Area Forecast Discussion
Issued by NWS Sioux Falls, SD

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FXUS63 KFSD 181736
AFDFSD

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SIOUX FALLS SD
1136 AM CST TUE NOV 18 2014

.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 344 AM CST TUE NOV 18 2014

STRATUS CONTINUES TO STREAM SOUTHWARD ACROSS THE AREA THIS
MORNING...KEEPING TEMPERATURES FROM FALLING OFF AS MUCH AS
PREVIOUSLY THOUGHT. BECAUSE OF THIS...WIND CHILL VALUES HAVE
GENERALLY REMAINED IN THE SINGLE DIGITS BELOW ZERO ACROSS THE ENTIRE
AREA...WHICH IS FAR SHY OF WIND CHILL ADVISORY CRITERIA...SO WENT
AHEAD AND CANCELLED THE CURRENT WIND CHILL HEADLINE REMAINING OVER
SOUTHWESTERN MINNESOTA AND PORTIONS OF NORTHWESTERN IOWA.

OTHERWISE...THE MAIN CHALLENGE TODAY WILL BE THE EXTENT OF CLOUD
COVER AND POSSIBLE IMPACT ON TEMPERATURES. MODEL RH TIME SECTIONS
INDICATE THE LOWER CLOUDS CURRENTLY OVER THE AREA TO SLOWLY PULL OFF
TO THE EAST INTO EARLY AFTERNOON...THOUGH QUICKLY FOLLOWED BY
INCREASING MID CLOUDS OUT AHEAD OF THE NEXT SYSTEM TO IMPACT THE
AREA. SO THINKING THAT THE OVERALL THEME FOR THE DAY WILL BE MOSTLY
CLOUDY SKIES WITH SOME POSSIBLE BREAKS IN THE MID AFTERNOON. WITH AN
APPROACHING SURFACE TROUGH FROM THE WEST...WINDS WILL PULL AROUND TO
THE SOUTHWEST BY AFTERNOON...AND IN A WARM AIR ADVECTION REGIME WILL
SEE TEMPERATURES CLIMB OVER YESTERDAY...THOUGH POSSIBLY STUNTED
SOMEWHAT BY THE AFOREMENTIONED CLOUD COVER AND SNOW ON THE GROUND. AT
THIS POINT...LOOKING AT HIGHS IN THE TEENS OVER OUR NORTHEASTERN
ZONES TO NEAR 30 OVER SOUTH CENTRAL SOUTH DAKOTA.

BY TONIGHT A COLD FRONT SWINGS ACROSS THE REGION...AND WITH RAPID
SURFACE PRESSURE RISES IN A COLD AIR ADVECTION REGIME NORTHWESTERLY
WINDS WILL BEGIN TO PICK UP OVERNIGHT. THIS MAY RESULT IN SOME
PATCHY BLOWING SNOW...AND MAY GET ENOUGH FORCING AS A SHORTWAVE
DROPS SOUTHWARD ON A NORTHWESTERLY UPPER LEVEL FLOW TO KICK OFF SOME
VERY LIGHT MEASURABLE SNOW THROUGH OUR NORTH AND EAST...AS WELL AS
BRING SCATTERED FLURRIES OUTSIDE OF THIS AREA...WHICH WILL OF COURSE
VERY BRIEFLY AGGRAVATE VISIBILITIES EVEN MORE. AS THE WINDS PICK UP
TONIGHT...ENHANCED MIXING WILL ALLOW FOR STEADY OR SLOWLY RISING
TEMPERATURES...BEFORE THE COLD AIR ADVECTION WINDS OUT WITH READINGS
BEGINNING TO FALL OFF BY VERY LATE TONIGHT. WILL PROBABLY GENERALLY
REACH OUR OVERNIGHT LOWS AFTER 12Z ON WEDNESDAY WHEN READINGS WILL
BE MAINLY IN THE TEENS...TO AROUND 20 THROUGH THE MISSOURI RIVER
CORRIDOR.

.LONG TERM...(WEDNESDAY THROUGH MONDAY)
ISSUED AT 344 AM CST TUE NOV 18 2014

OVERALL WEAK SUBSIDENCE IN POST-FRONTAL AIR MASS...BUT WITH SHALLOW
CONVECTIVE LAYER TAPPING TEMPS IN FAVORED SNOW-GROWTH ZONE...CANNOT
RULE OUT ISOLATED TO SCATTERED FLURRIES THROUGH THE DAY WEDNESDAY.
THIS ALONG WITH CONTINUED GUSTY NORTHWEST WINDS WILL MAINTAIN THREAT
OF SOME SPOTTY BLOWING SNOW AS WELL...WITH LOWER VISIBILITY LARGELY
TIED TO ANY FLURRIES IN THE AREA.

COLD AIR SETTLES BACK INTO THE REGION THROUGH THURSDAY AS SURFACE
RIDGE SLIDES ACROSS THE AREA. SOUTHERLY WINDS AND INCREASING CLOUDS
THURSDAY NIGHT SHOULD LIMIT TEMPERATURE FALL...WITH READINGS LIKELY
RISING IN SOME SPOTS DURING THE LATTER HALF OF THE NIGHT. STRONG
WARMING ALOFT SEEN FRIDAY THROUGH SATURDAY NIGHT...AND WHILE FULL
WARMING WILL LIKELY NOT BE SEEN AT THE SURFACE...SHOULD BE ABLE TO
PUSH READINGS INTO THE 30S ACROSS THE SOUTHWEST CWA FRIDAY...AND
OVER MOST OF THE FORECAST AREA ON SATURDAY AND SUNDAY. POTENTIAL FOR
INCREASING LOW LEVEL MOISTURE TO BECOME TRAPPED BENEATH FAIRLY STOUT
INVERSION...AND WITH WEAK WARM ADVECTION ABOVE THIS LAYER...WILL
HAVE TO WATCH FOR POSSIBLE DRIZZLE/FREEZING DRIZZLE FRIDAY/FRIDAY
NIGHT.

GENERAL MODEL CONSENSUS HOLDS SOUTHERN STREAM SYSTEM WELL SOUTHEAST
OF THE AREA...KEEPING MOST OF OUR FORECAST AREA DRY SATURDAY THROUGH
SUNDAY. ATTENTION THEN TURNS TO NORTHERN STREAM WAVE DIGGING INTO
THE NORTHERN PLAINS/UPPER MIDWEST SUNDAY NIGHT THROUGH MONDAY. BOTH
GFS AND ECMWF HAVE AT LEAST LIGHT PRECIP SPREADING INTO THE REGION
WITH THIS SYSTEM...AND DESPITE WARM WEEKEND...TEMPS COOL ENOUGH WITH
THE WAVE TO PRODUCE MAINLY SNOW TO START THE WORK WEEK.

&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z WEDNESDAY AFTERNOON)
ISSUED AT 1133 AM CST TUE NOV 18 2014

BACK EDGE OF THE CLOUD COVER WILL SHIFT THROUGH SIOUX FALLS
TEMPORARILY LEADING TO MVFR CONDITIONS. OTHERWISE...VFR CONDITIONS
ARE EXPECTED TO PREVAIL TILL A COLD FRONT MOVES THROUGH TONIGHT.
CONDITIONS WILL BE FAR FROM PRISITINE THOUGH...AS STILL EXPECTING
MID LEVEL CLOUDS TO INCREASE THIS AFTERNOON. BEHIND THE
FRONT...GUSTY NORTHWEST WINDS WILL PREVAIL WITH MVFR CONDITIONS
AND LIGHT SNOW...ESPECIALLY ACROSS SOUTHWEST MN.

&&

.FSD WATCHES/WARNINGS/ADVISORIES...
SD...NONE.
MN...NONE.
IA...NONE.
NE...NONE.
&&

$$

SHORT TERM...JM
LONG TERM...JH
AVIATION...



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