000 
FXUS63 KUNR 040320
AFDUNR

AREA FORECAST DISCUSSION FOR WESTERN SD AND NORTHEASTERN WY
NATIONAL WEATHER SERVICE RAPID CITY SD
920 PM MDT FRI OCT 3 2008

.DISCUSSION...00Z DATA/GUIDANCE SUPPORTS CURRENT FORECAST WELL.
SHORTWAVE SLOWLY MOVING TOWARD THE CWA THIS EVENING WITH ISOLATED
SHRA/TSRA. HAVE EXPANDED POPS A BIT FURTHER NORTH AND SOUTHEAST TO
COVER CURRENT TRENDS. REST OF FORECAST IN GOOD SHAPE.

&&

.AVIATION...VFR CONDITIONS EXPECTED OVERNIGHT WITH HIGH BASED
SHRA/TSRA ACTIVITY LOW IN COVERAGE.

&&

.PREV DISCUSSION... /ISSUED 300 PM MDT FRI OCT 3 2008/ 

DISCUSSION...CURRENT SURFACE ANALYSIS SHOWS LOW PRESSURE OVER 
CENTRAL MT...WITH LEE TROF EXTENDING SOUTHWARD ACROSS WY AND INTO 
THE CENTRAL HIGH PLAINS. RELATIVELY TIGHT PRESSURE GRADIENT ACROSS 
THE WESTERN DAKOTAS IS RESULTING IN BREEZY SOUTHEAST WINDS ACROSS 
PORTIONS OF THE AREA...ESPECIALLY NORTHWEST SD. A HIGH AMPLITUDE 
RIDGE REMAINS OVER THE REGION. SKIES ARE PARTLY CLOUDY ACROSS 
NORTHEAST WY...WITH MOSTLY SUNNY SKIES ELSEWHERE. TEMPS ARE MOSTLY 
IN THE 70S. A FEW SHOWERS AND STORMS ARE NOTED ON REGIONAL RADAR 
ACROSS SOUTHEASTERN WY. 

FORECAST STILL ON TRACK FOR AN UNSETTLED AND COOLER PATTERN TO 
DEVELOP OVER THE NEXT SEVERAL DAYS AS RIDGE SHIFTS EAST AND BROAD 
UPPER TROF OFF THE WEST COAST MOVES INLAND. CHANGES MADE TO THE 
FORECAST THROUGH THE WEEKEND WERE RELATIVELY MODEST...MAINLY 
INVOLVING POPS. 

FOR TONIGHT...SKIES WILL BECOME PARTLY CLOUDY IN GENERAL. A WEAK 
UPPER LEVEL DISTURBANCE IS MOVING ACROSS EASTERN UT...NORTHWEST 
CO...AND SOUTHERN WY RIGHT NOW AND WILL TRACK ACROSS THE CWA 
TONIGHT. THERE COULD BE A FEW SHOWERS AND STORMS TONIGHT... 
ESPECIALLY FROM THE BLACK HILLS AREA EASTWARD AS THIS ENERGY SLOWLY 
TRACKS ACROSS. LOWS WILL BE IN THE MID 40S TO MID 50S. BREEZY 
CONDITIONS CAN BE EXPECTED ACROSS PARTS OF THE AREA...ESPECIALLY 
NORTHEAST WY AND NORTHWEST SD.     

A FEW SHOWERS AND THUNDERSHOWERS COULD LINGER ACROSS THE FAR 
NORTHERN AND EASTERN CWA IN THE MORNING...OTHERWISE SKIES WILL 
GENERALLY BE PARTLY CLOUDY. CHANCES FOR PCPN WILL DEVELOP IN THE 
AFTERNOON ACROSS NORTHEAST WY AND THE HILLS AS ATMOS DESTABILIZES 
AND ANOTHER UPPER LEVEL WAVE APPROACHES. HIGHS WILL AGAIN MOSTLY BE 
IN THE 70S TO AROUND 80 DEGREES. SOUTHEASTERLY WINDS WILL INCREASE 
ACROSS THE AREA IN THE MORNING...WITH WINDY CONDITIONS BY THE 
AFTERNOON. WINDS WILL LIKELY APPROACH ADVISORY CRITERIA FOR A TIME 
IN THE AFTERNOON ACROSS PARTS OF NORTHWEST AND CENTRAL SD...BUT NOT 
SURE THEY WILL BE STRONG ENOUGH FOR ANY PROLONGED PERIOD OF TIME TO 
JUSTIFY AN ADVISORY...SO WILL LET MID SHIFT GET ANOTHER LOOK AT IT. 
SHOWER AND THUNDERSTORM CHANCES WILL INCREASE ACROSS MOST OF THE 
AREA SATURDAY NIGHT AS WAVE MOVES NORTHEASTWARD. BETTER CHANCES WILL 
REMAIN ACROSS THE WESTERN HALF OF THE CWA.  

AS UPPER TROF MOVES FURTHER EAST INTO THE ROCKIES ON SUNDAY...THE 
SYSTEM WILL BEGIN TO SPLIT...WITH MAIN BATCH OF ENERGY GOING SOUTH 
INTO THE CENTRAL AND SOUTHERN PLAINS. NORTHERN BRANCH WILL GENERALLY 
MOVE ACROSS MT AND NORTHERN PORTIONS OF THE NORTHERN PLAINS. A COLD 
FRONT WILL SLOWLY CROSS THE AREA SUNDAY AND SUNDAY NIGHT. HIGH TEMPS 
ON SUNDAY WILL BE IN THE 60S AND 70S...WARMEST ACROSS SOUTHERN AND 
EASTERN PORTIONS OF THE CWA. BETTER CHANCES FOR SHOWERS AND POSSIBLY 
A FEW WEAK STORMS WILL BE ACROSS NORTHERN PORTIONS OF THE CWA...WITH 
SOUTHWESTERN PORTIONS OF THE CWA LIKELY DRY SLOTTED FOR A TIME. A 
FEW AREAS COULD RECEIVE SOME SIGNIFICANT RAINFALL LATER IN THE 
WEEKEND...BUT CHANCES FOR A MORE WIDESPREAD RAINFALL ARE LOOKING 
RATHER LOW. 

EXTENDED...UPPER TROF/LOW WILL MOVE SLOWLY THROUGH THE NRN PLAINS ON 
MONDAY...BRINGING WDSPRD PCPN AND COOLER CONDITIONS TO THE REGION. 
TUES/WED WILL SEE A FLAT UPPER RIDGE BUILD INTO REGION BRINGING DRY 
WX AND WARMER TEMPS. NEXT UPPER SYS WL BEGIN TO INTENSIFY IN PACIFIC 
NW LATE IN WEAK BRINGING IN A GRADUAL COOLER TREND...AND POSSIBLY 
THE FIRST SNOW OF SEASON TO SOME AREAS BY NEXT WEEKEND.

AVIATION...VFR CONDITIONS WILL CONTINUE THRU FCST PERIOD.

&&

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

$$

HELGESON