000
FXUS63 KFSD 191617
AFDFSD

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SIOUX FALLS SD
1117 AM CDT WED JUN 19 2013

.UPDATE...
ISSUED AT 1101 AM CDT WED JUN 19 2013

SHORTWAVE CAN BE SEEN ON WATER VAPOR IMAGERY FROM SOUTH CENTRAL
SOUTH DAKOTA INTO CENTRAL NEBRASKA MOVING OFF TO THE NORTHEAST. MAYBE
EVEN A WEAK MCV TYPE SIGNATURE ENTERING GREGORY COUNTY. QUESTION
BECOMES WHAT HAPPENS WITH CONVECTION THIS AFTERNOON. SKIES ARE
CLEARER THAN FORECAST...THUS DID GO AHEAD AND RAISE HIGHS A COUPLE
MORE DEGREES ACROSS THE WHOLE CWA...BUT PROBABLY STILL NOT HIGH
ENOUGH INS SOME SPOTS. MODEL DEWPOINTS CONTINUE TO RUN HIGH...MAKING
ASSESSING AFTERNOON CAPE A BIT DIFFICULT. IF WE CONTINUE TO MIX OUT
OUR DEWPOINTS INTO THE MID 50S...CAPE WOULD ONLY BE BETWEEN 500 AND
1000 J/KG. HOWEVER IF DEWPOINTS IN THE LOW 60S ARE ABLE TO CREEP UP
AHEAD OF THE WAVE CAPE WOULD END UP OVER 2000 J/KG. CURRENTLY HAVE A
BIT OF A CAP AROUND 600 MB...HOWEVER THIS IS FORECAST TO WEAKEN
THROUGH THE DAY WITH THE APPROACH OF THE WAVE. DRY AIR ENTRAINMENT
ABOVE 700 MB WILL LIKELY LIMIT USABLE CAPE SOME AS WELL. EITHER WAY
IT APPEARS THAT CIN WILL BECOME NEAR ZERO THIS AFTERNOON...AND WITH
THE WAVE TIMING RIGHT DURING PEAK HEATING...WOULD EXPECT THERE TO BE
SCATTERED THUNDERSTORM DEVELOPMENT THIS AFTERNOON. VEERING LOW LEVEL
WIND FIELDS INTRODUCE ENOUGH SHEAR FOR SOME MULTICELL POTENTIAL.
STILL THINK MOST STORMS WILL BE BELOW SEVERE LIMITS...WITH WINDS
GUSTING TO 45 MPH AND UP TO DIME SIZE HAIL. HOWEVER IF DEWPOINTS STAY
UP AND CAPE VALUES BEGIN TO EXCEED 2000 J/KG...WOULD ANTICIPATE AT
LEAST AN ISOLATED SEVERE HAIL REPORT. SO WILL JUST HAVE TO MONITOR
THE MESOANALYSIS THROUGH THE AFTERNOON AND SEE IF AND WHEN SCATTERED
STORMS GET GOING.

&&

.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 12Z TAFS THROUGH 12Z THURSDAY MORNING)
ISSUED AT 636 AM CDT WED JUN 19 2013

SCATTERED THUNDERSTORMS POSSIBLE TODAY...MAINLY WEST OF THE JAMES
RIVER THE MORNING...WITH THE THREAT SPREADING ACROSS THE ENTIRE FORECAST
AREA AFTER 18Z. IT DOES LOOK LIKE COVERAGE WILL BE TOO SPARSE FOR
ANY MENTION IN TAFS THROUGHOUT THE DAY...WITH PERHAPS A SLIGHTLY
BETTER POTENTIAL AFTER 06Z. THE STRONGER STORMS COULD PRODUCE SMALL
HAIL AND GUSTY WINDS TO AROUND 45 MPH. VFR CONDITIONS WILL
PREVAIL...BUT COULD SEE A BRIEF DIP TO MVFR CONDITIONS IN STORMS.
BREEZY SOUTHEAST WINDS THROUGHOUT THE FORECAST AREA LATE MORNING
THROUGH AFTERNOON.


&&

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

$$

UPDATE...CHENARD
SHORT TERM...
LONG TERM...
AVIATION...