FXUS65 KLKN 032204
AFDLKN

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ELKO NV
204 PM PST THU DEC 3 2009

.SYNOPSIS...A DRY AIRMASS FROM THE NORTH WILL KEEP TEMPERATURES
ON THE CHILLY SIDE ALONG WITH CLEAR SKIES THROUGH FRIDAY. A COLD
FRONT SATURDAY WILL BRING EVEN COLDER TEMPERATURES TO NEVADA OVER
THE WEEKEND AND INTO EARLY NEXT WEEK. LIGHT SNOW WILL BE POSSIBLE
ACROSS THE NORTH LATE SATURDAY SPREADING ACROSS THE ENTIRE AREA
BY EARLY NEXT WEEK. 
&&

.SHORT TERM...ECMWF AND GFS IN FAIRLY GOOD AGREEMENT THROUGH
SATURDAY MORNING. BY SATURDAY...MODELS HAVE TROF OVER NORTHERN
PORTION OF CWA...EXCEPT ECMWF HAS THE LOW CLOSED AND DEEPER
ASSOCIATED WITH THE FIRST SHORTWAVE. EC HAS THIS FEATURE KICKING
OUT TO THE EAST AS SECOND UPPER LOW PUSHES INTO THE PACIFIC
NORTHWEST ON SUNDAY. AT THE SAME TIME GFS PLACES THE UPPER LOW
INTO NORTHERN PARTS OF CA AND NV. EITHER SOLUTION...LOW LEVEL
MOISTURE LIMITED ATTM SO HAVE LOWERED POPS OVER THE WEEKEND. WITH
A COLDER AIRMASS PUSHING INTO THE AREA SUNDAY HAVE LOWERED 
TEMPERATURES MOST AREAS ABOUT 5 DEGREES.

.LONG TERM...SUNDAY NIGHT THROUGH NEXT THURSDAY. NOT MUCH CHANGE IN 
12Z GUIDANCE COMPARED TO PREVIOUS RUN...WITH ACTIVE WEATHER PATTERN 
EXPECTED IN THE EXTENDED PERIOD AS PROGRESSIVE PACIFIC ZONAL FLOW 
BECOMES ESTABLISHED OVER THE WESTERN CONUS.  TEMPERATURES WILL BEGIN 
THIS PERIOD WELL BELOW AVG...BEFORE WARMING TO AVG BY 
WEDNESDAY...WITH PRECIP EXPECTED TO BE ABOVE AVG. CONFIDENCE IS HIGH 
IN OVERALL SYNOPTIC FLOW...BUT MINOR DIFFERENCES IN SHORTWAVE 
FEATURES HAVE LEAD TO LOW CONFIDENCE IN QPF FORECASTS.

SUNDAY NIGHT INTO MONDAY MORNING A CUT-OFF 500H LOW OVER THE PACIFIC 
NW COAST WILL DROP INTO THE NORTHERN GREAT BASIN...WITH CYCLOGENESIS 
FORECASTED OVER CENTRAL NV.  STILL SOME DIFFERENCES WITH MODELS ON 
HOW DEEP THE UPPER LEVEL LOW WILL DIG ACROSS THE WEST. GFS IS THE 
DEEPEST GUIDANCE AND HAS THE SURF LOW DEVELOP OVER VEGAS...THUS 
KEEPING THE DEEPEST MOISTURE ROTATING AROUND THE BASE OF THE TROUGH 
WELL SOUTH OF THE CWA.  THE ECMWF IS MUCH FURTHER NORTH WITH THE 
SURFACE LOW AND HAS BEST FGEN FORCING AND MOISTURE OVER THE CWA. TO 
EARLY TO TELL...SO TOOK THE MIDDLE GROUND AND KEPT HIGHEST POPS ON 
MONDAY THROUGH THE CENTRAL CWA AND TRENDED SOUTH MONDAY NIGHT. 
 
QUICK BREAK ON TUESDAY AS A SHORTWAVE MID-LEVEL RIDGE MOVES OVER THE 
REGION...BUT IT WILL BE COLD WITH HIGHS STILL IN THE 30S. BY 
WEDNESDAY AFTERNOON ANOTHER PACIFIC TROUGH WILL APPROACH THE GREAT 
BASIN...WITH SW WAA FLOW. MOUNTAIN SNOW AND VALLEY RAIN EXPECTED 
WITH THIS WARMER SYSTEM BEGINNING LATE WEDNESDAY AND LASTING INTO 
THURSDAY.  THIS MID-WEEK SYSTEM LOOKS TO BE THE WETTEST OF THE 
SYSTEMS...BUT TO EARLY TO PINPOINT HOW MUCH QPF AND SNOW LEVELS.    
&&

.AVIATION...VFR CONDITIONS WILL CONTINUE OVER THE NEXT 24 HOURS WITH 
CLEAR SKIES OVER THE REGION. WINDS WILL BE OUT OF THE NORTH AND 
NORTHWEST...WITH LOCAL SLOPE WINDS DURING THE NIGHT. 

.LKN WATCHES/WARNINGS/ADVISORIES...NONE. 
&&

$$

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