Area Forecast Discussion
Issued by NWS Rapid City, SD

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000
FXUS63 KUNR 302045
AFDUNR

AREA FORECAST DISCUSSION FOR WESTERN SD AND NORTHEASTERN WY
NATIONAL WEATHER SERVICE RAPID CITY SD
245 PM MDT THU APR 30 2015

.SHORT TERM...THIS EVENING THROUGH FRIDAY NIGHT
ISSUED AT 225 PM MDT THU APR 30 2015

20Z SFC ANALYSIS SHOWS N-S ORIRENTED TROUGH OVER CENTRAL SOUTH
DAKOTA WITH GUSTY NORTHWEST WINDS TO THE WEST OF THE TROUGH AND
GUSTY SOUTHERLY WINDS TO THE EAST. SFC HIGH PRESSURE WAS CENTERED
OVER NC WY. UPPER SHORTWAVE COMBINED WITH INSTABILITY DUE TO CAA
ALOFT IS PRODUCING SCATTERED SHOWERS AND ISOLATED THUNDESRSTORMS
ACROSS PARTS OF THE FORECAST AREA THIS AFTN...WITH A WEAKLY
DEFINED LINE OF SHOWERS FROM NC-SW SD ALONG THE REGION OF BEST LL
CAA.

FOR TONIGHT...THE PRECIPITATION WILL GRADUALLY SHIFT TO THE
SOUTHEAST THIS EVENING ALONG WITH THE UPPER SHORTWAVE. IT LOOKS
LIKE THE SFC BOUNDARY WILL ALMOST STALL OVER SOUTH CENTRAL SOUTH
DAKOTA AND ENERGY CURRENTLY MOVING NORTHEASTWARD OUT OF COLORADO
WILL CREATE A CHANCE OF SHOWERS AND THUNDERSTORMS IN THE REGION OF
A DEVELOPING LL JET ALONG THE BOUNDARY OVER SC SD. GUSTY NORTHWEST
WINDS WILL GRADUALLY DECREASE THIS EVENING.

ON FRIDAY... ZONAL FLOW ALOFT WILL TAKE OVER AS A BROAD RIDGE SETTLES
OVER THE DESERT SOUTHWEST. WEAK SURFACE HIGH WILL SLIDE ACROSS THE
DAKOTAS DURING THE DAY...PRODUCING MOSTLY SUNNY SKIES AND
RELATIVELY LIGHT WINDS. HIGH TEMPERATURES WILL CLIMB INTO THE MID
60S TO MID 70S. MOSTLY CLEAR SKIES WILL PERSIST THROUGH FRIDAY
NIGHT WITH LOWS IN THE 40S.

.LONG TERM...SATURDAY THROUGH THURSDAY
ISSUED AT 225 PM MDT THU APR 30 2015

VERY WARM CONDITIONS ARE EXPECTED ON SATURDAY WITH THERMAL RIDGE
CROSSING THE CWFA. BEST CHANCE FOR TSRA WILL BE OVER CNTRL SD
ALONG/AHEAD OF A SURFACE TROF. FLOW ALOFT WILL BE NEARLY ZONAL
SUNDAY THROUGH TUESDAY WITH COOLER...BUT NEAR TO SLIGHTLY ABOVE
AVERAGE...TEMPERATURES FILTERING INTO THE NRN PLAINS. SEVERAL
DISTURBANCES EMBEDDED IN THE FLOW WILL BRING NEARLY DAILY CHANCES
FOR SHRA/TSRA...ESPECIALLY DURING THE AFTERNOON/EVENING HOURS.
FLOW ALOFT THEN BECOMES SW BY MID WEEK AS A DEEP TROF DEVELOPS
OVER THE WRN CONUS. BOTH GFS/ECMWF CONTINUE TO SHOW A STRONG
DISTURBANCE EJECTING INTO THE CNTRL/NRN PLAINS WED/THU WHICH WOULD
BRING INCREASING CHANCES FOR PCPN.

&&

.AVIATION...FOR THE 18Z TAFS THROUGH 18Z FRIDAY
ISSUED AT 225 PM MDT THU APR 30 2015

A COLD FRONT WILL CONTINUE TO CROSS SCNTRL SD THIS
AFTN/EVNG BRINGING GUSTY NW WINDS...ESPECIALLY TO THE WRN SD PLAINS.
ISOLATED TO SCATTERED SHOWERS AND TSTORMS WILL CONTINUE TO DEVELOP
ACROSS THE AREA THROUGH THE LATE AFTN AND EVNG HOURS. MVFR
CONDITIONS ARE POSSIBLE NEAR ANY PRECIP. OTHERWISE VFR CONDITIONS
ARE EXPECTED THROUGH FRIDAY.

&&

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

$$

SHORT TERM...10
LONG TERM...13
AVIATION...13



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