315
FXUS65 KREV 160944
AFDREV
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE RENO NV
244 AM PDT WED OCT 16 2013
.SYNOPSIS...
A DRY AND COOL NORTHERLY FLOW WILL PERSIST ACROSS THE SIERRA AND
WESTERN NEVADA THROUGH FRIDAY AND THEN WEAKEN AS A RIDGE OF HIGH
PRESSURE OFF THE WEST COAST SHIFTS INLAND. THE NEXT COUPLE OF NIGHTS
ARE GOING TO BE COLD BEFORE TEMPERATURES BEGIN TO MODERATE LATE
IN THE WEEK.
&&
.SHORT TERM...
CLEAR CONDITIONS EVIDENT ON SATELLITE IMAGERY ACROSS MUCH OF
CALIFORNIA AND NEVADA THIS MORNING. THIS COUPLED WITH A VERY DRY
AIR MASS ALOFT AND LIGHT WINDS IS ALLOWING MANY VALLEYS TO COOL
AROUND 5 DEGREES FROM WHAT WAS OBSERVED 24 HOURS AGO. DO EXPECT
TEMPERATURES TO CONTINUE TO DROP BELOW FREEZING THIS MORNING
ACROSS WESTERN NEVADA WHILE THE SIERRA VALLEYS DIP INTO THE TEENS
AND 20S.
NO SIGNIFICANT CHANGES TO THE WEATHER IN THE NEXT FEW DAYS AS WE
REMAIN UNDER THE INFLUENCE OF A BLOCKING PATTERN WITH A RIDGE SET
UP AROUND 135W. WILL ONLY SEE A WEAK SHORTWAVE IMPULSE DIVE SOUTH
FROM THE GULF OF ALASKA TODAY, BUT ONLY EXPECTING SOME INCREASED
HIGH CLOUDS WITH NO PROSPECTS FOR PRECIPITATION OR SIGNIFICANT
INCREASES IN WINDS WITH ITS PASSAGE. MIXING WILL BE A LITTLE
DEEPER THIS AFTERNOON AS THE WAVE PASSES WHICH WILL RESULT IN
WARMER HIGH TEMPERATURES THIS AFTERNOON. HIGHS ACROSS WESTERN
NEVADA WILL REACH INTO THE MID TO UPPER 60S WITH LOWER 60S ACROSS
SIERRA VALLEYS. OVERNIGHT LOWS WILL CONTINUE TO BE SUBFREEZING
ACROSS MOST AREAS THROUGH THE START OF THE WEEKEND AS LIGHT WINDS
AND DRY CONDITIONS PREVAIL. A FEW DEGREES OF COOLING EXPECTED ON
THURSDAY AS WINDS SWITCH BACK OUT OF THE NORTHEAST AND NEAR SEASON
AVERAGES BY FRIDAY WITH MID 60S OVER WESTERN NEVADA AND LOW 60S
ACROSS THE SIERRA. FUENTES
.LONG TERM...SATURDAY THROUGH TUESDAY...
MEDIUM RANGE MODELS AND MOST GEFS ENSEMBLE MEMBERS CONTINUE TREND OF
BUILDING A RIDGE ALONG THE WEST COAST EARLY IN THE EXTENDED PERIOD
THEN ROLLING THE RIDGE OVER BY EARLY MONDAY. THIS CREATES A
PSEUDO-REX TYPE PATTERN THAT LASTS ONLY A SHORT TIME BEFORE THE
RIDGE REBUILDS AND THE AXIS SLIDES A BIT FARTHER EAST. GIVEN NO
SIGNIFICANT CHANGES TO THE BROAD PATTERN...ONLY VERY MINIMAL CHANGES
WERE MADE TO THE GOING FORECAST.
THERE ARE SOME VERY SUBTLE DIFFERENCES IN MODEL SOLUTIONS THAT ARE
MAINLY OF THE NATURE OF HOW FAR EAST OR WEST THE RIDGE AXIS DEVELOPS
AND HOW WARM MID LEVEL TEMPS BECOME. THE DIFFERENCES APPEAR LARGELY
INCONSEQUENTIAL IN THE BROADER SCHEME OF THE FORECAST. ONE ASPECT OF
THE FORECAST THAT IS STILL PROBLEMATIC COULD BE VALLEY HIGH TEMPS
EACH DAY. MODEL GUIDANCE CONTINUES TO RISE ALTHOUGH VERY LIGHT NORTH
TO EAST FLOW WITH DECREASING DIRECT SOLAR HEATING SHOULD ARGUE FOR
LESS ABILITY TO MIX EFFECTIVELY...KEEPING TEMPS BELOW AVERAGE. SO
OVERALL HIGHS WERE KEPT ON THE LOWER SIDE OF GUIDANCE. MAINLY 60S IN
THE LOWER VALLEYS...WHICH WILL BE NEAR THE TEMPS IN THE HIGHER
VALLEYS OF THE SIERRA AS WELL. DRY AIRMASS AND LACK OF CLOUDS WILL
PROMOTE BELOW AVERAGE OVERNIGHT LOWS IN THE VALLEYS EACH DAY. MID
SLOPES AND RIDGES WILL BE WARMER AS TEMPS ALOFT RISE. THIS SHOULD
REINFORCE INVERSIONS EACH DAY AND LIMIT MIXING HEIGHTS FOR
PRESCRIBED BURNS. 20
&&
.AVIATION...
LIGHT FLOW THIS MORNING BECOMES WESTERLY AND INCREASES SLIGHTLY
AHEAD OF WEAK FAST MOVING TROUGH THAT DROPS THROUGH THE REGION
TONIGHT. SFC WIND GUSTS SHOULD BE NO MORE THAN 15-20 KTS TODAY. VFR
CONDITIONS WITH A AREAS OF HAZE DUE TO SMOKE FROM A FEW PRESCRIBED
BURNS AROUND THE TAHOE BASIN. THIS WILL MIX OUT LATER TODAY. REINFORCED
LOW LVL NORTH TO NORTHEAST FLOW AND A DRY AIRMASS SHOULD LIMIT FOG
DEVELOPMENT IN SHELTERED VALLEYS TONIGHT AS WELL. 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)