Area Forecast Discussion
Issued by NWS Twin Cities, MN

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FXUS63 KMPX 152214
AFDMPX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TWIN CITIES/CHANHASSEN MN
514 PM CDT TUE APR 15 2014

.UPDATE...
ISSUED AT 514 PM CDT TUE APR 15 2014

ISSUED A WINTER WEATHER ADVISORY JUST TO THE WEST AND SOUTH OF THE
WINTER STORM WARNING AREA FOR LATE TONIGHT THROUGH WEDNESDAY
NIGHT. VARIOUS WRF SOLUTIONS SUPPORT MODERATE AREAS OF SNOW
ON THE PERIPHERY OF THE WARNING AREA LATE TONIGHT INTO WEDNESDAY
NIGHT...WHICH WAS ALREADY IN PLACE FROM THE DAY SHIFT. CONFIDENCE
IS HIGHEST ON AMOUNTS REACHING 4 TO 6 INCHES IN STEVENS...POPE...DOUGLAS
AND STEARNS COUNTIES WHERE LITTLE TO NO RAIN IS EXPECTED ON
WEDNESDAY. IT BECOMES MORE PROBLEMATIC ON SNOW AMOUNTS THE FARTHER
EAST YOU GO...ESPECIALLY ACROSS THE NORTH METRO AND INTO WEST
CENTRAL WISCONSIN ALONG HIGHWAY 64. THE THINKING WAS THAT THERE
COULD BE SEVERAL INCHES OF SNOW FALL QUICKLY IN THESE AREAS
WEDNESDAY MORNING BEFORE A MIX OR CHANGEOVER TO RAIN OCCURS...WITH A
CHANGE BACK TO ALL SNOW LATE IN THE DAY WITH MORE ACCUMULATION
LIKELY. THIS COULD IMPACT BOTH THE MORNING AND EVENING RUSH HOUR.
A FINAL CONCERN IS THAT CHIPPEWA COUNTY WI MAY APPROACH OR EXCEED
WARNING CRITERIA LATE WEDNESDAY MORNING AND IT MAY MAY NEED AN
UPGRADE TO A WARNING.

&&

.SHORT TERM...(THIS EVENING THROUGH WEDNESDAY NIGHT)
ISSUED AT 232 PM CDT TUE APR 15 2014

FOCUS IS ON THE SHORTWAVE TROUGH TRACKING FROM THE PACIFIC
NORTHWEST ACROSS THE NORTHERN ROCKIES ON AFTERNOON WATER VAPOR
IMAGERY. A HEALTHY LOW LEVEL JET WILL KICK IN OVERNIGHT AHEAD OF SAID
FEATURE...WITH WARM AIR ADVECTION PROCESSES ENSUING LOCALLY AFTER
06Z WEDNESDAY. EXPECT A BAND OF SNOW TO EXPAND WEST TO EAST ACROSS
CENTRAL MN INTO WEST CENTRAL WISCONSIN BETWEEN 06Z AND 12Z.
SOUTHERN SITES /SOUTH OF INTERSTATE 94/ COULD ESCAPE THIS PRIMARY
BAND OVERNIGHT...BUT A MORE WIDESPREAD/FORMIDABLE AREA OF PRECIP
WILL OVERSPREAD THE AREA DURING THE LATE MORNING AND AFTERNOON
HOURS ON WEDNESDAY. PRECIP TYPE IS CERTAINLY CHALLENGING WITH THIS
EVENT...BUT CONFIDENCE IS FAIRLY HIGH THAT THE PRIMARY FORM OF
PRECIP IN NORTHERN AREAS /LONG PRAIRIE TO CAMBRIDGE MN AND ALONG
AND NORTH OF HWY 8 IN WI/ WILL BE SNOW. ALL OF THE MODELS INDICATE
AT LEAST 6-10 INCHES WILL FALL IN THE WARNING AREA BETWEEN EARLY
WEDNESDAY MORNING AND THURSDAY MORNING...WITH 15.12Z RUNS OF THE
NAM...GFS...AND GEM MODELS EVEN INDICATING A BAND OF 12-18 INCHES
ACROSS POLK/BARRON/RUSK COUNTIES. WHILE THE FORCING IS CERTAINLY
THERE...COULD LOSE A FAIR AMOUNT OF THAT PRECIP AS RAIN IF THE
MODELS ARE OFF ON THEIR TIMING OF THE CHANGEOVER. HAVE THEREFORE
LEANED A BIT MORE CONSERVATIVELY TOWARD THE 15.12Z ECMWF...WHICH
FEATURES 5-10 INCHES ACROSS THE WARNING AREA...AND A ECMWF/NAM
BLEND FOR THE TWIN CITIES TO EAU CLAIRE...WHICH YIELDS 1-3 INCHES.

.LONG TERM...(WEDNESDAY NIGHT THROUGH TUESDAY)
ISSUED AT 245 PM CDT TUE APR 15 2014

SPLIT FLOW WILL LEAD TO A RATHER QUIET PERIOD IN THE EXTENDED AS
TEMPERATURES GRADUALLY WARM TO NEAR THE SEASONAL AVERAGE BY THE
BEGINNING OF NEXT WEEK. THE BEST CHANCE FOR RAIN WILL BE SATURDAY
INTO SUNDAY IN ASSOCIATION WITH THE H850 THETA_E ADVECTION AS
NORTHWEST FLOW TRANSITIONS TO A MORE ZONAL PATTERN.

AT THE START OF THE PERIOD THURSDAY MORNING THE SURFACE RIDGE OF
HIGH PRESSURE WILL BE CENTERED ACROSS WESTERN MN AND GRADUALLY SHIFT
EASTWARD THROUGHOUT THE DAY. FORECAST SOUNDINGS SHOW A BACKING WIND
PROFILE IN THE LOWEST 10KFT...AND THE WEAK COLD AIR ADVECTION
TOGETHER WITH MID LEVEL CLOUDS WILL KEEP AFTERNOON HIGHS GENERALLY
IN THE LOWER 40S TO THE SOUTH...AND UPPER 30S ACROSS THE NORTH WHERE
THE FRESH SNOW IS EXPECTED.

A SHORTWAVE ON THE BACK SIDE OF A LOW AMPLITUDE LONGWAVE TROUGH WILL
BECOME ELONGATED INTO A STRIP OF POSITIVE VORTICITY AS IT RIDES THE
UPSTREAM RIDGES ACROSS THE UPPER MIDWEST FRIDAY. A FEW LIGHT
RAIN/SNOW SHOWERS ARE POSSIBLE...BUT THE PRECIP SHOULD REMAIN
CONFINED TO THE EASTERN DAKOTAS AND SOUTHWESTERN MN. THE BEST CHANCE
FOR PRECIP WILL BE OVER THE WEEKEND WITH THE AFOREMENTIONED THETA_E
ADVECTION DOWNSTREAM OF ANOTHER 500MB WAVE THAT IS FORECAST TO TAKE
ON A NEGATIVE TILT AS IT MOVES INTO CENTRAL CANADA AND HUDSON BAY.
THERMODYNAMIC PROFILES SUPPORT THIS PRECIP AS ALL RAIN...EXCEPT FOR
A FEW SNOW FLAKES IN WEST CENTRAL WI. AS OF NOW RAINFALL TOTALS LOOK
TO BE AROUND 0.25 TO 0.50 INCHES.

&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z WEDNESDAY AFTERNOON)
ISSUED AT 232 PM CDT TUE APR 15 2014

VFR CONDITIONS ARE EXPECTED THIS EVENING UNTIL SNOW MOVES INTO
WEST CENTRAL MN LATE TONIGHT. THE FIRST BAND WILL AFFECT KAXN AND
KSTC BETWEEN 09Z AND 12Z WEDNESDAY. THE OTHER SITES WILL LIKELY
MISS OUT ON THE FIRST WAVE OF PRECIP OVERNIGHT...BUT THEN
WIDESPREAD PRECIP WILL EXPAND ACROSS THE AREA THROUGH HIGH
CONFIDENCE IN MVFR/IFR CONDITION LATE IN THE DAY TOMORROW. PRECIP
TYPE DURING THE DAY WILL LIKELY BE RAIN OR RAIN/SNOW AT ALL SITES
EXCEPT KAXN AND POSSIBLY KSTC/KRNH...BUT THEN SITES WILL GRADUALLY
CHANCE BACK OVER TO SNOW ON WEDNESDAY EVE.

WINDS WILL BE SCREAMING BETWEEN 1000-3000FT BETWEEN 06Z AND 15Z
WEDNESDAY. THE THREAT FOR LOW LEVEL WIND SHEAR WILL BE THE HIGHEST
FROM SOUTH CENTRAL MN INTO WEST CENTRAL WI /KEAU/ WHERE 0-1KM
SHEAR MAGNITUDE IS PROGGED TO BE AROUND 50 KTS/KM.

KMSP...
THERE IS A SLIGHT CHNACE OF VERY LIGHT SNOW OR RAIN/SNOW AFTER 09Z
WEDNESDAY...BUT THE MEASURABLE PRECIP WILL HOLD OFF UNTIL AFTER
17Z WED. SHOULD BE IN THE FORM OF RAIN THROUGH THE
AFTERNOON...WITH A CHANGEOVER TO WET SNOW WEDNESDAY EVE. A
40-50KT LOW LEVEL JET WILL DEVELOP OVERNIGHT...ALTHOUGH HAVE NOT
INCLUDED A MENTION OF LLWS IN THE TAF AS IT LOOKS TO BE MORE OF A
SPEED VS. DIRECTIONAL SHEAR.

/OUTLOOK FOR KMSP/

WED NGT...MVFR/IFR. RAIN CHANGING TO SNOW EARLY. WINDS NNE 10-15 KTS.
THU...VFR. WINDS NNE 10-15 KTS.
FRI...MAINLY VFR. SLGT CHC MVFR CIGS WITH -RA/-SN.
FRI NIGHT. WINDS NE 10 KTS.


&&

.MPX WATCHES/WARNINGS/ADVISORIES...
MN...WINTER STORM WARNING FROM 4 AM WEDNESDAY TO 4 AM CDT THURSDAY
     FOR MNZ042>045-050-052-053.

     WINTER WEATHER ADVISORY FROM 7 AM WEDNESDAY TO 4 AM CDT THURSDAY
     FOR MNZ051-061-063.

     WINTER WEATHER ADVISORY FROM 4 AM WEDNESDAY TO 4 AM CDT THURSDAY
     FOR MNZ041-047>049.

WI...WINTER STORM WARNING FROM 4 AM WEDNESDAY TO 4 AM CDT THURSDAY
     FOR WIZ014.

     WINTER WEATHER ADVISORY FROM 7 AM WEDNESDAY TO 7 AM CDT THURSDAY
     FOR WIZ025-027.

     WINTER WEATHER ADVISORY FROM 7 AM WEDNESDAY TO 4 AM CDT THURSDAY
     FOR WIZ023.

     WINTER STORM WARNING FROM 7 AM WEDNESDAY TO 7 AM CDT THURSDAY
     FOR WIZ015-016.

&&

$$

UPDATE...RAH
SHORT TERM...LS
LONG TERM...JRB
AVIATION...LS






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