Area Forecast Discussion
Issued by NWS Sioux Falls, SD

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FXUS63 KFSD 311659
AFDFSD

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SIOUX FALLS SD
1059 AM CST SAT JAN 31 2015

.UPDATE...
ISSUED AT 1052 AM CST SAT JAN 31 2015

PER LATEST MODEL RUNS HAVE UPDATED THE FORECAST TO INCREASE QPF
AMOUNTS...AND IN TURN SNOWFALL AMOUNTS...THROUGH AREAS GENERALLY
FROM THE INTERSTATE 90 CORRIDOR AND SOUTHWARD. RELATED TO
THAT...UPGRADED PORTIONS OF THE WINTER WEATHER ADVISORY TO A
WARNING FOR MOST OF NORTHWESTERN IOWA...NORTHEASTERN NEBRASKA AND
EXTREME SOUTHEASTERN SOUTH DAKOTA WHERE 6 TO 8 INCHES OF SNOW IS
LIKELY THROUGH SUNDAY MORNING. WILL MOST LIKELY HAVE TO REFINE
CURRENT HEADLINES A BIT MORE FOR THE AFTERNOON PACKAGE BASED ON
12Z MODEL RUNS. ALSO REMOVED RAIN FROM THE FORECAST IN OUR FAR
SOUTH THIS AFTERNOON IN ANTICIPATION OF WET BULBING WHICH WOULD
QUICKLY RESULT IN ANY RAIN CHANGING TO SNOW.

&&

.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 332 AM CST SAT JAN 31 2015

THIS SNOW SYSTEM HAS BECOME STRONGER WITH EACH RUN SINCE YESTERDAY
AND NOW IS EXPECTED TO BRING SIGNIFICANT SNOW ACCUMULATIONS TO MOST
OF OUR FORECAST AREA...WITH THE GREATEST AMOUNTS IN NORTHWEST IOWA.
DESPITE INITIALLY MILD LOW LEVEL TEMPERATURES...STEADY COOLING IS
STARTING TO CALL IN QUESTION AN INITIAL MIXTURE OF RAIN WITH THE
SNOW IN THE FAR SOUTH. GIVEN THE EXPECTED RAPID DEVELOPMENT OF
PRECIPITATION TODAY...WITH KEEP A MIXTURE OVER A SMALL AREA FAR
SOUTH INTO THIS. TEMPERATURES OF COURSE WILL NOT GET TOO FAR TODAY
BEFORE COOLING...GIVEN HOW MILD THEY ARE EARLY THIS MORNING.

MODELS HAVE VERY GOOD AGREEMENT OF PRECIPITATION PATTERN AND
AMOUNTS. THINK HERE THE AMOUNTS ARE IN GENERAL SLIGHTLY OVERDONE.
HOWEVER...THE CERTAIN COOLING AND A LOT OF THE LIFT DESTINED TO BE
IN THE DENDRITIC ZONE SHOULD MAKE FOR SOME DECENT ACCUMULATIONS.
AMOUNTS SHOULD STAY LESS THAN 8 INCHES IN NORTHWEST IOWA BUT NOT
VERY MUCH LESS. GIVEN THE MODERATE WINDS AND SOME DRIFTING BUT
LITTLE OR NO BLOWING SNOW EXPECTED...PLUS AN EVENT DURATION WELL
OVER 12 HOURS IN THAT AREA...WILL KEEP THE HIGHLIGHT TO JUST AN
ADVISORY FOR NOW. THE ADVISORY WILL EXTEND NORTH AND WEST TO PART OF
SOUTHWEST MN...THE FSD AREA...MITCHELL AND THE FAR SOUTHWEST CORNER
OF THE AREA IN GREGORY COUNTY. AM STARTING THE ADVISORY LATE THIS
AFTERNOON/ 3 PM CST/ FAR SOUTH AND AT THE START OF THE EVENING/ 6 PM
CST / FURTHER NORTH. SNOW SHOULD BE TAPERING OFF FAR WEST LATE
TONIGHT BUT WILL KEEP THE ADVISORY THROUGH TONIGHT THERE...AND INTO
SUNDAY EAST.

THE COLD AIR COMING IN WILL DROP TEMPERATURES TO THE SINGLE DIGITS
NORTHWEST TO THE TEENS SOUTHEAST TONIGHT. WINDS MAY GET TO THE
BREEZY CATEGORY BUT NOT STRONG ENOUGH TO BLOW THE SNOW HIGHER THAN
DRIFTING LEVEL.

.LONG TERM...(SUNDAY THROUGH FRIDAY)
ISSUED AT 332 AM CST SAT JAN 31 2015

PROGRESSIVE NORTHWEST FLOW WILL ALLOW ACTIVE WEATHER TO CONTINUE
THROUGH THE MIDDLE OF NEXT WEEK...FOLLOWED BY QUIET CONDITIONS FOR
THE SECOND HALF OF THE WEEK.

STORM SYSTEM IMPACTING THE AREA SATURDAY NIGHT WILL PUSH OFF TO THE
EAST ON SUNDAY. MODERATE SNOWFALL WILL BE MAINLY CONFINED TO THE
EASTERN HALF OF THE FORECAST AREA ON SUNDAY MORNING BEFORE
DIMINISHING FROM WEST TO EAST IN THE AFTERNOON. NORTHERLY WINDS
INCREASE TO AROUND 15 TO 25 MPH WITH SOME HIGHER GUSTS TO 30 MPH.
THIS SHOULD ALLOW SOME BLOWING AND DRIFTING OF SNOW...PARTICULARLY
IN OPEN AREAS. AM CONCERNED THAT THE BLOWING SNOW MAY BE OF GREATEST
CONCERN IN NORTHWEST IOWA WHERE THE HEAVIEST SNOWFALL IS EXPECTED.
THIS MAY POINT MORE TOWARDS NEEDING A WINTER STORM WARNING INSTEAD
OF AN ADVISORY IN OUR FAR SOUTHEAST...BUT THINK THAT STARTING WITH
AN ADVISORY AND SEEING IF WINDS LOOK STRONGER IN FUTURE RUNS IS A
GOOD START FOR NOW. DEFINITELY SOMETHING FOR THE DAY SHIFT TO LOOK
AT.

MUCH COLDER TEMPERATURES RUSH INTO THE REGION ON SUNDAY...WHICH WILL
RESULT IN NEARLY STEADY OR FALLING TEMPERATURES THROUGH THE DAY.
CLEARING SKIES ON SUNDAY NIGHT...FRESH SNOWPACK AND WINDS SHARPLY
DECREASING WILL BRING A MUCH COLDER NIGHT. LOWS WILL DROP INTO THE
SINGLE DIGITS BELOW ZERO...BUT WITH LIGHT WINDS THE WIND CHILLS
STAY OUT OF ADVISORY TERRITORY.

A MID LEVEL SHORTWAVE SLIPS ACROSS THE NORTHERN PLAINS ON MONDAY.
TEMPERATURES MODERATE SLIGHTLY AHEAD OF THE WAVE WITH RETURN FLOW
BRIEFLY RETURNING. STRATUS WILL ACCOMPANY THIS WAVE AND WHILE
SUPPORT IS PRETTY WEAK...COULD SEE A FEW FLAKES DEVELOP IN THE OUR
FAR EAST MONDAY AFTERNOON AND EVENING. TEMPERATURES WARM FURTHER ON
TUESDAY WITH HIGHS RECOVERING INTO THE MID 20S NORTHEAST TO NEAR 40
IN THE LOWER BRULE. ANOTHER MID LEVEL WAVE DROPPING ALONG THE
NORTHWEST FLOW WILL BRING ANOTHER CHANCE FOR SOME LIGHT SNOW IN THE
AFTERNOON...CLOSELY FOLLOWED BY ANOTHER WAVE TUESDAY NIGHT. ANOTHER
SHOT OF COLD AIR ADVECTION FOLLOWS...WITH HIGHS ONLY IN THE MID
TEENS TO LOWER 20S ON WEDNESDAY.

UPPER LEVEL RIDGING FINALLY BEGINS TO REBOUND TO OUR WEST ON
THURSDAY AND FRIDAY. TEMPERATURES MODERATE SOME ON THURSDAY...BUT
FRIDAY READINGS IMPROVE INTO THE 30S AND EVEN SOME 40S IN SOUTH
CENTRAL SD.

&&

.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z SUNDAY MORNING)
ISSUED AT 535 AM CST SAT JAN 31 2015

CEILINGS BELOW 1K FEET WITH AREAS OF VISIBILITY 3-5SM NORTHERN
THIRD OF THE AREA AT 12Z WILL SPREAD SOUTH OVER ALL OF THE AREA
31/12Z-18Z. 31/18Z-01/00Z CEILINGS MAY BRIEFLY IMPROVE TO 1-2K
FEET BUT CEILINGS AOB 1K FEET AND VISIBILITIES BELOW 3SM IN SNOW
WILL DEVELOP OVER THE AREA FROM THE S 31/21Z-01/03Z. IFR
CONDITIONS IN SNOW WILL CONTINUE THROUGH 01/12Z EXCEPT
IMPROVEMENT TO MVFR EXPECTED WESTERN THIRD OF THE AREA OR MAINLY
WEST OF THE JAMES RIVER 01/06Z/12Z.


&&

.FSD WATCHES/WARNINGS/ADVISORIES...
SD...     WINTER STORM WARNING FROM 3 PM THIS AFTERNOON TO NOON CST SUNDAY
     FOR SDZ070-071.

     WINTER WEATHER ADVISORY FROM 3 PM THIS AFTERNOON TO 6 AM CST
     SUNDAY FOR SDZ050-063-068-069.

     WINTER WEATHER ADVISORY FROM 6 PM THIS EVENING TO NOON CST
     SUNDAY FOR SDZ062-066-067.

     WINTER WEATHER ADVISORY FROM 6 PM THIS EVENING TO 6 AM CST
     SUNDAY FOR SDZ059>061-064-065.

MN...WINTER WEATHER ADVISORY FROM 6 PM THIS EVENING TO NOON CST
     SUNDAY FOR MNZ089-090-098.

IA...WINTER STORM WARNING FROM 3 PM THIS AFTERNOON TO NOON CST SUNDAY
     FOR IAZ020>022-031-032.

     WINTER STORM WARNING FROM 6 PM THIS EVENING TO NOON CST SUNDAY
     FOR IAZ001>003-012>014.

NE...WINTER STORM WARNING FROM 3 PM THIS AFTERNOON TO NOON CST SUNDAY
     FOR NEZ013-014.

&&

$$

UPDATE...JM
SHORT TERM...
LONG TERM...
AVIATION...



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