Area Forecast Discussion
Issued by NWS Sioux Falls, SD

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FXUS63 KFSD 080012
AFDFSD

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SIOUX FALLS SD
615 PM CDT TUE JUL 7 2015

.SHORT TERM...(THIS EVENING THROUGH WEDNESDAY)
ISSUED AT 314 PM CDT TUE JUL 7 2015

RATHER QUIET WEATHER CONDITIONS PERSIST IN THE SHORT TERM PORTIONS
OF THE FORECAST. HIGH PRESSURE CONTINUES TO DRIFT THROUGH THE
WESTERN GREAT LAKES...BRINGING LOWER HUMIDITY...COOLER
TEMPERATURES...AND SHOVING THE NEAR SFC SMOKE FIELD WEST OF THE
AREA. THE SMOKE WILL NOT BE GONE FOR GOOD HOWEVER...AS WESTERLY MID-
HIGH LVL WINDS WILL KEEP THE SMOKE OVERHEAD...ALTHOUGH WELL
ALOFT...INTO WEDNESDAY.

GIVEN FALLING DEW POINTS...HAVE LOWERED MIN TEMPERATURES...
ESPECIALLY IN THE EASTERN HALF OF THE CWA. TEMPERATURES WILL ONLY BE
A HANDFUL OF DEGREES AWAY FROM RECORD LOWS FOR THIS TIME OF THE
YEAR.  CIRRUS AND MID-CLOUDS WILL BEGIN TO INCREASE FROM THE WEST AS
MID-LVL WAVES BEGIN TO EJECT INTO THE WESTERN PLAINS. THERE COULD BE
LINGERING SHOWERS OVER THE WESTERN HALF OF SD TRYING TO MOVE EAST BY
MID-MORNING...HOWEVER A VERY DRY SUBCLOUD 800:500 MB LAYER PERSISTS
AND SHOULD LIMIT ANY POTENTIAL TO SPRINKLES. TEMPERATURES WILL WARM
SLIGHTLY ON WEDNESDAY...BUT STILL REMAIN BELOW NORMAL.

.LONG TERM...(WEDNESDAY NIGHT THROUGH TUESDAY)
ISSUED AT 314 PM CDT TUE JUL 7 2015

ANY ISOLATED SHOWERS/THUNDERSTORMS SHOULD REMAIN TIED TO THE
CONVERGENCE BOUNDARY OFF TO THE WEST/NORTH OF THE CWA THROUGH THE
NIGHT...AS BOUNDARY HAS NO REAL PUSH OTHER THAN ANY SHORT TERM
PRECIPITATION COOLING. AIRMASS TO THE EAST REMAINS QUITE
DRY...WHICH SHOULD MAKE NORTHERN EDGE OF WAVE MOVING ACROSS
EASTERN NEBRASKA AND IOWA DURING THE NIGHT INERT. WITH DRIER
AIRMASS...EXPECT THAT LOWS WILL SHADE TO THE COOLER SIDE WITH
LIGHT WINDS.

HEIGHTS START TO BUILD ACROSS THE AREA ON THURSDAY...AND WILL BE A
TREND INTO THE WEEKEND TO DEVELOP A MORE TYPICAL SUMMER PATTERN...
INTERRUPTED BRIEFLY BY IMPACTS FROM A FEW WAVES PASSING THROUGH
THE REGION. THE FIRST OF THESE WAVES WILL BE APPROACHING BY LATE
DAY THURSDAY FROM THE SOUTHWEST...AGAIN MOVING INTO AN AIRMASS
WHICH IS FAIRLY DRY AND STABLE. THE MISSOURI VALLEY COULD BE IN AN
AREA WHERE A COUPLE OF LATE DAY LIGHT SHOWERS STRAY. SYNOPTIC WARM
FRONT REMAINS TO THE SOUTH...AND MOST SIGNS ARE POINTING TOWARD
DEVELOPMENT IN KANSAS/NEBRASKA SLIDING EAST ALONG THE BOUNDARY AS
WAVE MOVES THROUGH...WHICH WILL DIVERT LOW LEVEL JET FROM
TRANSPORTING MOISTURE INTO THE AREA AS SHEARING MID LEVEL PUSHES
ACROSS THE AREA LATER THURSDAY NIGHT AND EARLY FRIDAY. NOT ONLY
WOULD THIS DIMINISH PRECIP CHANCE...BUT ALSO DECREASE ELEVATED
INSTABILITY. SUGGESTION HERE IS THEN TO KEEP POPS FAIRLY LOW
ESPECIALLY NORTH AND WEST...GREATEST IN THE SOUTHEAST...AND
OVERALL MINIMIZE MENTION OF THUNDER.

WITH DRY AIR...DIURNAL RANGE COULD BE A BIT TO THE LARGER SIDE AND
HAVE TWEAKED A BIT COOLER FOR LOWS...ESPECIALLY EAST AWAY FROM
SLIGHTLY STRONGER GRADIENT...AS WELL AS ALLOWED A BIT MORE MIXING
ON HIGHS TO THE UPPER 70S AND LOWER 80S THURSDAY. A COUPLE DEGREES
FURTHER WARMING ON FRIDAY...ESPECIALLY WEST. WILL START TO NOTICE
INCREASE IN DEWPOINTS ON FRIDAY.

FRIDAY NIGHT INTO SATURDAY WOULD APPEAR TO BE THE BEST WINDOW FOR
GETTING SCATTERED CONVECTION INTO THE AREA. WEAK WAVE WILL RIDE UP
AGAINST THE UPSTREAM SIDE OF THE RIDGE...BUT AGAIN MAY FIND LOW
LEVEL JET DISRUPTED BY ACTIVITY ALONG BOUNDARY TO THE
SOUTH...SPLITTING DYNAMICS AND THERMODYNAMICS AROUND THE AREA.
GRADUALLY...A MUCH STRONGER SIGNAL FOR POTENTIAL INSTABILITY AND
WARMING WEST...WHILE A STRUGGLE WITH LINGERING CLOUDS AND
INCREASING MOISTURE EAST LEADING TO LOWER 80S EAST TO LOWER 90S
WEST ON SATURDAY.

TEMPS ALOFT CONTINUE TO WARM INTO SUNDAY...BEFORE WAVE OF
QUESTIONABLE TIMING BEGINS TO KNOCK HEIGHTS BACK AS IT MOVES
ACROSS THE NORTHERN PLAINS...DIGGING TOWARD MINNESOTA. 90S WOULD
SEEM TO BE FAIRLY CERTAIN FOR MOST...EVEN UPPER 90S IN THE WEST...
AS CAP CONTRIBUTES TO A VERY HUMID DAY. WOULD NOT EXPECT MUCH IN
TERMS OF CONVECTION GIVEN CAP THROUGH THE DAYTIME...MORE LIKELY
IGNITING IN THE EVENING. WAVE TRACK FAVORS CONVECTION OVER THE
NORTHEAST THIRD OF THE CWA

12Z ECMWF STARTS A NEW IDEA OF BACKING/STALLING A NORTHWEST TO
SOUTHEAST BAROCLINIC ZONE OVER THE HEART OF THE CWA...PRESENTING A
DAILY PRECIPITATION CHANCE. DEEP LAYER FLOW IS PRETTY WEAK TO
SUGGEST ANY SIGNIFICANT SEVERE THREAT AT THIS TIME. FOR NOW...
HAVE CENTERED CHANCE AROUND MONDAY WITH JET STREAK...AND A BIT
MORE HEAVY HANDED WITH CHANCES NORTH/EAST. AS SUCH...CLOUDS AND
PRECIP WOULD ALMOST CERTAINLY REQUIRE DROPPING TEMPS BACK SOMEWHAT
ON MONDAY. HOWEVER...THE SEASONAL WARMTH SHOULD CONTINUE PAST THE
END OF THE FORECAST.

&&

.AVIATION...(FOR THE 00Z TAFS THROUGH 00Z WEDNESDAY EVENING)
ISSUED AT 615 PM CDT TUE JUL 7 2015

LIGHT WINDS GENERALLY EAST TO SOUTHEAST OVERNIGHT AS SURFACE HIGH
PRESSURE AXIS SLIDES THROUGH THE REGION. WINDS BECOME MORE SOUTHERLY
ON WEDNESDAY...BUT STILL GENERALLY BELOW 15KTS.

CEILINGS REMAINING VFR THROUGH THE PERIOD. LIGHT WINDS AND RECENT
RAINS MAY ALLOW SHALLOW FOG TO DEVELOP TOWARDS DAYBREAK...BUT WITH
DEW POINTS EVEN IN THE AREAS OF HEAVIER RAIN MIXING INTO THE MID-
UPPER 40S THIS AFTERNOON...LIKELIHOOD OF ANY WIDESPREAD FOG IS LOW.

&&

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

$$

SHORT TERM...DUX
LONG TERM...CHAPMAN
AVIATION...JH



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