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000
FXUS63 KUNR 242334
AFDUNR

AREA FORECAST DISCUSSION FOR WESTERN SD AND NORTHEASTERN WY
NATIONAL WEATHER SERVICE RAPID CITY SD
534 PM MDT FRI MAY 24 2013

.SHORT TERM...THIS EVENING THROUGH SATURDAY NIGHT
ISSUED AT 222 PM MDT FRI MAY 24 2013

UPPER ANALYSIS SHOWS A LOW CIRCULATING OVER THE NORTHWEST CONUS
AND THE RIDGE AXIS EAST OF THE CWA. SOUTHWEST FLOW IS SETTING UP
OVER THE REGION. SURFACE MAP SHOWS LOW MOVING INTO NORTHWEST SOUTH
DAKOTA...WITH A TIGHT PRESSURE GRADIENT PERSISTING ACROSS CENTRAL
SOUTH DAKOTA. SOUTHERLY WINDS REMAIN GUSTY ACROSS SOUTH CENTRAL
SOUTH DAKOTA...BUT HAVE DECREASED SINCE EARLIER THIS MORNING.
WINDS ARE SHIFTING TO THE NORTHWEST BEHIND THE LOW...AND TEMPS ARE
CLIMBING INTO THE 60S AND LOWER 70S.

WINDS WILL BECOME LIGHT OVERNIGHT. A FEW SHOWERS AND THUNDERSTORMS
ARE POSSIBLE ACROSS SOUTHERN PORTIONS OF THE AREA...MAINLY AFTER
MIDNIGHT...AS MUCAPE INCREASES TO 1500-2000 J/KG. LOWS WILL BE IN
THE MID-40S TO MID-50S.

SOUTHWEST FLOW WILL CONTINUE ON SATURDAY...WITH A WAVE MOVING
THROUGH THE CWA. SOUTHEAST WINDS WILL INCREASE AHEAD OF THE
LOW-LEVEL TROUGH...BRINGING IN MOISTURE...WITH DEW POINTS 50-60
DEGREES. A SWATH OF SBCAPE OF 2500-3500 J/KG SETS UP ACROSS MUCH OF
THE CWA BY 21Z...WITH BEST FORCING ALONG THE SD/WY BORDER FOR THE
AFTERNOON...MOVING EASTWARD WITH THE TROUGH IN THE EVENING. EXPECT
SHOWERS AND THUNDERSTORMS TO START SATURDAY MORNING AS THE EAST
WINDS PUSH MOISTURE UP AGAINST THE HILLS...AND THEN BECOME MORE
WIDESPREAD AND INTENSE IN THE AFTERNOON AS FORCING AND INSTABILITY
INCREASE AND ALIGN. PRECIPITABLE WATER IS BETWEEN 1 AND 1.5
INCHES...WHICH IS IN THE 99TH PERCENTILE FOR LATE MAY...SO HEAVY
RAIN CAN BE EXPECTED WITH THESE STORMS. ALTHOUGH BEST 0-1 KM SRH
DOES NOT LINE UP WITH BEST LFC/LCL HEIGHTS...WOULD NOT RULE OUT
THE POSSIBILITY FOR AN ISOLATED TORNADO. HIGHS SATURDAY WILL BE IN
THE MID-70S TO MID-80S...WITH LOWS SATURDAY NIGHT IN THE UPPER 40S
TO UPPER 50S.

&&

.LONG TERM...SUNDAY THROUGH FRIDAY
ISSUED AT 222 PM MDT FRI MAY 24 2013

PERSISTENT TROF ACROSS THE PACIFIC NORTHWEST WILL KEEP
THE NORTHERN PLAINS UNDER ACTIVE SOUTHWEST FLOW LATE IN THE WEEKEND
INTO EARLY NEXT WEEK. DAILY CHANCES FOR TSTMS WILL CONTINUE AS LIGHT
EAST TO SOUTHEAST BOUNDARY LAYER FLOW CONTINUES TO BRING MOIST AIR
INTO THE REGION...AND WEAK ENERGY EJECTS OUT OF THE WESTERN TROF
INTO THE NORTHERN PLAINS. LONGER RANGE GUIDANCE IS STILL SUGGESTING
A STRONG NEGATIVELY TILTED UPPER TROF WORKING THROUGH THE NRN PLAINS
MID/LATE NEXT WEEK WHICH COULD PROVIDE WDSPRD SIGNIFICANT RAINFALL.
TEMPERATURES WILL REMAIN ABOVE AVERAGE...WITH HIGHS GENERALLY IN THE
70S AND LOWER 80S ACROSS THE AREA THROUGH THE MIDDLE OF NEXT
WEEK...WITH SOME COOLING EXPECTED TOWARDS THE END OF THE WEEK.

&&

.AVIATION...(FOR THE 00Z TAFS THROUGH 00Z SATURDAY EVENING)
ISSUED AT 527 PM MDT FRI MAY 24 2013

A TROUGH OF LOW PRESSURE WILL EVENTUALLY STALL OVER WESTERN SD AS
ANOTHER UPPER LEVEL DISTURBANCE APPROACHES THE REGION. ISOLD
SHRA/TSRA WILL BE POSSIBLE SATURDAY MORN...WITH COVERAGE
INCREASING IN THE AFTERNOON WITH SOME STORMS POSSIBLY BECOMING
SEVERE OVER PORTIONS OF NERN WY AND WRN SD. MVFR TO IFR CIGS/VIS
WILL BE POSSIBLE IN ANY TS. OTHERWISE...VFR CONDITIONS ARE
EXPECTED.


&&

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

$$

SHORT TERM...POJORLIE
LONG TERM...JOHNSON
AVIATION...JC