Area Forecast Discussion
Issued by NWS Rapid City, SD

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FXUS63 KUNR 181720
AFDUNR

AREA FORECAST DISCUSSION FOR WESTERN SD AND NORTHEASTERN WY
NATIONAL WEATHER SERVICE RAPID CITY SD
1120 AM MDT MON AUG 18 2014

.UPDATE...
ISSUED AT 915 AM MDT MON AUG 18 2014

CURRENT SURFACE ANALYSIS SHOWS LOW PRESSURE OVER NORTHEAST ND WITH
HIGH PRESSURE OVER THE NORTHERN ROCKIES. UPPER LEVEL ANALYSIS
SHOWS TROF OVER SOUTH CENTRAL CANADA...WITH NORTHWESTERLY FLOW
OVER MOST OF THE NORTHERN HIGH PLAINS. DRIER AIR IS IN PLACE
ACROSS THE AREA FOR TODAY...WITH DEWPOINTS MOSTLY IN THE UPPER 40S
AND 50S. ISOLATED SHOWERS OVER SOUTHWESTERN SD HAVE DISSIPATED OR
MOVED SOUTH OF THE AREA. TEMPS ARE IN THE UPPER 60S TO MID 70S AT
THIS HOUR. NORTHWESTERLY WINDS ARE INCREASING AND WILL BE BREEZY
AT TIMES ACROSS MUCH OF THE WESTERN SD PLAINS THROUGH THE
AFTERNOON.

HAVE UPDATED TO REMOVE POPS FOR SOUTHWESTERN SD THIS MORNING AND
MAKE MINOR TWEAKS TO CLOUD COVER. WILL KEEP A SLIGHT CHANCE FOR
SHOWERS AND STORMS THIS AFTERNOON ACROSS FAR NORTHWESTERN SD AS A
SHORTWAVE MOVES ACROSS ND.

&&

.SHORT TERM...TODAY THROUGH TUESDAY NIGHT
ISSUED AT 231 AM MDT MON AUG 18 2014

UPPER LEVEL ANALYSIS HAS LARGE TROF ACROSS SOUTHERN CANADA AND THE
NORTHERN PLAINS...WITH RIDGE ACROSS THE SOUTHWEST CONUS. SKIES ARE
MOSTLY CLEAR. AT THE SURFACE...LOW PRESSURE CENTER AND ASSOCIATED
COLD FRONT HAS PUSHED INTO WESTERN MINNESOTA...WITH HIGH PRESSURE
OVER MONTANA AND THE WESTERN DAKOTAS. WINDS ARE LIGHT AND
TEMPERATURES AT 2 AM ARE IN THE 50S TO LOWER 60S.

TODAY AND TONIGHT....DRY NORTHWEST FLOW WILL KEEP CONDITIONS FAIR
AND DRY ACROSS MUCH OF THE AREA. SOME ISOLATED AFTERNOON SHOWERS
WILL BE POSSIBLE ACROSS FAR NORTHWEST SOUTH DAKOTA. BREEZY
NORTHWEST WINDS ARE EXPECTED TO DEVELOP OVER THE SOUTH DAKOTA
PLAINS BY MIDDAY. HIGH TEMPERATURES WILL BE IN THE LOWER 70S TO
MID 80S. SKIES WILL BE MOSTLY CLEAR OVERNIGHT WITH LOW
TEMPERATURES FALLING INTO THE 50S TO LOWER 60S.

TUESDAY AND TUESDAY NIGHT...UPPER TROF SHIFTS EAST AS WEAK RIDGE
BUILDS ACROSS THE NORTHERN PLAINS. MOST OF THE DAY WILL BE MOSTLY
SUNNY WITH HIGH TEMPERATURES CLIMBING INTO THE UPPER 70S TO UPPER
80S. SOUTHWEST UPPER FLOW DEVELOPS LATE IN THE DAY AS WESTERN
TROF DEEPENS. SHORTWAVE ENERGY EJECTS OUT OF THE TROF AND ENTERS
WESTERN PORTIONS OF THE AREA LATE IN THE AFTERNOON...AND CROSSES
THE REMAINDER OF THE FORECAST AREA OVERNIGHT. SHOWERS AND
THUNDERSTORMS ARE EXPECTED WITH A FEW STRONGER STORMS POSSIBLE.
LOW TEMPERATURES TUESDAY NIGHT WILL BE IN THE MID 50S TO MID 60S.

&&

.LONG TERM...WEDNESDAY THROUGH SUNDAY
ISSUED AT 231 AM MDT MON AUG 18 2014

A SIGNIFICANT UPPER TROF IS EXPECTED TO WORK THROUGH THE WRN CONUS
IN THE MID/LATE WEEK PERIOD...THEN INTO THE PLAINS OVER THE WEEKEND.
THE FIRST SUBSTANTIAL SHORT WAVE WILL EJECT OUT OF THE TROF ON
WEDNESDAY AND BRING A GOOD CHANCE OF PCPN TO OUR REGION. PCPN
CHANCES WILL THEN REMAIN FAIRLY HIGH THROUGH THE WEEKEND AS THE
UPPER TROF EVOLVES SLOWLY EWD. TEMPS WILL REMAIN FAIRLY WARM DURING
THE MID WEEK PERIOD...BUT THEN COOL SUBSTANTIALLY BY THE WEEKEND AS
THE TROF MOVES INTO THE PLAINS.

&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z TUESDAY)
ISSUED AT 1117 AM MDT MON AUG 18 2014

VFR CONDITIONS ARE EXPECTED THROUGH THE FORECAST PERIOD. A WARM
FRONT WILL SHIFT NORTH TONIGHT AND POSSIBLY SUPPORT AN ISOLD
SHRA/TS INVOF THE BLACK HILLS AND SE LATE TONIGHT.

&&

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

$$

UPDATE...26
SHORT TERM...15
LONG TERM...JOHNSON
AVIATION...JC





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