Area Forecast Discussion
Issued by NWS Reno, NV

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000
FXUS65 KREV 192130
AFDREV

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE RENO NV
230 PM PDT SAT APR 19 2014

.SYNOPSIS...

WEAK HIGH PRESSURE WILL REMAIN INTO SUNDAY WITH ABOVE NORMAL
TEMPERATURES. WINDS WILL INCREASE MONDAY AHEAD OF A STRONG COLD
FRONT WITH 20 TO 25 DEGREES OF COOLING BY TUESDAY. THERE WILL ALSO
BE SOME CHANCES FOR RAIN AND SNOW WITH LIGHT ACCUMULATIONS IN THE
HIGHER ELEVATIONS OF THE SIERRA. A BREAK IS EXPECTED WEDNESDAY AND
THURSDAY WITH THE POSSIBILITY OF ANOTHER SYSTEM LATE IN THE WEEK.

&&

.SHORT TERM...
WEAK HIGH PRESSURE BUILDING OVERHEAD WITH JUST SOME FLAT CUMULUS
DEVELOPMENT. WITH MOST CUMULUS ACTUALLY SHOWING A DECREASING TREND
IN COVERAGE AND DEPTH OVER MONO/MINERAL COUNTIES, I REMOVED THE
THREAT OF THUNDERSTORMS THIS EVENING AND EXPECT OVERALL A CLEAR
NIGHT WITH COOL OVERNIGHT TEMPERATURES.

SUNDAY REMAINS MILD WITH LIGHT WINDS BEFORE THE NEXT SYSTEM
ARRIVES LATE MONDAY. MODELS REMAIN IN GOOD AGREEMENT WITH THE
OVERALL TRACK. SREF SHOWS THE NAM IS LIKELY SLOW WITH THE SPREAD
ON THE EAST SIDE OF THE GUIDANCE, MORE IN LINE WITH THE GFS/EC
SCENARIOS AND WILL RUN WITH THE LATTER. EXPECT ANOTHER MILD DAY
MONDAY AS WINDS INCREASE WITH BREEZY CONDITIONS FOR THE SIERRA AND
WESTERN NEVADA. WINDS INCREASE FURTHER ALOFT MONDAY NIGHT AS THE
COLD FRONT NEARS AND MOVES THROUGH TUESDAY MORNING.

WITH 700 MB WINDS PEAKING NEAR 50 KTS, COULD BE A BRIEF PERIOD OF
DOWNSLOPE WINDS. HOWEVER, MODELS SHOW MORE TRAPPED LEE WAVES AND
THE FAST MOVEMENT OF THE SYSTEM ALSO DISCOURAGES ANY STRONG WINDS.
STILL THINK PEAK GUSTS AROUND 50 MPH ARE POSSIBLE TUESDAY MORNING
AHEAD OF THE FRONT ALONG THE 395 CORRIDOR SOUTH OF SUSANVILLE AND
LOCALLY HIGHER GUSTS. ELSEWHERE, PEAK GUSTS LOOK TO BE AROUND 40
MPH. BEHIND THE FRONT, AS SFC LOW PRESSURE DEEPENS OVER UTAH,
EXPECT THE WINDS TO CONTINUE TO GUST TO 40-45 MPH WITH THE
TIGHTENING SURFACE GRADIENT AND STRONG COLD AIR ADVECTION.

AS FOR PRECIP, EXPECT ALMOST ALL OF IT TO BE POST-FRONTAL. THE NAM
REMAINS VERY DRY AND WILL DISCOUNT ITS SOLUTION AND GO WITH THE
WETTER GFS/EC. IN GENERAL, STRONG, DYNAMIC SYSTEMS LIKE THIS TEND
TO LEAN TOWARD THE WETTER MODELS. EVEN SO, IT APPEARS BEST CHANCE
FOR PRECIP WILL BE FOR THE TAHOE BASIN TO WESTERN LASSEN COUNTY
AND NORTHERN WASHOE COUNTY. THIS IS WHERE THE BEST MOISTURE AND
FORCING WILL COINCIDE. THE BEST SHOT WILL BE TUESDAY MORNING WITH
SCATTERED SHOWERS MOST EVERYWHERE TUESDAY IN THE MOIST UNSTABLE
AIR BEHIND THE FRONT. AMOUNTS WILL BE LIGHT WITH AROUND 1/4 INCH
IN THE FAVORED AREAS AND A FEW HUNDREDTHS AT BEST EVERYWHERE ELSE.
SNOW LEVELS LOOK TO START AROUND 7500 FEET AS PRECIP COMMENCES,
BUT WILL FALL TO AROUND 5000 FEET OR SO BEHIND THE FRONT TUESDAY.
LIGHT ACCUMULATIONS ARE POSSIBLE IN THE SIERRA ABOVE 7000 FEET
TUESDAY MORNING.

TEMPERATURES TUESDAY WILL BE MUCH COLDER, AROUND 20 DEGREES OR SO
FROM THOSE SEEN MONDAY. EXPECT A COOL NIGHT TUESDAY NIGHT AS THE
SYSTEM DEPARTS AND SKIES GRADUALLY CLEAR. EXPECT FREEZING
TEMPERATURES AGAIN FOR MUCH OF WESTERN NEVADA, ALTHOUGH ALONG THE
SIERRA FRONT, RENO/CARSON CITY PROPER MAY STAY A LITTLE ABOVE.
WALLMANN

.LONG TERM...WEDNESDAY THROUGH SATURDAY...
GENERALLY DRY CONDITIONS ARE EXPECTED FOR WEDNESDAY AND THURSDAY,
WITH POSSIBILITY FOR PRECIPITATION RETURNING TOWARD THE END OF THE
WEEK AND THROUGH NEXT WEEKEND. THE 12Z GUIDANCE WAS MORE
FRAGMENTED AND PRODUCED LOWER QPF AMOUNTS WITH THE UPCOMING STORM
SYSTEM FRIDAY AND SATURDAY COMPARED TO THE PREVIOUS GUIDANCE.
HOWEVER, THIS TENDENCY TO GO TOO DRY HAS BEEN OBSERVED ON SEVERAL
12Z MODEL RUNS, ONLY TO REVERT TO A WETTER SCENARIO AGAIN WITH THE
SUBSEQUENT 00Z RUNS. THEREFORE WE WILL MAINTAIN THE MAINLY CHANCE
POPS ALREADY IN THE FORECAST BUT NOT GO ANY HIGHER AT THIS TIME.

FOR WEDNESDAY, A FEW LINGERING SHOWERS WILL BE POSSIBLE IN PARTS OF
NORTHWEST NV IN THE MORNING BEHIND THE DEPARTING TROUGH. OTHERWISE
DRY CONDITIONS ARE EXPECTED WITH SOME DECREASE IN CLOUD COVER MAINLY
SOUTH OF INTERSTATE 80. ALTHOUGH TEMPERATURES WILL START TO REBOUND
COMPARED TO TUESDAY, HIGHS SHOULD REMAIN SLIGHTLY BELOW NORMAL WITH
LOWER 60S FOR WESTERN NV VALLEYS AND LOWER-MID 50S NEAR THE SIERRA.

FOR THURSDAY, FLAT RIDGE AXIS MOVES ACROSS NEVADA DURING THE DAY,
ALLOWING FOR ONE MORE DAY OF WARMING, WITH HIGHS AROUND 70 DEGREES
FOR THE LOWER ELEVATIONS. THE FIRST BAND OF MOISTURE ASSOCIATED WITH
NEXT TROUGH MAY BRING A FEW SHOWERS INTO FAR NORTHEAST CA-NORTHWEST
NV THURSDAY AFTERNOON AND NIGHT.

FOR FRIDAY AND SATURDAY, TROUGH MOVES CLOSER TO THE WEST COAST AND
INCREASES POSSIBILITY OF PRECIPITATION FOR THE REGION, ALTHOUGH THE
MODEL UNCERTAINTIES DESCRIBED ABOVE LEAD TO LOWER CONFIDENCE IN THE
RAIN AND SNOW AMOUNTS. THE GENERAL IDEA FOR THIS FORECAST KEPT
MENTION OF RAIN OR SNOW INTACT FOR ALL AREAS WITH HIGHER
PROBABILITIES NEAR THE SIERRA. IF THE TROUGH DOES NOT DIG FAR ENOUGH
SOUTH, LEE SIDE SHADOWING WOULD CUT DOWN RAIN AMOUNTS FOR MOST OF
WESTERN NV ESPECIALLY WEST OF HIGHWAY 95. SNOW LEVELS MAY FALL TO
LAKE LEVEL AROUND TAHOE STARTING FRIDAY NIGHT, BUT ARE SUBJECT TO
CHANGE DEPENDING ON THE TRACK OF THIS TROUGH. FOR LATE APRIL,
SIGNIFICANT SNOW ACCUMULATIONS ARE UNLIKELY BELOW 7000 FEET
ESPECIALLY DURING THE DAYTIME HOURS, UNLESS STRONG FORCING BOOSTS
THE SNOWFALL INTENSITY.

SOUTHWEST TO WEST WINDS WILL ALSO INCREASE BOTH FRIDAY AND SATURDAY
WITH POSSIBLE GUSTS TO 40 MPH IN SOME LOWER ELEVATIONS, AND ABOVE
50 MPH ON THE SIERRA RIDGES. TEMPERATURES WILL FALL EACH DAY DUE TO
INCREASING CLOUD COVER AND PRECIPITATION CHANCES, WITH PROJECTED
HIGHS MAINLY IN THE 60S FOR WESTERN NV AND AROUND 50 DEGREES NEAR
THE SIERRA BY SATURDAY. MJD

&&

.AVIATION...
VFR CONDITIONS PREVAIL THRU SUNDAY, EXCEPT FOR A 20 PERCENT
CHANCE OF SOME FZFG AFFECTING VSBY/CIGS AT KTRK EARLY SUNDAY
MORNING MAINLY BTWN 11-15Z. LESS FOG COVERAGE AND DEPTH COMPARED
TO THIS MORNING. W-NW WIND GUSTS 25-30 KT FOR WESTERN NV AND
SLIGHTLY LESS FOR THE SIERRA/TAHOE TERMINALS THRU EARLY THIS
EVENING, WITH SOME MOUNTAIN WAVE TURBULENCE EAST OF THE SIERRA
CREST. MUCH LIGHTER NE-E WINDS EXPECTED ALL AREAS SUNDAY.

NEXT STORM SYSTEM WILL MOVE INTO THE WEST COAST ON MONDAY WITH
STRONG WINDS LIKELY OVER THE SIERRA. THIS WILL LEAD TO MOUNTAIN
WAVES WITH SURFACE GUSTS TO 35-45 KTS MONDAY AFTERNOON THROUGH
TUESDAY. SHOWERS WILL ALSO LEAD TO MVFR CONDITIONS WITH SNOW
POSSIBLE AT THE SIERRA TERMINALS. MJD/BRONG

&&

.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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