Area Forecast Discussion
Issued by NWS Reno, NV

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000
FXUS65 KREV 261130
AFDREV

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE RENO NV
330 AM PST WED NOV 26 2014

.SYNOPSIS...
HIGH PRESSURE WILL BRING WELL ABOVE NORMAL TEMPERATURES AND DRY
CONDITIONS THROUGH FRIDAY. LOW PRESSURE WILL MOVE INTO THE WEST
COAST FRIDAY NIGHT WITH PERIODS OF GUSTY WINDS, RAIN AND SIERRA
SNOW INTO EARLY NEXT WEEK.

&&

.SHORT TERM...
AN UPPER RIDGE WILL BUILD DIRECTLY OVER THE SIERRA AND WESTERN
NEVADA TODAY. SUBSIDENCE WARMING UNDER THE RIDGE HAS REALLY
CRUNCHED INVERSIONS DOWN THIS MORNING. FOR INSTANCE, FOOTHILL
(BETWEEN 5500 AND 7500 FEET) TEMPERATURES AROUND THE RENO-TAHOE
AREA ARE CURRENTLY RUNNING IN THE MID 40S TO LOWER 50S WHILE
VALLEY TEMPERATURES ARE IN THE MID 20S TO MID 30S. WITH WINDS
REMAINING FAIRLY LIGHT TODAY, THE INVERSIONS SHOULD PROMOTE THE
CONTINUED TRAPPING OF POLLUTANTS IN THE LOWER VALLEYS OF WESTERN
NEVADA.

FOR THANKSGIVING DAY THROUGH FRIDAY, THE STRONG RIDGE OF HIGH
PRESSURE WILL CONTINUE TO BRING ABOVE TO WELL ABOVE NORMAL
TEMPERATURES TO EASTERN CALIFORNIA AND WESTERN NEVADA. AS FAR AS
INVERSIONS, WINDS ALOFT BEGIN TO INCREASE ON THANKSGIVING DAY AS
THE RIDGE AXIS SHIFTS EAST OF THE REGION. MODEL SOUNDINGS OVER
RENO SHOW MIXING HEIGHTS INCREASING BY THURSDAY AFTERNOON WITH 700
MB WINDS OF 30 TO 40 KTS. THIS SHOULD ALLOW AIR TO MIX IN THE
LOWER VALLEYS FOR AN EASING OF POLLUTANT CONCERNS.

FRIDAY NIGHT, THE UPPER RIDGE WILL FLATTEN OUT AS ENERGY OVER THE
PACIFIC OCEAN SQUEEZES INTO THE PACIFIC NORTHWEST. THIS WILL PUSH
A NARROW MOISTURE BAND (AROUND AN INCH PWAT OVER NORTHERN CA) INTO
NORTHEAST CALIFORNIA, MAINLY NORTH OF LAKE TAHOE. TRAVEL IMPACTS
EAST OF THE CREST FRIDAY NIGHT LOOK MINIMAL WITH THE BAND AS SNOW
LEVELS OVER NORTHEAST CALIFORNIA REMAIN NEAR 6,500 FEET OR SLIGHTLY
HIGHER WITH THE RELATIVELY MILD PACIFIC SOURCE OF THE AIRMASS AND
NARY A COLD FRONT IN SIGHT. SNYDER

.LONG TERM...SATURDAY THROUGH TUESDAY...
OVERALL CONFIDENCE HAS DECREASED THIS MORNING AS THE 00Z ECMWF HAS
DRAMATICALLY SHIFTED WEST WITH MAIN TROUGH FOR THIS WEEKEND INTO
MON-TUE. IT BRINGS A MORE NORTHERN SHORTWAVE FEATURE THROUGH THE
NORTHERN SIERRA AND WESTERN NV SAT-SUN AS FRONT SAGS INTO THE REGION
FROM THE NORTH. THE 00Z OPERATIONAL GFS HAS HELD MORE PERSISTENT
TO WHAT WE HAVE BEEN SEEING IN MODELS THE LAST FEW NIGHTS AND HAS
MUCH LESS PRECIPITATION OVER WESTERN NV AND LIGHTER QPF FOR THE
SIERRA THIS WEEKEND AND THEN PROGRESSES TROUGH THROUGH THE REGION
MONDAY PER OUR CURRENT FORECAST. WHILE THE GFS IS MAINTAINING
PERSISTENCE, ONE THING TO WATCH IS THE ENSEMBLE SPREADS IN BOTH
THE GFS/ECMWF WHICH HAVE SHOWN QUITE A VARIABILITY ON THE
SOUTHWEST FLANK OF THE EAST PACIFIC TROUGH. THIS COULD LEND SOME
CREDENCE TO A SLOWER TIMING OF TROUGH PUSHING INTO THE WEST COAST
EARLY NEXT WEEK. IN FACT. A QUICK LOOK AT THE 06Z GFS IS YET
SLOWER. THE 00Z ECMWF DOES NOT HAVE THE MAIN SYSTEM WORKING
ACROSS UNTIL TUE-WED WHICH IS IN LINE WITH THE 12Z ECMWF ENSEMBLE
MEAN. WE BUMPED POPS UP A LITTLE ACROSS WESTERN NV FOR THE WEEKEND
AS A NOD TO THE ECMWF AND THE WEEKEND SHORTWAVE. WE ALSO BEGAN TO
INDICATE A SLOWED TIMING OF THE MAIN TROUGH BY LOWERING POPS
ACROSS WESTERN NV SUNDAY NIGHT. WE HAVE MADE FEW CHANGES MON-TUE
GIVEN THE INCREASING VARIABILITY IN THE DETAILS, BUT ADDITIONAL
SLOWING IS POSSIBLE. HOHMANN

&&

.AVIATION...
VFR CONDITIONS EXPECTED THRU THANKSGIVING DAY AS HIGH PRESSURE
PREVAILS OVER CA-NV. RIDGE LEVEL WINDS WILL INCREASE ON THURSDAY
AS THE RIDGE AXIS SHIFTS EAST OF AREA.

&&

.REV WATCHES/WARNINGS/ADVISORIES...
NV...NONE.
CA...NONE.
&&

$$

FOR MORE INFORMATION FROM THE NATIONAL WEATHER SERVICE VISIT...
HTTP://WEATHER.GOV/RENO (ALL LOWER CASE)






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