Area Forecast Discussion
Issued by NWS Sioux Falls, SD

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FXUS63 KFSD 281133
AFDFSD

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SIOUX FALLS SD
633 AM CDT TUE APR 28 2015

.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 416 AM CDT TUE APR 28 2015

CURRENT SURFACE OBSERVATIONS SHOW THE WIND SHIFT LINE ALIGNED FROM
MARSHALL MN...TO SIOUX FALLS TO JUST EAST OF YANKTON. 10 TO 15 MPH
WINDS BEHIND THE WIND SHIFT HAVE ALLOWED TEMPERATURES TO REMAIN IN
THE MID AND UPPER 40S ACROSS OUR WESTERN ZONES COUPLED WITH
SUBSTANTIALLY HIGHER DEW POINT TEMPERATURES ALSO. BOTH THE NAM AND
GFS DO POINT TO A LOWERING OF THE CURRENT MID AND UPPER CLOUD DECK
AS THE SHORT WAVE CROSSES OUR FORECAST AREA. THEREFORE LEFT THE
MENTION OF ISOLATED SPRINKLES OR LIGHT SHOWERS IN FOR NOW...
ESPECIALLY ACROSS THE EASTERN HALF OF OUR FORECAST AREA BY MIDDAY
AND AFTERNOON. BUT HONESTLY MEASURABLE RAINFALL WILL LIKELY BE VERY
TOUGH TO FIND. CONCERNING HIGHS TODAY...LOOKS LIKE LITTLE CHANGE IS
NEEDED FROM THE PREVIOUS FORECAST. THE MIXED LAYER GIVES READINGS
MAINLY IN THE UPPER 60S AND LOWER 70S...WITH SIOUX CITY PROBABLY
TOPPING OUT IN THE MID 70S.

AS THE SURFACE WINDS GO LIGHT TONIGHT COUPLED WITH CLEAR OR CLEARING
SKIES...LOWERED LOWS TO BELOW GUIDANCE READINGS IN THE LOW LYING
AREAS. ACTUALLY THE BIAS CORRECTED ECMWF AND GEM REGIONAL LOOKED IN
THE BALL PARK AND PICKED UP ON THIS IDEA.

.LONG TERM...(WEDNESDAY THROUGH MONDAY)
ISSUED AT 416 AM CDT TUE APR 28 2015

MIXY AND DRY CONDITIONS ARE EXPECTED ON WEDNESDAY AS HIGH PRESSURE
MOVES OVER THE AREA.  WITH DRY ATMOSPHERE...HAVE SIDED WITH WARMER
BIAS CORRECTED GUIDANCE VALUES.

SIMILAR STORY ON THURSDAY AS RETURN FLOW STARTS TO SET UP.  WITH
INCREASING SOUTHERLY WINDS COULD SEE AN ELEVATED FIRE DANGER
ESPECIALLY IN THE EAST WHERE THE DRY AIR ALOFT IS MORE PRONOUNCED.
HAVE RH VALUES FORECAST TO FALL INTO THE 20-30 PERCENT RANGE
THROUGHOUT THE AFTERNOON HOURS.

COLD FRONT MOVES THROUGH THE AREA THURSDAY NIGHT INTO FRIDAY
MORNING.  VERY LITTLE MOISTURE AVAILABLE WITH THE GULF SHUT
DOWN....SO HAVE KEPT POPS IN THE SLIGHT CHANCE TO LOW CHANCE RANGE.
HAVE SLIGHTLY HIGHER POPS IN THE NORTH CLOSER TO THE MID LEVEL WAVE
WHICH LEADS TO SLIGHTLY MORE INSTABILITY ALOFT.

ANY LINGERING CONVECTION SHIFTS EAST OF THE EAST ON FRIDAY LEADING
TO ANOTHER MILD DAY ACROSS THE AREA.  HAVE RAISED FORECAST HIGHS
CLOSER TO BC NUMBERS...ESPECIALLY ACROSS CENTRAL AND EASTERN SOUTH
DAKOTA WHERE CLOUD COVER WON/T BE AN ISSUE.

OVER THE WEEKEND...LOOKS LIKE A RELATIVELY QUIET START TO THE
WEEKEND...BUT WITH INCREASING SOUTHERLY FLOW AND A WARM FRONT
LIFTING THROUGH THE AREA...SHOULD SEE ENOUGH MOISTURE RETURN WITH
THE LOW LEVEL JET SATURDAY NIGHT THAT ELEVATED THUNDERSTORMS WILL BE
POSSIBLE.  COLD FRONT IS EXPECTED TO MOVE THROUGH THE AREA SUNDAY
NIGHT...LEADING TO THE CHANCE OF A SECOND ROUND OF CONVECTION.

HAVE REMOVED GUIDANCE POPS FROM THE FORECAST FOR MONDAY...AS COOLER
DRIER AIR RETURNS TO THE REGION.  HAVE INCREASED WINDS SATURDAY
THROUGH MONDAY OVER CONS ALL VALUES BASED ON WINDS ALOFT.

&&

.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z WEDNESDAY MORNING)
ISSUED AT 630 AM CDT TUE APR 28 2015

SOME MVFR WILL BE FOUND AT THE KHON TAF SITE EARLY THIS MORNING.
BUT ALL INDICATIONS PER NAM AND GFS DATA...AS WELL AS UPSTREAM
OBSERVATIONS SHOW THAT THE MVFR CEILINGS SHOULD WANE DURING THE
MID MORNING HOURS...LEAVING LOWER END VFR FOR KHON. VFR SHOULD
ALSO PREVAIL FOR KFSD AND KSUX. THERE COULD BE SOME VERY LIGHT
SHOWERS OR SPRINKLES MOVING FROM WEST TO EAST TODAY...BUT ANY
RAINFALL WILL BE TOO LIGHT TO MENTION IN THE TAF SITES.

&&

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

$$

SHORT TERM...MJ
LONG TERM...
AVIATION...MJ


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