Area Forecast Discussion
Issued by NWS Sioux Falls, SD

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746
FXUS63 KFSD 081733
AFDFSD

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SIOUX FALLS SD
1133 AM CST MON FEB 8 2016

.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 404 AM CST MON FEB 8 2016

HEADLINE DECISIONS ARE THE PRIMARY CHALLENGE THIS MORNING. AS
ANTICIPATED...DID NOT RECEIVE A LOT OF SNOW ACCUMULATION FROM THIS
SYSTEM...THOUGH ADMITTEDLY MEASUREMENT DIFFICULT AT BEST GIVEN
WIDESPREAD 30-50+ MPH WINDS THROUGHOUT THE PERIOD OF FALLING SNOW.
SEEING A NUMBER OF SURFACE OBSERVATIONS WITHIN BLIZZARD WARNING AREA
REPORTING VISIBILITY BELOW 1 MILE AS OF 3 AM...WITH REPORTS OF NEAR
ZERO VISIBILITY IN OPEN COUNTRY. OCCASIONAL SNOW SHOWERS CONTINUE TO
WRAP SOUTHWARD NEAR/EAST OF I-29 THROUGH MIDDAY...AS ANOTHER LOBE OF
ENERGY DROPS SOUTH THROUGH THE AREA. SHOULD SEE A DECREASE IN SNOW
COVERAGE AND PARTIAL CLEARING THROUGH THE AFTERNOON WITH INCREASING
SUBSIDENCE AS SYSTEM PULLS EAST. FOR THIS REASON...18Z EXPIRATION
TIME OF THE WINTER HEADLINES SEEMS REASONABLE AT THIS TIME.

LATEST DATA SUGGESTS THAT WIND ADVISORY LEVEL WINDS WILL LINGER OVER
MUCH OF THE AREA INTO THE AFTERNOON...AND HAVE EXTENDED PORTIONS OF
THE WIND ADVISORY WEST OF I-29 INTO THE MID-LATE AFTERNOON. QUANDARY
COMES WITH WHAT TO DO FOR HEADLINES IN OUR EAST WHERE THE CURRENT
WINTER WEATHER ADVISORY/BLIZZARD WARNING EXPIRE AT 18Z. CONTEMPLATED
ISSUING SHORT WIND ADVISORY TO COVER THE STRONGER WINDS THROUGH THE
AFTERNOON ACROSS THE EAST...BUT HAVE SOME UNCERTAINTY WHETHER WINTER
HEADLINES WILL NEED TO BE EXTENDED BEYOND 18Z. THUS OPTED TO FORGO
WIND ADVISORY IN THE EAST FOR NOW...AND INSTEAD WILL LET DAY SHIFT
MONITOR CONDITIONS AND MAKE DECISION LATER THIS MORNING WHETHER ANY
WINTER HEADLINES NEED TO BE EXTENDED...OR IF CONDITIONS IMPROVE
ENOUGH THAT THEY CAN BE REPLACED WITH A WIND ADVISORY.

BEYOND THE HEADLINES...TEMPERATURES WILL SEE LITTLE MOVEMENT TODAY
AS STRONG NORTHERLY FLOW CONTINUES TO REINFORCE COLD AIR MASS WHICH
SETTLED IN OVERNIGHT. EXPECT HIGHS IN THE UPPER TEENS AND 20S NEAR
AND EAST OF THE JAMES VALLEY...WITH READINGS INTO THE LOWER 30S IN
SOUTH CENTRAL SOUTH DAKOTA. WINDS DIMINISH SOME TONIGHT...BUT WILL
REMAIN ON THE BREEZY SIDE IN THE EAST. THIS WILL ALLOW FOR SUB-ZERO
WIND CHILLS IN THE EAST TONIGHT AS TEMPERATURES FALL INTO THE SINGLE
DIGITS AND TEENS MOST AREAS.

.LONG TERM...(TUESDAY THROUGH SUNDAY)
ISSUED AT 404 AM CST MON FEB 8 2016

BRISK NORTHERLY WINDS ARE SLATED TO CONTINUE ON TUESDAY IN ADVANCE
OF LOW LEVEL RIDGE AXIS NOSING IN ALONG THE I 29 CORRIDOR THROUGH
THE DAY. LOWER LEVEL THERMAL GRADIENT NOW LOOKS TO LARGELY REMAIN
WEST OF THE CWA THROUGH THE DAY...AND WILL TAKE UNTIL LATE DAY TO
FIND ANY LARGER SCALE MEAGER SUPPORT FOR LIFT ALONG THIS BOUNDARY.
THEREFORE...HAVE SHAVED BACK THE LOW SNOW CHANCES FOR MOST AREAS FOR
MOST OF THE DAY...RELEGATING TO THE EXTREME WEST LATE DAY INTO THE
OVERNIGHT PERIOD. WINDS WILL DIMINISH TUESDAY NIGHT...BUT COULD SEE
SOME WIND CHILLS DIP TOWARD ADVISORY LEVELS OF -20 TO -25 IF THEY
DO NOT DROP MORE THAN EXPECTED.

BAROCLINIC ZONE DOES APPEAR TO WANDER EASTWARD ON WEDNESDAY WITH
WAVE SLIDING SOUTHEAST ACROSS THE PLAINS. A LITTLE INCREASE IN
FRONTOGENETIC FORCING...BUT MODELS ALL OVER THE BOARD WITH LOCATION
OF SHALLOWLY SLOPED FRONTAL ZONE.  IF GREATER CONSISTENCY CAN BE
FOUND IN SOLUTION...WOULD BE MORE COMFORTABLE IN ADVERTISING
LEGITIMATE LIGHT SNOW CHANCE ON WEDNESDAY INTO WEDNESDAY NIGHT.
HOWEVER...AS THINGS STAND...HAVE ONLY RUN WITH A FEW FLURRIES WITH
TEMPS IN FAVORABLE ICE PRODUCTION RANGE.  LOWEST LEVELS SHOULD
MAINLY KEEP ANY MORE NOTABLE WARMING BOTTLED UP WEST...PERHAPS
MODERATING A BIT IN THE EXTREME WESTERN AREAS.

LARGE SCALE PATTERN REMAINS FAIRLY STABLE THROUGH THE EARLY WEEKEND
WITH DEEP TROUGH EAST AND RIDGE WEST...REINFORCED BY WAVE THURSDAY
NIGHT AND FRIDAY BEFORE LARGER SCALE RIDGE BEGINS SHIFTING EASTWARD
THIS WEEKEND. WITH SOME AGREEMENT IN WAVE / BUT AGAIN NOT IN THERMAL
BOUNDARY LOCATION / HAVE CARRIED A CHANCE OF LIGHT SNOW THURSDAY
NIGHT ACROSS THE HEART OF THE CWA...BOTH AWAY FROM DRIER RIDGE EAST
AND THE WARMER SIDE OF THE BOUNDARY WEST. BEHIND WAVE...APPEARANCES
ARE TO ALLOW A STRONGER PUSH OF SHALLOW COLD AIR SOUTHWARD INTO THE
PLAINS THROUGH EARLY SATURDAY.  TREND CONTINUES TO BE COLDER FOR
TEMPS FRIDAY THROUGH SATURDAY...AND HAVE ADJUSTED LOWER...THOUGH
MOST LIKELY NOT NEARLY ENOUGH FOR SATURDAY MORNING IF POTENTIAL
OVERLAP OF LIGHTER WINDS AND CLEAR SKIES MATERIALIZES.

A BIT STRONGER WAVE MAY FLATTEN RIDGE TOWARD SUNDAY. DEVELOPMENT OF
WARM ADVECTION ZONE LOOKS TO SATURATE UP A BIT MORE EAST OF THE
AREA...BUT CLOSE ENOUGH TO KEEP IN SOME LOW POPS. SOME FAIRLY
SIGNIFICANT THERMAL RANGES BETWEEN SOLUTIONS...WITH ENOUGH
UNCERTAINTY TO LET THINGS BE FOR NOW...SAFE ENOUGH TO ADVERTISE
AN AWAITED MODERATION TO TEMPS.

&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z TUESDAY AFTERNOON)
ISSUED AT 1128 AM CST MON FEB 8 2016

STRONG WINDS AND BLOWING SNOW WILL REMAIN THE MAIN FOCUS
TODAY...ESPECIALLY ALONG AND EAST OF THE I29 CORRIDOR. WIDESPREAD
IFR AND LIFR CONDITIONS WILL CONTINUE THROUGH THE AFTERNOON...WITH
GRADUALLY IMPROVEMENT TO MVFR VISIBILITIES FROM WEST TO EAST THIS
AFTERNOON. WINDS WILL PERSIST AROUND 25 TO 40 KT IN THIS
AREA...THEN GRADUALLY DECREASE LATE AFTERNOON THROUGH THE
OVERNIGHT. DESPITE DECREASING WINDS...OVERNIGHT CONDITIONS WILL
REMAIN BREEZY OVERALL. VFR CEILINGS WILL ALSO RETURN FROM WEST TO
EAST THROUGH THIS EVENING.

&&

.FSD WATCHES/WARNINGS/ADVISORIES...
SD...WINTER WEATHER ADVISORY UNTIL 6 PM CST THIS EVENING FOR SDZ040-
     055-056-062-067-071.

     WIND ADVISORY UNTIL 5 PM CST THIS AFTERNOON FOR SDZ065-066-
     068>070.

     WIND ADVISORY UNTIL NOON CST TODAY FOR SDZ038-052-053-058-059-
     064.

     WIND ADVISORY UNTIL 3 PM CST THIS AFTERNOON FOR SDZ039-054-060-
     061.

MN...WINTER WEATHER ADVISORY UNTIL 6 PM CST THIS EVENING FOR MNZ098.

     BLIZZARD WARNING UNTIL 6 PM CST THIS EVENING FOR MNZ071-072-080-
     081-089-090-097.

IA...WINTER WEATHER ADVISORY UNTIL 6 PM CST THIS EVENING FOR IAZ001-
     012-020-031.

     BLIZZARD WARNING UNTIL 6 PM CST THIS EVENING FOR IAZ002-003-013-
     014-021-022-032.

NE...WINTER WEATHER ADVISORY UNTIL 6 PM CST THIS EVENING FOR NEZ014.

     WIND ADVISORY UNTIL 5 PM CST THIS AFTERNOON FOR NEZ013.

&&

$$

SHORT TERM...JH
LONG TERM...CHAPMAN
AVIATION...



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