Area Forecast Discussion
Issued by NWS Sioux Falls, SD

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000
FXUS63 KFSD 212046
AFDFSD

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SIOUX FALLS SD
346 PM CDT MON JUL 21 2014

.SHORT TERM...(THIS EVENING THROUGH TUESDAY)
ISSUED AT 312 PM CDT MON JUL 21 2014

THOUGH CLOUD COVER IS BLUNTING TEMPERATURES A BIT EAST OF THE JAMES
RIVER...DEW POINTS HAVE CLIMBED INTO THE MID TO UPPER 70S...MAKING
THE HEAT ADVISORY WELL ON. THE CLOUDS...LOW INT HE EAST WITH SOME
HIGH BASED MIDDLE CLOUDS PASSING ABOVE...SHOULD CONTINUE TO DECREASE
THROUGH THE EARLY EVENING.

STORM CHANCES ARE OF COURSE NIL THROUGH THE EARLY EVENING...AND THIS
NIL CHANCE MAY JUST EXTEND THROUGH THE NIGHT. AM GOING TO LEAVE A
SLIGHT CHANCE OF STORMS LATER ON TONIGHT OVER THE FAR NORTHEASTERN
CORNER FOR POSSIBLE CELLS JUST SOUTH OF THE MAIN SYSTEM TO THE NORTH
MOVING DOWN TO THE SOUTHEAST...BUT THAT IS ALL IT SEEMS WORTH RIGHT
NOW. EVEN AT NIGHT MID LEVEL TEMPERATURES WILL BE TOO WARM TO
SUPPORT CONVECTION WITH THE UPPER SUPPORT MOVING BY TO THE NORTH.

IT WILL STILL BE A WARM AND VERY MUGGY NIGHT...WITH THE FRONT AND
THE BEGINNINGS OF THE COOLER INFLOW WAITING UNTIL THE END OF THE
NIGHT AND EARLY TUESDAY MORNING. LOW TEMPERATURES WILL BE IN THE
LOWER 70S EXCEPT MAYBE A COUPLE DEGREES INTO THE UPPER 60S FAR
WEST/NORTHWEST. TUESDAY WILL THUS HAVE A VERY WARM MUGGY START WITH
SLOW BUT STEADY IMPROVEMENT FROM THE NORTH...AND THIS SHOULD GET TO
THE SOUTHEAST PART OF THE AREA DURING THE AFTERNOON. TUESDAY SKIES
AT THIS TIME ARE EXPECTED TO BE PARTLY TO MOSTLY SUNNY. AM A LITTLE
CONCERNED ABOUT A BAND OF POST-FRONTAL LOW CLOUDS BEFORE THE DRYING
IN THE NORTHERLY FLOW REALLY ARRIVES...BUT DO NOT THINK THIS BAND
WOULD BE LONG LASTING AT ANY POINT. WITH ANY UPPER AND THERMAL
SUPPORT PASSING ON EAST DURING TONIGHT...DO NOT SEE ANY STORM
CHANCES HIGH ENOUGH TO MENTION.

.LONG TERM...(TUESDAY NIGHT THROUGH MONDAY)
ISSUED AT 312 PM CDT MON JUL 21 2014

DETERMINISTIC NAM AND GFS ARE IN EXCELLENT AGREEMENT IN THE
INTERMEDIATE RANGE FROM TUESDAY NIGHT THROUGH THURSDAY. THIS LENDS
CONFIDENCE TO THE FORECAST. UPPER RIDGE BUILDS AGAIN TO OUR
SOUTHWEST...CENTERED ROUGHLY IN EASTERN COLORADO ON WEDNESDAY...
THEN SHIFTS A BIT SOUTHWARD INTO THE SOUTHWEST U.S. BY THURSDAY.
LOOKING PURELY AT THE 500MB HEIGHTS...ONE WOULD THINK THAT HOT
TEMPERATURES WOULD BE IN STORE FOR THE MIDDLE OF THE WEEK. HOWEVER
OUR AREA IS GREATLY TEMPERED BY COOL...CANADIAN HIGH PRESSURE
MOVING SLOWLY ACROSS THE PLAINS BEHIND TONIGHTS SHORT WAVE.
SURFACE DEW POINTS WILL BE MORE MODERATED HELPING TO GIVE MILD
TEMPERATURES TUESDAY NIGHT AND WEDNESDAY NIGHT. HIGHS ON WEDNESDAY
AND THURSDAY WILL GENERALLY BE IN THE UPPER 70S TO MID
80S...EXCEPT FOR READINGS NEAR 90 IN SOUTH CENTRAL SD ON THURSDAY
WHICH IS CERTAINLY NOTHING REAL OUTSTANDING FOR THEM THIS TIME OF
YEAR.

WHICH BRINGS US TO PRECIPITATION CHANCES. RETURN OF A STRONG LOW
LEVEL JET AND ELEVATED INSTABILITY MAY BE ENOUGH TO SPARK SOME
SHOWERS AND THUNDERSTORMS FIRST IN OUR WESTERN ZONES WEDNESDAY
NIGHT...MOVING EASTWARD DEEPER INTO OUR FORECAST AREA ON THURSDAY.
THE NAM WAS MORE BULLISH THAN THE GFS IN DEVELOPING DECENT QPF
OVER OUR REGION ON THURSDAY...BECAUSE IT HAS A MUCH TIGHTER MID
LEVEL THERMAL GRADIENT. BUT THE GFS IS COOLER AT 700MB AS OPPOSED
TO THE NAM. THE ECMWF AND GEM GLOBAL ARE ALSO GETTING IN ON THE
ACTION IN DEVELOPING CONVECTION AS THEY PUMP UP THE ELEVATED
INSTABILITY. BUT AT THIS POINT...CERTAINLY DO NOT WANT TO GO MORE
THAN CHANCE POPS AT ANY SINGLE LOCATION DUE TO THE WARM MID LEVEL
TEMPERATURES.

IN THE EXTENDED PORTION OF THE FORECAST...THE 12Z ECMWF IS DELAYED
IN ARRIVING...BUT FORTUNATELY THERE CONTINUES TO BE PRETTY GOOD
AGREEMENT BETWEEN THE 00Z ECMWF/12Z GFS AND 12Z GEM GLOBAL. THE
UPPER RIDGE BEGINS TO FLATTEN AS A STRONG UPPER TROUGH MOVES
EASTWARD NEAR THE CANADIAN BORDER TO OUR NORTHWEST ON FRIDAY
ALLOWING SHORT WAVE ENERGY TO MOVE THROUGH OUR AREA THURSDAY NIGHT
AND FRIDAY. THIS WILL KEEP THE CHANCES FOR STORMS GOING...WITH A
MARKED SURFACE WIND SHIFT COMING OUT OF THE NORTH MOVING THROUGH
LATE FRIDAY AND FRIDAY NIGHT. THEN THE AFOREMENTIONED UPPER TROUGH
DIVES SOUTHEASTWARD LATE THIS WEEKEND USHERING IN A FETCH OF
COOLER AIR BY SUNDAY AND MONDAY. THE UPPER TROUGH COULD BE ENOUGH
TO SPARK A FEW SHOWERS ON SUNDAY IN OUR EASTERN ZONES...BUT
OTHERWISE THE SATURDAY THROUGH MONDAY TIME FRAME LOOKS PRETTY DRY.
CONCERNING TEMPERATURES...BECAUSE OF THE BREAK DOWN OF THE UPPER
RIDGE AND A SURFACE NORTHERLY FLOW...TEMPERATURES DO NOT LOOK HOT
BY ANY STRETCH OF THE IMAGINATION FRIDAY THROUGH MONDAY...
ESPECIALLY FOR MID SUMMER.

&&

.FSD WATCHES/WARNINGS/ADVISORIES...
SD...HEAT ADVISORY UNTIL 9 PM CDT THIS EVENING FOR SDZ038>040-050-
     052>071.

MN...HEAT ADVISORY UNTIL 9 PM CDT THIS EVENING FOR MNZ071-072-080-081-
     089-090-097-098.

IA...HEAT ADVISORY UNTIL 9 PM CDT THIS EVENING FOR IAZ001>003-012>014-
     020>022-031-032.

NE...HEAT ADVISORY UNTIL 9 PM CDT THIS EVENING FOR NEZ013-014.

&&

$$

SHORT TERM...
LONG TERM...MJ







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