Area Forecast Discussion
Issued by NWS Sioux Falls, SD

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000
FXUS63 KFSD 142049
AFDFSD

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SIOUX FALLS SD
249 PM CST SUN DEC 14 2014

.SHORT TERM...(THIS EVENING THROUGH MONDAY)
ISSUED AT 248 PM CST SUN DEC 14 2014

LARGE...MOIST ALMOST SPRING LIKE SYSTEM REALLY GETTING WRAPPED UP
THIS AFTERNOON IN NORTH TEXAS. AT THE SURFACE THE COLD FRONT HAS
WORKED ACROSS MOST OF SOUTH DAKOTA AND WAS APPROACHING SIOUX FALLS
AT 2030Z. STARTING TO BECOME CONCERNED THAT THIS SURGE EAST OF THE
LOW LEVEL COLD AIR AND THE VERY WOUND UP NATURE OF THE UPPER LOW
WILL BRING A BIGGER THREAT FOR FREEZING PRECIPIATION THAN PREVIOUSLY
THOUGHT. LATEST TREND IN THE 18Z NAM HINTS THAT THIS MAY BE THE CASE
AS THE WARM LAYER ALOFT STILL IN PLACE THROUGH 18Z OVER MUCH OF
SOUTHWEST MINNESOTA AND FAR EASTERN SD. THIS CONTINUES TO LOOK LIKE
THE FOCAL POINT WHERE THE WARM MOIST AIR ALOFT WRAPS BACK FROM THE
NORTHEAST OVER THE TOP OF THE COLDER AIR AT THE SURFACE. WILL OPT
FOR A WARNING OVER A HANDFUL OF COUNTIES IN THIS AREA AS ICING
POTENTIAL LOOKS TO BE ABOUT 2 TENTHS OF AN INCH...AND POSSIBLY A
LITTLE MORE...COUPLED WITH THE LIKELIHOOD OF 2 TO 3 INCHES OF SNOW
IN THE AFTERNOON AND EVENING AND NORTH WINDS LIKELY GUSTING TO ABOUT
35 TO 40 MPH.  STILL SOME HOPE THAT SURFACE TEMPERATURES DOWN THE
INTERSTATE 29 CORRIDOR COULD STAY JUST A TOUCH ABOVE FREEZING BUT
THAT HOPE IS BEGINNING TO DWINDLE A BIT AS THIS COLDER AIR SURGES
EAST TODAY AND THE WARM LAYER ALOFT STAYS IN PLACE A BIT LONGER.

ANOTHER AREA OF CONCERN WILL BE OVER PARTS OF SOUTH CENTRAL SOUTH
DAKOTA WHERE THE INITIAL SURGE OF THE COLD FRONT ALOFT/PV ANOMOLY
SWINGS NORTH TONIGHT AND REALLY LOOKS TO INTERACT NICELY WITH THE
LOW LEVEL THERMAL GRADIENT THAT IS DEVELOPING RIGHT NOW. MODELS IN
VERY GOOD AGREEMENT WITH OVERALL PRECIPITATION AMOUNTS WITH ONLY THE
ECMWF A LITTLE FARTHER SOUTH ON THE LOCATION OF THE HEAVIEST
PRECIPITATION. SINCE THE ECMWF DYNAMICS ARE IN FAIRLY CLOSE
ALIGNMENT WITH THE OTHER MODELS WILL KEEP AXIS OF HIGHEST
PRECIPITATION PRETTY CLOSE TO PREVIOUS FORECAST.

ON A SIDE NOTE NOT OUT OF THE QUESTION TO HEAR A RUMBLE OF THUNDER
NEAR SIOUX CITY INTO PARTS OF NORTHWEST IOWA AS SOUNDINGS HINTING AT
JUST A TOUCH OF ELEVATED INSTABILITY EARLY THIS EVENING.

AS THE WAVE SHIFTS EAST ON MONDAY THE TROWAL COLLPASES AND THE MAJOR
THREAT FOR ICING WILL END. EXPECTING MAINLY A BRIEF ONE TO TWO HOUR
TRANSITION WINDOW FROM RAIN TO MINOR ICING TO SNOW OVER THE
REMAINDER OF SOUTHEAST SD INTO NORTHWEST IOWA. THE SNOW WILL THEN
BUILD INTO THE AREA WITH THE HEAVIEST AMOUNTS FROM ABOUT LAKE ANDES
TO BROOKINGS. OTHER THAN CHARLES MIX AND GREGORY COUNTIES AREAS TO
THE NORTH WILL SEE SOMETHING CLOSER TO 3 TO 5 INCHES.

.LONG TERM...(MONDAY NIGHT THROUGH SUNDAY)
ISSUED AT 248 PM CST SUN DEC 14 2014

RELATIVELY QUIET PERIOD IN THE EXTENDED AS EARLY WEEK SYSTEM LIFTS
TO THE NORTHEAST AND SECOND SYSTEM DIVES INTO THE GREAT LAKES
REGION. THIS SYSTEM REMAINS CUT OFF FROM THE JET STREAM WHICH IS
CONCENTRATED ACROSS THE SOUTHERN US...SO SYSTEM IS RELATIVELY SLOW
TO MOVE.  AS THE PATTERN GRADUALLY EVOLVES...EXPECT UPPER LEVEL
RIDGE TO BUILD ACROSS THE NORTH PLAINS LATE IN THE WEEK.  MODELS
HAVE COME INTO BETTER AGREEMENT ON LATE WEEK SYSTEM AS ENERGY
REMAINS CONCENTRATED SOUTH OF THE FORECDAST AREA UNDER THE JET.  AS
SUCH...HAVE A DRY FORECAST THROUGH THE PERIOD.  IN
GENERAL...TEMPERATURES APPEAR TO BE FAIRLY SEASONAL...WITH THE
COOLEST TEMPERATURES TUESDAY NIGHT AS WEAK SURFACE RIDGE BUILDS INTO
THE AREA FROM THE NORTH.  THEREAFTER...A GRADUAL WARMING TREND IS
EXPECTED THROUGH THE WEEKEND.

&&

.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z MONDAY MORNING)
ISSUED AT 547 AM CST SUN DEC 14 2014

IFR-LIFR CONDITIONS WILL DOMINATE THROUGH THE PERIOD...THOUGH
BRIEF IMPROVEMENT TO MVFR-LOW END VFR IS POSSIBLE...MAINLY IN
AREAS WEST OF THE I-29 CORRIDOR. PRIMARILY LIGHT-MODERATE DRIZZLE
AND FOG THROUGH THE DAY WILL GRADUALLY INCREASE TO BONAFIDE RAIN
SPREADING OVER THE AREA TONIGHT. LOCATIONS WEST OF I-29 WILL SEE
THE RAIN BECOME A WINTRY MIX OF FREEZING RAIN/SLEET AFTER 06Z AS
COLDER SURFACE AIR BEGINS TO UNDERCUT LINGERING WARM LAYER ALOFT.
EVENTUALLY THE MIXED PRECIPITATION WILL SWITCH TO SNOW AS LAYERS
ALOFT COOL...HOWEVER THIS NOT LIKELY TO OCCUR AT KHON UNTIL AFTER
THIS TAF PERIOD.


&&

.FSD WATCHES/WARNINGS/ADVISORIES...
SD...WINTER WEATHER ADVISORY FROM 4 AM TO 6 PM CST MONDAY FOR SDZ039-
     053-054-059-060-065-068.

     WINTER STORM WARNING FROM 8 AM TO 6 PM CST MONDAY FOR SDZ040-056.

     WINTER WEATHER ADVISORY FROM 8 AM TO 6 PM CST MONDAY FOR SDZ055-
     061-062-066-069.

     WINTER WEATHER ADVISORY FROM MIDNIGHT TONIGHT TO 6 PM CST MONDAY
     FOR SDZ052-057-058-064.

     WINTER STORM WARNING FROM MIDNIGHT TONIGHT TO 6 PM CST MONDAY
     FOR SDZ050-063.

MN...WINTER STORM WARNING FROM 8 AM TO 6 PM CST MONDAY FOR MNZ071-072-
     080-097.

     WINTER WEATHER ADVISORY FROM 8 AM TO 6 PM CST MONDAY FOR MNZ081-
     089-098.

IA...NONE.
NE...NONE.
&&

$$

SHORT TERM...08
LONG TERM...
AVIATION...JH



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