Area Forecast Discussion
Issued by NWS Rapid City, SD

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000
FXUS63 KUNR 241709
AFDUNR

AREA FORECAST DISCUSSION FOR WESTERN SD AND NORTHEASTERN WY
NATIONAL WEATHER SERVICE RAPID CITY SD
1109 AM MDT SUN AUG 24 2014

.SHORT TERM...TODAY THROUGH MONDAY NIGHT
ISSUED AT 251 AM MDT SUN AUG 24 2014

UPPER LOW CONTINUES TO SPIN ACROSS WY/MT WITH DRY AIR PUSHING INTO
THE SW PORTION OF THE FORECAST AREA. RADAR STILL SHOWS SOME SHOWERS
CONTINUING OVER NW SD...BUT THE MAJORITY OF THE SHOWERS HAVE MOVED
OUT OF THE FORECAST AREA. SURFACE OBS ARE SHOWING SOME FOG OVER NW
SOUTH DAKOTA...HOWEVER EXPECT WINDS TO COME UP AROUND 12Z THUS
HAVE LEFT OUT FOG MENTION IN FORECAST PACKAGE.

EXPECT MAINLY DRY CONDITIONS TODAY AS THE LOW MOVES NE INTO
ND/CANADA BY TONIGHT. MUCH COLDER AIR WILL ADVECT INTO THE
NORTHERN PLAINS ON THE BACKSIDE OF THE LOW...BRINGING FALL LIKE
TEMPERATURES TO THE AREA. HIGHS WILL BE IN THE UPPER 50S/MID 60S
OVER NE WY/NW SD WHERE CLOUDS WILL LIKELY PERSIST OVER MUCH OF THE
DAY. OTHERWISE TEMPS SHOULD GET INTO THE UPPER 60S TO UPPER 70S
WHERE SKIES ARE MOSTLY SUNNY. WILL ALSO SEE BREEZY/WINDY CONDITIONS
WITH A FAIRLY TIGHT PRESSURE GRADIENT ACROSS THE AREA.

FOR TONIGHT...WINDS WILL SUBSIDE AROUND SUNSET AS SURFACE HIGH
PRESSURE BUILDS IN FROM THE WEST. LOWS OVERNIGHT WILL BE CHILLY WITH
READINGS IN THE 40S/LOW 50S AND EVEN SOME 30S IN THE BLACK HILLS.

ON MONDAY...POSITIVELY TILTED UPPER TROF DIGS ACROSS THE WESTERN
CONUS WITH WEAK SHORTWAVE RIDGE IN SOUTHWEST FLOW ALOFT. SOME
QUESTION AS TO HOW MUCH THUNDERSTORM ACTIVITY THERE WILL BE
MONDAY...AS SURGE OF WARM MID LEVEL AIR RESULTS IN DECENT CAP.
BETTER CHANCE COMES MONDAY NIGHT WITH INCREASING 700MB THETA-E
ADVECTION.

&&

.LONG TERM...TUESDAY THROUGH SATURDAY
ISSUED AT 251 AM MDT SUN AUG 24 2014

MID/LONG RANGE MODEL SOLUTIONS DIFFER GREATLY IN HOW THEY HANDLE THE
UPPER TROUGH OVER THE WEST COAST. THE GFS MOVES THE TROUGH ACROSS
THE NORTHERN PLAINS ON TUESDAY AND WEDNESDAY. THE ECMWF AND THE GEM
SHOW THE UPPER LOW BECOMING CUT OFF OVER THE CENTRAL ROCKIES
TUESDAY...WITH STRONG UPPER DIVERGENCE ACROSS WESTERN SOUTH DAKOTA
TUESDAY/WEDNESDAY. THAT SOLUTION WOULD CREATE A POTENTIAL FOR HEAVY
RAIN AS PWAT VALUES INCREASE TO AROUND 1.5 INCHES. GEM/ECMWF
SOLUTIONS SHOW THE UPPER LOW/TROF EJECTING ACROSS THE FORECAST AREA
WEDNESDAY NIGHT INTO THURSDAY...INDICATING THAT THUNDERSTORMS COULD
LINGER OVER SOUTH CENTRAL SOUTH DAKOTA INTO THURSDAY. DRIER AND
WARMER WEATHER IS EXPECTED ON FRIDAY AND SATURDAY.

&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z MONDAY)
ISSUED AT 1106 AM MDT SUN AUG 24 2014

VFR CONDITIONS EXPECTED ACROSS MUCH OF THE AREA THIS
AFTERNOON/EVENING...WITH GUSTY WEST WINDS. ISOLATED RAIN SHOWERS
AND LCL MVFR CIGS POSSIBLE ACROSS PORTIONS OF NORTHEAST WYOMING
AND NORTHWEST SOUTH DAKOTA...MAINLY ALONG THE MONTANA BORDER. MVFR
CIGS WILL SLIP SOUTHWARD TONIGHT ACROSS NORTHEAST WYOMING AND
NORTHWEST SOUTH DAKOTA.

&&

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

$$

SHORT TERM...MLS
LONG TERM...10
AVIATION...7






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