Area Forecast Discussion
Issued by NWS Sioux Falls, SD

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FXUS63 KFSD 211721
AFDFSD

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SIOUX FALLS SD
1121 AM CST WED JAN 21 2015

.UPDATE...
ISSUED AT 1114 AM CST WED JAN 21 2015

HAVE TWEAKED THE FORECAST A COUPLE OF TIMES THIS MORNING...BUT
OVERALL THE TRENDS ARE STILL ON TRACK. LOOKING AT UPSTREAM RADAR
AND OBSERVATIONS...THERE REALLY IS NOT A WHOLE LOT GOING ON. THIS
AFTERNOON WILL LIKELY JUST SEE OCCASIONAL FLURRIES DOTTED
THROUGHOUT THE FORECAST AREA WITH A MINIMAL CHANCE THAT ANY SNOW
WILL ACTUALLY STICK...ESPECIALLY NOTING THE AFTERNOON TEMPERATURES
WHICH WILL BE MILD FOR THIS TIME OF YEAR.

&&

.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 317 AM CST WED JAN 21 2015

THE PRIMARY CONCERNS THROUGH THE FORECAST REMAIN WITH LIGHT SNOW
CHANCES TODAY...DEGREE OF WARMUP INTO THIS WEEKEND...AND WEAK SYSTEM
MOVING THROUGH THE REGION SATURDAY NIGHT INTO SUNDAY.  THE
PREVAILING THEME THROUGH OUT THE FORECAST CONTINUES TO ADVERTISE
ABOVE NORMAL TEMPERATURES THROUGH THE END OF THE MONTH.

EARLY THIS MORNING...VERY LIGHT SNOW CONTINUES TO ROTATE THROUGH THE
AREA AS ONE PV ANOMALY PIVOTS THROUGH NORTH CENTRAL IOWA AND A
SECOND WAVE BEGINS TO DROP SOUTHWARD INTO NORTH CENTRAL SD. AS THE
FIRST WAVE CONTINUES TO MOVE SOUTHEAST...EXPECTING A BIT OF A
DROPOFF IN PRECIP THROUGH THE MORNING HOURS...WITH SOME CONTINUED
LIGHT SNOWS ALONG INVERTED TROUGH AXIS STRETCHED BACK NW THROUGH
THE CWA. SECOND SHORTWAVE WILL ROTATE INTO THE AREA LATER BY MID-
DAY...BUT GIVEN THE OPEN NATURE OF THE WAVE...LARGE SCALE LIFT IS
NOT EXPECTED TO BE THAT STRONG. NEVERTHELESS...SOUNDINGS CONTINUE
TO SHOW SATURATION PERIODICALLY DEEP ENOUGH TO PRODUCE LIGHT SNOWS
THROUGH THE AFTERNOON HOURS. ACCUMULATIONS WILL CONTINUE TO BE
VERY LIGHT...WITH AN ADDITIONAL TENTH OR TWO THROUGH THE DAY.

LIGHT SNOW OR FLURRIES MAY CONTINUE WELL INTO THE OVERNIGHT
HOURS...BEFORE BACK EDGE OF UPPER TROUGH SWINGS THROUGH BY
DAYBREAK THURSDAY.

.LONG TERM...(THURSDAY THROUGH TUESDAY)
ISSUED AT 317 AM CST WED JAN 21 2015

FROM THURSDAY THROUGH SATURDAY...THE PREVAILING THEME WILL BE ABOVE
NORMAL TEMPERATURES AS SURFACE WINDS SWING TO THE SOUTHWEST AND LOW
LEVEL WARM ADVECTION INTENSIFIES. TEMPERATURES WILL WARM INTO THE
30S TO NEAR 40 IN THE MISSOURI RIVER VALLEY THURSDAY.  40S WILL
OVERSPREAD THE REGION ON FRIDAY AHEAD OF A WEAK SHORTWAVE ZIPPING
THROUGH THE REGION.  GFS/NAM/EC INDICATE A NARROW CORRIDOR OF MID-
UPR LVL CLOUDS MOVING THROUGH FRIDAY AFTERNOON AND EVENING.  LATER
SHIFTS MAY NEED TO INTRODUCE A LOW END POP OR SPRINKLES.  ANOTHER
DAY IN THE 40S IS LIKELY ON SATURDAY AS WARM WESTERLY WINDS PREVAIL.

MODEL GUIDANCE REMAINS SPREAD OUT REGARDING UPPER TROUGH SWINGING
THROUGH THE AREA LATE SATURDAY INTO SUNDAY. GFS DIGGING THIS WAVE
MUCH DEEPER AND FURTHER WEST THAN THE EC/GEM OR ENSEMBLE GUIDANCE.
EITHER WAY...THIS CLIPPER WILL BE IN AND OUT OF THE REGION IN A
MATTER OF LESS THAN 12 HOURS. BRINGING THE POTENTIAL FOR A LIGHT
RAIN/SNOW MIXTURE INTO SUNDAY.

THE OUTLOOK INTO NEXT WEEK LOOKS QUIET AND WARM.  OBVIOUS
DISCREPANCIES REGARDING THE AMPLITUDE OF RIDGING OVER THE WESTERN
HALF OF THE CONUS...BUT THE PREVAILING THEME WOULD SUGGEST ABOVE
NORMAL TEMPERATURES AND NO MAJOR STORM SYSTEMS.

&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z THURSDAY AFTERNOON)
ISSUED AT 1114 AM CST WED JAN 21 2015

THIS AFTERNOON AND EVENING WILL LIKELY SEE MOSTLY MVFR TO LOWER
END VFR CONDITIONS THROUGHOUT THE FORECAST AREA. REDUCTIONS IN
VISIBILITY DUE TO SNOWFALL SHOULD NOT BE A GREAT CONCERN...AS ONLY
FLURRIES ARE BEING NOTED UPSTREAM FROM THE FORECAST AREA. A BIGGER
QUESTION CONCERNING THE CEILINGS ARRIVES AFTER EVENING TONIGHT.
WINDS OFF THE SURFACE IN THE 925MB-850MB LAYER BEGIN TO TURN
WESTERLY AFTER MIDNIGHT TONIGHT...THEN GO SOUTHWESTERLY THURSDAY
MORNING. THE CURRENT OBSERVATIONS ARE MAINLY SHOWING VFR IN
WESTERN AND CENTRAL NEBRASKA...SO ITS POSSIBLE THAT SOME DRIER LOW
LEVEL AIR MAY ENTRAIN IN LATER TONIGHT. THE TAFS WERE PLAYED THIS
WAY...BUT IT NEEDS TO BE NOTED THAT THE NAM DOES KEEP A LOT OF LOW
LEVEL MOISTURE AROUND THROUGH THE ENTIRE NIGHT AND THURSDAY
MORNING...WHEREAS THE GFS DRIES OUT THE LOWER LEVELS. FOR NOW...
FAVORED THE GFS.

&&

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

$$

UPDATE...MJ
SHORT TERM...DUX
LONG TERM...DUX
AVIATION...MJ



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