Area Forecast Discussion
Issued by NWS Sioux Falls, SD

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918
FXUS63 KFSD 092322
AFDFSD

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SIOUX FALLS SD
522 PM CST TUE FEB 9 2016

.SHORT TERM...(THIS EVENING THROUGH WEDNESDAY)
ISSUED AT 240 PM CST TUE FEB 9 2016

MAIN CONCERN IN THE SHORT TERM WILL BE THE INCREASING CHANCE OF
LIGHT SNOW LATE TONIGHT THROUGH THE DAY WEDNESDAY. LOW LEVEL
BAROCLINIC ZONE EXTENDING NORTH TO SOUTH ACROSS CENTRAL SOUTH DAKOTA
WILL BEGIN ADVANCING SLIGHTLY EASTWARD LATE TONIGHT...NEARING THE
JAMES RIVER VALLEY BY MID MORNING ON WEDNESDAY. MEANWHILE A MID
LEVEL WAVE DROPS SOUTH SOUTHEAST FROM CANADA...MOVING THROUGH THE
FORECAST AREA DURING THE DAY WEDNESDAY. WITH BROAD BUT WEAK LIFT AND
A MODEST FORCING...A BAND OF LIGHT SNOW NOSES INTO CENTRAL SD LATE
TONIGHT THEN SPREADS SOUTHEAST THROUGH THE REGION DURING THE DAY.

EXPECT SOME LIGHT SNOW LATE TONIGHT IN OUR FAR WEST...THEN SPREADS
INTO THE I29 CORRIDOR AROUND DAYBREAK THROUGH MID-MORNING AND ACROSS
OUR EASTERN HALF LATE MORNING. THE LIGHT SNOW EXITS WEST TO EAST IN
THE AFTERNOON. SOUTH CENTRAL SOUTH DAKOTA...WEST OF THE JAMES WHERE
SATURATION IN THE DENDRITIC LAYER WILL BE PROBLEMATIC...MAY NOT SEE
MUCH IN THE WAY OF PRECIPITATION. ELSEWHERE...ACCUMULATIONS WILL
RANGE FROM AROUND HALF INCH TO 2 INCHES OF FLUFFY SNOW. WITH
TEMPERATURES IN THE SINGLE DIGITS AND TEENS ACROSS OUR CENTRAL AND
EASTERN COUNTIES WHERE THE GREATEST SNOW CHANCES LIE...EXPECT SOME
FAIRLY HIGH RATIOS ON THE ORDER OF 15:1 TO 20:1. ALONG THE WESTERN
FRINGES OF THE PRECIPITATION SNOW WILL BE MUCH LESS EFFICIENT.

WITH THE THERMAL BOUNDARY ACROSS THE AREA...BOTH LOW AND HIGH
TEMPERATURES WILL VARY GREATLY. EXPECT LOWS TO PLUMMET TO A FEW
DEGREES EITHER SIDE OF ZERO IN OUR EXTREME EAST...WHILE WARM AIR
ADVECTION MOVING INTO OUR WESTERN BORDER AND INCREASING MID CLOUDS
WILL HOLD LOWS IN THE LOWER 20S IN OUR WEST. MAY EVEN SEE SOME NON
DIURNAL READINGS LATE TONIGHT IN THIS AREA. SIMILARLY....HIGHS ON
WEDNESDAY WILL RANGE FROM THE LOWER TEENS NEAR THE BUFFALO RIDGE AND
IOWA GREAT LAKES...TO THE MID 30S IN GREGORY COUNTY.

.LONG TERM...(WEDNESDAY NIGHT THROUGH TUESDAY)
ISSUED AT 240 PM CST TUE FEB 9 2016

AFTER LIGHT SNOW EXITS QUICKLY SOUTHEAST WEDNESDAY NIGHT...THURSDAY
LOOKS TO BE CHILLY...BUT QUIET FOR MOST AREAS. OUR NEXT CHANCE FOR
LIGHT SNOW WILL FALL QUICKLY ON THE HEELS OF WEDNESDAYS
SYSTEM...WITH ANOTHER MINOR SHORTWAVE TRACKING THROUGH THE BRISK
NORTHWESTERLY FLOW ALOFT.  MID-LVL LIFT...SLIGHTLY HIGHER THAN
WEDNESDAYS SYSTEM...WILL BEGIN TO OVERSPREAD THE REGION LATE ON
THURSDAY...WITH AN INCREASE IN UPPER SUPPORT PROVIDED BY LEFT EXIT
REGION OF AN INTENSIFYING JET STREAK CROSSING THE ROCKIES. WHILE
MODEL QPF REMAINS ON THE LIGHT SIDE...MODELS HAVE FOCUSED IN ON THE
POTENTIAL FOR PROLONGED LIGHT QPF OVER THE HEART OF THE CWA INTO
FRIDAY MORNING.  SNOW AMOUNTS SHOULD GENERALLY REMAIN UNDER AN INCH.

COLD HIGH PRESSURE WILL ENTER THE REGION ON FRIDAY...LINGERING INTO
THE UPCOMING WEEKEND. ECMWF/GFS DIFFER A BIT ON THE ARRIVAL OF THE
COLDEST AIR ON FRIDAY...BUT PREFER THE SLIGHTLY MORE AGGRESSIVE GFS.
THAT SAID...AREA SETTING UP FOR A VERY COLD START TO SATURDAY
MORNING....ESPECIALLY IN THE EASTERN ZONES. WITH MID-LVL WARM
ADVECTION QUICKLY DEVELOPING FRIDAY NIGHT AND A LIKELY INCREASE IN
CIRRUS IN THE NW FLOW...SOME CONCERNS THAT WESTERN ZONES MAY BE TOO
COLD. IF FORECAST DOES MATERIALIZE...ADVISORY CRITERIA WIND CHILLS
MAY BE FELT OVER PARTS OF MN/IA/SD COUNTIES INTO SATURDAY MORNING.

OUR NEXT CHANCE OF SNOW WILL ARRIVE SATURDAY INTO SUNDAY AS A FAIRLY
STRONG WAVE EXITS THE PACIFIC NORTHWEST AND ENTERS THE PLAINS
SATURDAY NIGHT. GFS MUCH STRONGER THAN THE ECMWF...AND THEREFORE
LIFTS WARM ADVECTION SNOW BAND QUICKLY THROUGH AND NORTHEAST OF THE
CWA. WITH A WEAKER ECMWF SOLUTION PREFERRED...FEEL THAT THIS SNOW
MAY STALL CLOSER TO THE CWA...AND ESPECIALLY THE NORTHEASTERN HALF OF
THE CWA. THIS SYSTEM WOULD HAVE THE HIGHEST RISK OF A FEW INCHES OF
SNOW...BUT THE TRACK IS VERY UNCERTAIN ATTM.

BEHIND THIS WEEKEND SYSTEM...TRENDS CONTINUE TO SUPPORT A WARMUP
INTO NEXT WEEK.

&&

.AVIATION...(FOR THE 00Z TAFS THROUGH 00Z WEDNESDAY EVENING)
ISSUED AT 520 PM CST TUE FEB 9 2016

VFR CONDITIONS THROUGH MOST OF TONIGHT WITH WINDS BECOMING LIGHT
AND VARIABLE. LIGHT SNOW WILL DEVELOP IN THE NORTH TOWARD 10Z THEN
OVERSPREAD THE AREA THROUGH WEDNESDAY MORNING...RESULTING IN
LOWERING CEILINGS AND REDUCED VISIBILITIES.

&&

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

$$

SHORT TERM...
LONG TERM...DUX
AVIATION...JM



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