Area Forecast Discussion
Issued by NWS Twin Cities, MN

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000
FXUS63 KMPX 142135
AFDMPX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TWIN CITIES/CHANHASSEN MN
335 PM CST SUN DEC 14 2014

.SHORT TERM...(THIS EVENING THROUGH MONDAY)
ISSUED AT 335 PM CST SUN DEC 14 2014

ATTENTION IN THE SHORT TERM WAS DIRECTED AT THE POTENTIAL FOR A
SIGNIFICANT ICING EVENT ON MONDAY OVER PORTIONS OF WEST CENTRAL AND
SOUTHWEST MINNESOTA. THE CULPRIT IS A COLD FRONT ALONG THE DAKOTAS/
MN BORDER LATE THIS AFTERNOON THAT WILL MOVE INTO EASTERN MN BY
DAYBREAK MONDAY ALLOWING COLDER AIR...NEAR 0 DEG C...TO FILTER
INTO WESTERN MN BY EARLY MONDAY MORNING. THIS COLDER AIR WILL BE
OVERRUN BY PRECIPITATION ASSOCIATED WITH A LOW PRESSURE SYSTEM
MOVING NORTHEAST FROM THE CENTRAL PLAINS. THE DETERMINISTIC RUNS
TODAY WERE PRETTY CONSISTENT ON PUSHING UP TO A THIRD OF AN INCH
OF QPF INTO PORTIONS OF WEST CENTRAL MN ON MONDAY...WITH MUCH OF
THIS POTENTIALLY FALLING AS FREEZING RAIN IF THE SURFACE
TEMPERATURE IS AT OR BELOW FREEZING. THERE COULD ALSO BE A
CONSIDERABLE AMOUNT OF SLEET WITH A WARM NOSE REMAINING AT OR
ABOVE 3 DEG C THROUGH THE MORNING. THE INTERESTING PART IS THAT
THE CAMS HAD MUCH MORE PRECIPITATION FARTHER NORTH AND WEST THAN
THE DETERMINISTIC (0.50-0.75 INCHES). THE REFLECTIVITY PROGS FROM
BOTH THE ARW AND NMM SHOW SWARMS OF CONVECTIVE ELEMENTS RIDING
NORTHWARD THROUGH SOUTH CENTRAL AND WEST CENTRAL MN DURING THE
MORNING AND INTO CENTRAL MN DURING THE AFTERNOON. THE PTYPE FROM
BOTH INDICATED QUITE A PERIOD OF FREEZING RAIN. THE SREF
PROBABILITIES FOR THE FREEZING RAIN WERE IN THE 60 TO 80 PERCENT
RANGE FOR WEST CENTRAL. THE NAM BUFKIT PROFILES FROM KATY AND KRWF
SHOWED THE FREEZING RAIN POTENTIAL QUITE WELL IF YOU USED THE HIGHER
QPF AMOUNTS. BY AFTERNOON...THE WINTRY MIX WILL BEGIN TO CHANGE TO
SNOW IN THE FAR WESTERN MN AND WORK EAST...BEING JUST WEST OF THE
TWIN CITIES BY EVENING. SNOW AMOUNTS UP TO 2 INCHES ARE EXPECTED
IN FAR WESTERN MN MONDAY AFTERNOON AFTER THE CHANGEOVER. THESE
COULD BE HIGHER IF THE CHANGE OCCURS EARLIER THAN FORECAST. IN
ADDITION...NORTHERLY WINDS FROM 20 TO 30 KNOTS WILL DEVELOP ON
MONDAY IN THE WAKE OF THE COLD FRONT. THE MAVMOS FOR KMOX...ONE OF
OUR WINDY SITES...SHOWS NORTH WINDS AT 32 KNOTS AT THE END OF THE
DAY. THE STRONG WINDS AND ICING COULD RESULT IN SOME POWER
OUTAGES. HENCE...WE PUSHED OUT A SMALL WINTER STORM WARNING FOR
MONDAY/MONDAY EVENING COVERING THE REDWOOD FALLS...MONTEVIDEO AND
WILLMAR AREAS WHERE THE RISK FOR SIGNIFICANT ICING IS GREATEST. WINTER
WEATHER ADVISORIES SURROUND THE WARNING AND STRETCH UP INTO
CENTRAL MN. OTHERWISE...EASTERN AREAS OF THE CWA WILL SEE
WIDESPREAD RAIN ON MONDAY WITH MORNING HIGHS IN THE UPPER 40S.

.LONG TERM...(MONDAY NIGHT THROUGH SUNDAY)
ISSUED AT 335 PM CST SUN DEC 14 2014

MAIN ITEM OF INTEREST IS THE UPPER LEVEL WAVE APPROACHING THE TX/OK
PANHANDLES. THIS SYSTEM BY ITSELF WOULD PRODUCE A MAJOR WINTER STORM
AS IT ALREADY HAS BEGUN TO TAKE ON A NEGATIVE TILT. HOWEVER...THE
FULL POTENTIAL OF THIS UPPER LEVEL PV ANOMALY WILL NOT BE REALIZED
DUE TO A NORTHERN STREAM SHORTWAVE WHICH FORECAST TO MOVE EAST
SOUTHEAST TOWARD NORTHERN MN/WI. THIS INTERACTION WILL PREVENT OUR
AFOREMENTIONED PANHANDLE HOOK FROM RAPIDLY INTENSIFYING AS IT TURNS
NORTHEAST TOWARD WI. RATHER...THE THERMAL FIELDS AND OMEGA PROFILES
WHICH WILL BE LINING UP AT THE START OF THE PERIOD MONDAY EVENING
ACTUALLY BECOME LESS FAVORABLE OVERNIGHT...THUS ENDING THE THREAT
FOR HEAVY SNOW.

ANY TIME TWO UPPER LEVEL FEATURES INTERACT IS PRESENTS A
CHALLENGE...AND THIS CASE IS NO DIFFERENT. THE WARM AIR THAT HAS
BEEN IN PLACE ACROSS THE REGION...CHARACTERIZED BY H850-700 TEMPS IN
EXCESS OF 10C...WILL LINGER ACROSS THE REGION AND MELT ANY ICE
CRYSTALS THAT FALL TRHOUGH IT...SETTING THE STAGE FOR THE FREEZING
PRECIP ACROSS WESTERN MN MENTIONED IN THE SHORT TERM PART OF THE
DISCUSSION. BY 00Z TUESDAY...THIS WARM NOSE WILL STILL BE ACROSS
EASTERN MN AND WESTERN WI...BUT FORECAST MODELS SHOW SURFACE TEMPS
ABOVE FREEZING. AS THE SYSTEM MATURES MONDAY NIGHT...THE PRECIP WILL
TRANSITION FROM RAIN TO SNOW. THEREFORE NOT ANTICIPATING FREEZING
RAIN IMPACTS ALONG AND EAST OF I-35. ONCE THE TRANSITION OCCURS FROM
RAIN TO SNOW...THE OMEGA PROFILE QUICKLY WEAKENDS AND DISSAPPEARS BY
06Z TUESDAY. THEREFORE EXPECT ACCUMULATING SNOW TO BE OVER BY THE
TUESDAY MONRING COMMUTE.

ON TUESDAY THE NORTHERN STREAM WAVE WILL STRENGTHEN CONSIDERABLY AS
IT GOES FROM 2 PV UNITS TO 4 PV UNITS ON THE 500MB SURFACE...WHILE
THE SOUTHERN STREAM STORM WEAKENS AND EVENTUALLY DISSIPATES.
HOWEVER...THE PROFILE IS DRY WITH THIS NORTHERN STREAM WAVE...SO
ADDED A FEW FLURRIES IN THE FORECAST BASED OF THE FORECAST
SOUNDINGS...BUT NOTHING MEASURABLE IS EXPECTED.

LOOKING AHEAD...THE MAIN JET WILL BE TO THE SOUTH...KEEPING THE
UPPER MIDWEST DRY WITH SEASONABLE TEMPERATURES. A FEW WEAK WAVES
COULD BRING FLURRIES/LIGHT SNOW SHOWERS...BUT OPTED FOR A DRY
FORECAST TRHOUGH THE WEEKEND.

&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z MONDAY AFTERNOON)
ISSUED AT 1140 AM CST SUN DEC 14 2014

WIDESPREAD CEILINGS UNDER 1K FORECAST FOR THE DURATION OF THE TAF
PERIOD. VISIBILITIES WILL REMAIN A HALF MILE OR LESS ACROSS
MUCH OF CENTRAL MN AND WEST CENTRAL WI. VISIBILITIES HAVE IMPROVED
TO MVFR FROM THE TWIN CITIES AND POINTS SOUTHWEST. HOWEVER...NOT
CONFIDENT THIS WILL HOLD ONCE WE HEAD INTO THE EVENING HOURS WITH
VISIBILITIES SLIPPING BACK INTO THE 3/4SM-2SM RANGE. DRIZZLE AND
LIGHT RAIN WILL BECOME MORE COMMON TONIGHT AS A LOW PRESSURE
SYSTEM AND COLD FRONT MOVE IN FROM THE DAKOTAS. PROFILE DATA
SUGGESTS SOME LIGHT FREEZING RAIN/SLEET WILL OCCUR AT KAXN MONDAY
MORNING BEFORE CHANGING OVER TO LIGHT SNOW IN THE AFTERNOON. KRWF
SHOULD STAY ALL RAIN THROUGH 18Z...BUT SIGNIFICANT FREEZING
RAIN/SNOW MAY NOT BE TOO FAR WEST OF KRWF MONDAY MORNING AND WILL
NEED TO WATCHED.

KMSP...KEPT CEILINGS UNDER 1K THROUGH THE PERIOD. ALSO BROUGHT
VISIBILITIES BACK BELOW 2SM DURING THE NIGHT. STEADY RAIN WILL
MOVE IN MONDAY MORNING AND PERSIST THROUGH THE DAY. RAIN CHANGING
TO SNOW MONDAY EVENING IN THE 00Z-02Z TIME FRAME. SNOW ACCUMULATION
AROUND 3 INCHES MONDAY NIGHT.

/OUTLOOK FOR KMSP/

TUESDAY...MVFR. CHANCE OF LIGHT SNOW. WINDS NW 10-15G20KTS.
WEDNESDAY...VFR. WINDS NW 10 KTS.
THURSDAY...VFR. WINDS W 5 KTS.

&&

.MPX WATCHES/WARNINGS/ADVISORIES...
MN...WINTER WEATHER ADVISORY FROM 6 AM MONDAY TO MIDNIGHT CST MONDAY
     NIGHT FOR MNZ041-047-048-054-055-074-082.

     DENSE FOG ADVISORY UNTIL NOON CST MONDAY FOR MNZ041>045-047>053-
     055-057>059-061-063.

     WINTER WEATHER ADVISORY FROM NOON MONDAY TO 3 AM CST TUESDAY FOR
     MNZ042-043-049-058-066-067-075.

     WINTER WEATHER ADVISORY FROM 3 PM MONDAY TO 6 AM CST TUESDAY FOR
     MNZ044-045-050>052-059-068.

     WINTER STORM WARNING FROM 6 AM MONDAY TO MIDNIGHT CST MONDAY
     NIGHT FOR MNZ056-057-064-065-073.

WI...DENSE FOG ADVISORY UNTIL NOON CST MONDAY FOR WIZ014>016-023>028.

&&

$$

SHORT TERM...RAH
LONG TERM...JRB
AVIATION...RAH






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