Area Forecast Discussion
Issued by NWS Rapid City, SD

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000
FXUS63 KUNR 310150
AFDUNR

AREA FORECAST DISCUSSION FOR WESTERN SD AND NORTHEASTERN WY
NATIONAL WEATHER SERVICE RAPID CITY SD
750 PM MDT THU OCT 30 2014

.UPDATE...
ISSUED AT 746 PM MDT THU OCT 30 2014

01Z SURFACE ANALYSIS HAD HIGH PRESSURE OVER SOUTHWEST MB WITH
NORTHEAST UPSLOPE FLOW OVER THE CWA. 00Z BIS SOUNDING OVERLAID ON
00Z KUNR SOUNDING SUPPORTS ST/FG DEVELOPMENT. LATEST FOG PRODUCT
SHOWED ST STARTING TO ADVANCE SOUTHWEST AS BOUNDARY LAYER COOLS
AND UPSLOPE FLOW CONTINUES. 00Z RAP/HRRR SHOW ST ACCELERATING
SOUTHWEST THIS EVENING AND ENVELOPING THE BLACK HILLS OVERNIGHT.
SOME FOG WILL DEVELOP ON NORTH/EAST SLOPES OF THE BLACK HILLS.

FORECAST BEING UPDATED TO ADJUST FOR SLOWER ST/BR INTRUSION BASED
ON LATEST SATELLITE TRENDS.

&&

.SHORT TERM...THIS EVENING THROUGH FRIDAY NIGHT
ISSUED AT 217 PM MDT THU OCT 30 2014

UPPER LEVEL RIDGE COVERS THE WESTERN CONUS...WITH SURFACE HIGH
OVER SASKATCHEWAN. LOW STRATUS COVERS MUCH OF ND AND
NORTHERN/EASTERN SD. NORTHERLY WINDS ARE ABOUT 10-15 KTS...AND
TEMPS RANGE FROM THE UPPER 30S IN THE NORTH TO THE MID 50S FARTHER
SOUTH.

SURFACE HIGH WILL DRIFT SOUTHWARD TONIGHT...CAUSING WINDS TO BECOME
LIGHT AND EASTERLY. LOW CLOUDS ARE EXPECTED TO MOVE SOUTHWARD AS
WELL...DEVELOPING INTO FOG AS THEY APPROACH HIGHER ELEVATIONS. FOG
IS EXPECTED FORM AROUND THE EASTERN FOOTHILLS EARLY THIS EVENING AND
EXPAND ACROSS MUCH OF WESTERN SD OVERNIGHT...WRAPPING AROUND THE
SOUTHERN HILLS INTO NORTHEASTERN WYOMING BY EARLY FRIDAY MORNING.
LOWS WILL RANGE FROM THE LOWER 20S ACROSS CENTRAL SD TO THE LOWER
30S IN PARTS OF NORTHEASTERN WY.

FOG WILL DIMINISH BY MID MORNING. THE SURFACE HIGH WILL SLIDE
EAST ON FRIDAY...AND RETURN FLOW WILL INCREASE ACROSS THE AREA AS
THE A SURFACE LOW APPROACHES AND THE PRESSURE GRADIENT TIGHTENS. THE
STRONGEST SOUTHEASTERLY WINDS WILL BE OVER THE NORTHWESTERN
CORNER OF SD...REACHING WIND ADVISORY CRITERIA AROUND NOON. AREAS
TO THE EAST AND SOUTH WILL BE MARGINAL...BUT DECIDED TO ADD THEM
TO THE WIND ADVISORY. UNDER PARTLY CLOUDY SKIES...HIGHS WILL RANGE
FROM THE LOWER 40S ACROSS CENTRAL SD...TO THE UPPER 50S IN PARTS
OF NORTHEASTERN WY.

ANYONE PARTAKING IN OUTDOOR ACTIVITIES FRIDAY EVENING WILL HAVE DRY
AND BREEZY WEATHER. TEMPERATURES WILL RANGE FROM THE MID 30S ACROSS
CENTRAL SD...TO THE MID 50S IN NORTHEASTERN WY.

&&

.LONG TERM...SATURDAY THROUGH THURSDAY
ISSUED AT 217 PM MDT THU OCT 30 2014

MODELS IN GOOD AGREEMENT THROUGH EARLY NEXT WEEK. UPPER
LEVEL RIDGE SHIFTS EASTWARD ON SATURDAY AS STRONG UPPER LOW MOVES
INTO THE WESTERN CONUS. LOW LEVEL THERMAL RIDGE ACROSS THE AREA
SATURDAY...WITH TEMPERATURES ABOVE AVERAGE. MAIN UPPER LOW SWINGS
ACROSS THE NORTHERN ROCKIES INTO EASTERN MONTANA SUNDAY...WITH WEAK
COLD FRONT SLIDING INTO WESTERN SOUTH DAKOTA. SECONDARY LOW
CONTINUES TO DIG INTO FOUR CORNERS AREA. WITH SPLITTING UPPER
FLOW...MAIN FORCING REMAINS NORTH AND SOUTH OF FORECAST AREA. BEST
CHANCE OF PRECIPITATION WILL BE ALONG FRONTAL BOUNDARY SUNDAY NIGHT
ACROSS SOUTH CENTRAL SOUTH DAKOTA. DRY AND COOLER WEATHER EXPECTED
FOR THE MIDDLE OF THE WEEK.

&&

.AVIATION...(FOR THE 00Z TAFS THROUGH 00Z FRIDAY EVENING)
ISSUED AT 512 PM MDT THU OCT 30 2014

MVFR/LOCAL IFR CIGS ACROSS NORTHWEST SOUTH DAKOTA WILL SLIDE
SOUTHWEST AND DEVELOP THIS EVENING...REACHING THE NORTHERN/EASTERN
SLOPES OF THE BLACK HILLS CREATING IFR VSBYS DUE TO FOG.
WIDESPREAD IFR CIGS THEN EXPECTED OVERNIGHT ACROSS MOST OF WESTERN
SOUTH DAKOTA INTO NORTHEAST WYOMING...WITH LIFR CIGS/VSBYS AROUND
THE BLACK HILLS. CONDITIONS WILL SLOWLY IMPROVE INTO FRIDAY
AFTERNOON.

&&

.UNR WATCHES/WARNINGS/ADVISORIES...
SD...WIND ADVISORY FROM NOON TO 6 PM MDT FRIDAY FOR SDZ001-002-
     012>014-026-031-032-072-073.

WY...NONE.
&&

$$

UPDATE...HELGESON
SHORT TERM...POJORLIE
LONG TERM...7
AVIATION...HELGESON




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