Area Forecast Discussion
Issued by NWS Twin Cities, MN

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000
FXUS63 KMPX 021713
AFDMPX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TWIN CITIES/CHANHASSEN MN
1113 AM CST TUE FEB 2 2016

.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 410 AM CST TUE FEB 2 2016

SIGNIFICANT SNOW AND WIND ON TRACK TO IMPACT EASTERN AND SOUTHERN
AREAS OF THE FA TODAY AND TONIGHT. THE CULPRIT IS A LOW PRESSURE
STORM SYSTEM OVER THE SOUTHERN PLAINS EARLY THIS MORNING. THE
SURFACE LOW WILL HEAD NORTHEAST TODAY...REACHING EASTERN IA
TONIGHT AND THE WESTERN GREAT LAKES BY WEDNESDAY MORNING.

THE LEADING EDGE OF THE SNOW WAS JUST SOUTH OF MN EARLY THIS
MORNING. A STRONG BAND OF MID LEVEL FRONTOGENESIS WILL LIFT
NORTHEAST ACROSS THE EASTERN FA DURING THE LATE MORNING AND
AFTERNOON HOURS ACCOMPANIED BY LOW LEVEL WAA AND VERY IMPRESSIVE
DIFFERENTIAL DIVERGENCE. THIS WILL RESULT IN A BAND OF HEAVY
SNOW...WITH ACCUMULATIONS OF 1-2 INCHES PER HOUR...SPREADING FROM
SOUTH CENTRAL MN BY MID MORNING ON NORTHWARD THROUGH THE TWIN
CITIES AND WESTERN WI THIS AFTERNOON. THIS BAND OF HEAVY SNOW IS
WHERE TWO-THIRDS OF OUR TOTAL SNOW ACCUMULATION COMES FROM. THE
EVENING COMMUTE WILL BE A MESS. WHILE THIS IS OCCURRING...NORTHERLY
WINDS WILL BE ON THE INCREASE...WITH SPEEDS NEAR 30 MPH SUSTAINED
ACROSS SOUTH CENTRAL MN FROM LATE MORNING ONWARD. BUFKIT PROFILE
DATA CONTINUES TO SUPPORT GUSTS TO 45 MPH DURING THE LATE
AFTERNOON AND EVENING ACROSS SOUTH CENTRAL MN. SPEEDS FARTHER
NORTH WILL BE MORE IN THE 20 TO 25 MPH ALONG WITH CONSIDERABLE
BLOWING AND DRIFTING SNOW. THE SNOW WILL BEGIN TO DIMINISH AFTER
MIDNIGHT AND LIKELY BE OVER BEFORE DAYBREAK WEDNESDAY.

THE MAIN STICKING POINT WITH THIS SYSTEM REMAINS THE SNOW RATIOS.
THERE IS QUITE A DIFFERENCE BETWEEN COBB AND THE AIR FORCE METHOD.
USED VALUES CLOSER TO CLIMATOLOGY (13:1) WHICH WAS MORE OF A
MIDDLE GROUND BETWEEN THE TWO EXTREMES. IN THE END...VERY LITTLE
CHANGE WAS NOTED TO THE OVERALL TOTAL SNOWFALL FORECAST FROM THE
DAY SHIFT . WE STILL EXPECT BETWEEN 6 AND 12 INCHES IN THE
WARNING AREAS...WITH THE HIGH END AMOUNTS FROM FAIRMONT AND ALBERT
LEA ON NORTHEAST THROUGH RED WING TO NEAR EAU CLAIRE. THE TWIN
CITIES METRO IS IN THE 6 TO 8 INCH RANGE FROM NORTHWEST TO
SOUTHEAST. DUE TO A SLIGHT SHIFT NORTHWEST WITH THE QPF
OVERNIGHT...WE DID ADD ANOKA AND POLK COUNTIES TO THE WINTER STORM
WARNING AREA. IN ADDITION...WITH MORE SNOW EXPECTED FROM WEST
CENTRAL INTO CENTRAL MN...COUNTIES FROM LAC QUI PARLE THROUGH
STEARNS TO MILLE LACS AND KANABEC WERE ADDED TO THE WINTER
WEATHER ADVISORY. ALTHOUGH SNOW IN THESE AREAS WILL BE IN THE 2 TO
4 INCH RANGE...ITS THE WIND WITH BLOWING AND DRIFTING SNOW THAT
PROMPTED THE EXPANSION WESTWARD.

IN THE TEMPERATURE DEPARTMENT...YET ANOTHER MILD DAY ON TAP WITH
HIGHS IN THE UPPER 20S TO LOWER 30S. EVEN TONIGHT...LOWS ARE WELL
ABOVE SEASONAL VALUES WITH READINGS IN THE MIDDLE TEENS TO LOWER
20S FORECAST.

.LONG TERM...(WEDNESDAY THROUGH MONDAY)
ISSUED AT 410 AM CST TUE FEB 2 2016

THE HIGHLIGHTS OF THE LONG TERM PERIOD INCLUDE TWO WEAK SHORTWAVES
MOVING THROUGH LATER THIS WEEK...ZONAL FLOW ALLOWING TEMPERATURES TO
WARM THIS WEEKEND...AND THE ARCTIC AIR INTRUSION FOR EARLY NEXT WEEK
THAT THE GUIDANCE HAS CONSISTENTLY INDICATED.

BY DAYBREAK WEDNESDAY...THE SURFACE LOW WILL BE NEAR MILWAUKEE...AND
THE SYSTEM DECAYING AS IT MOVES NORTHEAST.  CYCLONIC CIRCULATION ON
THE BACK SIDE OF THE SYSTEM WILL PRODUCE LIGHT SNOW LINGERING AS FAR
WEST AS EASTERN MN.  NOTHING MORE THAN A DUSTING TO A FEW TENTHS OF
AN INCH WOULD COME OF ANY LINGERING SNOW AT THAT POINT.  WITH THE
SYSTEM EXITING THE REGION A TAD SLOWER...THE POPS WERE PULLED BACK
TO THE WEST 30 TO 50 MILES. WITH WINDS TURNING NORTHWESTERLY AND A
FRESH SNOW COVER ACROSS SOUTHERN MN THROUGH WEST CENTRAL WI...WENT
ON THE COOL SIDE OF THE GUIDANCE FOR TEMPERATURES TOMORROW AND
TOMORROW NIGHT.  WIDESPREAD SINGLE DIGIT LOWS ARE EXPECTED BY
THURSDAY MORNING...WITH SOME SUB-ZERO LOWS POSSIBLE ESPECIALLY IN
THE AREAS THAT RECEIVE THE MOST SNOW ON TUESDAY.

THURSDAY AND THURSDAY NIGHT...THE GFS AND THE ECMWF ARE IN GOOD
AGREEMENT ON A SHORTWAVE RACING SOUTHEAST THROUGH CANADA AND BRINING
LIGHT SNOW TO OUR REGION ON THURSDAY.  A DUSTING...TO A FEW TENTHS
OF SNOW LOOKS TO BE ALL THIS WAVE WOULD PRODUCE AS IT QUICKLY MOVES
THROUGH OUR AREA.

FOR FRIDAY...A STRONGER PV ANOMALY WILL FOLLOW A SIMILAR PATH
THROUGH CANADA AND MOVE THROUGH THE UPPER MIDWEST. THERE WONT BE A
LOT OF MOISTURE TO WORK WITH...BUT THIS WAVE COULD PRODUCE AN INCH
OF SNOW ACROSS A PORTION OF THE UPPER MIDWEST...EXACTLY WHERE IS
DIFFICULT TO SAY THIS FAR OUT IN TIME. CONTINUED TO INCLUDE LOW
END POPS ACROSS THE FORECAST AREA FOR THIS WAVE ON FRIDAY THROUGH
FRIDAY NIGHT.

AS FOR THE WEEKEND...THE GFS AND ECMWF ARE IN GOOD AGREEMENT ON THE
UPPER FLOW BECOMING ZONAL WHICH WILL ALLOW TEMPERATURES TO RISE
INTO THE 30S FOR MUCH OF THE AREA...AS A LOW PRESSURE SYSTEM WORKS
ACROSS SOUTH CENTRAL CANADA...ENCOURAGING WARM AIR ADVECTION IN
THE LOW LEVELS ACROSS OUR AREA...WHICH IS WHY POPS COME BACK INTO
THE FORECAST FOR SUNDAY NIGHT INTO MONDAY MORNING.

ONCE THAT SYSTEM PASSES BY...THE UPPER PATTER QUICKLY BECOMES HIGHLY
AMPLIFIED WITH A DEEP LONGWAVE TROUGH OVERHEAD...AND STRONG
NORTHERLY FLOW...ALLOWING ARCTIC AIR TO POUR SOUTH INTO OUR REGION.
EXPECT NEXT WEEK TO BE COLDER THAN NORMAL GIVEN THE ARCTIC AIR
INTRUSION.

&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z WEDNESDAY AFTERNOON)
ISSUED AT 1115 AM CST TUE FEB 2 2016

CONFIDENCE REMAINS HIGH FOR PERIODS OF MODERATE TO HEAVY SNOWFALL
WITH RATES OF 1/2 TO 1 INCH PER HOUR OR GREATER AT TIMES ACROSS
PORTIONS OF SOUTHERN MN AND WEST CENTRAL WI THIS AFTN. THE MAIN
AIRPORTS IMPACTED ARE KRWF/KMSP/KRNH/KEAU UNTIL 00Z. INITIALLY
WINDS WILL SUSTAINED AROUND 15-20 KTS... WITH GUSTS OF 24-28 KTS
THRU 21Z... AFT 21Z WINDS WILL INCREASE WITH SUSTAINED WINDS OF
20-25 KTS ALONG WITH GUSTS OF 30-36 KTS ACROSS SOUTHERN
MN...ESPECIALLY IN SW/SC MN. CONDITIONS WILL SLOWLY IMPROVE
OVERNIGHT...WITH BLOWING SNOW CONTINUING THRU 12Z ALONG WITH IFR
VSBYS AT TIMES AT KRWF/KMSP/KRNH/KEAU.

KMSP...

HIGH CONFIDENCE ON MODERATE-HEAVY SNOWFALL DEVELOPING THIS
AFTERNOON. RATES OF 3/4 OF AN INCH PER HOUR OR HIGHER WILL OCCUR
BETWEEN 1830-20Z. CONFIDENCE IS LOWER IF THESE CONDITIONS WILL
CONTINUE THRU THE REMAINDER OF THE AFTERNOON...BUT HIGH ENOUGH
CONFIDENCE OF LIGHT TO MODERATE SNOWFALL THRU 00Z. GUSTY WINDS OF
20-24 KTS...WILL INCREASE AFT 21Z WITH GUSTS OVER 30 KTS LIKELY
DURING THE LATE AFTN AND INTO THE EARLY EVENING HOURS. CONDITIONS
WILL SLOWLY IMPROVE OVERNIGHT...BUT BLOWING SNOW WILL REMAIN A
CONCERN THRU WEDNESDAY MORNING. EXPECT CIGS TO REMAIN IN THE IFR
OR LOWER THRU THIS EVENING ONCE SNOW DEVELOPS.

/OUTLOOK FOR KMSP/

THU...MAINLY VFR. SLGT CHC MVFR/-SN. WIND SW 5-10 KTS.
FRI...MAINLY VFR. SLGT CHC MVFR/-SN. WIND S 5-10 KTS.

&&

.MPX WATCHES/WARNINGS/ADVISORIES...
WI...WINTER STORM WARNING UNTIL 6 AM CST WEDNESDAY FOR WIZ014>016-
     023>028.

MN...WINTER STORM WARNING UNTIL 6 AM CST WEDNESDAY FOR MNZ060>063-
     067>070-075>078.

     WINTER WEATHER ADVISORY UNTIL 6 AM CST WEDNESDAY FOR MNZ044-045-
     049>059-064>066.

     BLIZZARD WARNING UNTIL 6 AM CST WEDNESDAY FOR MNZ073-074-082>085-
     091>093.

&&

$$

SHORT TERM...RAH
LONG TERM...SPD
AVIATION...JLT


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