000
FXUS63 KFSD 190837
AFDFSD

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SIOUX FALLS SD
337 AM CDT WED JUN 19 2013

.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 337 AM CDT WED JUN 19 2013

SHORT WAVE DRIFTING OVER AREA TODAY FROM THE WEST WILL PROVIDE
SOME LIFT AND CONVERGENCE FOR SHOWERS AND STORMS AS INSTABILITY
STEADILY INCREASES. LOW LEVEL WINDS ALSO INCREASE SLOWLY...THROUGH
HAVE DOUBTS THAT MUCH SURFACE BASED CONVECTION WILL INITIATE LATE
IN THE DAY AS WAVE WILL ALMOST BE ON ITS WAY OUT. ACTIVITY SHOULD
THEREFORE BE MOSTLY ELEVATED. WITH MID LEVEL WIND FIELDS MARGINAL
AT BEST...NOT OUTLOOKING SEVERE STORMS BUT HAVING THE LOW 5
PERCENT THREAT FOR OUR AREA AS SPC DOES SEEMS REASONABLE. WITH LOW
LEVEL WARMING...TEMPERATURES SHOULD BE WARMER...BUT WILL KEEP
HIGHS BELOW GUIDANCE VALUES DUE TO CLOUD DOVER ASSOCIATED WITH
WAVE. THIS WILL ALSO BE A NEGATIVE FACTOR IN THE HEATING FOR ANY
SURFACE BASED STORMS...AND ALSO ANY SEVERE THREAT THROUGH TONIGHT.
WITH WAVE MOVING OUT BUT LOW LEVEL WINDS CONTINUING TO
INCREASE...A STORM THREAT SHOULD CONTINUE THROUGH TONIGHT...OR AT
LEAST RETURN LATE TONIGHT. TEMPERATURES TONIGHT WILL OF COURSE BE
WARMER AS LOW LEVEL MOISTURE INCREASES...AND WE START THINKING
ABOUT MODEST SUMMERTIME HUMID CONDITIONS.

.LONG TERM...(THURSDAY THROUGH TUESDAY)
ISSUED AT 337 AM CDT WED JUN 19 2013

THURSDAY THUNDERSTORM THREAT IS LIKELY TO START WITH MORE NON
SEVERE ELEVATED CONVECTION FROM TONIGHT. TIMING AND COVERAGE
UNCERTAIN AS IT USUALLY IS WITH THESE TYPE OF STORMS. HOWEVER
LATER IN THE DAY CONDITIONS APPEAR TO BECOME MORE FAVORABLE FOR
SOME SURFACE BASED STORMS. WITH BETTER HEATING AND INCREASINGLY
FAVORABLE WIND FIELDS FOR STORMS...SOME MODEST SEVERE THREAT SEEMS
TO BE THERE FOR LATE THURSDAY OVER THE AREA. BY THURSDAY NIGHT THE
BEST LOW LEVEL WINDS AND INSTABILITY BECOME CONCENTRATED OVER THE
SOUTHEAST PART OF OUR AREA...WITH THE RESULTING LIFT EXTENDING
INTO SOUTHWEST MN AND PERHAPS UP TO BKX. ORGANIZED SEVERE SEEMS
POSSIBLE EAST THURSDAY NIGHT AFTER THE LATE DAY STORMS AFFECT THE
AREA TO THE WEST. AGAIN TIMING AND COVERAGE UNCERTAIN AND IT IS
HARD TO SQUEEZE OUT STRONGER THAN HIGH CHANCE OR BARELY LIKELY
POPS...BUT THERE SEEMS A DECENT CONDITIONAL SEVERE THREAT FOR
WHERE STORMS AFFECT THE AREA. TEMPERATURES AND HUMIDITY CONTINUE
TO BECOME A BIT MORE SUMMERLIKE THURSDAY.

WESTERN USA TROUGH APPROACHING WILL BRING CONTINUED HUMID
CONDITIONS AND SCATTERED STORMS AT TIMES FRIDAY THROUGH THE
WEEKEND...WITH THE BETTER CHANCES OF STORMS AND ALSO THE SEVERE
THREAT MAINLY DURING THE NIGHTTIME HOURS. PASSAGE OF THIS TROUGH
IS CURRENTLY EXPECTED TO BRING MOSTLY DRY WEATHER FOR EARLY NEXT
WEEK THOUGH FOR NOW HAVE FOLLOWED GUIDANCE CONTINUING SOME CHANCE
INTO MONDAY. SOME DECREASE IN HUMIDITY SEEMS LIKELY BUT
TEMPERATURES WILL BE DECENTLY WARM.

&&

.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z WEDNESDAY NIGHT)
ISSUED AT 1103 PM CDT TUE JUN 18 2013

VFR CONDITIONS EXPECTED TO DOMINATE THROUGH THE PERIOD. ISOLATED
ELEVATED THUNDERSTORMS WILL BE POSSIBLE WEST OF THE JAMES RIVER
VALLEY AFTER 09Z TONIGHT...WITH THE POTENTIAL EXPANDING EASTWARD
ACROSS THE AREA AFTER 14Z WEDNESDAY MORNING. BRIEF MVFR VISIBILITY
WILL BE POSSIBLE IN ANY OF THESE STORMS...HOWEVER EXPECTED AREAL
COVERAGE IS TOO LOW TO INCLUDE MENTION IN TAFS AT THIS TIME. SLIGHTLY
BETTER CHANCE OF SURFACE BASED STORMS DEVELOPING DURING THE MID TO
LATE AFTERNOON AND HAVE INCLUDED THIS FOR THE KHON TAF LOCATION...
THOUGH CONFIDENCE STILL NOT HIGH ON EXACT TIMING. INCREASING
SOUTHEAST TO SOUTH LOW LEVEL FLOW EXPECTED AS SURFACE RIDGE AXIS
SHIFTS EAST OF THE FORECAST AREA WEDNESDAY MORNING...WITH GUSTS AT
OR ABOVE 20KTS FOR MOST AREAS 19/17Z-20/01Z.


&&

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

$$

SHORT TERM...
LONG TERM...
AVIATION...JH