FXUS65 KREV 091210
AFDREV

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE RENO NV
410 AM PST WED DEC 9 2009

.SHORT TERM...
ANOTHER FRIGID MORNING FOR THE WESTERN GREAT BASIN AND SIERRA.
TEMPERATURES ARE ALREADY IN THE MINUS 5 TO MINUS 15 DEGREE RANGE
FOR MANY VALLEY LOCATIONS THIS MORNING. IN ADDITION...WITH THE
DAYS OF SOLID INVERSIONS AND SNOW COVER WE HAVE BEGUN TO SEE AREAS
OF FREEZING FOG...ESPECIALLY IN THE CARSON SINK AND ALONG HIGHWAY
50 FROM FALLON EASTWARD. WE HAVE THROWN OUT A FREEZING FOG ADVISORY
BASED ON OBSERVATIONS IN FALLON AND A FEW POINTS EAST.

ANOTHER VERY COLD DAY IN ON TAP WITH HIGHS 15-20 DEGREES BELOW
AVERAGE AND STRONG INVERSIONS MAKING HIGHS COLDER IN MANY OF THE
LOWEST VALLEYS (BELOW 5000 FEET) THAN AREAS ABOVE. WEDNESDAY
NIGHT...I EXPECT SOME TEMPERATURE MODERATION (ESPECIALLY FOR THE
WESTERN CWA) AS CLOUDS FROM A WEAK PACIFIC SYSTEM MOVE IN OVERNIGHT.
CLOUDS ARE NOT EXPECTED TO THICKEN UNTIL LATE EVENING OR AFTER SO
TEMPERATURES WILL STILL HAVE THE CHANCE TO DROP OFF QUICKLY WEDNESDAY
EVENING...ESPECIALLY EAST OF RENO. IN ANY CASE...I STILL EXPECT WELL
BELOW AVERAGE LOW TEMPS WEDNESDAY NIGHT WITH SNOW COVER ALLOWING
MAXIMUM RADIATIVE COOLING.

THURSDAY AND FRIDAY...A COUPLE OF MINOR DISTURBANCES WILL SQUEEZE
INTO THE WEST BRINGING THE CHANCE FOR SOME PERIODS OF LIGHT SNOW...
ESPECIALLY LATE FRIDAY AND FRIDAY NIGHT WITH THE SECOND MORE
POTENT SYSTEM. DESPITE WARMING ALOFT...SNOW LEVELS STILL LOOK TO
REMAIN DOWN TO ALL VALLEY FLOORS UNTIL SATURDAY AS CLOUD COVER...
MODEST WINDS ALOFT...AND SNOW COVER IN THE VALLEYS ALL CONSPIRE TO
KEEP SOUNDING PROFILES ISOTHERMAL FROM THE RIDGETOPS TO THE SURFACE.
SNYDER

.LONG TERM...SATURDAY THROUGH TUESDAY...
MODELS IN DECENT AGREEMENT IN THE LONG TERM BUT SHOW ENOUGH 
DIFFERENCES FOR SATURDAY TO MAKE THE FORECAST A BIT UNCERTAIN. 
SYSTEM SET TO ARRIVE SAT RIDING A 120+ KT JET STREAM WHICH ALL 
MODELS SHOW. EC IS FURTHER SOUTH THAN GFS WITH JET AND HAS A BIT 
BETTER SUPPORT FROM GEFS. DID INCREASE CHC OF PRECIP...BUT ONLY FOR 
AREAS SOUTH OF HWY 50. IF EC VERIFIES...THIS IS WHERE BRUNT OF STORM 
WOULD BE FELT WITH JUST A GLANCING BLOW TO THE NORTH. GFS WOULD HIT 
ABOUT 100 MILES FURTHER NORTH AFFECTING MOST AREAS.

QUESTIONS REMAIN WITH REGARD TO HOW HIGH THE SNOW LEVELS WILL
RISE. ALL MODELS SHOW STRONG WAA ALOFT...BUT EXPECT LLVLS TO WARM
ONLY SLOWLY. WILL KEEP SNOW LEVELS NEAR ALL VALLEY FLOORS...PERHAPS
AS HIGH AS 5000 FEET DOWN SOUTH BUT THATS IT. ALSO...FURTHER SOUTH
EC SOLUTION WOULD BE ALL SNOW EXCEPT FOR A RAIN/SNOW MIX ON THE
VALLEY FLOORS OF SE MINERAL COUNTY.

COLD FRONT WITH SYSTEM TO MOVE THROUGH SUN EVENING WITH TROF AXIS 
PASSAGE SUN MORNING. EXPECT SNOW LEVELS AT ALL VALLY FLOORS BY THEN 
WITH PRECIP CONTINUING THROUGH MID-DAY SUN FOR SIERRA AND MORE 
SHOWERS FOR WRN NV. TEMPS TO REMAIN BELOW NORMAL THROUGH THE WEEKEND.

EARLY NEXT WEEK...RIDGING EXPECTED TO DEVELOP OVER THE WRN CONUS. 
RIDGING NOT EXPECTED TO BE STRONG...BUT ENOUGH TO DEFCT INCOMING 
SYSTEMS MORE TO PACNW. STILL...JET WILL BE JUST NORTHWEST OF THE 
AREA SO THERE COULD BE SOME PRECIP OVER NORTHWEST 1/4 OF THE CWA. 
HAVE LEFT CHC POPS THERE WITH IT DRY ACROSS THE SOUTHEAST HALF. 
TEMPS SHOULD BE WARMING BACK TO NEAR NORMAL WITH SNOW LEVELS RISING 
TO NEAR 7000 FEET BY TUES. WALLMANN
&&

.AVIATION...
MAIN CONCERN IS FOG THIS AM. SOME PATCHY FOG CONTINUES AROUND 
KRNO/KLOL/KTRK AND THIS WILL CONTINUE THROUGH 16Z. THE DENSEST FOG OF 
VIS BLO 1/2SM WILL BE NEARBY BUT NOT EXPECTED TO AFFECT THE 
TERMINALS. STILL...ABT 70 PCT CHC OF SEEING PDS OF 1SM...BUT DO NOT 
THINK IT WILL GET LOWER.

OTHERWISE WINDS TO REMAIN LIGHT WITH VFR CONDS. MID-HIGH CLOUDS 
TONIGHT SHOULD KEEP IT VFR AND KEEP IT WARM ENUF TO PREVENT FOG FROM 
FORMING. WALLMANN 
&&

.REV WATCHES/WARNINGS/ADVISORIES...
NV...FREEZING FOG ADVISORY UNTIL 12 PM PST WEDNESDAY FOR ZONE 4.
CA...NONE. 
&&

$$

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