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000
FXUS63 KFSD 110854
AFDFSD

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SIOUX FALLS SD
354 AM CDT TUE JUN 11 2013

.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 352 AM CDT TUE JUN 11 2013

ONGOING ACCAS ACTIVITY IN AREA OF MID LEVEL ISENTROPIC LIFT/THETA-E
ADVECTION MOVING ACROSS NORTHERN SD AT THIS TIME...AROUND NORTHERN
PERIPHERY OF DECENT MID LEVEL CAP ACROSS WESTERN SD. WEAK LIFT FROM
THETA-E ADVECTION IS SEEN POSSIBLY AS FAR SOUTH AS I-90 CORRIDOR.
HOWEVER...MID LEVEL CAP BUILDS EASTWARD WITH TIME...AND SHOULD KEEP
MOST ACTIVITY NORTH OF OUR FORECAST AREA. THUS WILL CONTINUE WITH
JUST SLIGHT CHANCE POPS ACROSS OUR NORTH FOR THIS MORNING. STRONG
CAPPING INVERSION REMAINS IN PLACE ACROSS THE FORECAST AREA THROUGH
THE AFTERNOON...WITH CONVECTIVE INHIBITION VALUES ANYWHERE FROM
200-500J/KG FOR PARCELS BELOW 700MB. THUS THINK DEVELOPMENT IN THIS
AREA WILL BE VERY UNLIKELY PRIOR TO 00Z AND WILL LEAVE THE AFTERNOON
DRY. TEMPS A LITTLE TRICKY WITH STRONG INVERSION ALOFT...AS SLIGHTLY
BETTER MIXING THAN EXPECTED COULD RESULT IN QUICK TEMPERATURE JUMP
AT THE SURFACE. HOWEVER...MOST GUIDANCE REMAIN ON THE CONSERVATIVE
SIDE WITH HIGHS FROM RIGHT AROUND 80 NORTHEAST TO MID-UPPER 80S IN
THE MISSOURI RIVER VALLEY AND DID NOT STRAY FROM THIS MUCH FOR TODAY.

TOUGH CALL ON CONVECTION FOR TUESDAY NIGHT AS ATMOSPHERE IS UNSTABLE
BUT APPEARS TO BE EFFECTIVELY CAPPED.  IF ANY CONVECTION IS ABLE TO
OVERCOME THE CAP IN THE WESTERN HIGH PLAINS IT IS EXPECTED TO WORK
TOWARDS THE CWA.  QUESTIONS REMAIN AS TO WHETHER CONVECTION WILL
REMAIN INTACT AS IT WORKS INTO AN INCREASING CAP.  BEST CHANCES FOR
CONVECTION APPEAR TO BE ACROSS THE NORTHWEST CORNER OF THE FORECAST
AREA IN CENTRAL SOUTH DAKOTA WHERE THE CAP IS WEAKEST IN PART DUE TO
SHORT WAVE MOVING ACROSS THE AREA.  FAIRLY STEEP ELEVATED LAPSE RATE
FROM 400-600 MB CONTINUE TO SUGGEST LARGE HAIL AS THE MAIN SEVERE
WEATHER THREAT TUESDAY NIGHT.

.LONG TERM...(WEDNESDAY THROUGH MONDAY)
ISSUED AT 352 AM CDT TUE JUN 11 2013

SHORT WAVE CONTINUES TO SHIFT EAST THROUGH THE DAY ON
WEDNESDAY...AND MODELS SEEM TO INDICATE THAT STORMS MAY DEVELOP IN
THE POST FRONTAL ENVIRONMENT BUILDING SOUTH THROUGHOUT THE DAY. AT
THE SURFACE...INCREASING NORTHERLY FLOW DEVELOPS ON THE BACK SIDE
OF THE DEPARTING LOW PRESSURE SYSTEM. ATMOSPHERE ONLY APPEARS TO
BE WEAKLY CAPPED...SO RAISED POPS INTO THE CHANCE RANGE ACROSS
MUCH OF THE CWA WITH A PARTICULAR EMPHASIS IN THE EAST. SHEAR AND
CAPE PROFILES DO NOT NECESSARY SUGGEST A SEVERE THREAT...BUT WITH
AROUND 1.5 INCHES OF PRECIPITABLE WATER COULD BE LOOKING AT HEAVY
RAIN ANYWHERE STORMS ARE ABLE TO DEVELOP.

AFTER WEDNESDAY...LOOKING AT A BRIEF BREAK WHERE REGION CAN DRY OUT
FOR A DAY OR TWO WITH SURFACE RIDGE ACROSS THE REGION.  RAISED POPS
EARLY FRIDAY MORNING AS WARM AIR/THETA E ADVECTION COMBINED WITH
30-35 KNOT LOW LEVEL JET APPEARS TO BE ENOUGH TO RESULT IN ELEVATED
THUNDERSTORM DEVELOPMENT.  AM NOT EXPECTING WIDESPREAD SEVERE
POTENTIAL...BUT A FEW OF THE STRONGER STORMS COULD PRODUCE
MARGINALLY SEVERE HAIL.

KEPT SOME CHANCE POPS MAINLY FOR THE MORNING HOURS ON FRIDAY AS
ELEVATED STORMS ARE EXPECTED TO GRADUALLY DIE AWAY AS THE LOW LEVEL
JET WEAKENS. APPEARS THE ATMOSPHERE THEN BECOMES CAPPED MUCH OF THE
DAY ON FRIDAY...BUT MAY BE DEALING WITH A FAIR AMOUNT OF CONVECTIVE
DEBRIS WHICH COULD LIMIT HEATING SOME.  WITH SUN FAIRLY STRONG THIS
TIME OF YEAR...ONLY SHAVED A FEW DEGREES OFF HIGHS BUT THIS WILL BE
SOMETHING TO BE CONSCIOUS OF IN FUTURE PACKAGES.

COLD FRONT IS EXPECTED TO MOVE THROUGH SOUTH DAKOTA FRIDAY NIGHT
INTO SATURDAY...HOWEVER...THE FRONT APPEARS TO WEAKEN AS IT WORKS
EAST. EVENTUALLY STALLING OUT IN AN EAST WEST FASHION THIS WEEKEND
NEAR THE FORECAST AREA.

THE FORECAST THERE BECOMES INCREASINGLY MURKY WITH A SERIES OF WAVES
MOVING THROUGH IN DIRTY ZONAL FLOW.  LEFT MID RANGE POPS IN THE
FORECAST THROUGH THE WEEKEND INTO EARLY NEXT WEEK...BUT LEFT SUNDAY
AND MONDAY DRY DURING THE DAYLIGHT HOURS WITH LACK OF BROAD-SCALE
FORCING ACROSS THE FORECAST AREA.

&&

.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z TUESDAY NIGHT)
ISSUED AT 1045 PM CDT MON JUN 10 2013

VFR CONDITIONS ARE EXPECTED TO PREVAIL THROUGH EARLY MORNING.
AREAS OF LIGHT FOG MAY DEVELOP MAINLY AFTER 09Z AND BEFORE 13Z
DUE TO LOW LEVEL MOISTURE ADVECTION AND RADIATIONAL COOLING.
HOWEVER...THE COVERAGE AND VSBYS ARE NOT EXPECTED TO BE NEARLY AS
WIDESPREAD AND LOW AS LAST NIGHT DUE TO HIGHER WINDS AND SOME
HIGHER CLOUDS ADVECTING IN FROM HIGH PLAINS STORMS. ISOLD TO SCT
SHRA/TSRA WILL BE MOVING EAST THROUGH MAINLY SOUTHEAST SOUTH
DAKOTA STARTING EARLY THIS TUESDAY MORNING THROUGH LATE MORNING.
WILL MENTION VCTS IN KHON TAF BUT CONFIDENCE IN OCCURRENCE AT
ACTUAL TAF SITE IS LOW. EAST WINDS WILL INCREASE AS A WARM FRONT
APPROACHES FROM THE SOUTH TUESDAY AFTERNOON.


&&

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

$$

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