Area Forecast Discussion
Issued by NWS Rapid City, SD

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000
FXUS63 KUNR 311642
AFDUNR

AREA FORECAST DISCUSSION FOR WESTERN SD AND NORTHEASTERN WY
NATIONAL WEATHER SERVICE RAPID CITY SD
1042 AM MDT FRI JUL 31 2015

.UPDATE...
ISSUED AT 1024 AM MDT FRI JUL 31 2015

BASED ON THE 12Z MODELS HAVE EXPANDED THE AREA WHERE
THUNDERSTORMS WILL BE POSSIBLE LATE THIS AFTERNOON AND THIS
EVENING. INSTABILITY REMAINS RATHER WEAK THIS AFTERNOON AND WITH
VERY LITTLE SHEAR OVER NERN WY AND THE BLKHLS AREA EXPECT ANY
THUNDERSTORMS THAT MAY DEVELOP TODAY TO REMAIN ISOLATED AND
SHORT IN DURATION. DUE TO DRY LOW LEVELS GUSTY SFC WINDS LOOK TO
BE THE MOST LIKELY RESULT OF ANY CONVECTION. MID LEVEL INSTABILITY
INCREASES TONIGHT POSSIBLY LEADING TO LONGER LASTING TSTMS EAST
OF THE BLKHLS MOVING EASTWARD TONIGHT ESP FROM SWRN INTO SC SD.

&&

.SHORT TERM...TODAY THROUGH SATURDAY NIGHT
ISSUED AT 236 AM MDT FRI JUL 31 2015

BROAD UPPER RIDGING WILL REMAIN ACROSS THE WRN CONUS THROUGH THE
REMAINDER OF THE WEEK. SURFACE HIGH PRESSURE WILL DOMINATE THE NRN
PLAINS TODAY BRINGING GENERALLY DRY WEATHER TO THE AREA.
TEMPERATURES WILL RISE INTO THE UPPER 80S TO MID 90S ACROSS THE
PLAINS...AND 80S OVER THE BLACK HILLS. WITH DEWPOINTS IN THE 40S TO
LOW 50S...THERE WONT BE MUCH MOISTURE/CAPE AVAILABLE FOR CONVECTION.
BUT CANT RULE OUT ISOLATED STORMS OVER THE HILLS INTO THE SRN PTNS
OF THE CWA MAINLY IN THE LATE AFTN/EVNG. OTHERWISE MOSTLY SUNNY
SKIES ARE EXPECTED AREAWIDE WITH RELATIVELY LIGHT WINDS. HIGH
PRESSURE WILL SLIDE EWD TONIGHT WITH RETURN FLOW SETTING UP ACROSS
NE WY/WRN SD. GOOD THETA E ADVECTION SET UP THE LOW/MID LEVELS WITH
STEEP LAPSE RATES. COULD SEE ELEVATED STORMS DEVELOP THROUGH THE
NIGHT...ESPECIALLY AS A SUBTLE UPPER WAVE AND WEAK COLD FRONT CROSS
THE AREA THROUGH EARLY SAT MRNG. BULK OF CONVECTION WILL BE EAST OF
THE CWA BY MID MORNING. WITH DRIER AIR RETURNING TO THE CWA...NOT
MUCH CONVECTION EXPECTED THROUGH THE DAY SATURDAY. HIGHS WILL BE IN
THE MID 80S TO MID 90S.

.LONG TERM...SUNDAY THROUGH THURSDAY
ISSUED AT 236 AM MDT FRI JUL 31 2015

GFS/ECMWF IN DECENT AGREEMENT WITH THE OVERALL PATTERN
FOR MUCH OF NEXT WEEK. HOWEVER...MINOR TIMING DIFFERENCES EXIST WITH
IMPULSES MOVING THROUGH THE NORTHERN PLAINS.

SUNDAY WILL BE WARM AND DRY AS UPPER RIDGE BUILDS ACROSS THE PLAINS.
HIGHS INTO THE 90S WITH RELATIVE HUMIDITY DROPPING TO AROUND 15
PERCENT. MIGHT BE SOME FIRE WEATHER CONCERNS...BUT WINDS LOOK
RELATIVELY LIGHT AT THIS TIME. THUNDERSTORM CHANCES INCREASE FOR THE
FIRST HALF OF THE WEEK. RIDGE BEGINS TO BREAK DOWN MONDAY AS IMPULSE
AND ASSOCIATED PLUME OF MID LEVEL MOISTURE LIFTS FROM THE DESERT
SOUTHWEST INTO THE ROCKIES. MAIN IMPULSE THEN LIFTS INTO THE
NORTHERN PLAINS TUESDAY. FOR THE LAST HALF OF THE WEEK...UPPER HIGH
REMAINS ANCHORED ACROSS THE SOUTHERN/CENTRAL PLAINS...WITH FLAT
RIDGE ACROSS THE NORTHERN PLAINS. SERIES OF SHORTWAVES RIDE OVER THE
RIDGE...WITH LOW LEVEL BAROCLINIC ZONE ACROSS THE AREA. THIS RESULTS
IS A DAILY CHANCE OF THUNDERSTORMS. TEMPERATURES WILL BE NEAR
AVERAGE.

&&

.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z SATURDAY MORNING)
ISSUED AT 508 AM MDT FRI JUL 31 2015

VFR CONDITIONS EXPECTED THROUGH TONIGHT.


&&

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

$$

UPDATE...WFO UNR
SHORT TERM...13
LONG TERM...7
AVIATION...7


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