Area Forecast Discussion
Issued by NWS Rapid City, SD

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FXUS63 KUNR 022100
AFDUNR

AREA FORECAST DISCUSSION FOR WESTERN SD AND NORTHEASTERN WY
NATIONAL WEATHER SERVICE RAPID CITY SD
300 PM MDT SUN AUG 2 2015

.SHORT TERM...THIS EVENING THROUGH MONDAY NIGHT
ISSUED AT 300 PM MDT SUN AUG 2 2015

CURRENT SURFACE ANALYSIS SHOWS FRONTAL BOUNDARY NOW FROM CENTRAL
MT THROUGH NORTHEAST WY AND ACROSS FAR NORTHERN NEB. UPPER LEVEL
ANALYSIS CONTINUES TO SHOW RIDGE OVER THE WESTERN CONUS...WITH
NORTHWESTERLY FLOW OVER THE NORTHERN PLAINS. MONSOONAL MOISTURE IS
IN PLACE OVER MUCH OF THE WESTERN STATES AND INTO THE SOUTHERN
PLAINS. SKIES ARE SUNNY ACROSS MUCH OF THE AREA WITH TEMPS IN THE
MID 80S TO LOWER 90S ACROSS THE PLAINS...UPPER 70S TO MID 80S IN
THE BLACK HILLS. A FEW CLOUDS REMAIN ACROSS PORTIONS OF NORTHEAST
WY AND SOUTHWEST SD...WITH ISOLATED SHOWERS AND THUNDERSTORMS TO
THE SOUTH OF THE CWA NEAR THE FRONTAL BOUNDARY. A COUPLE OF
BUILDUPS OVER THE SOUTHERN BLACK HILLS HAVE PRODUCED MAINLY
LIGHT SHOWERS/SPRINKLES SO FAR. WINDS ARE FROM THE NORTH TO
NORTHEAST IN MOST AREAS.

THE HOT AND MAINLY DRY WEATHER PATTERN OF THE LAST WEEK OR SO WILL
CONE TO AN END EARLY THIS WEEK AS THE RIDGE TO THE WEST BREAKS DOWN
ENOUGH TO ALLOW A SERIES OF UPPER LEVEL DISTURBANCES TO CROSS THE
REGION. CHANCES FOR SHOWERS AND THUNDERSTORMS WILL BEGIN TO INCREASE
LATE MONDAY INTO MONDAY NIGHT...AND ESPECIALLY ON TUESDAY.

FOR TONIGHT...SKIES WILL REMAIN CLEAR IN MANY AREAS. A LOW LEVEL
SOUTHERLY JET WILL DEVELOP ACROSS WESTERN NEB AND NOSE INTO
SOUTHWEST SD OVERNIGHT. A SHOWER OR STORM IS POSSIBLE OVER PORTIONS
OF SOUTHWEST INTO SOUTH CENTRAL SD OVERNIGHT. WILL ADD A SLIGHT CHANCE
FOR SHOWERS AND STORMS FROM SHANNON COUNTY EASTWARD TO MELLETTE AND
TODD CO. LOWS TONIGHT WILL BE IN THE MID 50S TO MID 60S WITH LIGHT
EAST TO NORTHEAST WINDS IN MOST AREAS.

WILL SEE A VERY GRADUAL INCREASE IN CLOUDS ON MONDAY FROM THE
SOUTHWEST AS SHORTWAVE ENERGY WITHIN THE RIDGE MOVES NORTHEAST
ACROSS THE GREAT BASIN INTO THE CENTRAL ROCKIES. THE CLOUDS AND
WEAKENING RIDGE WILL HELP TO BRING A SLIGHT COOLDOWN IN TEMPS...WITH
HIGHS IN THE 80S ON THE PLAINS AND MOSTLY 70S IN THE BLACK HILLS.
CHANCES FOR SHOWERS AND STORMS SHOULD REMAIN LIMITED TO PORTIONS OF
NORTHEAST WY AND SOUTHWEST SD IN THE AFTERNOON...WITH CHANCES
INCREASING A BIT AND SPREADING NORTH AND EAST ACROSS MUCH OF THE CWA
MONDAY NIGHT. THE THREAT FOR SEVERE STORMS LOOKS MINIMAL ON MONDAY
AT THIS POINT...BUT A STRONG STORM OR TWO IS POSSIBLE ACROSS
SOUTHERN PORTIONS OF THE CWA LATE IN THE DAY AND EVENING.

.LONG TERM...TUESDAY THROUGH SUNDAY
ISSUED AT 300 PM MDT SUN AUG 2 2015

CHANCE FOR THUNDERSTORMS INCREASE THIS WEEK...WITH BEST
CHANCE COMING TUESDAY INTO WEDNESDAY. 00Z MODELS CONTINUE TO SHOW
UPPER IMPULSE KNOCKING DOWN RIDGE TUESDAY/TUESDAY NIGHT. SLIGHT
DIFFERENCES WITH GFS/ECMWF/GEM...TRACKING SURFACE LOW ACROSS
SOUTHERN SOUTH DAKOTA/NEBRASKA. 00Z NAM  MUCH STRONGER WITH SURFACE
TO 700MB LOW THAN THE OTHER MODELS. IT APPEARS NAM IS SUFFERING WITH
CONVECTIVE FEEDBACK ISSUES...AS IT DUMPS 6+ INCHES OF RAIN OVER THE
BLACK HILLS. AREA WILL BE PRIMED FOR THUNDERSTORMS AS LOW LEVEL
EASTERLY FLOW INCREASES BL MOISTURE AND MID LEVEL MOISTURE SURGES
NORTHWARD FROM THE SOUTHWESTERN U.S. CAPE/SHEAR SUGGEST MARGINAL
SEVERE STORMS POSSIBLE TUESDAY...BUT MAIN THREAT WILL BE LOCALLY
HEAVY RAIN. WENT WITH COOLER TEMPERATURES FOR HIGHS
TUESDAY/WEDNESDAY WITH ABUNDANT CLOUD COVER/PRECIPITATION.

THUNDERSTORM CHANCES CONTINUE INTO THE WEEKEND. GFS/ECMWF BRING NEXT
UPPER TROF THROUGH THE NORTHERN PLAINS THURSDAY. FLAT UPPER RIDGE
THEN SETS OVER THE ROCKIES AS TROF MOVES INTO THE WESTERN CONUS.
SEVERAL WEAK SHORTWAVES MOVE OVER THE RIDGE INTO THE NORTHERN
PLAINS.

&&

.AVIATION...FOR THE 18Z TAFS THROUGH 18Z MONDAY
ISSUED AT 300 PM MDT SUN AUG 2 2015

VFR CONDITIONS EXPECTED THROUGH TONIGHT.


&&

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

$$

SHORT TERM...26
LONG TERM...10
AVIATION...10


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