000
FXUS63 KUNR 132019
AFDUNR

AREA FORECAST DISCUSSION FOR WESTERN SD AND NORTHEASTERN WY
NATIONAL WEATHER SERVICE RAPID CITY SD
219 PM MDT THU JUN 13 2013

.SHORT TERM...THIS EVENING THROUGH FRIDAY NIGHT
ISSUED AT 107 PM MDT THU JUN 13 2013

CURRENT SURFACE ANALYSIS PLACES LOW OVER NORTH-CENTRAL WYOMING
INTO SOUTH-CENTRAL MONTANA WHILE HIGH REMAINS OVER THE UPPER
MIDWEST. PRESSURE GRADIENT OVER OUR AREA CONTINUES TO PRODUCE
GUSTY SOUTH/SOUTHEASTERLY WINDS. UPPER LEVEL ANALYSIS PLACES
RIDGE AXIS SHIFTING OVER THE EASTERN DAKOTAS WITH LOW OVER THE
PACIFIC NORTHWEST. ACTIVE SWRLY FLOW CONTINUES AHEAD OF THE UPPER
LOW PRODUCING A FEW THUNDERSTORMS OVER THE ERN ROCKIES INTO PTNS
OF THE NRN PLAINS.

FOR THE REST OF TODAY INTO TONIGHT...UPPER TROF SLOWLY WORKS ITS
WAY OVER THE ROCKIES WHILE SFC LOW SHIFTS OVER NORTHEAST WYOMING
IN THE EVENING...THEN TRANSITIONS NORTHWARD AS A COLD FRONT STARTS
TO WORK INTO THE AREA. CONVECTION CONTINUES TO TRY AND DEVELOP
OVER NERN WYOMING...BUT STRONG CAPPING HAS SO FAR INHIBITED ANY
STRONG DEVELOPMENT. CAP ERODES SOME LATER IN THE AFTERNOON/EARLY
EVE. WITH AMPLE INSTABILITY (1.5-2 KJ/KG) AND STRONG DEEP LAYER
SHEAR (50KT+ 0-6KM) ANY STORM THAT DOES DEVELOP AND BECOME
ESTABLISHED WILL HAVE SEVERE POTENTIAL. FOCUS FOR CONVECTION
SHIFTS TO THE NORTH AND EAST OVERNIGHT AS LOW LEVEL JET/THETA-E
ADVECTION INCREASES.

ON FRIDAY...UPPER LOW LIFTS INTO SASKATCHEWAN WITH MAIN AREA OF
PRECIP SHIFTING NORTH. COLD FRONT CONTINUES TO PUSH THROUGH MUCH OF
THE AREA IN THE MORNING...WORKING TO THE EAST OF THE CWA BY EARLY
AFTERNOON. THIS WILL MAKE HIGH TEMP FORECAST A BIT TRICKY AS IT
WILL BE DEPENDENT ON TIMING OF THE FRONT. PRECIP CHANCES WILL
TAPER IN THE WAKE OF THE FRONT AS ATMOS STABILIZES AND DRIER AIR
WORKS IN.

&&

.LONG TERM...SATURDAY THROUGH THURSDAY
ISSUED AT 107 PM MDT THU JUN 13 2013

UPPER LOW TRACKS ACROSS SRN SASKATCHEWAN/MANITOBA
ON SATURDAY...WITH SURFACE HIGH ACROSS SRN MT INTO WRN SD.
THERE MAY BE JUST ENOUGH RETURN FLOW/INSTABILITY FOR AN AFTN/EVE
TSTM AROUND THE BLKHLS. UPPER TROF THEN DIGS INTO THE PAC NW EARLY
NEXT WEEK...WITH RIDGE BUILDING INTO THE NRN PLAINS. THIS WILL
RESULT IN WARMER TEMPERATURES ALONG WITH ISOLATED/SCATTERED TSTMS
EACH DAY. UPPER RIDGE BREAKS DOWN MID/LATE WEEK AS SW FLOW ALOFT
INCREASES WITH UPPER TROF WORKING INTO THE NRN ROCKIES. TSTMS COULD
BECOME A BIT MORE ACTIVE IN OUR AREA GIVEN A RETURN TO SW FLOW ALOFT.

&&

.AVIATION...FOR THE 18Z TAFS THROUGH 18Z FRIDAY AFTERNOON
ISSUED AT 107 PM MDT THU JUN 13 2013

VFR CONDITIONS WILL CONTINUE THROUGH THIS AFTERNOON.
ISOLD TSTMS POSSIBLE LATE THIS AFTN AND EVENING WITH LCL GUSTY WINDS
AND IFR VSBY...MAINLY ACROSS NERN WY AND FAR WRN SD. A COLD FRONT
WILL MOVE THROUGH EARLY FRIDAY AND BRING A PERIOD OF GUSTY NW
WINDS...AS WELL AS A BRIEF PERIOD OF MVFR CIGS TO NERN WY AND NWRN
SD.

&&

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

$$

SHORT TERM...77
LONG TERM...JOHNSON
AVIATION...JOHNSON