000
FXUS63 KFSD 142026
AFDFSD

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SIOUX FALLS SD
326 PM CDT FRI JUN 14 2013

.SHORT TERM...(THIS EVENING THROUGH SATURDAY)
ISSUED AT 325 PM CDT FRI JUN 14 2013

SEVERE THUNDERSTORM THREAT STILL EXISTS OVER THE AREA LATE THIS
AFTERNOON AND EVENING. CONVERGENCE IS STRENGTHENING AT/NEAR THE
SURFACE OVER NORTHEAST NEBRASKA AND THIS CONVERGENCE COUPLED WITH A
BOUNDARY THAT EXTENDS SOUTH OF THERE SHOULD PROVIDE A FOCUS FOR
THUNDERSTORM DEVELOPMENT. VIRTUALLY ALL OF THE MODELS...INCLUDING
THE HIGH RESOLUTION MODELS SUGGEST THIS AREA FOR DEVELOPMENT AND
ONLY DIFFER ON HOW FAR NORTH THE STRONG UPDRAFTS WILL BE. SUSPECT
THAT DEVELOPMENT WILL OCCUR IN NORTHWEST KANSAS TO CENTRAL NEBRASKA
THEN WORK NORTHEAST. WHILE CAPPING WILL NEED TO BE OVERCOME...LIKELY
NEEDING HIGH TEMPERATURES CLOSE TO 95 DEGREES...IF ANYTHING COULD
DEVELOP IT SHOULD QUICKLY BECOME SEVERE. MODELS STILL HINTING AT
SURFACE BASED CAPE VALUES OF 3000 TO 3500 J/KG WITH DEEP LAYER SHEAR
OF ABOUT 30 TO 35 KNOTS. THE SURFACE TO 1 KM SHEAR ALSO SUGGESTED TO
BE AROUND 20 KNOTS SO A TORNADO WOULD BE POSSIBLE. AT THIS TIME
DAKOTA AND DIXON COUNTIES APPEAR TO HAVE THE HIGHEST THREAT FOR
TORNADOES IN THE SIOUX FALLS CWA. THERE HAVE BEEN SOME HINTS THAT
SOME SHOWERS AND THUNDERSTORMS COULD DEVELOP OVER THE FAR WESTERN
CWA AS THE UPPER LEVEL SUPPORTS SWINGS INTO THE AREA BUT WILL NOT
INCLUDE ANY CHANCES YET AS CONFIDENCE IN THAT IS TOO LOW.

THE CHANCE FOR SHOWERS AND THUNDERSTORMS WILL CONTINUE IN THE FAR
SOUTHERN CWA ON SATURDAY AS THE UPPER LEVEL WAVE MOVES THROUGH.
INSTABILITY AND SHEAR MUCH WEAKER ON SATURDAY SO MORE GENERAL
CHANCES WITH NO SEVERE THUNDERSTORMS EXPECTED.

.LONG TERM...(SATURDAY NIGHT THROUGH FRIDAY)
ISSUED AT 325 PM CDT FRI JUN 14 2013

PRECIP CHANCES ACROSS NORTHWEST IOWA APPEAR TO WANE FAIRLY RAPIDLY
SATURDAY EVENING WITH SURFACE BOUNDARY AND CONVECTION EXPECTED TO
FOCUS ALONG AND SOUTH OF I-80.  SURFACE RIDGE NOSES INTO THE
REGION...RESULTING IN GOOD RADIATIVE CONDITIONS.

SURFACE RIDGE BEGINS TO DRIFT TO THE SOUTH AND EAST ON SUNDAY WITH
INSTABILITY ALOFT STARTING TO CREEP INTO SOUTH CENTRAL SOUTH
DAKOTA.  INSTABILITY APPEARS TO BE FAIRLY CAPPED WITH WARM LAYER
NEAR 700 MB.  WHILE ELEVATED INSTABILITY CREEPS NORTHWARD THROUGHOUT
THE DAY...CAP ONLY WEAKENS SUBSTANTIALLY ENOUGH ALONG THE MISSOURI
RIVER VALLEY WITH LACK OF STRONG UPPER LEVEL SUPPORT.  MAY GET A
LITTLE SUPPORT FROM RIGHT REAR QUADRANT OF STRENGTHENING JET
STREAK...BUT STILL MAY BE DIFFICULT TO OVER COME 60-100 J/KG OF
ELEVATED CIN.  AS SUCH...LEFT SLIGHT CHANCE/LOW CHANCE POPS
THROUGHOUT THE DAY BUT AM EXPECTING THE FOCUS TO BE SOUTH OF THE
FORECAST AREA.

AS COLD FRONT WORKS THROUGH THE AREA SUNDAY NIGHT HAVE SLIGHT
CHANCE/LOW END CHANCE POPS MAINLY ACROSS NORTHWEST IOWA AND ADJACENT
AREAS. STILL NOT A TON OF INSTABILITY TO WORK WITH...SO IF ANYTHING
DEVELOPS EXPECTING MAINLY GENERAL THUNDERSTORMS WITH JUST AN
ISOLATED THREAT OF SEVERE WEATHER AT BEST.

SURFACE RIDGE BUILDS BACK INTO THE AREA MONDAY INTO TUESDAY CREATING
RELATIVELY QUIET BENIGN WEATHER FOR MID JUNE.  WINDS APPEAR TO BE
FAIRLY LIGHT WITH DEW POINTS IN THE MID AND UPPER 50S.

THEREAFTER...A SERIES OF SHORTWAVES MOVE ACROSS THE NORTHERN PLAINS
WEDNESDAY AND BEYOND ORIGINATING FROM THE UPPER LOW OVER THE PACIFIC
NORTHWEST.  TIMING OF THE WAVES IS DIFFICULT THAT FAR OUT...SO LEFT
POPS SIMILAR TO GUIDANCE WITH FOCUS MORE TOWARDS THE END OF THE
PERIOD.

&&

.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z SATURDAY MORNING)
ISSUED AT 616 AM CDT FRI JUN 14 2013

SCATTERED THUUNDERSTORMS WILL DEVELOP ACROSS MAINLY THE EASTERN
PORTIONS OF THE AREA TODAY...THOUGH CONFIDENCE ON TIMING IS LOW.
THE BETTER CHANCES WILL REMAIN EAST OF SIOUX FALLS...THOUGH CANNOT
RULE OUT A PERIOD OF THUNDERSTORM ACTIVITY ANYTIME TODAY AROUND
KFSD...WITH BRIEF REDUCED VISIBILITIES IN A HEAVIER STORM.
NORTHWESTERN IOWA AND SOUTHWESTERN MINNESOTA WILL HAVE A BETTER
CHANCE...ESPECIALLY THIS AFTERNOON AND EVENING. AS WINDS DIE OFF
TONIGHT AT KFSD AND KSUX...MAY SEE MVFR VISIBILTIES DEVELOP LATER
AT NIGHT.


&&

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

$$

SHORT TERM...08
LONG TERM...
AVIATION...JM