Area Forecast Discussion
Issued by NWS Sioux Falls, SD

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000
FXUS63 KFSD 270519
AFDFSD

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SIOUX FALLS SD
1119 PM CST FRI DEC 26 2014

.SHORT TERM...(THIS EVENING)
ISSUED AT 329 PM CST FRI DEC 26 2014

UPPER LEVEL STILL ON TARGET TO MOVE OVER THE AREA THIS EVENING AND
OVERNIGHT.  WATER VAPOR IMAGERY DEPICTS THE WAVE QUITE WELL AND
SURPRISINGLY THE MODELS ARE HANDLING PRETTY WELL.  AS THE WAVE
APPROACHES...MID LEVEL CONVERGENCE WILL BE INCREASING ACROSS THE
SOUTHERN SECTIONS OF THE FORECAST AREA.  QG FORCING INITIALLY TO
WEST SOUTHWEST OF SIOUX FALLS AND AS THE NIGHT GOES ON...IT
GRADUALLY SHIFTS EAST.  WAS A LITTLE CONCERNED ABOUT SNOW AMOUNTS
ACROSS SOUTHEAST SOUTH DAKOTA...BUT MID LEVEL FRONT SHOULD SHIFT
EAST INTO NORTHWEST IOWA AND SOUTHWEST MINNESOTA SHORTLY AFTER
MIDNIGHT AND THEREBY TAKING HEAVIEST SNOW ALONG WITH IT.  WITH THE
STRONGEST FORCING THIS EVENING AND INTO THE EARLY OVERNIGHT
HOURS...MOST OF THE ACCUMULATION SHOULD OCCUR AT THAT TIME...BUT
WITH THE SLOWER SPEED OF THE SYSTEM THAN WHAT WAS EARLIER
FORECAST...HELD ONTO THE SNOW A LITTLE LONGER INTO SATURDAY MORNING
IN NORTHWEST IOWA AND SOUTHWEST MINNESOTA.  ALONG WITH THE SAME
THOUGHT PROCESS ON THE SPEED...I DECIDED TO START BOTH OF THE
ADVISORIES AT 00Z.  ALSO DECIDED TO ADD IDA AND BUENA VISTA COUNTIES
TO THE ADVISORY.  FEEL MOST OF THE HEAVIEST OF THE SNOW WILL STAY
NORTHWEST OF THOSE COUNTIES...BUT THERE COULD BE POCKETS OF AMOUNTS
THAT REACH THE CRITERIA.  PLUS THIS MATCHES UP WELL WITH SURROUNDING
OFFICES AS WELL.  TEMPS OVERNIGHT WONT CHANGE MUCH DUE TO CLOUD
COVER...BUT THERE SHOULD BE ENOUGH THINNING TO ALLOW TEMPS TO FALL
IN THE NORTHWEST PORTION OF THE CWA OR IN THE HURON AREA.

.LONG TERM...(SATURDAY THROUGH FRIDAY)
ISSUED AT 329 PM CST FRI DEC 26 2014

AS BAND OF SNOW SHIFTS EAST SATURDAY MORNING...EXPECT SKIES TO
GRADUALLY CLEAR THROUGHOUT THE DAY. 925 HPA TEMPS FALL THROUGHOUT
THE DAY...AND WITH CLEARING SKIES AND FRESH SNOW COVER...EXPECT
RELATIVELY SMALL RECOVERY IN TEMPERATURES THROUGH THE DAY.

MODEL SOUNDINGS SATURDAY NIGHT SHOW THE POTENTIAL FOR FOG ACROSS THE
AREA...BUT WITH TEMPERATURES REMAINING SUBFREEZING THROUGH THE DAY
THINK THIS IS MORE OF AN ARTIFACT OF THE COLD AIR THAN ANYTHING
ELSE...SO LEFT MENTION OF FOG OUT OF THE FORECAST FOR NOW.

TEMPERATURES ARE EXPECTED TO REMAIN NEAR SEASONAL LEVELS ON SUNDAY
AS BACK DOOR COLD FRONT APPROACHES FROM THE NORTH.  AS THE COLD
FRONT WORKS THROUGH SUNDAY NIGHT INTO MONDAY...COULD SEE SOME LIGHT
SNOWFALL ACROSS THE AREA AND HAVE CONTINUED CHANCE POPS FOR A LARGE
PORTION OF THE FORECAST AREA.

RELATIVELY COOL TEMPERATURES EXPECTED MUCH OF THE WEEK NEXT WEEK AS
ARCTIC AIRMASS MOVES IN AND 925 HPA TEMPS FALL TO AROUND -20 C.
HAVE SIDED TOWARDS THE COOLER SIDE OF GUIDANCE WITH SNOW COVER AND
THE EXPECTATION OF LIMITED SKY COVER.

TEMPERATURES ARE EXPECTED TO MODERATE WEDNESDAY INTO THURSDAY AHEAD
OF THE NEXT ARCTIC PUSH FROM THE NORTH.  PRECISE TIMING OF THIS NEXT
ARCTIC PUSH IS ILL DEFINED...BUT HAVE SIDED TOWARDS A SLIGHTLY
SLOWER PROGRESSION AND HAVE THUS KEPT THE POPS CONTAINED TO THE
NORTH ON FRIDAY.

&&

.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z SATURDAY NIGHT)
ISSUED AT 1119 PM CST FRI DEC 26 2014

SNOW BAND ACROSS THE AREA WILL PROVIDE THE GREATEST AVIATION
CONCERN OVER THE NEXT 6 HOURS. WIDESPREAD MVFR TO IFR CEILINGS
EXPECTED THROUGH THE NIGHT...AND INTO THE MORNING HOURS ACROSS
AREAS EAST OF INTERSTATE 29. AREAS WITHIN THE SNOW BAND WILL
FEATURE WIDESPREAD IFR AND BRIEFLY LIFR VISIBILITY. CONDITIONS
IN TERMS OF VISIBILITY WILL IMPROVE LATER NIGHT...WITH CEILINGS
BREAKING TO VFR GRADUALLY BY MIDDAY.

&&

.FSD WATCHES/WARNINGS/ADVISORIES...
SD...WINTER WEATHER ADVISORY UNTIL 9 AM CST SATURDAY FOR SDZ056-061-
     062-065>067.

     WINTER WEATHER ADVISORY UNTIL 6 AM CST SATURDAY FOR SDZ068>071.

MN...WINTER WEATHER ADVISORY UNTIL 9 AM CST SATURDAY FOR MNZ080-081-
     089-090-097-098.

IA...WINTER WEATHER ADVISORY UNTIL 9 AM CST SATURDAY FOR IAZ001>003-
     012>014-021-022-032.

     WINTER WEATHER ADVISORY UNTIL 6 AM CST SATURDAY FOR IAZ020-031.

NE...WINTER WEATHER ADVISORY UNTIL 6 AM CST SATURDAY FOR NEZ013-014.

&&

$$

SHORT TERM...HEITKAMP
LONG TERM...
AVIATION...CHAPMAN



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