Area Forecast Discussion
Issued by NWS Rapid City, SD

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000
FXUS63 KUNR 301720
AFDUNR

AREA FORECAST DISCUSSION FOR WESTERN SD AND NORTHEASTERN WY
NATIONAL WEATHER SERVICE RAPID CITY SD
1120 AM MDT SAT AUG 30 2014

.SHORT TERM...TODAY THROUGH SUNDAY NIGHT
ISSUED AT 313 AM MDT SAT AUG 30 2014

A LONGWAVE TROUGH IS CROSSING THE WRN CONUS...WITH UPPER RIDGING
OVER THE NRN PLAINS ATTM. SURFACE HIGH PRESSURE REMAINS IN CONTROL
OVER CNTRL CANADA TO THE NRN PLAINS. HIGH PRESSURE WILL SLIDE EWD
TODAY WITH STRONG RETURN FLOW SETTING UP OVER THE HIGH PLAINS.
BREEZY SE WINDS WILL SET UP ACROSS THE WRN SD PLAINS THROUGH THE
DAY. UPPER FLOW WILL BECOME MORE SWRLY AS THE UPPER TROUGH
APPROACHES FROM THE WEST...WITH A SURFACE LOW STRENGTHENING OVER
CNTRL/ERN MT. A STRONG UPPER WAVE OVER ID INTO THE GREAT BASIN WILL
MOVE E/NE THROUGH THE DAY BRINGING CHANCES FOR STORMS LATER THIS
AFTN INTO THE EVNG. THE DAY WILL START OFF QUIET WITH MOSTLY SUNNY
SKIES...THEN PRECIP DEVELOPING WEST OF THE CWA WILL BEING MOVING
INTO NE WY AND FAR WRN SD THIS AFTN. STRONG CAP WILL LIMIT STORM
DEVELOPMENT TO MAINLY IN THE LATE AFTN. SOME STORMS ARE EXPECTED TO
DEVELOP OVER THE BLKHLS BUT THINK THE NRN BLKHLS WILL HAVE THE
BETTER CHANCE OF PRECIP GIVEN THE BETTER ENVIRONMENT. SURFACE LOW
WILL CROSS THE NRN CWA INTO THE EVENING AS THE STRONG WAVE CROSSES
THE REGION...WITH A COLD FRONT PUSHING THROUGH TONIGHT. WITH
INCREASING SHEAR THIS EVENING OVER NE WY/NW SD...SOME SUPERCELL
DEVELOPMENT IS EXPECTED ESPECIALLY OVER NW SD WHERE MLCAPE IS
1000-1500 J/KG. STRONG WINDS AND LARGE HAIL WILL BE THE MAIN
THREATS. STORMS WILL END/PUSH EAST OF THE CWA LATER TONIGHT AS THE
UPPER WAVE CONTINUES TOWARD THE UPPER MIDWEST.

A QUICK BREAK IN PRECIP IS EXPECTED LATE TONIGHT...BUT THE NEXT
CHANCE OF SHOWERS/STORMS WILL BE SUNDAY MORNING AS THE MAIN TROUGH
AXIS APPROACHES. PRECIP WILL CROSS THE CWA THROUGH THE DAY SUNDAY
AS AN UPPER WAVE ROUNDS THE BASE OF THE TROUGH. HAVE INCREASED
POPS DURING THE DAYTIME HOURS. HAVE DROPPED TEMPS OVER NE WY AS
COLD AIR CONTINUES TO FILTER IN FROM THE W/NW. TEMPS OVER NE WY
SHOULD BE LIMITED TO THE 60S...WHILE WRN SD REACHES THE 70S.
PRECIP WILL END LATE SUNDAY OR SUNDAY EVENING AS THE TROUGH AXIS
PUSHES EAST OF THE CWA.

&&

.LONG TERM...MONDAY THROUGH FRIDAY
ISSUED AT 313 AM MDT SAT AUG 30 2014

SHORTWAVE IN CYCLONIC FLOW PASSES ACROSS THE NORTHERN PLAINS
MONDAY. WITH STEEP MID LEVEL LAPSE RATES...SCATTERED SHRA/TSRA
EXPECTED. UPPER TROF DIGS INTO THE PACIFIC NORTHWEST
TUE/WED...WITH FLAT RIDGE ACROSS THE NORTHERN PLAINS. THIS WILL
BRING DRY WEATHER AND ABOVE AVERAGE TEMPERATURES FOR MID WEEK.

&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z SUNDAY)
ISSUED AT 1118 AM MDT SAT AUG 30 2014

SCATTERED TSRA WILL DEVELOP ACROSS NORTHEAST WY THIS
AFTERNOON...SPREADING EAST ACROSS NORTHWEST SD THROUGH THIS
EVENING. ISOLATED -TSRA MAY DEVELOP OVER SOUTHWEST INTO SOUTH
CENTRAL SD THIS EVENING. IFR VSBYS EXPECTED WITH THE STRONGEST
STORMS ALONG WITH HAIL/GUSTY WINDS. OUTSIDE OF STORMS...VFR
CONDITIONS ARE EXPECTED.

&&

.UNR WATCHES/WARNINGS/ADVISORIES...
SD...NONE.
WY...NONE.
&&

$$

SHORT TERM...13
LONG TERM...7
AVIATION...HELGESON




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