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000
FXUS63 KMPX 050132
AFDMPX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TWIN CITIES/CHANHASSEN MN
732 PM CST WED DEC 4 2013

.SHORT TERM...(THIS EVENING THROUGH THURSDAY)
ISSUED AT 320 PM CST WED DEC 4 2013

DEEPENING LOW PRESSURE WAS LOCATED IN NORTHEAST IOWA AT MID
AFTERNOON. THE LOW WILL CONTINUE TO STRENGTHEN AS IT MOVES
NORTHEAST ACROSS WISCONSIN...LAKE SUPERIOR...AND INTO ONTARIO
OVERNIGHT. THE CC PRODUCT FROM THE KMPX DUAL POL RADAR NICELY
DEPICTED THE SNOW/MIX PRECIPITATION LINE MOVING SLOWLY EAST ACROSS
THE ST CROIX RIVER VALLEY INTO WISCONSIN EARLY THIS AFTERNOON.
850MB TEMPERATURES OVER EAU CLAIRE REMAIN VERY WARM...BUT WILL
COLLAPSE DURING THE LATE AFTERNOON WITH RAIN CHANGING TO SLEET AND
SNOW AND THEN TO ALL SNOW. SO...PORTIONS OF WEST CENTRAL WISCONSIN
WILL SEE LIMITED SNOWFALL TOTALS DUE TO THE EXPECTED LOW LEVEL
WARMTH. STILL...SLEET AND FREEZING RAIN WILL CERTAINLY HAVE AN
IMPACT ON TRAVEL CONDITIONS THERE. WIDESPREAD SNOWFALL WILL
CONTINUE LIFTING NORTH THROUGH MINNESOTA FOR THE REMAINDER OF THE
AFTERNOON AND INTO THE EVENING. THE FORECAST CARRIES LIKELY POPS
THROUGH 03Z ACROSS MUCH OF THE AREA. THE 15Z RUN OF THE HOPWRF
SUPPORTED THIS IDEA AS IT DEVELOPED A SECONDARY AREA OF SNOW
DEVELOPING AROUND 00Z NEAR THE SOUTH DAKOTA BORDER AND MOVING ENE
THROUGH 06Z ACROSS CENTRAL MN. THIS SECONDARY AREA WILL BE FIRMLY
IN THE COLD AIR THAT IS COMING...MEANING IT WILL BE MUCH LIGHTER
/WITH HIGHER SNOW TO LIQUID RATIOS/. THE CONCERN WITH THIS ROUND
OF LIGHT SNOW IS THE BLOWING SNOW AND THE POOR VISIBILITIES THAT
IT MAY CAUSE FROM WEST CENTRAL INTO SOUTH CENTRAL MINNESOTA.
THEREFORE...WITH THE POTENTIAL FOR WHITE-OUT CONDITIONS WEST AND
SOUTH...ACCUMULATING SNOW SLOWLY DIMINISHING NORTH AND MIXED
PRECIPITATION CHANGING TO ALL SNOW EAST...WILL KEEP CURRENT
HEADLINES AS THEY ARE.

THE STRONG NORTHWEST WINDS WILL USHER IN MUCH COLDER AIR INTO THE
REGION OVERNIGHT...AS TEMPERATURES IN THE 20S AND 30S THIS
AFTERNOON PLUMMET OVERNIGHT TO NEAR ZERO ACROSS WESTERN MN AND
AROUND 10 ABOVE IN WESTERN WI. WIND CHILL VALUES WILL DROP INTO
THE MINUS TEENS OVERNIGHT ACROSS THE AREA. IN ADDITION... EXPECT
TO SEE FLURRIES THURSDAY MORNING. TEMPERATURES THURSDAY REALLY
WILL NOT MODERATE AS COLD AIR ADVECTION CONTINUES ON THE BACK SIDE
OF THE EXITING LOW PRESSURE SYSTEM.

.LONG TERM...(THURSDAY NIGHT THROUGH WEDNESDAY)
ISSUED AT 320 PM CST WED DEC 4 2013

THE TWO WEATHER HIGHLIGHTS IN THE EXTENDED ARE THE COLD
TEMPERATURES/WIND CHILLS...AND THE CHANCE FOR LIGHT SNOW SUNDAY
AND MONDAY. AT THE START OF THE PERIOD...BITTERLY COLD AIR WILL
BE IN PLACE ACROSS THE REGION...BUT THE COLD ADVECTION WILL HAVE
ENDED FOR THE MOST PART. 3HR SURFACE PRESSURE RISES OFF THE NAM
ARE ON THE ORDER OF 2MB/3HR...SO WINDS WILL DECREASE OVERNIGHT TO
AROUND 10MPH. LOW TEMPERATURES WILL DROP TO NEAR -15F ACROSS
WESTERN MN...AND -5F IN EASTERN MN AND WESTERN WI. WIND CHILL
VALUES WILL BE -20 TO -30F ON FRIDAY MORNING...SO WILL LIKELY
ADDRESS THESE WITH WIND CHILL ADVISORIES ONCE THE WINTER STORM
WARNING EXPIRES THURSDAY MORNING. THE COLD AIR WILL REMAIN IN
PLACE THROUGHOUT THE PERIOD...WITH TEMPERATURES EXPECTED TO BE 20
TO 30 DEGREES BELOW THE SEASONAL AVERAGE FOR EARLY DECEMBER.

THE NEXT FEATURE OF INTEREST IS THE POTENTIAL FOR A LOW DENSITY
SNOWFALL CENTERED AROUND SUNDAY NIGHT. THE GFS/GEM/ECMWF 04.12 ALL
HAVE A SHORTWAVE MOVING SOUTHEAST OF THE REGION. DESPITE THE
4-CORNERS ORIGINATION...THE THERMAL PROFILE OF THIS WAVE WILL BE
MUCH MORE CLIPPER LIKE IN NATURE. FORECAST SOUNDINGS OFF THE GFS
SHOW LIGHT WINDS VEERING WITH HEIGHT AND A DEEP DENDRITIC ZONE.
THIS FITS THE CONCEPTUAL MODEL OF HIGH SNOW RATIOS...SO HAVE
INCREASED THE VALUES IN EXCESS OF 30:1. ALTHOUGH QPF AMOUNTS WILL
BE LIGHT...AS OF NOW COULD SEE AROUND 3 INCHES IN SOUTHEASTERN MN
AND WESTERN WI.

&&

.AVIATION...(FOR THE 00Z TAFS THROUGH 00Z THURSDAY EVENING)
ISSUED AT 652 PM CST WED DEC 4 2013

BACK EDGE OF PRONOUNCED SNOW SWATH HAS RADPILY ERODED TO THE
E...LEAVING VERY LIGHT WRAP-AROUND SNOWFALL IN THE ERN DAKOTAS
INTO NW MN AS THE REMAINING SUSTAINED AREAS OF SNOWFALL WITHIN THE
REGION. CLOSER TO THE TERMINALS...FLURRIES LOOK TO BE THE MAIN
PRECIP ISSUE...AT ANY TIME PRECIP IS ACTUALLY RECORDED...THROUGH
THE OVERNIGHT HOURS. THE OTHER ISSUE BECOMES BLOWING/DRIFTING SNOW
IN WRN MN AS STRONG WINDS DEVELOP BEHIND THE DEPARTING LOW PRES
CENTER. THIS WOULD START AFFECTING KAXN-KRWF FIRST LATE THIS
EVENING THEN SPREAD EWD OVERNIGHT. SO...ALTHOUGH THE FALLING SNOW
WILL COME TO AN END...THE BLOWING/DRIFTING MAY CONTINUE TO CAUSE
VSBY ISSUES. CIGS WILL SLOWLY IMPROVE OVERNIGHT THRU TMRW...BUT
STRONG COLD AIR ADVECTION COMBINED WITH MOISTURE WITHIN THE 1-3
KFT LAYER WILL BE ENOUGH TO MAINTAIN CIGS FOR AT LEAST HALF THE
DAY TMRW. DRIER AIR MOVES IN BY LATE TMRW...ALLOWING VFR CONDS TO
PREVAIL.

KMSP...AFTER A BRIEF BOUT OF VFR CEILINGS AT INITIALIZATION... LOW
CEILINGS HAVE RETURNED AND WILL REMAIN AROUND 1000 FT THRU
MIDNIGHT. SOME OCNL FLURRIES WILL DRIFT THRU BUT ANY SIGNIFICANT
SNOWFALL HAS COME TO AN END. THE MAIN ISSUE WILL BE
BLOWING/DRIFTING SNOW THAT MAY REDUCE VSBY FOR A PORTION OF THE
OVERNIGHT HOURS. OTHERWISE...BY THE PRE-DAWN HOURS...VSBY WILL BE
AT LEAST 6SM AND REMAIN AS SUCH THROUGH THE TAF PERIOD. STRONG W
WINDS WILL CONTINUE THRU THU EVE THEN SETTLE DOWN SLIGHTLY THU
NIGHT. CEILINGS LOOK TO RISE ABOVE THE 1700 FT LAYER DURG THE PRE-
DAWN HOURS...THEN EVENTUALLY SCATTER OUT DURG THE AFTN HOURS.

/OUTLOOK FOR KMSP/
THU NIGHT...VFR. W WIND 5-15 KT.
FRI...MVFR CIGS PSBL. W WIND 5-15 KT.
FRI NIGHT...VFR. W WIND LESS THAN 10 KT.
SAT...VFR. VARIABLE WIND 5 KT OR LESS.

&&

.MPX WATCHES/WARNINGS/ADVISORIES...
MN...WINTER WEATHER ADVISORY UNTIL 6 AM CST THURSDAY FOR MNZ069-070-
     076>078-082>085-091.

     WINTER STORM WARNING UNTIL 6 AM CST THURSDAY FOR MNZ041>045-
     047>068-073>075.

WI...WINTER WEATHER ADVISORY UNTIL 6 AM CST THURSDAY FOR WIZ024>028.

     WINTER STORM WARNING UNTIL 6 AM CST THURSDAY FOR WIZ014>016-023.

&&

$$

SHORT TERM...SPD
LONG TERM...JRB
AVIATION...JPC