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000
FXUS63 KFSD 022343
AFDFSD

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SIOUX FALLS SD
543 PM CST MON MAR 2 2015

.SHORT TERM...(THIS EVENING THROUGH TUESDAY)
ISSUED AT 251 PM CST MON MAR 2 2015

THE MODELS HAVE REALLY COME INTO GOOD AGREEMENT ON THE OVERALL
PATTERN FOR TONIGHT. THE FOCUS FOR HEAVIEST SNOW CONTINUES TO BE IN
THE NORTHERN CWA...AS WELL AS THE FAR WESTERN CWA. WARMER AND MORE
MOIST AIR IS BUILDING NORTHWARD THROUGH NEBRASKA WHICH IS PUSHING
THE DENDRITIC LAYER HIGHER AND FARTHER NORTH. THIS IS MUCH OF THE
DRIVING FORCE BEHIND WHY THE BETTER PRECIPITATION IS GOING TO BE IN
THE NORTHERN CWA. AS THE WAVE MOVES ONTO THE WESTERN HIGH PLAINS
LATE TONIGHT THE MID LEVEL BOUNDARY WILL SLOW AND STALL OUT NEAR
HIGHWAY 14 AND WITH MID LEVEL WINDS BACKING A LITTLE CONVERGENCE
ALONG THIS BOUNDARY WILL INCREASE AND ALLOW SNOW TO DEVELOP. AT THIS
TIME BELIEVE THAT SOMEWHERE BETWEEN HE 700MB AND 750MB FRONT WILL
BE THE MAIN FOCUS WITH SOME MARGINAL AMOUNT OF INSTABILITY AVAILABLE
ABOUT THIS. WITH THIS IN MIND THE TIMING OF THE UPPER LEVEL WAVE
SHOULD BRING SNOW INTO CHAMBERLAIN AND HURON BY ABOUT 9Z WITH THE
FRONT RAPIDLY FILLING IN TOWARDS BROOKINGS AND MARSHALL. SLIGHTLY
LOWER CONFIDENCE TOWARDS SOUTHWEST MINNESOTA AS THE MID LEVEL FRONT
COULD SLIP JUST A BIT NORTH OF THIS AREA...BUT TOO CLOSE TO IGNORE
POTENTIAL RIGHT NOW. THIS HEAVIER BAND OF SNOW WILL BE IN PLACE AT
THESE LOCATIONS FROM ABOUT 9Z THROUGH 12-13Z...THEN START SLIDING
RAPIDLY SOUTH AS THE WAVE MOVES THROUGH. BY 18Z VIRTUALLY ALL OF THE
PRECIPITATION SHOULD BE EAST OF THE AREA AS LARGE SCALE SUBSIDENCE
FILLS IN. ALONG WITH THIS SNOWFALL WILL BE A VERY STRONG NORTH
WIND...ALBEIT THE MAJORITY OF THE STRONGEST WINDS SHOULD OCCUR AFTER
THE SNOW FALLS. THE BEST CHANCE FOR A COMBINATION OF FALLING SNOW
WILL BE ALONG THE WESTERN AND NORTHERN FRINGES OF THE CWA. SO WITH
AN EXPECTATION OF 2-4 INCHES IN THESE LOCATIONS AND WINDS GUSTING TO
40 TO 50 MPH A BLIZZARD WARNING WILL BE HOISTED. JUST TO THE SOUTH
AND EAST OF THIS WARNING A WINTER WEATHER ADVISORY WILL BE
ISSUED...MAINLY ALONG INTERSTATE 90 AND JUST SOUTH OF THERE IN SOUTH
DAKOTA INTO SOUTHWEST MINNESOTA. AT THIS TIME SNOWFALL AMOUNTS SOUTH
OF THE HURON TO MARSHALL LINE LOOK LIGHT ENOUGH THAT WIDESPREAD LESS
THAN A QUARTER MILE VISIBILITY SEEMS UNLIKELY. THERE WILL BE SOME
BLOWING AND DRIFTING SNOW HOWEVER SO STILL POTENTIALLY NASTY TRAVEL
CONDITIONS. NORTHWEST IOWA WILL NOT SEE ANY HEADLINES AT THIS TIME
BUT IT WILL BE AN AREA TO WATCH...MAINLY FROM ABOUT MIDNIGHT TO 8 AM
WHERE THE SOUNDINGS ARE HINTING AT THE POTENTIAL FOR SOME LIGHT
FREEZING DRIZZLE. IF IT CAN BECOME WIDESPREAD ENOUGH THEN AN
ADVISORY FOR SOME LIGHT ICING MAY BE NEEDED.

TEMPERATURES WILL FALL A BIT THIS EVENING THEN REMAIN STEADY OR RISE
SLIGHTLY LATE TONIGHT...BEFORE STARTING THE DOWNWARD SPIRAL THROUGH
THE DAY ON TUESDAY. TEMPERATURES AROUND SUNRISE TUESDAY MORNING
LIKELY TO BE IN THE MID 20S TO LOWER 30S WITH SUNSET TEMPERATURES IN
THE SINGLE DIGITS AND LOWER TEENS.

.LONG TERM...(TUESDAY NIGHT THROUGH MONDAY)
ISSUED AT 251 PM CST MON MAR 2 2015

FOCUS IN THE MEDIUM RANGE IS ON THE WARM UP AS STRONG CHINOOK
PATTERN SETS UP.  HAVE CONTINUED TO NUDGE FORECAST HIGHS UPWARDS
LATE IN THE WEEK...AND BOLSTERED HIGHS ON SUNDAY INTO MONDAY AS 925
HPA TEMPS WARM WELL INTO THE SINGLE DIGITS ABOVE ZERO.  AS LONG AS
THE WESTERLY FLOW IS ABLE TO REMAIN AT THE SURFACE...THINK THE
POTENTIAL FOR STRATUS IS REDUCED.  HAVE THEREFORE SIDED WITH
FORECAST HIGHS AT OR ABOVE ENSEMBLE MEMBERS WITH LIMITED SNOW COVER
EXPECTED ACROSS THE AREA. MODELS SUGGEST A WAVE MAY TRY TO DROP
THROUGH THE AREA ON SATURDAY INTO SUNDAY...BUT MOISTURE IS SEVERELY
LIMITED SO KEPT FORECAST DRY FOR NOW.

&&

.AVIATION...(FOR THE 00Z TAFS THROUGH 00Z TUESDAY EVENING)
ISSUED AT 543 PM CST MON MAR 2 2015

THE MAIN FOCUS IN THIS TAF PERIOD IS THE WELL ADVERTISED SHARP
COLD FRONT MOVING EASTWARD WITH AN UPPER TROUGH. HAVE TIMED THE
COLD FRONT AND PRECIPITATION CHANCES BASED OFF OF THE 18Z NAM AND
GFS...USING THE GFS MOISTURE FIELDS AS THE PRIMARY GUIDANCE FOR
CEIILNGS BUT THE WIND FIELD MORE OFF OF THE NAM. EXPECT LOWER END
MVFR TO IFR CONDITIONS IN SNOW AND BLOWING SNOW BEHIND THE COLD
FRONTAL PASSAGE AT KFSD AND KSUX...WITH A FREEZING DRIZZLE THREAT
LATE TONIGHT AND EARLY TUESDAY AT KSUX...WITH LESS OF A THREAT OF
THIS POTENTIAL AT KFSD. BLOWING SNOW CONDITIONS WILL LIKELY BECOME
QUITE ACUTE AT KHON TUESDAY MORNING BEHIND THE COLD FRONT AND A
BLIZZARD WARNING IS IN EFFECT FOR THAT AREA.

&&

.FSD WATCHES/WARNINGS/ADVISORIES...
SD...WINTER WEATHER ADVISORY FROM 10 AM TO 5 PM CST TUESDAY FOR
     SDZ054>056-059>062-065>067.

     BLIZZARD WARNING FROM 11 AM TO 6 PM CST TUESDAY FOR SDZ040.

     WINTER WEATHER ADVISORY FROM 7 AM TO 3 PM CST TUESDAY FOR SDZ050-
     063-064.

     BLIZZARD WARNING FROM 7 AM TO 3 PM CST TUESDAY FOR SDZ038-039-
     052-053-057-058.

MN...BLIZZARD WARNING FROM 11 AM TO 6 PM CST TUESDAY FOR MNZ071-072.

     WINTER WEATHER ADVISORY FROM 11 AM TO 6 PM CST TUESDAY FOR
     MNZ080-081-089-090-097-098.

IA...NONE.
NE...NONE.
&&

$$

SHORT TERM...08
LONG TERM...
AVIATION...MJ