HAMweather.com Area Forecast Discussion for County Warning Area UNR

Thu, 16 Feb 2012 07:28:26 GMT
AREA FORECAST DISCUSSION FOR WESTERN SD AND NORTHEASTERN WY
NATIONAL WEATHER SERVICE RAPID CITY SD
944 PM MST WED FEB 15 2012

.AVIATION...06Z TAFS
VFR CONDITIONS EXPECTED THROUGH THURSDAY EVENING.

.PREV DISCUSSION... /ISSUED 235 PM MST WED FEB 15 2012/ 

DISCUSSION...21Z SURFACE ANALYSIS HAS CANADIAN HIGH PRESSURE
SETTLING OVER THE NORTHERN ROCKIES AND NORTHERN GREAT PLAINS.
TEMPERATURES ARE IN THE 30S WITH WEST TO NORTHWEST WINDS 10 TO 20
MPH. UPPER LEVEL ANALYSIS HAS BROAD TROF OVER THE WESTERN CONUS
WITH SEVERAL EMBEDDED SHORTWAVES. UPPER RIDGE IS BUILDING JUST OFF
THE WEST COAST.

FOR TONIGHT...CANADIAN HIGH PRESSURE WILL BRING PARTLY CLOUDY TO
MOSTLY CLEAR SKIES WITH COOL TEMPERATURES. LOWS WILL BE NEAR TO
SLIGHTLY BELOW AVERAGE...IN THE TEENS. BREEZY NORTHWEST WINDS WILL
DIMINISH BY EARLY EVENING.

ON THURSDAY...QUIET WEATHER IS EXPECTED AS AREA REMAINS BETWEEN
SYSTEMS IN SPLIT FLOW PATTERN. WEAK LOW PASSING THROUGH NORTH
DAKOTA WILL BRING WESTERLY WINDS TO OUR AREA...BECOMING A BIT
BREEZY OVER NORTHWESTERN SOUTH DAKOTA. WITH WARMER AIRMASS
SHIFTING IN...HIGHS WILL RETURN TO ABOVE AVERAGE...IN THE 30S TO
MID 40S.

FOR FRIDAY...WEAK CLIPPER SYSTEM IN NORTHWEST FLOW SLIDES THROUGH
WESTERN PORTIONS OF THE AREA EARLY...BRINGING A COOLER DAY TO THE
REGION. BEST CHANCES OF LIGHT ACCUMULATIONS WILL BE ACROSS
NORTHEAST WYOMING AND THE NORTHERN BLACK HILLS. NORTHWEST WINDS
WILL BE BREEZY AGAIN ACROSS THE SOUTH DAKOTA PLAINS.

EXTENDED...SPLIT FLOW...FEATURING AN UPPER LEVEL RIDGE OVER THE 
NORTHERN PLAINS NEAR THE NORTHERN BRANCH OF THE JET STREAM...WILL 
BRING MILD AND DRY WEATHER TO THE AREA SATURDAY AND MOST OF SUNDAY. 
UNCERTAINTY INCREASES SIGNIFICANTLY WITH FORECAST FOR SUNDAY NIGHT 
INTO EARLY NEXT WEEK. MEDIUM RANGE MODELS HAVE BEEN VERY 
INCONSISTENT WITH REGARD TO UPPER LEVEL SYSTEM THAT DEVELOPS ACROSS 
THE WESTERN CONUS OVER THE WEEKEND. 12Z GFS CUTS OFF AN UPPER LOW 
OVER THE SOUTHWESTERN CONUS...WITH WEAKER ENERGY CROSSING THE 
NORTHERN AND CENTRAL PLAINS LATE SUNDAY INTO MONDAY. 12Z ECMWF 
BRINGS MAIN TROF FURTHER NORTH ACROSS THE REGION SUNDAY NIGHT AND 
MONDAY...WHILE 12Z CANADIAN IS GENERALLY IN BETWEEN THESE TWO 
SOLUTIONS. WILL KEEP CHANCES FOR PCPN LATE SUNDAY INTO MONDAY FOR 
MOST OF THE AREA...WITH THE BETTER CHANCES ACROSS SOUTHERN PORTIONS 
OF THE CWA FOR THE TIME BEING. ANOTHER SYSTEM IN NORTHWEST FLOW 
COULD AFFECT THE AREA BY MIDWEEK. TEMPERATURES SHOULD GENERALLY BE 
NEAR TO SLIGHTLY ABOVE AVERAGE EARLY NEXT WEEK. 

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