Area Forecast Discussion
Issued by NWS Sioux Falls, SD

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FXUS63 KFSD 231733
AFDFSD

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SIOUX FALLS SD
1233 PM CDT MON MAR 23 2015

.UPDATE...
ISSUED AT 1103 AM CDT MON MAR 23 2015

REINFORCING EASTERLY WINDS WILL HOLD STRATUS INTO THE CWA FOR THE
MAJORITY OF THE DAYTIME HOURS. THE WESTERN FLANK OF THIS CLOUD
DECK WILL SLOWLY ERRODE EASTWARD BY LATER THIS AFTERNOON. AS A
RESULT...HAVE LOWERED TEMPERATURES IN THE EASTERN ZONES...AND
EXTENDED THE DURATION OF STRATUS THROUGH THE AFTERNOON.

&&

.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 414 AM CDT MON MAR 23 2015

COMPLICATED FORECAST ACROSS THE FORECAST AREA TODAY.  FRONTAL
BOUNDARY STALLED NEAR THE I 29 CORRIDOR WILL BE STUBBORN TO SHIFT
EAST AS SOUTHERLY FLOW INCREASES AHEAD OF APPROACHING LOW FROM THE
WEST.  EAST OF THE FRONT...EASTERLY FLOW WILL KEEP LOW CLOUDS AND
STRATUS LOCKED IN PLACE SEVERELY AFFECTING MIXING AND HIGH
TEMPERATURES.  WITH STUBBORN STRATUS EXPECTED TO HANG THROUGHOUT THE
BETTER PART IF NOT THE ENTIRE DAY ACROSS SOUTHWEST MINNESOTA...HAVE
LOWERED FORECAST HIGHS.  SHORT TERM HIGH RES MODELS ARE IN AGREEMENT
THAT FOG WILL ALSO DEVELOP ALONG THE SPINE OF THE BUFFALO RIDGE.  AT
THIS POINT...HAVE NOT SEEN VISIBILITIES FALL AT ALL...AND WITH
STRATUS IN PLACE AM NOT SURE HOW WIDESPREAD THE FOG POTENTIAL WILL
BE.  FOR NOW...HAVE TAKEN A CONSERVATIVE WAIT AND SEE APPROACH...BUT
WILL BE MONITORING VISIBILITIES CLOSELY THROUGH SUNRISE FOR THE
POTENTIAL FOR FOG.

FAIRLY DRY ATMOSPHERE EXISTS AHEAD OF THE APPROACHING WAVE
TONIGHT...AND HAVE CONCENTRATED THE POPS MAINLY AFTER 03Z TONIGHT.
STRONG ISENTROPIC LIFT COUPLED WITH LOW LEVEL MOISTURE ADVECTION
WILL LIKELY LEAD TO THE DEVELOPMENT OF LIGHT PRECIPITATION THROUGH
THE OVERNIGHT.  HAVE CONCENTRATED POPS ALONG THE 750-800 MB BOUNDARY
ALONG THE MISSOURI RIVER VALLEY TOWARDS TUESDAY MORNING. WITH
TEMPERATURES HANGING IN THE UPPER 30S...ANY PRECIPITATION SHOULD
REACH THE SURFACE AS RAIN.

.LONG TERM...(TUESDAY THROUGH SUNDAY)
ISSUED AT 414 AM CDT MON MAR 23 2015

POTENT SOUTHERN STREAM SHORTWAVE TRACKS ACROSS NEBRASKA ON TUESDAY
AS IT INTENSIFIES...WHILE THE NORTHERN STREAM WAVE SLOWS AND DEEPENS
IN WESTERN NORTH DAKOTA. WHILE THERE ARE STILL SOME MINOR
DIFFERENCES IN WAVE TRACKS...THE GENERAL CONSENSUS IS THAT SOUTHERN
WAVE WILL BE THE MAIN FOCUS FOR PRECIPITATION IMPACTS ACROSS THE
FORECAST AREA. WENT WITH A BLEND OF THE GFS...GEM AND ECMWF FOR
TIMING PURPOSES. PRECIPITATION WILL BECOME INCREASINGLY LIKELY
ACROSS OUR SOUTHERN AND WESTERN FORECAST AREA AS MID LEVEL
FRONTOGENETIC LIFT BECOMES FOCUS NEAR THE MISSOURI RIVER TUESDAY
MORNING AND STRONG UPPER LEVEL DYNAMICS PUSH INTO EASTERN NEBRASKA
AND THE MISSOURI VALLEY. BY AFTERNOON...MODERATE TO HEAVY RAINFALL
WILL BE WIDESPREAD ACROSS THE BULK OF THE FORECAST AREA. WITH SOME
WEAK ELEVATED INSTABILITY POSSIBLE MAINLY ACROSS NORTHWEST IOWA AND
NORTHEAST NEBRASKA IN THE AFTERNOON...MAY SEE A FEW RUMBLES OF
THUNDER...HOWEVER GIVEN HOW WEAK THIS INSTABILITY IS...WILL LEAVE
OUT THUNDER MENTION FOR NOW.

WHILE RAIN LOOKS TO BE THE PRIMARY WEATHER TYPE...CLOUDY SKIES AND
COOL SOUTHEAST FLOW WILL PREVENT MUCH WARMING DURING THE DAY ACROSS
THE FORECAST AREA. THIS WILL BE PARTICULARLY CONCERNING IN SOUTHWEST
MINNESOTA WHERE TEMPERATURES BEGIN THE DAY BELOW FREEZING AND ARE
NOT EXPECTED TO WARM MUCH ABOVE FREEZING. PRECIPITATION CHANCES
REMAIN LOW IN THE MORNING...BUT INCREASE DRAMATICALLY IN THE
AFTERNOON. TEMPERATURE PROFILES REMAIN CAUGHT BETWEEN PRIMARILY
SNOW...RAIN OR SLEET IN THE AFTERNOON AND THEN LEAN MORE TOWARDS
SNOWFALL IN THE LATE AFTERNOON AND EVENING. FOR NOW WILL GO WITH
RAIN IN THE AFTERNOON AND MIXING WITH OR BECOMING SNOW LATE
AFTERNOON INTO THE EVENING. HOWEVER...JUST A SLIGHT CHANGE IN THE
TEMPERATURE PROFILES COULD SPELL ENTIRELY RAIN OR SNOW.

QPF AMOUNTS HAVE THE POTENTIAL TO BE OVER A HALF INCH FOR A LARGE
PORTION OF THE FORECAST AREA. HEAVIEST AMOUNTS WILL BE AROUND 0.75
INCHES IN NORTHEAST NEBRASKA INTO NORTHWEST IOWA. GOING WITH AROUND
AN INCH OF SNOW NEAR THE BUFFALO RIDGE...BUT THIS AMOUNT MAY BE MUCH
HIGHER IF TEMPERATURES SUPPORT PRIMARILY SNOWFALL.

PRECIPITATION WILL TAPER OFF FROM WEST TO EAST TUESDAY EVENING AND
SHOULD EXIT THE FORECAST AREA AROUND MIDNIGHT. WEDNESDAY WILL BE
COOL WITH BLUSTERY - NEAR ADVISORY LEVEL NORTHWEST WINDS. THE
NORTHERN STREAM WAVE DIGS INTO NORTHERN MINNESOTA...HOWEVER MODELS
DIFFER IN HOW FAR SOUTH THE TROUGH DIGS. THE GEM IS THE OUTLIER WITH
THE SLOWER AND MORE SOUTHERLY TRACK...SO DISCOUNTED THIS SOLUTION.
WILL LEAVE OUT ANY PRECIPITATION MENTION ON WEDNESDAY.

COOL NORTHERLY FLOW KEEPS WARMING IN CHECK ON THURSDAY AND FRIDAY.
HIGHS WILL ONLY NE IN THE 30S TO MID 40S BOTH DAYS BUT DRY
CONDITIONS WILL PREVAIL. UPPER RIDGING SLIDES INTO THE PLAINS ON
SATURDAY...WITH A STRONG PUSH OF WARM AIR ADVECTION AND DECENT
MIXING MARKING THE RETURN OF ABOVE NORMAL TEMPERATURES. CONTINUED
THE TREND OF BOLSTERING HIGHS WITH BIAS CORRECTED GUIDANCE. HIGHS
WILL REACH THE 50S TO NEAR 70. DRY COLD FRONT PASSAGE ARRIVES
SATURDAY NIGHT...WITH SLIGHTLY COOLER HIGHS EXPECTED ON SUNDAY.

&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z TUESDAY AFTERNOON)
ISSUED AT 1220 PM CDT MON MAR 23 2015

MVFR/IFR STRATUS CONTINUES TO SLOWLY DISSOLVE THIS AFTERNOON.
HRRR/RAP INDICATE CLEARING AT ALL TERMINALS BY MID-AFTERNOON.
THROUGH THE EVENING HOURS VFR CONDITIONS ARE LIKELY.
HOWEVER...MID-LVL CLOUDS WILL INCREASE AHEAD OF A SYSTEM ARRIVING
FOR TUESDAY. RAIN CHANCES WILL INCREASE THROUGH DAYBREAK...WITH
MVFR/IFR CONDITIONS LIFTING NORTHEAST BY MID-MORNING.

&&

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

$$

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


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