Area Forecast Discussion
Issued by NWS Reno, NV

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FXUS65 KREV 270957
AFDREV

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE RENO NV
257 AM PDT WED AUG 27 2014

.SYNOPSIS...

HIGH PRESSURE BUILDING OVER THE REGION WILL BRING DRY CONDITIONS
WITH A WARMING TREND THROUGH THURSDAY, FOLLOWED BY INCREASING
WINDS AND CLOUD COVER FRIDAY AS THIS HIGH BEGINS TO WEAKEN. FOR
THE UPCOMING HOLIDAY WEEKEND, BREEZY CONDITIONS ARE LIKELY
SATURDAY AND POSSIBLY INTO SUNDAY, ALONG WITH A GRADUAL COOLING
TREND THROUGH LABOR DAY.
&&

.SHORT TERM...

TEMPERATURES WILL CONTINUE TO RISE TODAY AS HIGH PRESSURE BUILDS
OVER CALIFORNIA AND WESTERN NEVADA, WITH HIGHS NEAR 90 DEGREES IN
SOME VALLEY LOCATIONS. THURSDAY IS EXPECTED TO BE ABOUT 3-5
DEGREES WARMER THAN TODAY AS THE RIDGE AXIS SHIFTS INTO CENTRAL
NV, WHILE 700 MB TEMPS REACH THEIR PEAK VALUES OF 12 TO 13 C
ACROSS THE RENO-TAHOE REGION. LITTLE OR NO CLOUD COVER IS EXPECTED
TODAY THROUGH THURSDAY WHILE GENERALLY LIGHT WINDS PREVAIL.

ON FRIDAY, THE RIDGE IS PROJECTED TO FLATTEN OVER THE REGION AS
TROUGH APPROACHES THE PACIFIC NORTHWEST. MEANWHILE, HIGH LEVEL
MOISTURE ASSOCIATED WITH WEAKENING HURRICANE MARIE IS LIKELY TO
SPREAD OVER THE REGION. WITH MODEL SOUNDINGS SHOWING HUMIDITY
ABOVE 90 PERCENT IN THE 500-300 MB LAYER ALONG WITH DECENT UPWARD
MOTION IN THIS LAYER, THE RESULTANT CIRRUS DECK COULD BECOME
RATHER THICK BY FRIDAY AFTERNOON ESPECIALLY FROM I-80 SOUTHWARD.
THEREFORE WE HAVE TRENDED MAX TEMPS DOWN A FEW DEGREES FROM THE
PREVIOUS FORECAST. HOWEVER, NO RAIN IS EXPECTED AS AIR MASS BELOW
500 MB REMAINS RATHER DRY WITH LACK OF SUFFICIENT INSTABILITY.
SOME INCREASE IN WEST WINDS IS EXPECTED MAINLY NORTH OF HIGHWAY
50, WITH POTENTIAL GUSTS OF 25-30 MPH. MJD

.LONG TERM...SATURDAY THROUGH TUESDAY...

ONLY A FEW MINOR CHANGES WERE MADE TO PREVIOUS FORECAST. MEDIUM
RANGE MODELS REMAIN IN FAIRLY GOOD AGREEMENT THROUGH AT LEAST MONDAY
WITH FLATTENING OF THE RIDGE OVER OUR AREA AS A LONG WAVE TROUGH
DROPS INTO THE REGION FROM THE NORTH-NORTHWEST. OPERATIONAL MODELS
AND MOST GEFS ENSEMBLE MEMBERS NOW KEEP THE REMNANTS OF HURRICANE
MARIE WELL OFF THE WEST COAST WITH ONLY MID-HIGH LEVEL MOISTURE
LIKELY TO AFFECT OUR AREA.

THE BEST FORCING WITH THE TROUGH REMAINS NORTH OF THE AREA...
ALTHOUGH THE GEM IS TRYING TO PRODUCE SOME LIGHT QPF ON SATURDAY.
FOR NOW WILL LEAVE THE FORECAST DRY WITH JUST AN INCREASE IN CLOUDS.
WINDS COULD BE THE BIGGEST CONCERN IN THE EXTENDED. SATURDAY LOOKS
TO BE THE BREEZIEST DAY...BUT SUNDAY COULD BE BREEZY AS WELL.
THERMAL GRADIENT WILL BE THE STRONGEST SATURDAY AND BY SUNDAY MOST
OF THE AREA WILL BE BEHIND A SURFACE COOL FRONT.

CLOUD COVER THROUGH THE EXTENDED COULD AFFECT TEMPERATURES MORE THAN
WE ARE ACCOUNTING FOR AT THIS TIME. NUMERICAL GUIDANCE LOOKS LIKE
IT MIGHT BE A BIT TOO WARM...SO BY SUNDAY/MONDAY WE ARE AT OR
SLIGHTLY BELOW GUIDANCE.

BY TUESDAY MODELS BEGIN TO DIVERGE AS ECMWF HOLDS A FLAT RIDGE OVER
THE REGION WHILE GFS...AND GEM TO A LESSER EXTENT...BEGIN TO CARVE A
SECONDARY TROUGH SOUTH TOWARD THE REGION. GEFS ENSEMBLE MEMBERS HAVE
SOME SUPPORT FOR THIS SOLUTION AS WELL. FOR NOW WILL LEAVE FORECAST
UNCHANGED...BUT THE CONFIDENCE BEYOND MONDAY IN ANY SOLUTION IS
QUITE LOW. 20
&&

.AVIATION...

VFR CONDITIONS WITH NORTH-NORTHEAST LOW LEVEL FLOW TODAY. RIDGE
WINDS COULD BE GUSTY FROM THE EAST THIS MORNING...BUT WILL DECREASE
THROUGH THE DAY. RIDGE BUILDING OVER THE REGION WILL MEAN CONTINUED
VFR CONDITIONS AND LIGHT WINDS THROUGH THURSDAY. BY LATE FRIDAY
WINDS BECOME WESTERLY AND INCREASE AS AN UPPER LEVEL TROUGH OF LOW
PRESSURE APPROACHES THE REGION FROM THE NORTH. 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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