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000
FXUS63 KFSD 132357
AFDFSD

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SIOUX FALLS SD
657 PM CDT SUN APR 13 2014

.SHORT TERM...(THIS EVENING THROUGH MONDAY)
ISSUED AT 350 PM CDT SUN APR 13 2014

TRICKY FORECAST THROUGH THE REMAINDER OF THE LATE AFTERNOON AND
EARLY EVENING...WITH POTENTIAL SNOW ACCUMULATION IN OUR SOUTHEAST
DEPENDENT ON SURFACE TEMPERATURES AND SNOWFALL RATES. PRESENT RADAR
SHOWING A BROAD AREA OF PRECIPITATION EXTENDING SOUTHWARD OF A LINE
RUNNING FROM YANKTON TO JACKSON...WITH MUCH OF THIS PRECIPITATION
HAVING CHANGED OVER TO SNOW. MOST PLACES IN THIS AREA REMAIN ABOVE
FREEZING THIS AFTERNOON...THOUGH HOVERING IN THE MID 30S. PER
WEBCAMS AND SPOTTERS...MUCH OF THIS SNOW IS NOT STICKING...THOUGH A
FEW LOCALES INDICATING A DUSTING OF SNOW ON GRASSY AREAS. THIS AREA
OF SNOW LOOKS TO BE ASSOCIATED WELL WITH 750 MB FRONTOGENESIS ACROSS
THE AREA. THERE IS THE POTENTIAL THROUGH THE LATE AFTERNOON FOR SOME
DECENT SNOWFALL RATES WITH STRONG MID LEVEL THETA E ADVECTION AND
STEEP MID LEVEL LAPSE RATES...THOUGH ACCUMULATIONS WILL BE HAMPERED
BY SURFACE TEMPERATURES SITTING JUST ABOVE FREEZING AND WARM GROUND
TEMPERATURES FROM THE RECENT WARM SPELL. AT THIS POINT...LOOKING FOR
POSSIBLY UP TO 2 INCHES THROUGH THE REMAINDER OF THE AFTERNOON IN A
HEAVIER BAND...THEN AN ADDITIONAL HALF AN INCH TO AN INCH THROUGH
THE EVENING HOURS SOUTH AND EAST OF SIOUX CITY TO SPENCER AS
DYNAMICS WEAKEN. HAVE ALSO BEEN SEEING SOME PLACES REACHING WIND
ADVISORY CRITERIA THROUGH THE AFTERNOON...THOUGH HAS BEEN MARGINAL
AND HIT AND MISS ACROSS THE CWA...SO ELECTED NOT TO ISSUE A WIND
ADVISORY. IN SPITE OF THE WINDS...WOULD NOT EXPECT MUCH IN THE WAY
OF BLOWING SNOW WITH THE VERY WET NATURE OF THE SNOW. BY MID EVENING
MOST OF THE ACTIVITY SHOULD BE PULLING OUT OF THE AREA...WITH SLOWLY
DECREASING CLOUDS AND TEMPERATURES FALLING DOWN INTO THE LOWER TO
MID 20S. WINDS WILL ONLY SLOWLY DIE OFF FROM THE WEST OVERNIGHT AS
THE GRADIENT WEAKENS AS THE SYSTEM PULLS AWAY.

HIGH PRESSURE BUILDS SOUTHWARD THROUGH THE REGION ON MONDAY...AND
WITH THERMAL PROFILES CONTINUING TO COOL...TEMPERATURES WILL REMAIN
WELL BELOW NORMAL WITH HIGHS IN THE UPPER 30S TO LOWER 40S. THE COLD
TEMPERATURES WILL BE AGGRAVATED BY NORTHWESTERLY WINDS OF 15 TO 20
KT RANGE.

.LONG TERM...(MONDAY NIGHT THROUGH SUNDAY)
ISSUED AT 350 PM CDT SUN APR 13 2014

COOL TEMPERATURES ARE EXPECTED TO PREVAIL THROUGH THE WEEK AS
NORTHWEST FLOW DOMINATES.  THE EXCEPTION TO THE RULE WILL BE ON
TUESDAY AS SOUTHERLY FLOW DEVELOPS AHEAD OF A LOW MOVING ACROSS THE
NORTHERN PLAINS.  THERE IS A FAIR AMOUNT OF WARMING IN THE WARM
SECTOR OF THE LOW...THOUGH IS NOT AS AGGRESSIVE AS MODELS SUGGESTED
IN PREVIOUS RUNS. THEREFORE...BACKED OFF ON HIGHS A BIT...ESPECIALLY
ACROSS THE EASTERN AND NORTHERN HALF OF THE FORECAST AREA. WITH
STRONG LOW LEVEL JET DEVELOPING TUESDAY NIGHT SHOULD BE A RELATIVELY
MILD NIGHT ACROSS THE AREA. WITH 925 HPA TEMPS WARMING THROUGH THE
NIGHT WELL ABOVE ZERO...HAVE CONTINUED TO NUDGE LOWS UPWARD A DEGREE
OR TWO IN MOST LOCATIONS.

STRONG COLD FRONT IS EXPECTED TO MOVE THROUGH THE AREA ON
WEDNESDAY.  MODELS HANDLING THE MIDLEVEL FORCING A BIT DIFFERENT
WITH WHAT WERE A SERIES OF PHASED SYSTEMS.  NOW...MODELS KEEP THE
MID LEVEL ENERGY VERY SEPARATE...AND THE CWA IS UNDER THE INFLUENCE
OF THE NORTHERN WAVE.  THIS SYSTEM APPEARS TO BE WEAKER...AND THUS
HAVE CUT PRECIP AMOUNTS SOME.  STILL SOME CONCERN HOWEVER THAT
PRECIPITATION MAY MIX WITH AND CHANGE TO SNOW WEDNESDAY AFTERNOON
INTO WEDNESDAY NIGHT.

SYSTEM APPEARS TO SLOW DOWN AND BECOME MUCH STRONGER AS IT SHIFTS
EAST OF THE AREA WITH HIGH PRESSURE BUILDING INTO THE AREA FROM THE
NORTH.  WITH THE STRENGTH OF THE HIGH...HAVE CUT BACK THE WESTWARD
EXTENT OF THE GUIDANCE POPS...BUT HAVE KEPT CONDITIONS COOL THROUGH
FRIDAY WITH NORTHEAST FLOW AND 925 HPA TEMPS NEAR ZERO.

WARM UP EXPECTED TO BEGIN ON SATURDAY AS SOUTHERLY FLOW DEVELOPS
ACROSS THE AREA...BUT COLD FRONT EXPECTED TO MOVE THROUGH THE AREA
ON SATURDAY NIGHT.  AT THIS POINT...AIR MASS BEHIND THE FRONT
APPEARS TO BE RELATIVELY MILD...SO NOT MUCH MORE THAN A WIND SHIFT
MOVING THROUGH SATURDAY NIGHT WITH LITTLE CHANGE IN TEMPERATURES ON
SUNDAY.

&&

.AVIATION...(FOR THE 00Z TAFS THROUGH 00Z MONDAY EVENING)
ISSUED AT 657 PM CDT SUN APR 13 2014

MVFR-IFR CEILINGS AND IFR-LIFR VISIBILITY IN LINGERING SNOW BAND EAST
OF HIGHWAY 60 IN NORTHWEST IOWA AT THE START OF THE PERIOD WILL
IMPROVE THROUGH THE EVENING AS DRIER AIR WORKS INTO THE REGION FROM
THE NORTHWEST AND BRINGS PRECIPITATION TO AN END. BY 06Z...EXPECT VFR
CONDITIONS TO PREVAIL THROUGH THE END OF THE PERIOD. GUSTY NORTH
WINDS WILL PERSIST THROUGH THE PERIOD...THOUGH STRONGEST GUSTS IN
EXCESS OF 30KT SHOULD LIKEWISE DIMINISH BY 06Z. AFTER 06Z...GUSTS
AROUND 25KT SHOULD BE MORE COMMON...WITH NORTH-NORTHWEST GUSTS OF
20-25KT LIKELY MUCH OF THE DAY MONDAY.

&&

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

$$

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