY AREAS
ALONG/EAST OF I-35 WEDNESDAY AFTERNOON. GIVEN THE FORECAST EWRD
PROGRESSION OF THE FRONT...OR RATHER THE LACK THERE OF...IT MAKES
SENSE THAT MORE PRECIP WOULD MAKE IT INTO THE ERN HALF OF THE CWA
BOTH DAYS. THIS FRONT LOOKS TO BE JUST INTO WRN MN 12Z WED...ABOUT
100 MILES WEST OF I-35 12Z THU...WITH A SFC LOW TRACKING NORTH ALONG
THE BOUNDARY DURING THE DAY THURSDAY ACROSS CENTRAL WI BEFORE THE
FRONT GETS KICKED EAST OF THE AREA WITH GUSTO THURSDAY NIGHT.

BOTH WEDNESDAY AND THURSDAY...SEVERE CHANCES LOOK PRETTY MUCH
NON-EXISTENT...AS THE INSTABILITY HIGH ENOUGH TO CONSIDER A SEVERE
THREAT LOOKS TO REMAIN SOUTH OF MN. GIVEN THE DYNAMICS...WE WILL
HOWEVER SEE SOME HEALTHY RAINFALL AMOUNTS FOR EARLY OCTOBER FROM
THESE TWO WAVES...WHICH LOOK TO COME ABOUT 12 HOURS APART...WITH
WEDNESDAY NIGHT BEING A BIT OF A LULL. IN EACH CASE...A GOOD HALF TO
ONE INCH OF QPF LOOKS LIKELY...WITH TOTAL PRECIP EASILY GETTING UP
INTO THE 1-2 INCH RANGE EAST OF THE I-35 CORRIDOR. IN FACT...RUN
TOTAL QPFS FROM THE GFS/ECMWF/GEM ALL SHOW A SWATH OF 2-3 INCHES
GOING ACROSS WRN WI. GUESS THE MORAL OF THE STORY HERE IS EAU LOOKS
TO BUILD ON ITS YEAR-TO-DATE PRECIP SURPLUS...WHICH ALREADY SITS AT
A ROBUST 12.43 INCHES!

THURSDAY NIGHT WE AGAIN LOOK TO BRIEFLY DRY OUT AS WE GET INTO
SUBSIDENCE AND STRONG CAA IN THE WAKE OF THE FRONT...BUT PRECIP
LOOKS TO COME BACK ON FRIDAY. FOR FRIDAY...DID HAVE TO MODIFY THE
FORECAST FROM THE INITIALIZED BLEND. WITH THE CORE OF THE UPPER LOW
COMING OVERHEAD AND H85 TEMPS NOSE DIVING TO BELOW ZERO...FIRST
ORDER OF BUSINESS WAS TO UP SKY COVER AND DECREASE HIGHS. BUMPED
HIGHS DOWN INTO THE LOWER 50S...THOUGH GIVEN THE DEGREE OF
CAA...WOULD NOT BE SURPRISED IF WE DO NOT RISE MUCH ABOVE OUR LOWS
FRIDAY MORNING...WHICH WILL BE IN THE 40S. GIVEN THE STRONG PV
ANOMALY COMING IN ALSO INCREASED/EXPANDED POPS ACROSS THE ENTIRE
AREA...THOUGH IF THE ECMWF/GEM ARE RIGHT...THESE WILL NEED TO BE
UPPED SIGNIFICANTLY IN FUTURE FORECASTS. FINALLY...FRIDAY ALSO LOOKS
TO BE OUR FIRST POTENTIAL WIND ADVY DAY OF THE SEASON...WITH GFS
BUFR SOUNDINGS SHOWING MIX DOWN POTENTIAL WINDS UP TO 45 KTS. AT THE
VERY LEAST...EXPECT NW WINDS TO BE GUSTING TO BE 30 AND 40 MPH IN
OUR NORMAL WIND FAVORED AREAS...WITH SOME GUSTS GETTING UP TOWARD 45
MPH NOT OUT OF THE QUESTION.

FOR SATURDAY...WE WILL DRY OUT AS A SFC RIDGE WORKS ACROSS THE AREA.
WINDS WILL SLOWLY DIMINISH DURING THE DAY...THOUGH IT WILL BE A
CHILLY DAY...WITH LOWS STARTING OUT IN THE 30S AND HIGHS STRUGGLING
TO GET INTO THE LOW 50S...OR 10 TO 15 DEGREES BELOW NORMAL.
SUNDAY...THE ECMWF CONTINUES TO SHOW A 160 KT NWRLY JET STREAK
COMING DOWN FROM CANADA. THE LEFT EXIT REGION OF THIS JET WILL SEND
A CLIPPER DOWN ACROSS NRN MN. WE STILL LOOK TO BE IN THE WARM SECTOR
OF THE SYSTEM...THOUGH ISENTROPIC LIFT OUT AHEAD OF THE WAVE LOOKS
TO BE ENOUGH TO GENERATE SOME LIGHT SHOWERS MAINLY ALONG AND NORTH
OF THE I-94 CORRIDOR. DESPITE THE INCLUSION OF SOME LOW POPS...
SUNDAY IS STILL LOOKING LIKE A PERFECT DAY FOR THOSE RUNNING THE
TWIN CITIES MARATHON.

NEXT WEEK WE WILL SEE TEMPERATURES MODERATE AS THE WRN RIDGE
FLATTENS OUT AND WORKS EAST...WITH NO SIGNIFICANT STORM SYSTEMS
LOOKING TO BE IN THE OFFING.

&&

.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z WEDNESDAY MORNING)
ISSUED AT 710 AM CDT TUE SEP 30 2014

EXTENSIVE IFR/LOW MVFR CEILINGS COVER THE REGION WITH IFR VISIBILITIES
AROUND KAXN. ESE WINDS WILL CONTINUE TO INCREASE THIS MORNING
WHICH WILL AID IN BREAKING UP THE LOW CLOUDS WITH SITES BECOMING VFR.
THE STRONGEST SUSTAINED WINDS WILL BE FROM KAXN ON SOUTHWARD
WHERE NEAR 20 KNOT WINDS ARE EXPECTED BY LATE IN THE MORNING. A
BAND OF SHOWERS WILL ADVANCE INTO WEST CENTRAL AND SOUTHWEST MN
THIS AFTERNOON AHEAD OF A LOW PRESSURE SYSTEM MOVING NORTHWARD
ACROSS THE DAKOTAS. CONFIDENCE IS HIGHEST FOR THE SHOWERS AT
KAXN...KRWF AND KSTC. THUNDER CHANCES ARE BEST FROM KRWF ON
SOUTHWARD WITH VCTS USED. CONFIDENCE WANES ON THE SHOWERS CHANCES
EARLY IN THE NIGHT FOR THE EASTERN TAF AS THE SYSTEM BEGINS TO
SHEAR APART WITH VCSH INDICATED. ANOTHER AREA OF SHOWERS FROM A
SECOND LOW PRESSURE SYSTEM WILL SPREAD NORTHEAST ACROSS EASTERN MN
AND WESTERN WI LATE TONIGHT AND WEDNESDAY MORNING. WITH VERY MOIST
LOW LEVEL CONDITIONS ACROSS THE AREA TONIGHT...LOW MVFR/IFR
CEILINGS WILL REDEVELOP ONCE AGAIN AND LIKELY CONTINUE ON
WEDNESDAY.

KMSP...CEILINGS EXPECTED TO CLIMB ABOVE 017 BY NOON. CONFIDENCE IS
LOW ON SHOWER CHANCES THIS EVENING BUT HIGH ON SHOWERS ALONG WITH
LOW MVFR/IFR CEILINGS LATE TONIGHT AND WEDNESDAY.

/OUTLOOK FOR KMSP/

WED...IFR MRNG. MVFR AFTN. SHRA LIKELY. WINDS S-SE 10 KTS.
THU...MVFR. CHC IFR. SHRA LIKELY. WINDS NW 5-10 KTS.
FRI...MVFR. CHC -SHRA. WINDS NW 15-20 KTS WITH GUSTS 30-35 KTS.

&&

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

$$

SHORT TERM...RAH
LONG TERM...MPG
AVIATION...RAH







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