Area Forecast Discussion
Issued by NWS Twin Cities, MN

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FXUS63 KMPX 241822
AFDMPX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TWIN CITIES/CHANHASSEN MN
1222 PM CST TUE FEB 24 2015

.UPDATE...UPDATED FOR 18Z AVIATION DISCUSSION BELOW.

&&

.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 324 AM CST TUE FEB 24 2015

EARLY MORNING WATER VAPOR IMAGERY SHOWS THE FEATURE OF INTEREST OVER
NORTHERN MN THAT HAS THE POTENTIAL TO BRING A FEW SNOW SHOWERS TO
THE AREA LATER TODAY.

AHEAD OF THIS WAVE...TEMPERATURES HAVE ACTUALLY WARMED OVERNIGHT
WITH THE RELATED WARM FRONT BISECTING THE AREA AND ATTENDANT
SOUTHWESTERLY WINDS FOSTERING WEAK LOW LEVEL WARM AIR ADVECTION.

MODEL PREFERENCE FOR THE NEXT 12-15 HOURS /THROUGH MID AFTERNOON/ IS
THE 24.07Z HRRR...WHICH IS CORRELATING WELL WITH RADAR IMAGERY
OVERNIGHT. THIS RUN FEATURES SCATTERED LIGHT SNOW SHOWERS AND
FLURRIES TRACKING SOUTH AND EAST ACROSS CENTRAL MN/WI THIS MORNING.
DUE TO THE QUICK/SPOTTY NATURE OF THE SNOW SHOWERS...ACCUMULATIONS
SHOULD BE LIMITED TO A COUPLE TENTHS OF AN INCH OR LESS. THIS IS
WITH THE EXCEPTION OF WEST CENTRAL WI NEAR LADYSMITH/RICE
LAKE...WHERE SLIGHTLY BETTER/LONGER FORCING AND DEEPER MOISTURE
APPEAR SUFFICIENT FOR TOTALS TO AVERAGE AROUND ONE INCH.

WINDS SHIFT TO THE NORTHWEST IN THE WAKE OF THE FRONT...WITH GUSTS
TO BETWEEN 25 AND 35 KTS PERSISTING THROUGH THE DAY. CLOUDS DO
APPEAR TO SCATTER OUT AS SUBSIDENCE ENSUES BEHIND THIS FIRST
WAVE...BUT A RETURN TO CLOUDY SKIES IS EXPECTED TONIGHT AS THE NEXT
TROUGH APPROACHES FROM THE WEST. ASSOCIATED SNOW SHOWERS ARE
ANTICIPATED TO SCRAPE THE FAR SOUTHWESTERN CWA AFTER 09Z
WEDNESDAY...POSSIBLY ADVANCING AS FAR NORTH/NORTHEAST AS THE MN
RIVER VALLEY BY DAYBREAK.

.LONG TERM...(WEDNESDAY THROUGH MONDAY)
ISSUED AT 324 AM CST TUE FEB 24 2015

WHAT CONTINUES TO LOOK LIKE A CERTAINTY DURING THE EXTENDED IS
THE CONTINUATION OF WELL BELOW NORMAL TEMPERATURES. WHAT IS LOOKING
MORE UNCERTAIN IS THE POTENTIAL FOR ANY SNOW...ESPECIALLY WITH
RESPECT TO THE POTENTIAL FOR ACCUMULATING SNOW THIS WEEKEND.

DURING THE EXTENDED...THE BIGGEST CHANGE WE WILL SEE WITH THE UPPER
AIR PATTERN IS A SIGNIFICANT STRENGTHENING IN UPPER RIDGING DOWN
OVER THE BAHAMAS BY NEXT WEEKEND. BUILDING HEIGHTS DOWN THERE WILL
HELP LEAD TO MUCH HIGHER HEIGHTS BUILDING UP THE EAST COAST OF NORTH
AMERICA...WITH THE DEEP UPPER TROUGH OVER ERN CANADA GETTING PUSHED
FARTHER NW INTO THE CANADIAN ARCTIC. THIS WILL SHIFT THE PRIMARY
AXIS OF UPPER LEVEL TROUGHING FROM ITS CURRENT SE CONUS TO HUDSON
BAY ORIENTATION OVER TO A SW CONUS UP TO NORTH CENTRAL
CANADA/WESTERN HUDSON BAY ORIENTATION THIS WEEKEND. THIS PATTERN
SHIFT WILL HAVE TWO IMPACTS ON THE WEATHER HERE. FIRST THERE WILL BE
SOME MODERATION IN TEMPERATURES...BASICALLY GOING FROM DEPARTURES OF
15 TO 25 DEGREES BELOW NORMAL DURING THE WORK WEEK TO MORE 5 TO 15
DEGREES BELOW NORMAL BY THE END OF THE FORECAST PERIOD. THE OTHER
CHANGE WILL COME AS A SHIFT IN THE STORM TRACK...WHICH IS CURRENTLY
FROM THE SRN PLAINS INTO THE MID ATLANTIC. AS WE WORK INTO THE
BEGINNING OF NEXT WEEK WE WILL SEE THIS TRACK SHIFT NW...FROM THE
SRN PLAINS INTO THE GREAT LAKES. BUT IS THIS SHIFT ENOUGH TO GET
PRECIP AS FAR NW AS THE UPPER MS VALLEY? THAT IS STILL VERY MUCH
DEBATABLE.

THE LONG TERM GETS STARTED WITH A PRETTY POTENT FGEN BAND OF SNOW
MOVING INTO WRN IOWA BY 12Z WEDNESDAY. WE CONTINUE TO SEE TWO CAMPS
WITH HOW FAR NORTH THIS SNOW WILL BE...WITH THE ECMWF/CANADIAN
CONTINUING TO SHOW ABOUT AN INCH OF SNOW MAKING IT UP INTO SW AND SC
MN WHILE THE NAM/GFS ARE CONTINUING WITH THEIR MAINLY DRY SCENARIO
FOR THE ENTIRE MPX CWA. GIVEN THE AMOUNT OF DRY ADVECTION WE WILL BE
SEEING WITH THE NRLY LOW LEVEL WINDS TONIGHT THROUGH WEDNESDAY...
CONTINUED TO FAVOR THE DRIER SOLUTIONS WITH RESPECT TO PRECIP IN THE
MPX AREA. BECAUSE OF THAT...DID NOT CHANGE MUCH WITH POPS ON
WEDNESDAY...WITH SOME 30S/40S SW OF THE UPPER MN RIVER VALLEY THEN
DOWN ALONG THE I-90 CORRIDOR WEST OF ALBERT LEA.

FEW CHANGES WERE NEEDED FOR THURSDAY AND FRIDAY AS WE HAVE A 1040MB
HIGH SLIDE FROM THE DAKOTAS INTO IOWA. STILL LOOKS GOOD FOR HIGHS
IN THE SINGLE DIGITS ABOVE ZERO ON THURSDAY...OR 25 TO 30 DEGREES
BELOW NORMAL. IN ADDITION...WE STILL HAVE OUR WEST CENTRAL MN
COUNTIES SEEING WIND CHILLS BETWEEN 25 AND 30 DEGREES BELOW ZERO
WEDNESDAY NIGHT INTO THURSDAY MORNING. FORTUNATELY...AFTER THAT THE
RELAXING OF THE GRADIENT THURSDAY THROUGH FRIDAY NIGHT LOOKS TO KEEP
APPARENT TEMPS WARMER THAN THE -25 WIND CHILL ADVY THRESHOLD.

AS FOR THE WEEKEND...THE MODELS ARE DOING EXACTLY WHAT WE EXPECT
THEM TO DO WITH A SYSTEM THAT INVOLVES THE PHASING OF SRN STREAM
ENERGY WITH THE NRN STREAM THIS FAR OUT...CHANGING. SINCE LAST
NIGHT...THE BIGGEST SHIFT SEEN IN THE GUIDANCE IS A SOUTHEASTWARD
SHIFT...ESPECIALLY WITH THE ECMWF...WHICH HAS JOINED THE GFS AND
CANADIAN IN KEEPING JUST ABOUT ALL OF THE PRECIP SE OF THE MPX CWA
THIS WEEKEND. RIGHT NOW...OUR BEST SHOT AT PRECIP LOOKS TO COME
SAT/SAT NIGHT OUT AHEAD OF A COLD FRONT. AFTER THAT...THE PRECIP
WITH THE SRN STREAM WAVE ON SUNDAY INTO MONDAY LOOKS TO PASS SAFELY
SE OF THE MPX AREA. FOR THE WEEKEND...STAYED CLOSE TO A BLENDED
FORECAST /WHICH INCLUDES SOME WEIGHT FROM THE PREVIOUS FORECAST/...
WHICH KEPT CHANCE POPS GOING FOR THE ERN HALF OF THE AREA SAT
NIGHT/SUN...BUT REDUCED THEM BY 10-20 PERCENT.

&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z WEDNESDAY AFTERNOON)
ISSUED AT 1212 PM CST TUE FEB 24 2015

A WARM FRONTAL BOUNDARY PUSHED THROUGH THIS MORNING...AND WAS
REALLY MORE OF A MOISTURE BOUNDARY. SKIES CLEARED BEHIND IT AND
SURFACE DEW POINT TEMEPRATURES FELL FROM THE 20S TO THE SINGLE
DIGITS VERY QUICKLY. THE VFR TREND WILL CONTINUE THROUGH THE
REMAINDER OF THE DAY. A COLD FRONT ANALYZED THROUGH CENTRAL MN
WILL PUSH THROUGH THE FA THROUGH THIS AFTERNOON. CURRENT STRONG NW
WINDS WHICH ARE GUSTING OVER 30 KTS WILL CONTINUE UNTIL NEAR
SUNSET...AND TEMPERATURES WILL DECREASE QUICKLY BEHIND THE
FRONT THIS AFTERNOON ACROSS CENTRAL MN AND PROGRESSIVELY LATER TO
THE SOUTH. FOCUS SHIFTS TO A WAVE EXPECTED TO PRODCUE SNOW IN
SOUTHERN MN VERY LATE TONIGHT THROUGH TOMORROW. THE HEAVIEST
PRECIP FROM THIS WAVE WILL REMAIN SOUTH OF MN BUT 1-2" OF SNOW IS
A POSSIBILITY IN EXTREME SOUTHERN MN. NONE WILL FALL IN CENTRAL MN
OR WEST CENTRAL WI.

KMSP...THE WAVE FOR TOMORROW HAS SHIFTED SLIGHTLY NORTHEAST...BUT
MSP LOOKS TO BE ON THE EDGE OF THE PRECIP SHIELD AT THIS TIME.
SO...LEFT -SN OUT OF THE TAF DUE TO LOW CONFIDENCE IN IT REACHING
MSP. LATER SHIFTS WILL CONTINUE TO EVALUATE THIS TREND. AT THIS
TIME...THE EDGE OF THE PRECIP LOOKS TO BE WITHIN ONE COUNTY OF
HENNEPIN TO THE SOUTH.

/OUTLOOK FOR KMSP/
THU...VFR. WINDS NW 5-10 KTS.
FRI...VFR. WINDS WSW 5 KTS.
SAT...VFR. WINDS S 12-15G18 KTS.

&&

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

$$

SHORT TERM...LS
LONG TERM...MPG
AVIATION...SPD



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