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000
FXUS63 KFSD 101811
AFDFSD

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SIOUX FALLS SD
111 PM CDT MON MAR 10 2014

.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 406 AM CDT MON MAR 10 2014

ANOTHER MILD DAY ACROSS THE AREA...ALTHOUGH A WEAK COLD FRONTAL
PASSAGE WILL MEAN SLIGHTLY COOLER TEMPERATURE PROFILES THAN
YESTERDAY. CLOUD COVER WILL BE AT A MINIMUM THIS MORNING...BUT HIGH
AND MID LEVEL CLOUDS SHOULD INCREASE THROUGH THE DAY. THESE MAY END
UP A BIT THICKER THAN YESTERDAY...AND COULD THUS IMPACT HIGHS
SOME...ALTHOUGH STILL NOT EXPECTING A MAJOR IMPACT. ADJUSTED HIGHS
SOME BASED ON YESTERDAYS 925 MB TEMPERATURES AND RESULTING HIGHS
COMPARED TO TODAYS EXPECTED 925 MB READINGS. RESULT WAS TO INCREASE
THINGS A COUPLE DEGREES IN THE SNOW FREE AREA FROM PREVIOUS
FORECAST...WITH MID 60S COMMON. KEPT READINGS IN THE UPPER 40S TO
AROUND 50 IN THE SNOWPACK REGION...A FEW DEGREES WARMER THAN
TODAY...WHICH SEEMS TO MAKES SENSE GIVEN THE WARMER START.

ATTENTION THEN TURNS TO OUR NEXT SYSTEM WHICH BEGINS TO MOVE IN
MONDAY NIGHT. STRONG FRONTOGENESIS INTERACTING WITH THE APPROACHING
WAVE AND AN UPPER JET STREAK TO OUR NORTH...WILL RESULT IN
INCREASING LIFT AND SATURATION CROSS THE CWA. GIVEN THE INITIALLY
WARM BOUNDARY LAYER...EXPECTING PRECIPITATION TO START AS RAIN. AS
THE HEAVIER PRECIPITATION MOVES IN...THE BOUNDARY LAYER SHOULD COOL
ALLOWING A MIX AND CHANGEOVER TO SNOW. 0Z NAM AGAIN WAS AN
OUTLIER...AND EVEN IN DISAGREEMENT WITH THE SREF. THUS CONTINUED TO
STAY CLOSE TO A BLEND OF THE GFS...ECMWF AND SREF FOR QPF AND
TIMING. THIS BRINGS THE PRECIPITATION INTO OUR WEST AROUND
MIDNIGHT...SPREADING ACROSS THE HIGHWAY 14 CORRIDOR IN THE EARLY
MORNING HOURS...AND SINKING SOUTH TOWARDS INTERSTATE 90 IN THE 4 AM
TO 7 AM RANGE. GOING POPS LOOKED IN REAL GOOD SHAPE WITH REGARDS TO
LOCATION AND TIMING...AND MAIN ADJUSTMENT WAS JUST TO INCREASE POPS
AROUND MARSHALL...AS MODELS CONTINUE TO CONVERGE ON A MORE NORTHERN
INITIAL BAND PLACEMENT. AGAIN PRECIPITATION SHOULD BE MAINLY RAIN FOR
THE FIRST COUPLE HOURS...BEFORE GOING OVER TO SNOW. THROUGH
12Z...EXPECT SNOW ACCUMULATIONS OF AN INCH OR TWO ALONG HIGHWAY
14...AND LESS THAN AN INCH FURTHER SOUTH BETWEEN HIGHWAY 14 AND
INTERSTATE 90.

.LONG TERM...(TUESDAY THROUGH SUNDAY)
ISSUED AT 406 AM CDT MON MAR 10 2014

STRONG FRONTOGENETIC BAND OF PRECIPITATION IS EXPECTED TO MIGRATE
THROUGH THE FORECAST AREA ON TUESDAY.  HAVE FOLLOWED THE 700-750 MB
FRONTOGENETIC FORCING AS IT SEEMS TO COINCIDE FAIRLY WELL WITH THE
UPPER LEVEL DIV Q ALOFT.  WITH STRONG ENOUGH DYNAMICS...EXPECT
PRECIPITATION TO CHANGE OVER TO SNOW AS THE BAND MIGRATES TO THE
SOUTH AND EAST THROUGH THE FORECAST AREA. OUTSIDE OF THE MAIN
BAND...TEMPERATURES MAY BE WARM ENOUGH IN THE NEAR SURFACE LAYER TO
ALLOW FOR A MIX OR LIGHT RAIN.  SNOW SHOULD BE FAIRLY WET...AND
SIDED WITH AN 11:1 SNOW RATIO.  HAVE NOT CHANGED POPS MUCH FROM
PREVIOUS FORECAST...THOUGH DID SLOW THE PROGRESSION SLIGHTLY THROUGH
THE AFTERNOON HOURS ON TUESDAY. WITH PRECIPITATION THROUGH THE
BETTER PART OF THE DAY...EXPECT TEMPERATURES TO REMAIN STEADY OR
FALL SLIGHTLY ESPECIALLY IN THE EAST WHERE THE COLD AIR ADVECTION IS
STRONGER.

TEMPERATURES APPEAR TO REBOUND FAIRLY QUICKLY WEDNESDAY THROUGH
FRIDAY AS WEST TO SOUTHWEST FLOW RETURNS TO THE REGION. ON
WEDNESDAY...FRONT ONLY WORKS THROUGH THE WESTERN HALF OF THE
FORECAST AREA THROUGH PERIOD...AND MODELS ARE NOW HINTING AT A BATCH
OF STRATUS COMING DOWN ACROSS THE EASTERN EDGE OF THE CWA.  BOTH THE
GFS AND GEM SUGGEST THE POTENTIAL FOR PRECIPITATION WITH THE
STRATUS...BUT WITH THE DENDRITIC LAYER REMAINING DRY HAVE KEPT THE
FORECAST DRY THROUGH THE PERIOD.  WARMER AIR SWEEPS ACROSS THE AREA
WEDNESDAY NIGHT AND WITH CLEARING SKIES AND SOUTHWEST FLOW ALOFT
TEMPS LOOK TO WARM ABOVE NORMAL THURSDAY INTO FRIDAY.  A WEAK WAVE
MOVES THROUGH THE AREA THURSDAY NIGHT INTO FRIDAY NIGHT BUT DOES NOT
HAVE ANY MOISTURE TO WORK WITH.  A SECOND WAVE FOLLOWS ON A SIMILAR
TRAJECTORY ON SATURDAY INTO SATURDAY NIGHT.  MODELS DIFFERING ON HOW
THIS WAVE EVOLVES...BUT THE CONSENSUS APPEARS TO TAKE THE BULK OF
THE FORCING SOUTH OF THE FORECAST AREA SO HAVE LOWERED POPS TO
SLIGHT CHANCE ACROSS MOST OF THE FORECAST AREA.

&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z TUESDAY AFTERNOON)
ISSUED AT 1259 PM CDT MON MAR 10 2014

VFR CONDITIONS ARE EXPECTED THROUGH ARE 06Z/TUESDAY. A BAND OF LIGHT
RAIN WILL SPREAD EASTWARD ACROSS HIGHWAY 14 CORRIDOR...THROUGH AREAS
NORTH OF I90 BETWEEN 06Z AND 12Z THEN TRACK SOUTH SOUTHEAST ACROSS
THE REMINDER OF THE FORECAST AREA AROUND 12Z THROUGH THE END OF THE
TAF PERIOD. EXPECT THE LIGHT RAIN TO QUICKLY TRANSITION TO A RAIN AND
SNOW MIX THEN TO ENTIRELY SNOWFALL AS THE PRECIPITATION INTENSITY
PICKS UP. MVFR CEILINGS ARE EXPECTED TO BECOME WIDESPREAD WITH THE
ARRIVAL OF PRECIPITATION...WITH VISIBILITY DECREASES TO MVFR AND IFR
EXPECTED - COULD EVEN SEE BRIEF PERIODS OF LIFR IN HEAVY SNOW BANDS.
CLOSER TO THE MISSOURI VALLEY...PRECIPITATION WILL MAINLY BE RAIN OR
A MIX WITH LESSER SNOW ACCUMULATIONS. WINDS WILL ALSO BE ON THE
INCREASE FROM THE NORTH DURING THE DAYTIME ON TUESDAY WITH GUSTS
CLOSE TO 30 KT POSSIBLE.

&&

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

$$

SHORT TERM...CHENARD
LONG TERM...
AVIATION...