Weather Service Report


812 
FXUS65 KREV 281744
AFDREV

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE RENO NV
1044 AM PDT THU AUG 28 2014

.UPDATE...
A QUICK UPDATE TO THE FORECAST THIS MORNING TO INCREASE CLOUD
COVER ACROSS THE SURPRISE VALLEY INTO FAR NORTHERN WASHOE COUNTY
THIS MORNING. LATEST MODEL RUNS SHOW SOME MODEST SURFACE AND MID-
LEVEL INSTABILITY DEVELOPING NEAR THE OREGON BORDER THIS AFTERNOON
AS A WEAK SHORTWAVE IMPULSE APPROACHES THE REGION. COULD SEE SOME
CUMULUS DEVELOPMENT WITH AROUND A 10% CHANCE OF AN ISOLATED SHOWER
POSSIBLE. ALSO INCLUDED MENTION OF SMOKE ACROSS THE SAME REGION AS
SMOKE FROM FIRES IN SISKIYOU COUNTY IN NORTHERN CALIFORNIA DRIFTS
EASTWARD ACROSS FAR NORTHWESTERN NEVADA. FUENTES

&&

.PREVIOUS DISCUSSION... /ISSUED 236 AM PDT THU AUG 28 2014/ 

SYNOPSIS...

HIGH PRESSURE BUILDING OVER THE REGION WILL BRING DRY CONDITIONS
AND WARM AFTERNOON TEMPERATURES TODAY AND FRIDAY. LOW PRESSURE
WILL MOVE INTO THE PACIFIC NORTHWEST THIS WEEKEND WITH SOME
BREEZY CONDITIONS FRIDAY AND SATURDAY. NEAR AVERAGE TEMPERATURES
ARE EXPECTED FOR THE HOLIDAY WEEKEND.

&&

SHORT TERM...
A WEAK UPPER-LEVEL IMPULSE WILL TRACK ACROSS NORTHERN NV/SOUTHERN
OREGON THIS AFTERNOON BUT MOISTURE WILL BE VERY LIMITED AND AS
SUCH ONLY HIGH CLOUDS NEAR THE OREGON BORDER ARE EXPECTED WITH
THIS FEATURE.

WESTERLY WINDS ALOFT WILL INCREASE FRIDAY AFTERNOON AS A TROUGH
BEGINS TO MOVE ACROSS THE PACIFIC NORTHWEST. THE STRONGER WINDS
ABOVE 500 MB WILL MAINLY BE NORTH OF I-80 IN THE AFTERNOON BUT
WILL THEN SPREAD ACROSS THE SIERRA AND WESTERN NV FRIDAY EVENING.
HOWEVER, THE AIR MASS IS FAIRLY STABLE AND THE MIXING OF THESE
STRONGER WINDS TO THE SURFACE SHOULD BE LIMITED. EXPECT GUSTS UP
TO 25 MPH IN THE AFTERNOON, INCREASING UP TO 30 MPH IN THE
EVENING, MAINLY NORTH OF HIGHWAY 50. WIND PRONE LOCATIONS COULD
EXPERIENCE GUSTY WINDS/LOW HUMIDITY FRIDAY AFTERNOON WHICH COULD
COME CLOSE TO CRITICAL FIRE THRESHOLDS. HOWEVER, HUMIDITY WILL
RISE IN THE EVENING WHICH SHOULD LIMIT THE DURATION OF THESE
CONDITIONS TO A FEW HOURS OR LESS.

SATURDAY A WESTERLY JET WILL REMAIN POSITIONED OVER NORTHERN CA/NV
BUT AT THE SURFACE A NORTHERLY PRESSURE GRADIENT WILL NOT BE AS
CONDUCIVE TO GUSTY WESTERLY WINDS. AFTERNOON/EVENING WINDS SATURDAY
MAY BE JUST A NOTCH WEAKER THAN FRIDAY AND HUMIDITY SHOULD BE JUST
A BIT HIGHER AS WELL. JCM

LONG TERM...SUNDAY THROUGH WEDNESDAY...
ONLY MINOR CHANGES WERE MADE TO THE EXTENDED FORECAST. MEDIUM RANGE 
MODELS ARE IN GOOD AGREEMENT THROUGH MOST OF THE PERIOD. A BROAD 
TROUGH TO THE EAST OF THE REGION AND FLAT RIDGE TO THE SOUTHWEST 
SHOULD KEEP DRY NORTHWEST FLOW OVER THE FORECAST AREA THROUGH AT 
LEAST MONDAY. THERE ARE SOME DISAGREEMENTS IN THE UPPER LEVEL 
PATTERN BY EARLY TUESDAY AS THE DETERMINISTIC GFS TRIES TO DIG A LOW 
SOUTH OUT OF THE CANADIAN PAC SW INTO THE U.S. PAC NW. THIS WOULD 
LEAD TO STRONGER FLOW ALOFT ACROSS OREGON AND SOME INCREASE IN LOW 
LEVEL WINDS NORTH OF I-80. THE ECMWF IS NOT AS AGGRESSIVE WITH THIS 
SOLUTION...AND MOST GEFS ENSEMBLE MEMBERS DO NOT SUPPORT IT EITHER. 

LOW LEVEL FLOW IS LIGHT NORTH-NORTHEAST FOR SUNDAY THEN BECOMES MORE 
EASTERLY FOR MONDAY. TEMPERATURES SHOULD STAY AT OR SLIGHTLY BELOW 
NORMAL SUNDAY AND MONDAY. LOW LEVEL FLOW BECOMES MORE WESTERLY BY 
TUESDAY WITH INCREASING TEMPERATURES AS MIXING INCREASES. BY 
WEDNESDAY THE DETERMINISTIC MODELS DEEPEN THE TROUGH OVER THE PAC NW 
AND THIS SHOULD INCREASE SW FLOW ALOFT FOR OUR AREA. SO BUMPED UP 
WINDS SLIGHTLY FOR THAT TIME FRAME. 20

AVIATION...
VFR CONDITIONS THROUGH THE WEEKEND FOR ALL AREAS. THERE WILL BE AN 
INCREASE IN MID/HIGH CLOUDS THROUGH THE WEEKEND. WINDS REMAIN FAIRLY 
LIGHT TODAY BUT BEGIN TO INCREASE FRIDAY. GUSTS BOTH FRIDAY AND 
SATURDAY AFTERNOONS COULD REACH UP 25-30 KTS AT THE SURFACE EAST OF 
THE SIERRA. 20

&&

.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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