Area Forecast Discussion
Issued by NWS Sioux Falls, SD

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434
FXUS63 KFSD 051134
AFDFSD

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SIOUX FALLS SD
534 AM CST FRI FEB 5 2016

.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 351 AM CST FRI FEB 5 2016

A COUPLE OF SUBTLE MID-UPPER LEVEL WAVES EXPECTED TO IMPACT THE
FORECAST AREA TODAY. WITH THE FIRST WEAK WAVE...FORECAST BY ALL
MODELS TO TRACK EAST ACROSS NEBRASKA...WARM ADVECTION/ISENTROPIC
LIFT SHOULD SPREAD SOME DEEPER MOISTURE AND LIFT INTO SOUTHEAST
PARTS OF THE CWA BY MID-LATE MORNING. BY EARLY-MID AFTERNOON...THE
SECOND WAVE DROPS SOUTHEAST THROUGH THE DAKOTAS...AND SHOULD SEE
ADDITIONAL LIGHT SNOW WITH THIS WAVE. WILL CONTINUE TO CARRY THE
HIGHER POPS EAST WHERE MOISTURE DEPTH IS MORE FAVORABLE. HOWEVER...
MANY OF THE HIGHER RES MODELS ARE SHOWING POTENTIAL FOR ISOLATED TO
SCATTERED SHOWERS FARTHER SOUTHWEST INTO SOUTH CENTRAL SOUTH DAKOTA.
SEEING VERY LIGHT ECHOES WITH THE WAVE CURRENTLY IN WESTERN SOUTH
DAKOTA...SO HARD TO IGNORE THE POSSIBILITY AS IT MOVES SOUTHEAST
THIS AFTERNOON.

FORECAST SURFACE TEMPERATURES IN THE MID 30S WOULD SUGGEST A
POSSIBILITY OF RAIN/SNOW MIX SHOULD ANY SHOWERS DEVELOP. HOWEVER...
THE WARMER AIR IS PRETTY SHALLOW...SO ANY PRECIP REACHING THE GROUND
WOULD MOST LIKELY REMAIN SNOW. ACCUMULATIONS WITH EITHER OF THESE
FEATURES EXPECTED TO BE LIGHT...GENERALLY LESS THAN A HALF INCH.
TEMPERATURES TODAY SHOULD BE ON THE MILD SIDE OF NORMAL WITH UPPER
20S EAST TO MID 30S SOUTHWEST. WINDS WILL BE A LITTLE BREEZY AT
TIMES...BEGINNING ON THE BUFFALO RIDGE THIS MORNING AND EXPANDING
INTO NORTHWEST IOWA BY MIDDAY. COULD SEE SOME DRIFTING SNOW GIVEN
THE RECENT HEAVY SNOW IN THESE AREAS...BUT DO NOT THINK THE WIND
WILL BE STRONG ENOUGH TO CAUSE REDUCED VISIBILITY IN BLOWING SNOW.

LATTER WAVE EXITS THE AREA EARLY THIS EVENING...WHICH SHOULD BE
FOLLOWED BY PARTIAL CLEARING AS WEAK RIDGE MOVES ACROSS THE AREA. DO
NOT EXPECT TEMPERATURES TO DROP QUITE AS FAR AS EARLIER THIS MORNING
IN THE CLEAR SKIES...BUT SHOULD SEE THE COOLEST TEMPERATURES IN THE
LOWER-MID TEENS IN AREAS OVER THE HEAVIER SNOW IN NORTHWEST IOWA...
WITH READINGS CLOSER TO 20 ACROSS THE WESTERN CWA.

.LONG TERM...(SATURDAY THROUGH THURSDAY)
ISSUED AT 351 AM CST FRI FEB 5 2016

SATURDAY STILL LOOKS LIKE A PLEASANT DAY...ALBEIT IT WILL BE QUITE
BREEZY IN SOUTHWEST MN AS A SOUTHWEST FLOW DOMINATES THE AREA.
TRENDED TOWARD BLENDING SOME WARM ECMWF MOS GUIDANCE VALUES IN OUR
WESTERN ZONES FOR HIGHS AS SIGNIFICANT SNOW COVER IS LACKING FROM
THOSE AREAS. EVEN IF THEY HAD A DEEP SNOW PACK...THE 925MB
TEMPERATURES ARE QUITE WARM IN THAT LOCATION WHICH SHOULD EASILY
PRODUCE MID 40S. EAST OF THE JAMES RIVER VALLEY...A THICKER SNOW
PACK SHOULD KEEP HIGHS IN THE 30S.

THEN OUR WELL ADVERTISED UPPER LOW BEGINS TO ORGANIZE NEAR THE
CANADIAN BORDER SATURDAY NIGHT...BEFORE STRENGTHENING DRAMATICALLY
AND MOVING SOUTHWARD SUNDAY AND SUNDAY NIGHT DOWN THE MS VALLEY. THE
VARIOUS MODELS OFF OF THE CURRENT 00Z RUN ARE NOT AS BULLISH WITH
ANY PRECIP POTENTIAL SATURDAY NIGHT DUE TO A LACK OF MOISTURE BELOW
750-700MB. SOME LOWER CLOUDS HOWEVER DO EDGE INTO EAST CENTRAL SD
LATE AT NIGHT...AND THE THERMAL PROFILE LOOKS COLD ENOUGH FOR A VERY
SMALL CHANCE FOR LIGHT SNOW. BUT ANY SNOWFALL VERY LIKELY WILL NOT
MEASURE. DUE TO A WARM AIR MASS...INCREASING WINDS AND MID AND HIGH
CLOUDS...LOWS FOR THIS TIME OF YEAR WILL BE QUITE MILD SATURDAY
NIGHT...WITH READINGS IN THE UPPER 20S TO LOWER 30S.

THE MAIN STORY ON SUNDAY AND SUNDAY NIGHT ARE STRONG WINDS AND SNOW
SHOWERS. WENT AHEAD AND ISSUED A HIGH WIND WATCH FOR OUR SOUTHWEST
ZONES FOR SUNDAY...AS MIXED LAYER WINDS ON THE NAM AND ECMWF ARE 40
TO 55 KNOTS. THE GFS LOOKS RIDICULOUSLY STRONG AND OVER MIXED WITH
ITS WIND SPEEDS IN THE 925-850MB LAYER AND WERE NOT USED. OUR
SOUTHWEST ZONES SHOULD GET SOME LOWER CLOUDS BY MIDDAY SUNDAY RIGHT
WHEN THE STRONGEST MIXED WINDS ARE BEGINNING. HOWEVER THERE IS QUITE
A BIT OF DRY AIR BELOW 900-850MB WHICH SHOULD KEEP THE LOWER
ATMOSPHERE WELL MIXED IN THAT LOCATION...POINTING AT A DRY ADIABATIC
LAPSE RATE FROM ABOUT 900MB TO THE SURFACE. ELSEWHERE...IT WILL BE
WINDY...PROBABLY SOLID WIND ADVISORY CRITERIA. BUT THE STRATUS IS
DEEPER AND MORE ABUNDANT SNOW SHOWERS MAY ACT AS A FRICTIONAL DRAG
ON THE WIND SPEEDS. THE SOUNDINGS ARE STILL QUITE UNSTABLE THROUGH
ALMOST 700MB...BUT NOT TO THE DEGREE THAT THEY ARE IN OUR SOUTHWEST
ZONES. ONE AREA THAT IS A BIT CONCERNING TO INCLUDE IN A HIGH WIND
WATCH IS EXTENDING IT FURTHER EASTWARD TOWARD YANKTON. THE MO RIVER
VALLEY IN THAT AREA IS A CLASSIC FOR FUNNELING WEST TO NORTHWEST
WINDS. THEREFORE SPEEDS MAY BE HIGHER THAN FORECAST. BUT THAT IS TOO
PROBLEMATIC TO WARRANT A HIGH WIND WATCH AT THIS TIME.

AS MENTIONED IN THE PREVIOUS PARAGRAPH...SOUNDINGS ARE UNSTABLE AND
WITH COLD TEMPERATURES ALOFT...SNOW SHOWERS SHOULD OCCUR SUNDAY AND
SUNDAY NIGHT...ESPECIALLY ALONG AND EAST OF THE JAMES RIVER VALLEY.
IN OUR FORECAST AREA...SNOW AMOUNTS WILL BE LIGHT...GENERALLY LESS
THAN AN INCH. BUT THE STRONG WINDS WILL LIKELY PRODUCE BLOWING SNOW
CONCERNS ESPECIALLY WHEN SNOW IS ACTUALLY FALLING. IN PERIODS OF NO
SNOW...THE BLOWING SNOW POTENTIAL IS A LITTLE LESS...MORE OF A
DRIFTING ISSUE. BUT VISIBILITIES COULD BE QUITE POOR AT TIMES IN THE
BLOWING SNOW BOTH SUNDAY AND SUNDAY NIGHT. HIGHS ON SUNDAY WILL
PROBABLY BE REACHED ABOUT MIDDAY...THEN THE UPPER TROUGH WILL BEGIN
TO USHER IN COLDER AIR AS A COLD FRONT PUSHES SOUTHWARD. ON
MONDAY...925MB TEMPERATURES ARE COLD...ESPECIALLY EAST OF THE JAMES.
BUT THE MIXING POTENTIAL IS HIGHER THEN 925MB...THEREFORE HIGHS
SHOULD RANGE FROM NEAR 20 IN OUR FAR EASTERN AREAS...TO AROUND 30 IN
THE WEST. TEMPERATURES ALOFT OF -10C TO -20C REMAIN VERY FAVORABLE
FOR LIGHT SNOW PRODUCTION ON MONDAY EAST OF I 29. THEREFORE DESPITE
A MORE SHALLOW MOISTURE DEPTH...THINK FLURRIES ARE STILL A GOOD BET
FOR THOSE AREAS ALONG WITH BLOWING SNOW.

THE REST OF THE EXTENDED FORECAST IS QUIETER. THERE MAY BE A WEAK
WAVE MOVING DOWN ON TUESDAY FROM THE NORTHWEST...ALSO ASSOCIATED
WITH A WARM FRONT. BUT THAT IS TOO FAR OUT TO MENTION FLURRIES SINCE
THINGS COULD CHANGE WITH THE TIMING.

&&

.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z SATURDAY MORNING)
ISSUED AT 534 AM CST FRI FEB 5 2016

VFR CONDITIONS TO START THE PERIOD...BUT EXPECT MVFR CONDITIONS TO
DEVELOP AS AREAS OF LIGHT SNOW MOVE INTO THE AREA DURING THE LATE
MORNING TO EARLY AFTERNOON. BRIEF IFR VISIBILITY POSSIBLE IN SNOW
SHOWERS...HOWEVER LOWER CONFIDENCE IN TIMING/LOCATION PRECLUDES
MENTION IN TAFS AT THIS TIME. IMPROVEMENT TO VFR EXPECTED TO
SPREAD ACROSS THE REGION THROUGH THE EVENING.

&&

.FSD WATCHES/WARNINGS/ADVISORIES...
SD...HIGH WIND WATCH FROM SUNDAY MORNING THROUGH SUNDAY AFTERNOON FOR
     SDZ050-052-057-058-063-064.

MN...NONE.
IA...NONE.
NE...NONE.

&&

$$

SHORT TERM...JH
LONG TERM...MJ
AVIATION...JH



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