Area Forecast Discussion
Issued by NWS Sioux Falls, SD

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FXUS63 KFSD 250332
AFDFSD

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SIOUX FALLS SD
1032 PM CDT FRI JUL 24 2015

.SHORT TERM...(THIS EVENING THROUGH SATURDAY)
ISSUED AT 436 PM CDT FRI JUL 24 2015

FORECAST AREA IS PRETTY STABLE THIS EVENING BEHIND A COMPLEX OF
THUNDERSTORMS WHICH WERE TO THE EAST OF THE FORECAST AREA ALREADY
THIS MORNING. SO REALLY NOT A LOT GOING ON IN THE NEAR TERM. LATER
TONIGHT IS A BIT INTERESTING IN THAT THE ECMWF BEGINS TO SHOW SOME
GENEROUS PRECIPITATION ALONG THE LEADING EDGE OF A 700MB SHORT WAVE
ACROSS OUR SOUTH CENTRAL SD COUNTY ZONES. THIS TREND CONTINUES INTO
SATURDAY MORNING FROM EXTREME NORTHEAST NEBRASKA...UP TOWARD
CHAMBERLAIN AS THE WAVE MOVES INTO CENTRAL NEB. NOW THE MAIN SURFACE
FRONT LOOKS TO BE BOTTLED UP IN EXTREME SOUTHERN NEBRASKA. SO THIS
PRECIPITATION IS AIDED BY WINDS ALOFT...CLOSER TO THE 850MB LAYER...
AND THE ATMOSPHERE IS STILL NOT VERY UNSTABLE. IN FACT EVEN THOUGH I
HAVE TSRA IN THE GRIDS...IT IS POSSIBLE THAT THE PRECIPITATION MAY
FAVOR JUST PLAIN SHOWERS WITH ISOLATED THUNDERSTORMS. THE REST OF
THE MODELS ARE MUCH LESS BULLISH AND MORE SKITTISH WITH THE
PRECIPITATION IN THAT PART OF THE FORECAST AREA. THEREFORE SINCE THE
ECMWF IS A BIT OF AN OUTLIER...KEPT THE POPS IN OUR MO VALLEY AREA
IN THE 40 TO 50 PERCENT RANGE. THAT SAID QUITE FRANKLY...THE ECMWF
HAS HANDLED ORGANIZED CONVECTIVE TRENDS BETTER THAN MOST OTHER
MODELS THIS SUMMER SO IT IS HARD TO IGNORE.

BY SATURDAY AFTERNOON...OUR FORECAST AREA IS KIND OF CAUGHT IN
BETWEEN WHAT APPEARS TO BE TWO ORGANIZED AREAS OF PRECIP WELL OFF TO
OUR WEST AND NORTHWEST WITH THE NEXT SHORT WAVE...AND POSSIBLY ALONG
THE AFOREMENTIONED WARM FRONT CLOSER TO KANSAS. SO BELIEVE ONLY REAL
SKITTISH CHANCES FOR SHOWERS ARE WARRANTED ALONG AND WEST OF I 29
FOR THE AFTERNOON.

CONCERNING TEMPERATURES...ALL TRENDS POINTED TO LITTLE IN THE WAY OF
CHANGE IN LOWS FOR TONIGHT. HOWEVER ON SATURDAY...THERE WILL LIKELY
BE SOME MID LEVEL CLOUDINESS AT LEAST ALONG AND WEST OF I 29 WHICH
COULD HOLD TEMPERATURES DOWN A FEW DEGREES FROM WHAT THE MODELS WERE
SHOWING EARLIER. THEREFORE THE TREND FOR THE WESTERN HALF OF THE
FORECAST AREA WAS TOO COOL HIGHS OFF ABOUT A CATEGORY.

.LONG TERM...(SATURDAY NIGHT THROUGH FRIDAY)
ISSUED AT 436 PM CDT FRI JUL 24 2015

SHORTWAVE TRACKS EAST INTO THE NORTHERN PLAINS ON SATURDAY
EVENING...AND THE BIG QUESTION WILL BE WHETHER THE MAIN MOISTURE AND
ENERGY WILL BE TRAPPED SOUTH OF THE FORECAST AREA NEAR THE WARM
FRONT ALONG THE I80 CORRIDOR OR IF AN ORGANIZED AREA OF
THUNDERSTORMS CAN GET GOING NORTHWEST OF THE CWA AND TRACK THROUGH
THE FORECAST AREA OVERNIGHT. THE ECMWF AND TO A LESSER EXTENT THE
CANADIAN...IS SOMEWHAT OF AN OUTLIER IN KEEPING THE CRUX OF THE
PRECIPITATION TO OUR SOUTH. THE REMAINING MODELS HOWEVER HAVE A MORE
ROBUST SHORTWAVE NOSING ALONG OUR NORTHERN BORDER WITH A COMPLEX OF
STORMS IMPACTING THE AREA. WILL KEEP POPS LIMITED TO CHANCES GIVEN
THAT THE ECMWF HAS BEEN PREFORMING FAIRLY WELL RECENTLY.

THE UPPER RIDGE REBOUNDS ON SUNDAY...RESULTING IN CONTINUED HOT AND
MODESTLY HUMID CONDITIONS. WITH THE SHORTWAVE POTENTIALLY HANGING UP
TO OUR EAST...WILL LEAVE IN SOME LOW POPS NEAR THE BUFFALO RIDGE
SUNDAY MORNING...BUT THE REMAINDER OF THE DAY SHOULD BE DRY UNDER
PARTLY CLOUDY SKIES. HIGHS WILL REACH THE MID 80S TO LOWER 90S. NOT
A GREAT DEAL OF LIFT OR CONVERGENCE IN THE AREA INTO SUNDAY
NIGHT...BUT MAY SEE AN ISOLATED STORM CREEP INTO SOUTH CENTRAL SD IN
THE EVENING AS A VERY WEAK WAVE LIFTS INTO SOUTHWEST SOUTH DAKOTA.

POTENT UPPER TROUGH DEEPENS OVER THE NORTHERN ROCKIES EARLY NEXT
WEEK...WITH A SURFACE FRONT TRACKING THROUGH THE FORECAST AREA
DURING THE DAY TUESDAY.  AHEAD OF THE FRONT...BREEZY SOUTH SOUTHEAST
WINDS DEVELOP MONDAY INTO MONDAY NIGHT. ANOTHER HOT AND MUGGY DAY IS
EXPECTED SIMILAR TO SUNDAY. THUNDERSTORMS WILL AGAIN BE POSSIBLE
MONDAY NIGHT...BUT WITHOUT MUCH SUPPORT AGAIN...ONLY CHANCE POPS ARE
WARRANTED. WITH THE BOUNDARY MOVING THROUGH THE AREA TUESDAY AND
POSSIBLY STALLING ACROSS OUR EASTERN FORECAST AREA TUESDAY
NIGHT....CONVECTION CHANCES WILL BE LARGELY FOCUSED IN OUR EAST
TUESDAY AFTERNOON INTO THE EARLY MORNING HOURS WEDNESDAY.

SOME RELIEF TO THE HEAT AND HUMIDITY RETURNS WEDNESDAY AND THURSDAY
WITH COOLER NORTHWEST FLOW ALOFT. LOOK FOR DRY WEATHER...CLEAR SKIES
AND HIGHS IN THE 80S. THE UPPER RIDGE BEGINS REBUILDING TO THE WEST
LATE IN THE WEEK...SO A WARMING TREND SEEMS REASONABLE. THE GFS AND
ECMWF BOTH INDICATE THAT A BOUNDARY SLIDES THROUGH THE AREA AROUND
FRIDAY OR FRIDAY NIGHT...BUT UNCERTAINTY HERE IS HIGH ESPECIALLY
WITH THE TIMING OF THIS FEATURE.

&&

.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z SATURDAY NIGHT)
ISSUED AT 1029 PM CDT FRI JUL 24 2015

MAINLY VFR CONDITIONS EXPECTED THROUGH THE TAF PERIOD. ISOLATED
THUNDERSTORMS WILL BE POSSIBLE THROUGH THE MISSOURI RIVER VALLEY
LATE TONIGHT INTO SATURDAY MORNING...THOUGH EXPECT ANY ACTIVITY
TO REMAIN WEST OF TAF SITES. THUNDERSTORMS MAY REDEVELOP ON
SATURDAY EVENING...WITH BETTER CHANCES AROUND KHON AFTER 02Z.

&&

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

$$

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



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