Area Forecast Discussion
Issued by NWS Sioux Falls, SD

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000
FXUS63 KFSD 052310
AFDFSD

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SIOUX FALLS SD
510 PM CST FRI FEB 5 2016

.SHORT TERM...(THIS EVENING THROUGH SATURDAY)
ISSUED AT 325 PM CST FRI FEB 5 2016

AN UPPER LEVEL SHORTWAVE PRESENTLY SITUATED OVER NORTH CENTRAL SOUTH
DAKOTA THIS AFTERNOON WILL CONTINUE TO DROP TO THE SOUTH AND EAST
THROUGH THE EVENING. THIS FEATURE IS RESULTING IN SCATTERED SNOW
SHOWERS WEST OF INTERSTATE 29...AND THE GENERAL TREND THROUGH THE
REMAINDER OF THE AFTERNOON WILL BE FOR THESE SNOW SHOWERS TO PUSH
OFF TO THE EAST AND DWINDLE LATER IN THE AFTERNOON AS FORCING
WEAKENS. BY TONIGHT ANY OF THIS ACTIVITY WILL END WITH SLOWLY
DECREASING CLOUDS OVERNIGHT. IN SPITE OF CLEARING SKIES IT WILL BE A
RELATIVELY MILDER NIGHT AS THE LOW LEVEL FLOW TRANSITIONS TO
SOUTHWESTERLY...THIS THANKS TO LOW PRESSURE PUSHING OUT OF SOUTHERN
CANADA INTO THE NORTHERN ROCKIES/WESTERN HIGH PLAINS. LOWS ARE
LOOKING TO BE MID AND UPPER TEENS EAST OF INTERSTATE 29 TO LOWER 20S
TO THE WEST.

THE SOUTHWESTERLY FLOW WILL CONTINUE ON SATURDAY...AND WINDS WILL
PICK UP A BIT...MOST NOTABLY OVER THE BUFFALO RIDGE AREA...IN A
TIGHTENING GRADIENT WITH THE AFOREMENTIONED LOW TO THE NORTH AND HIGH
PRESSURE TO THE SOUTH. WHILE THERMAL PROFILES WILL BE WARMING ON
SATURDAY...TEMPERATURES WILL BE TEMPERED IN THE EAST BY SNOW
COVER...THOUGH LOCALES THROUGH THE JAMES RIVER VALLEY AND SOUTH
CENTRAL SOUTH DAKOTA WILL WARM NICELY. HIGHS WILL RANGE FROM THE
LOWER TO MID 30S EAST OF INTERSTATE 29...TO THE MID 40S THROUGH THE
HURON/MITCHELL/CHAMBERLAIN/LAKE ANDES CORRIDOR.

.LONG TERM...(SATURDAY NIGHT THROUGH FRIDAY)
ISSUED AT 325 PM CST FRI FEB 5 2016

MOST ACTIVE PERIOD OF WEATHER IN THE MEDIUM RANGE PORTIONS OF THE
FORECAST DEALS WITH THE CONDITIONS ON SUNDAY INTO MONDAY. BY SUNDAY
MORNING...A STRONG UPPER TROUGH WILL BEGIN TO DIG INTO THE NORTHERN
PLAINS. LOW-LVL TROUGH AXIS WILL SWING THROUGH THE REGION SATURDAY
NIGHT...WITH STEADILY INCREASING WINDS ALOFT THROUGH THE NIGHT.

SOUNDINGS CONTINUE TO SHOW A WELL MIXED ATMOSPHERE THROUGH THE
DAY...WITH MOMENTUM TRANSFER POTENTIALLY PULLING DOWN GUSTS TO 55
MPH OR GREATER.  A BIT CONCERNED ABOUT THE IMPACTS OF STRATUS
LIMITING THIS WIND POTENTIAL. FEEL THE GFS IS TOO AGGRESSIVE WITH
THE WINDS...AND FAVORED MORE TOWARDS THE NAM/ECMWF. HAVE BUMPED UP
WINDS THROUGH THE MO RIVER VALLEY THE JAMES RIVER VALLEY...WHERE
SOME CHANNELING SHOULD OCCUR. IN COORDINATION...HAVE EXTENDED THE
HIGH WIND WATCH SLIGHTLY FURTHER EAST. IN ALL OTHER AREAS...HIGH
END WIND ADVISORY CRITERIA SHOULD BE MET AND ADVISORIES WILL BE
LIKELY AT SOME POINT.

THE OTHER CONCERN WILL BE WITH THE POTENTIAL FOR CONVECTIVE SNOW
SHOWERS SUNDAY AFTERNOON AND NIGHT. SOUNDINGS INDICATING INCREASING
CAA ALOFT...REALLY ENHANCING THE LOW LVL LAPSE RATE. COULD SEE
SCATTERED TO NUMEROUS SNOW SQUALLS...ESPECIALLY EAST OF THE JAMES
RIVER INTO SUNDAY NIGHT.  WITH THAT SAID...BLOWING SNOW MODELS
INDICATE INCREASED PROBABILITIES OF BLOWING SNOW OVER MUCH OF THE
AREA...BUT ESPECIALLY OVER THE EASTERN HALF OF THE CWA THROUGH
SUNDAY NIGHT.  WHAT IS CONCERNING IS THAT ANY ADDITIONAL SNOWFALL
COULD LEAD TO NEAR WHITE-OUT CONDITIONS ALONG THE BUFFALO
RIDGE...AND AREAS WHERE FRESH DEEP SNOWPACK RESIDES SOUTHWARD INTO
NW PORTIONS OF IOWA. IN COORDINATION WITH SURROUNDING WFOS...WILL
ISSUE A BLIZZARD WATCH FOR THE RIDGE AREA AND ADJACENT AREAS OF
NORTHWEST IOWA...FOR THE COMBINATION OF SUBSTANCIAL BLOWING SNOW AND
FALLING SNOW. IT IS POSSIBLE THIS WATCH MAY NEED TO BE EXTENDED
FURTHER SOUTH AND WEST...BUT CONFIDENCE IS HIGHEST ATTM IN AREAS
OF SW MN AND PARTS OF NW IOWA.

FLOW ALOFT WILL GENERALLY REMAIN NORTHWESTERLY THROUGH MID-
WEEK...KEEPING THE AREA ALONG A NW-SE THERMAL GRADIENT ALOFT. LATER
SHIFTS MAY NEED TO INCREASE POPS TUESDAY INTO TUESDAY NIGHT...AND
AGAIN FRIDAY NIGHT...AS GFS/ECMWF ARE SHOWING SOME TRENDS OF AN
INCREASE OF WARM ADVECTION PRECIPITATION IN THESE TIMES.

TEMPERATURES WILL GENERALLY BE NEAR OR SLIGHTLY ABOVE
NORMAL...ALTHOUGH THERE ARE EXPECTATIONS OF A SIGNIFICANT GRADIENT
OF TEMPERATURES FROM NE TO SE ACROSS THE CWA THIS WEEK.

&&

.AVIATION...(FOR THE 00Z TAFS THROUGH 00Z SATURDAY EVENING)
ISSUED AT 509 PM CST FRI FEB 5 2016

MVFR CEILINGS WILL GRADUALLY MOVE SOUTHEAST OF THE AREA WITH VFR
CONDITIONS EXPECTED AFTER ABOUT 4Z IN MOST LOCATIONS. SPOTTY SNOW
SHOWERS WILL REMAIN POSSIBLE THROUGH ABOUT 1Z IN NORTHWEST IOWA.

&&

.FSD WATCHES/WARNINGS/ADVISORIES...
SD...HIGH WIND WATCH FROM SUNDAY MORNING THROUGH SUNDAY EVENING FOR
     SDZ038-050-052-053-057>060-063>065-068.

     BLIZZARD WATCH FROM SUNDAY AFTERNOON THROUGH LATE SUNDAY NIGHT
     FOR SDZ040.

MN...BLIZZARD WATCH FROM SUNDAY AFTERNOON THROUGH LATE SUNDAY NIGHT
     FOR MNZ071-072-080-081-089-090-097.

IA...BLIZZARD WATCH FROM SUNDAY AFTERNOON THROUGH LATE SUNDAY NIGHT
     FOR IAZ002-003-013-014-022.

NE...NONE.
&&

$$

SHORT TERM...JM
LONG TERM...DUX
AVIATION...08


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