Area Forecast Discussion
Issued by NWS Sioux Falls, SD

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FXUS63 KFSD 231739
AFDFSD

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SIOUX FALLS SD
1239 PM CDT SAT APR 23 2016

.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 358 AM CDT SAT APR 23 2016

MAIN CHALLENGE TODAY WILL BE THE WIND. STRONG SOUTHERLY GRADIENT
DEVELOPS TODAY AS LOW PRESSURE DEEPENS WEST OF THE BLACK HILLS. PURE
MIXING HINTS THAT THERE COULD BE PERIODS TODAY WHEN WE REACH OR
EXCEED WIND ADVISORY CRITERIA BUT THINKING THAT THE DEEPENING LOW
WILL HAVE A SLIGHT NEGATIVE AFFECT ON THE WINDS...MAINLY BY TRYING
TO BACK THEM TO 170 DEGREES OR SO WHILE THE WINDS ALOFT WILL BE 180
TO 190 DEGREES. SO...WILL LEAN TOWARDS A JUST PLAIN WINDY DAY WITH
SOME GUSTS AROUND 40 MPH POSSIBLE IN MANY LOCATIONS...ESPECIALLY
ALONG AND WEST OF INTERSTATE 29. TEMPERATURES WILL CLIMB NICELY
THROUGH THE DAY AS SOME OF THE WARMEST AIR IN QUITE AWHILE MOVES IN.
HIGHS MOST LIKELY FROM THE MID 70S TO LOWER 80S WITH DEW POINTS ALSO
IN THE LOWER 50S...SO NOT COMPLETELY DRIED OUT.

THE WINDS WILL REMAIN STRONG THROUGH THE NIGHT...ABOUT 15 TO 25
MPH...SO LOWS WILL BE VERY MILD. AIMING FOR MID AND UPPER 50S IN
MOST LOCATIONS...WHICH IS ABOUT A 20 DEGREE DIURNAL...SO WOULD NOT
BE SURPRISED TO SEE SOME SITES ONLY DROP INTO THE LOWER 60S.

PRECIPITATION/THUNDERSTORM CHANCES STILL MINIMAL BUT WILL NEED TO
KEEP AN EYE ON THE MOISTURE IN THE 800MB TO 700MB LAYER. IF WE CAN
GET ENOUGH MOISTURE INTO THIS LAYER THE LAPSE RATES ABOVE THIS ARE
STEEP ENOUGH TO SUPPORT AT LEAST ISOLATED TO SCATTERED SHOWERS AND
THUNDERSTORMS...NOTHING SEVERE. THE SLIGHTLY BETTER CHANCES WILL BE
EAST OF INTERSTATE 29 LATE TONIGHT.

.LONG TERM...(SUNDAY THROUGH FRIDAY)
ISSUED AT 358 AM CDT SAT APR 23 2016

TOUGH CALL ON POPS ON SUNDAY AS UPPER LOW MOVES INTO THE AREA.  LOW
LEVEL MOISTURE IS STILL A QUESTION.  ACROSS THE WEST MOISTURE
APPEARS TO BE VERY LIMITED...MAKING FOR VERY LIMITED PRECIPITATION
CHANCES.  FURTHER TO THE EAST ACROSS NORTHWEST IOWA INTO SOUTHEAST
MINNESOTA...DEEPER MOISTURE IS EXPECTED...POTENTIAL FOR SHOWERS AND
THUNDERSTORMS TO DEVELOP. FORECAST SOUNDINGS SUGGEST A CAP ACROSS
THE EAST....BUT CAN/T REALLY IDENTIFY TRIGGER MECHANISM BEYOND THE
UPPER LOW. BECAUSE OF THIS...PRECIPITATION CHANCES ARE QUESTIONABLE.
DIRECTIONAL AND SPEED SHEAR LOOK GOOD...SO IF SOMETHING IS ABLE TO
DEVELOP IN THE AFTERNOON HOURS...POTENTIAL FOR ISOLATED SEVERE
HAIL/WIND THREAT IN NORTHWEST IOWA. OVERALL... BEST CHANCES OF
PRECIPITATION APPEAR TO BE ACROSS THE NORTH SUNDAY NIGHT INTO MONDAY
MORNING AS UPPER LOW MOVES ACROSS THE AREA.

MAY HAVE SOME LINGERING RAIN ACROSS THE AREA ON MONDAY MORNING.  LOW
LYING STRATUS APPEARS TO BE FAIRLY STUBBORN...AND WITH EASTERLY
FLOW DEVELOPING AHEAD OF THE NEXT SYSTEM...MAY BE A STRUGGLE TO
WARM.

NEXT SYSTEM MOVES INTO THE PLAINS ON TUESDAY CREATING A FAIRLY GOOD
SET UP FOR PRECIPITATION TUESDAY NIGHT INTO WEDNESDAY.

HEADED INTO THE WEEKEND...A THIRD SYSTEM IS EXPECTED TO WORK INTO
THE WEST COAST ON THURSDAY AND BECOME SOMEWHAT DISORGANIZED AS IT
SHIFTS EAST. TRAJECTORY OF THIS SYSTEM IS SOMEWHAT UNCERTAIN...WITH
THE GFS FOCUSING WEST AND THE ECMWF FURTHER SOUTH AND EAST.  FOR
NOW...LEFT GUIDANCE POPS AS IS.

&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z SUNDAY AFTERNOON)
ISSUED AT 1239 PM CDT SAT APR 23 2016

LOCALIZED MVFR CEILINGS IN FAR EASTERN PARTS OF THE FORECAST AREA
ALONG HIGHWAY 71 CORRIDOR EXPECTED TO IMPROVE TO VFR BY 20Z. VFR
CONDITIONS WILL DOMINATE ACROSS THE REMAINDER OF NORTHWEST IOWA...
SOUTHWEST MINNESOTA AND SOUTHEAST SOUTH DAKOTA THROUGH THE PERIOD.
ELEVATED INSTABILITY AND INCREASING LOW LEVEL JET OVERNIGHT COULD
PRODUCE SPOTTY HIGH-BASED SHRA/TSRA. EXACT LOCATION OF DEVELOPMENT
IS UNCERTAIN AND THUS HAVE NOT INCLUDED ANY MENTION OF PRECIP IN
THE TAFS AT THIS TIME...THOUGH MODELS POINTING TOWARD THE BETTER
CHANCE WITHIN 09Z-14Z WINDOW AT KSUX/KHON THAN AT KFSD.

A 45-55KT LOW LEVEL JET WILL ALSO LEAD TO PERIOD OF LOW LEVEL
WIND SHEAR FOR KFSD/KSUX DURING THE OVERNIGHT...LARGELY DUE TO
SPEED DIFFERENCES BELOW 1500FT AS DIRECTIONS SHOULD ONLY VARY FROM
SOUTHEAST TO SOUTH THROUGH THE LAYER.

&&

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

$$

SHORT TERM...08
LONG TERM...BT
AVIATION...JH



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