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000
FXUS63 KFSD 091754
AFDFSD

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SIOUX FALLS SD
1154 AM CST MON DEC 9 2013

.UPDATE...
ISSUED AT 1147 AM CST MON DEC 9 2013

DECIDED TO LET THE WIND CHILL ADVISORY EXPIRE AT NOON. WIND CHILL
VALUES AROUND OR JUST BELOW 20 BELOW ZERO ARE STILL POSSIBLE FOR A
PERIOD OF TIME ALONG AND NORTH OF INTERSTATE 90...BUT IN GENERAL WE
SHOULD SEE SLIGHTLY WARMER READINGS...GENERALLY RUNNING IN THE SINGLE
DIGITS TO TEENS BELOW ZERO. SO DID NOT SEEM WORTH IT TO EXTEND THE
ADVISORY AT THIS POINT.

&&

.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 315 AM CST MON DEC 9 2013

COLDEST LOW LEVEL AIR MOVES ACROSS THE FORECAST AREA THIS MORNING...
WITH WIND CHILL ADVISORY LOOKING SOLID THROUGH MIDDAY. SOUTHERN
AREAS SHOULD SEE WIND CHILLS RISE ABOVE THE ADVISORY CRITERIA PRIOR
TO NOON EXPIRATION...WHILE NORTHEAST AREAS COULD SEE ADVISORY LEVEL
WIND CHILLS PERSIST AN HOUR OR TWO INTO THE EARLY AFTERNOON...BUT
WILL KEEP IT SIMPLE AND STICK WITH NOON EXPIRATION IN ALL AREAS FOR
NOW. DAY SHIFT CAN EXTEND THE NORTHEAST IF IT APPEARS COLDER AIR
WILL HANG AROUND LONGER THAN EXPECTED. RELATIVE WARMING THEN PUSHES
INTO WESTERN CWA THROUGH THE AFTERNOON. FAIR MIXING EXPECTED WITH
WESTERLY FLOW BECOMING SOUTHWEST IN THE LATE AFTERNOON...BUT WITH
COLD AIR MASS IN PLACE AND FRESH COATING OF SNOW IN MOST AREAS...
DECENT ALBEDO EFFECT FROM ABUNDANT SUNSHINE WILL LIKELY TO PUT AN
ADDITIONAL DAMPER ON TEMPS. NORTHEAST HALF OF THE FORECAST AREA ONLY
EXPECTED TO REACH ZERO TO 5 ABOVE...WHILE SOUTH CENTRAL SD PUSHES
TOWARD THE MID TEENS DURING THE DAYLIGHT HOURS.

WARM FRONT WILL MOVE ACROSS THE FORECAST AREA DURING THE EVENING AND
ANTICIPATE TEMPERATURES TO DIP A LITTLE JUST AFTER SUNSET...THEN
RISE 5-10 DEGREES THROUGH THE EVENING WITH MOST AREAS SEEING HIGHEST
TEMPS OF THE DAY AROUND MIDNIGHT. UNFORTUNATELY...WARMING WILL NOT
LAST LONG AS COMPACT WAVE DROPS SOUTHEAST AND DRAGS ANOTHER ARCTIC
FRONT THROUGH THE REGION AFTER MIDNIGHT AND DROPS TEMPERATURES BACK
INTO THE SINGLE DIGITS ACROSS THE NORTHERN CWA BY DAYBREAK TUESDAY.
GREATER LIFT WITH THE WAVE SHOULD REMAIN NORTH OF OUR AREA. HOWEVER
MODEST AMOUNT OF LOW-MID LEVEL MOISTURE INCREASE WITH TEMPS FIRMLY
IN FAVORED SNOW GROWTH RANGE...SO HAVE ADDED SOME LOW POPS FOR A FEW
HOURS THIS EVENING TO NORTHERN PARTS OF THE FORECAST AREA. SHOULD
ONLY BE A HUNDREDTH OF AN INCH QPF IF THAT...BUT SNOW RATIOS NEAR
20-1 COULD PRODUCE A DECENT DUSTING IN SOME AREAS. ALSO ADDED
MENTION OF BLOWING SNOW TONIGHT...MAINLY TO HIGHER ELEVATIONS FROM
EAST CENTRAL SD INTO SOUTHWEST MINNESOTA...WHERE WE COULD SEE GUSTY
SOUTHWEST WINDS AHEAD OF THE WAVE THIS EVENING...AND STRONGER WEST
TO NORTHWEST FLOW AS THE ARCTIC FRONT PASSES THROUGH OVERNIGHT.

.LONG TERM...(TUESDAY THROUGH SUNDAY)
ISSUED AT 315 AM CST MON DEC 9 2013

TUESDAY WILL BRING A CLIPPER WITH ANOTHER ARCTIC FRONT MOVING
INTO THE AREA...WITH THIS SYSTEM EXPECTED TO PASS QUICKLY
SOUTHEAST OF THE AREA BY LATE TUESDAY NIGHT. A BAND OF LIGHT SNOW
IS EXPECTED TO PEAK EARLY TUESDAY EVENING. THE SYSTEM WILL HAVE A
WNW/ESE AXIS... PROBABLY BETWEEN THE GEM/CANADIAN AND EC
SOLUTIONS...OR NORTH OF THE NAM AND GFS. WITH THE MEAGER MOISTURE
AND RAPID SPEED OF THE SYSTEM...AM PEAKING POPS AT 50 PERCENT TOPS
AND KEEPING ACCUMULATIONS LESS THAN ONE INCH. WE SHOULD OF COURSE
BE ABLE TO PINPOINT TRACK AND TIMING DETAIL BETTER DURING THE NEXT
COUPLE FORECAST CYCLES...AND INCREASE THE PEAK THREAT...AT LEAST
ON POPS. THIS SYSTEM WILL BE QUICKLY FOLLOWED BY A SPEEDY ARCTIC
HIGH WHICH SHOULD GENERALLY CLEAR SKIES OUT BY EARLY WEDNESDAY
MORNING. GUIDANCE TEMPERATURES STILL LOOK SEVERAL DEGREES TOO WARM
FOR TUESDAY NIGHT AND WEDNESDAY...SO WILL CONTINUE TO UNDERCUT
SAID GUIDANCE...IN FACT BY A BIT MORE THAN ON EARLIER FORECAST.
EVEN WITH MODEST WINDS...WIND CHILLS COULD TAKE ANOTHER ADVISORY
LEVEL DIP BY WEDNESDAY MORNING.

WEDNESDAY NIGHT IS FORECAST TO BE A TIME OF STRONG WARMING
ALOFT...AND TO SOME EXTENT AT THE SURFACE ALSO AFTER A RATHER
SLIGHT EARLY EVENING DROP. THE WARMING WILL PEAK THURSDAY BUT IT
SHOULD STILL BE RELATIVELY MILD...WITH TEMPERATURES IN SHOUTING
DISTANCE OF NORMAL...THROUGH FRIDAY. THERE IS SOME VARIANCE IN
MODEL SOLUTIONS ON THE STRENGTH OF AN EXPECTED SATURDAY COLD
INTRUSION. WILL GO WITH EXTENDED GUIDANCE WHICH KEEPS THE COLD
INTRUSION MODERATE AND IS WARMING THINGS UP ALREADY AGAIN FOR
SUNDAY...AND THIS IS WHAT THE GFS IS SHOWING. THE EC SHOWS A
STRONGER COLD SHOT FOR SATURDAY AND DELAYS MOST OF THE WARMING
UNTIL AFTER SUNDAY. WILL GO WITH A SLIGHT CHANCE OF LIGHT SNOW
NORTHEAST FRIDAY NIGHT AND SATURDAY AS THE COLDER AIR COMES
IN...BUT AM NOT THINKING WIDESPREAD SNOW AT THIS TIME.

&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z TUESDAY AFTERNOON)
ISSUED AT 1147 AM CST MON DEC 9 2013

VFR CONDITIONS WILL CONTINUE THROUGH THE DAY. A WAVE PASSING BY
TONIGHT MAY BRING A PERIOD OF FLURRIES OR LIGHT SNOW TO THE AREA. AND
WITH WINDS PICKING UP...A PERIOD OF MVFR OR BRIEFLY IFR VISIBILITIES
ARE POSSIBLE...MAINLY ALONG AND NORTH OF INTERSTATE 90...ALTHOUGH
COULD EVEN SEE SOME FLURRIES FURTHER SOUTH. WINDS THEN TURN
NORTHWESTERLY BEHIND THE COLD FRONT...WITH GUSTS AROUND 30 KTS LIKELY
AFTER MIDNIGHT INTO THE EARLY MORNING HOURS. SIGNS THAT SOME MVFR
STRATUS COULD LINGER BEHIND THE FRONT...WHICH IF IT DOES...CLOUD
TEMPERATURES WOULD BE COLD ENOUGH TO SUGGEST WE COULD GET SOME
FLURRIES OUT OF THE CLOUDS. WHICH COMBINED WITH THE WIND...COULD
CONTINUE TO CAUSE PERIODIC VISIBILITY REDUCTIONS INTO THE EARLY
MORNING HOURS. VFR CONDITIONS SHOULD BECOME WIDESPREAD AGAIN BY MID
MORNING WITH WINDS BEGINNING TO DIMINISH SOME AS WELL.

&&

.FSD WATCHES/WARNINGS/ADVISORIES...
SD...WIND CHILL ADVISORY UNTIL NOON CST TODAY FOR SDZ038>040-050-
     052>071.

MN...WIND CHILL ADVISORY UNTIL NOON CST TODAY FOR MNZ071-072-080-081-
     089-090-097-098.

IA...WIND CHILL ADVISORY UNTIL NOON CST TODAY FOR IAZ001>003-012>014-
     020>022-031-032.

NE...WIND CHILL ADVISORY UNTIL NOON CST TODAY FOR NEZ013-014.

&&

$$

UPDATE...CHENARD
SHORT TERM...JH
LONG TERM...
AVIATION...CHENARD