000
FXUS63 KFSD 061124
AFDFSD

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SIOUX FALLS SD
524 AM CST FRI DEC 6 2013

.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 248 AM CST FRI DEC 6 2013

REALLY NOT MUCH GOING ON IN THE SHORT TERM TODAY AND TONIGHT OTHER
THAN THE EXTREME COLD. SEE NO REASON TO ALTER THE CURRENT WIND CHILL
HEADLINES AS THEY ARE STILL ON TRACK AND CERTAINLY WARRANTED. 925MB
WINDS REMAIN STIRRED UP TODAY...GENERALLY IN THE 15 TO 20 KNOT RANGE
DUE TO COLD AIR ADVECTION WHICH CONTINUES TO OOZE IN. THE WORST OF
THE ADVECTION IS OVER...BUT 925MB TEMPERATURES ARE ONLY -19F TO -20F
ACROSS OUR FORECAST AREA TODAY SO THE DAMAGE IS ALREADY DONE. HIGHS
TODAY WILL STRUGGLE TO CLIMB ABOVE ZERO FOR ALL LOCATIONS GENERALLY
ALONG AND NORTH OF INTERSTATE 90...WITH MODESTLY WARMER 6 OR 7
DEGREES AROUND SIOUX CITY AND STORM LAKE. THEREFORE WIND CHILL
VALUES WILL ONLY MODERATE TO -15F TO -20F FOR MANY LOCATIONS ALONG
AND NORTH OF THE I 90 CORRIDOR. TONIGHT...THE WINDS WILL FINALLY
BEGIN TO NOTCH DOWN A BIT...ESPECIALLY ALONG AND WEST OF INTERSTATE
29. BUT EAST OF I 29 WE ARE STILL LOOKING AT 925MB WINDS NEAR 20
KNOTS ALL THE WAY THROUGH 12Z SATURDAY. THIS WILL HAVE THE AFFECT OF
KEEPING SOUTHWEST MN AND THE IA GREAT LAKES REGION WARMER...USING
THAT TERM LOOSELY...WHEN COMPARED TO MANY AREAS WEST OF I 29. BUT
THE WIND CHILLS WILL STAY FRIGID OF COURSE. THOUGHT ABOUT EXTENDING
THE WIND CHILL ADVISORY SOUTHWARD FOR SIOUX CITY AND STORM LAKE
TONIGHT. HOWEVER THEY ARE JUST NOT AS SOLID ON THE CRITERIA AS AREAS
JUST TO THEIR NORTH. BUT IT WILL BE COLD EITHER WAY.

.LONG TERM...(SATURDAY THROUGH THURSDAY)
ISSUED AT 248 AM CST FRI DEC 6 2013

A COLD START SATURDAY MORNING WILL GIVE WAY TO STEADILY INCREASING
CLOUDS AS WARM ADVECTION GETS GOING AT SEVERAL LEVELS. THIS
HAPPENS AS DECENT WAVE DIGS INTO LONG WAVE TROUGH POSITION OVER
SOUTHWESTERN USA. THE EC HAS BEEN PERFORMING BETTER THAN THE
OPERATIONAL GFS AND NAM ON THESE SYSTEMS AND IS FOLLOWED OVER
THOSE TWO. THE GEM UPPER PATTERN DOES NOT LOOK BAD BUT IT HANDLES
THE MOISTURE PATTERN POORLY. GOOD THERMAL ADVECTION PATTERN
DEVELOPS FOR BROAD ISENTROPIC LIFT AND RESULTING WIDESPREAD LIGHT
SNOW. THE LIGHT NATURE OF THE SNOW SHOULD BE ENHANCED SOME OVER
THE SOUTHEAST PART OF OUR FORECAST AREA DEPENDING ON THE STRENGTH
OF THE WAVE MOVING UP...AGAIN TRUST THE EC HERE...ESPECIALLY SINCE
IT DOES NOT LOOK LIKE AN EXTREME SOLUTION. TOTAL SNOWFALL SATURDAY
NIGHT THROUGH SUNDAY NIGHT COULD HIT 4 INCHES PLUS IN OUR
SOUTHEAST IF THIS VERIFIES...BUT WOULD NOT RULE OUT A SHARPER
SYSTEM AND THE POTENTIAL FOR MORE SNOWFALL. THE ABSENCE OF A RICH
MOISTURE SOURCE DUE TO THE COLD AIR DRIVING SO FAR SOUTH RULES OUT
ANY THOUGHT OF A WINTER STORM WATCH. ANYWAY...THE GFS AND
ESPECIALLY THE NAM APPEAR TO HANDLE POORLY THE BROAD LIFT
POTENTIAL OF THIS SYSTEM. THE SYSTEM SHOULD MOVE QUICKLY EAST OF
THE AREA SUNDAY NIGHT AS CANADIAN WAVE APPROACHING FROM THE
NORTHWEST FORCES IT ACROSS.

AFTER TEMPERATURES WARM SOME...ESPECIALLY ON LOWS...OVER THE
WEEKEND...ANOTHER COLD AIR BLAST WILL SPREAD IN SUNDAY NIGHT AND
MONDAY WITH THE ABOVE MENTIONED CANADIAN WAVE. A FAST MOVING
CLIPPER FOLLOWING IT SHOULD LIMIT THE WORST OF THIS NEXT COLD AIR
BLAST IN DURATION...AND MAY ALSO BRING SOME LIGHT SNOW OR FLURRIES
TO OUR NORTHEAST CORNER. AFTER THIS PASSES...A GRADUAL WARMING
SHOULD LAST THROUGH THE END OF THE WEEK...AND TAKE THE AREA OUT OF
THIS ARCTIC STRETCH. THE CHANCES OF LIGHT PRECIPITATION AFTER THE WEAK
MONDAY NIGHT SYSTEM SEEMING TOO SLIM TO MENTION AT THIS TIME.

&&

.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z SATURDAY MORNING)
ISSUED AT 522 AM CST FRI DEC 6 2013

ASIDE FROM LOCALIZED IFR STRATUS THIS MORNING ALONG THE MO RIVER
IN OUR SOUTH CENTRAL SD ZONES...CONDITIONS WILL BE VFR TODAY AND
TONIGHT.

&&

.FSD WATCHES/WARNINGS/ADVISORIES...
SD...WIND CHILL ADVISORY UNTIL 9 AM CST SATURDAY FOR SDZ038>040-050-
     052>071.

MN...WIND CHILL ADVISORY UNTIL 9 AM CST SATURDAY FOR MNZ071-072-080-
     081-089-090-097-098.

IA...WIND CHILL ADVISORY UNTIL 9 AM CST SATURDAY FOR IAZ001>003-
     012>014.

     WIND CHILL ADVISORY UNTIL NOON CST TODAY FOR IAZ020>022-031-032.

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

&&

$$

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