Area Forecast Discussion
Issued by NWS Sioux Falls, SD

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000
FXUS63 KFSD 092113
AFDFSD

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SIOUX FALLS SD
413 PM CDT WED APR 9 2014

.SHORT TERM...(THIS EVENING THROUGH THURSDAY)
ISSUED AT 412 PM CDT WED APR 9 2014

COLD FRONT WILL MOVE INTO THE FORECAST AREA FROM THE NORTHWEST EARLY
THIS EVENING AND SOUTHEAST OF THE AREA LATE TONIGHT. A BAND OF WEAK
SHOWERS AND A FEW THUNDERSTORMS STILL SEEMS PLAUSIBLE TONIGHT IN THE
MID LEVEL MOISTURE BAND TRAILING THE FRONT...BUT UPPER SUPPORT SEEMS
TOO WEAK TO SUPPORT MORE THAN VERY SPOTTY...PERHAPS ISOLATED...CELLS
THAT OF COURSE WILL BE HIGH BASED AND PUT DOWN LITTLE RAINFALL TO
THE SURFACE. THIS SHOULD END LATE TONIGHT. THE MOISTURE BAND IS
STILL EXITING OUR FAR SOUTHERN FORECAST AREA...SAY SUX TO
SLB...EARLY THURSDAY MORNING BUT BY THAT TIME SUPPORT...IF ANY...IS
EVEN WEAKER SO WILL CONTINUE TO KEEP MENTION OUT. OTHERWISE CLOUDS
WILL BEGIN TO DECREASE FROM THE NORTH LATE TONIGHT AND FINISH DOING
THAT THURSDAY MORNING...SO A DECENT AMOUNT OF SUNSHINE IS EXPECTED
THURSDAY...PERHAPS GIVING WAY TO INCREASING WARM ADVECTION CLOUDS
FROM THE WEST LATE IN THE DAY.

TODAYS DECENT AFTERNOON SOUTHWEST WINDS WILL BECOME NORTHWEST BEHIND
THE FRONT THIS EVENING AND IT MAY BE MARGINALLY BREEZY FOR A WHILE
TONIGHT. WINDS THURSDAY SHOULD BE STRONGEST...UP TO THAT BREEZY
LEVEL AGAIN...OVER THE NORTHEAST HALF OF THE AREA. WINDS WILL BE
SLIPPING PRETTY QUICKLY LATE IN THE DAY AS THE SURFACE RIDGE DRIFTS
OVER AND SOUTH OF THE AREA.

SURFACE COOLING TONIGHT SHOULD BE A LITTLE WEAKER THAN GUIDANCE LOWS
WITH THE CLOUDS AND BREEZE. GUIDANCE HIGH TEMPERATURES FOR THURSDAY
LOOK BETTER WITH LOW TO MID 60S EXPECTED.

.LONG TERM...(THURSDAY NIGHT THROUGH WEDNESDAY)
ISSUED AT 412 PM CDT WED APR 9 2014

FOR THURSDAY NIGHT...STILL KEPT A CHANCE FOR PASSING SHOWERS
ACROSS THIS AREA AS A SHORT WAVE MOVES THROUGH. THE MOISTURE DEPTH
IS PRIMARILY IN THE 800-500MB LAYER...AND ONLY LASTS FOR ABOUT 3
HOURS AT ANY GIVEN LOCATION...SO ANY RAIN THAT MAKES IT TO THE
GROUND WILL BE LIGHT...ALSO NOTING THAT DYNAMICS ARE WEAK.

AFTER THAT WAVE MOVES THROUGH...FRIDAY PROMISES TO BE ANOTHER
PLEASANT DAY. THE MAIN CONCERN IS STILL HIGH TEMPERATURES...AND
GIVEN THE 850MB TEMPERATURES OFF OF BOTH THE NAM AND GFS...MANY
GUIDANCE VALUES LOOK TOO COOL. THEREFORE OPTED TO GO WITH THE
WARMER GUIDANCE READINGS...MANY TIMES THE BIAS CORRECTED VALUES IN
THIS CASE...AND BUMPED THEM UP A TAD. FIRE WEATHER CONCERNS FOR
FRIDAY ARE DETAILED BELOW.

ON FRIDAY NIGHT...YET ANOTHER SHORT WAVE MOVES ACROSS THE UPPER
ZONAL FLOW AHEAD OF A STRONGER TROUGH TO THE WEST WHICH WILL
IMPACT OUR WEATHER LATER IN THE WEEKEND. THE FRIDAY NIGHT SHORT
WAVE IS BEING HANDLED DIFFERENTLY BY RESPECTIVE DETERMINISTIC
MODELS...AND AT THIS POINT DIFFICULT TO ASCERTAIN JUST HOW STRONG
IT IS. ONE THING FOR CERTAIN IS THAT WITH THE CLOUD COVER...IT
DOES LOOK RATHER MILD FOR LOWS. BUT FOR NOW...ONLY CHANCE POPS ARE
WARRANTED FOR MOST LOCATIONS UNTIL WE GET A BETTER HANDLE ON THIS
WAVE. THERE IS ENOUGH ELEVATED INSTABILITY THAT IF ANY PRECIP
OCCURS...IT WILL BE IN THE FORM OF THUNDERSTORMS.

THIS WAVE EXITS SATURDAY MORNING AND A COLD FRONT BEGINS TO OOZE
INTO OUR AREA. THERE IS STILL QUITE A BIT OF MODEL DISCREPANCY
WITH THE TIMING OF THE FRONT SO FOLLOWED CONSENSUS. AT THIS TIME...
IT APPEARS THE WIND SHIFT WILL MOVE THROUGH OUR ENTIRE FORECAST
AREA FAST ENOUGH THAT IT COULD VERY WILL LIMIT THUNDERSTORM
ACTIVITY. PLACED POPS ONLY IN OUR EAST AND SOUTHEAST ZONES. THE
COLD AIR IS NOT COINCIDENT RIGHT WITH THE FRONTAL TIMING SO
SATURDAY WILL STILL BE A WARM DAY...WITH HIGHS SIMILAR TO FRIDAYS
HIGHS.

TEMPERATURES STILL LOOK COOL IN THE EXTENDED PORTION OF THE
FORECAST SUNDAY THROUGH WEDNESDAY. THE MAIN TIME FRAME FOR CONCERN
WITH REGARDS TO PRECIPITATION IS SUNDAY. THE 12Z MODEL CONSENSUS
IS NOW SHOWING THAT THE UPPER TROUGH TO OUR WEST WILL NOT DIG AS
FAR WEST AS PREVIOUSLY FORECAST...THEREFORE CUTTING OFF OUR
FORECAST AREA FROM THE DEEPER MOISTURE WHICH WAS FORECAST OFF OF
YESTERDAYS MODEL RUNS AS NORTHERN STREAM ENERGY MOVES QUICKLY
ACROSS OUR AREA. THIS WILL PLACE OUR SOUTHERN ZONES IN THE BEST
CHANCE FOR PRECIP...BUT TEMPERATURES WILL CERTAINLY PLUMMET
EVERYWHERE.

&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z THURSDAY AFTERNOON)
ISSUED AT 1239 PM CDT WED APR 9 2014

VFR WILL CONTINUE THROUGH 10/18Z. THROUGH 10/00Z A FEW SURFACE
GUSTS FROM THE SOUTHWEST MAY APPROACH 25 KNOTS. 10/00Z-12Z
ISOLATED HIGH BASED SHOWERS AND THUNDERSTORMS MAY MOVE FROM NORTH
TO SOUTH OVER THE AREA BEHIND SOUTHWARD MOVING SURFACE COLD FRONT
WHICH WILL MOVE SOUTH OVER THE AREA 10/00Z-09Z. NORTHWEST SURFACE
WINDS WILL DEVELOP BEHIND COLD FRONT WITH GUSTS CURRENTLY EXPECTED
TO REMAIN BELOW 25 KNOTS.


&&

.FIRE WEATHER...

THE RED FLAG WARNING WILL BE CONTINUED THROUGH 7 PM CDT AS PLANNED.
CONDITIONS SO FAR HAVE BEEN VERIFYING EXCEPT FOR THE HIGHER DEW
POINTS AND HUMIDITIES IN SOUTHWEST MINNESOTA...AND THOSE DEWPOINTS
ARE LIKELY TO DROP SEVERAL DEGREES IN A COUPLE HOURS WHEN HEATING
GETS TO A POINT. AFTER 7 PM COOLING AND HIGHER HUMIDITIES WILL MAKE
ANY DEVELOPING NORTHWEST WINDS BEHIND THE COLD FRONT MOOT. ANOTHER
RED FLAG WARNING IS IN EFFECT FOR THURSDAY FOR SOUTHWEST MINNESOTA
AS NORTHWEST WINDS WILL BE STRONG ENOUGH AND RELATIVE HUMIDITIES
LOW ENOUGH TO MEET CRITERIA. THAT ONE WILL BE ENDED EARLIER...AT 5
PM CDT...AS THE WINDS WILL BE DECREASING RAPIDLY TOWARD EVENING.
LESSER FIRE DANGER WILL PREVAIL TO THE WEST AND SOUTH ON THURSDAY
DUE TO THE LESSER WINDS.

ALSO HELD OFF ON A FIRE WEATHER WATCH FOR FRIDAY AS MIXED LAYER
WINDS LOOK TOO LIGHT TO WARRANT RED FLAG CONDITIONS. BUT WITH
MINIMUM HUMIDITY VALUES REACHING RED FLAG CRITERIA WE WILL
CERTAINLY KEEP AN EYE ON FRIDAY FOR ANY INCREASE IN WINDS. AT THE
LEAST IT LOOKS LIKE A SOLID VERY HIGH FIRE DANGER DAY IN THE
GRASSLAND STATEMENT...WHICH IS ONLY ONE NOTCH BELOW RED FLAG
CRITERIA.

&&

.FSD WATCHES/WARNINGS/ADVISORIES...
SD...RED FLAG WARNING UNTIL 7 PM CDT THIS EVENING FOR SDZ255>258.

MN...RED FLAG WARNING UNTIL 7 PM CDT THIS EVENING FOR MNZ900.

     RED FLAG WARNING FROM NOON TO 5 PM CDT THURSDAY FOR MNZ900.

IA...RED FLAG WARNING UNTIL 7 PM CDT THIS EVENING FOR IAZ300-301.

NE...RED FLAG WARNING UNTIL 7 PM CDT THIS EVENING FOR NEZ249.

&&

$$

SHORT TERM...
LONG TERM...MJ
AVIATION...
FIRE WEATHER...






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