Area Forecast Discussion
Issued by NWS Reno, NV

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000
FXUS65 KREV 202116
AFDREV

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE RENO NV
216 PM PDT WED AUG 20 2014

.SYNOPSIS...
ISOLATED THUNDERSTORMS WILL END THIS EVENING OVER THE EASTERN
SIERRA AND WESTERN NEVADA SOUTH OF HIGHWAY 50. LOW PRESSURE WILL
MOVE INTO THE PACIFIC NORTHWEST AND BRING INCREASING WINDS FOR
THURSDAY AND FRIDAY. COOLER TEMPERATURES WILL REACH THE AREA FOR
SATURDAY WITH DRY CONDITIONS FOR MOST OF NEXT WEEK.

&&

.SHORT TERM...

ISOLATED SHOWERS AND LOW TOPPED THUNDERSTORMS ARE DEVELOPING OVER
THE EASTERN SIERRA FROM FROM MONITOR/EBBETTS PASS TO TIOGA PASS. A
FEW CELLS ARE ALSO TRYING TO DEVELOP OVER DOUGLAS, LYON AND
MINERAL COUNTIES. HOWEVER THERE IS A STRONG CAP JUST ABOVE 20000
FEET, WHICH WILL LIMIT VERTICAL DEVELOPMENT. THE STRONGER SHOWERS
AND STORMS WILL PRODUCE SOME RAINFALL AND MAY GENERATE OUTFLOW
WINDS TO 40 MPH. ALSO THERE IS A SLIGHT CHANCE FOR SHOWERS NORTH
OF CEDARVILLE TO LOVELOCK, WHERE A WAVE IS PASSING ALONG THE
NORTHERN NEVADA BORDER.

NEXT FORECAST ISSUE IS THE SYSTEM DROPPING SOUTH INTO THE PACIFIC
NORTHWEST FROM THE GULF OF ALASKA. HIGH CONFIDENCE THIS SYSTEM
WILL IMPACT THE SIERRA AND WESTERN NEVADA DUE TO THE RIDGE ALONG
140W. AFTERNOON WINDS WILL INCREASE FOR THURSDAY, BUT FRIDAY LOOKS
TO BE DAY WITH HIGHER WINDS AS A JET SEGMENT PASSES OVER NORTHEAST
CALIFORNIA AND NORTHWEST NEVADA. PEAK WINDS FRIDAY AFTERNOON OF
30-45 MPH ARE POSSIBLE NORTH OF HIGHWAY 50, WITH GUSTS NEAR 30 MPH
SOUTH OF HIGHWAY 50. THIS BRINGS UP THE POTENTIAL FOR HAZARDOUS
BOATING CONDITIONS ON AREA LAKES, AND CRITICAL FIRE WEATHER
CONCERNS AS A LARGE AREA OF DRY AIR ROUNDS THE BASE OF THE LOW.
SEE THE FIRE WEATHER DISCUSSION BELOW FOR MORE DETAILS.

TEMPERATURE WILL COOL THE NEXT COUPLE DAYS AS THE LOW DROPS INTO
NORTHWEST NEVADA. BY FRIDAY HIGHS IN THE LOWER VALLEYS WILL DROP
OFF INTO THE MID TO UPPER 80S WITH 70S FOR THE SIERRA. BRONG

.LONG TERM...SATURDAY THROUGH WEDNESDAY...

A TROUGH OVER THE ROCKIES IS EXPECTED TO PROVIDE DRY NORTH-NORTHWEST
FLOW ALOFT BRINGING COOLER AIR SOUTHWARD ACROSS THE SIERRA AND
WESTERN NV. IN FACT, TEMPERATURES SATURDAY AFTERNOON ARE EXPECTED TO
BE NEARLY 10 DEGREES BELOW NORMAL. THESE NORTH WINDS SHOULDN`T BE
STRONG, BUT A FEW HOURS WITH GUSTS AROUND 20 MPH ARE POSSIBLE AS THE
BOUNDARY OF COOLER AIR TRANSITIONS SOUTHWARD. A WEAK TROUGH REMAINS
OVER THE WEST SUNDAY, WITH LIGHT WINDS AND A SUNNY AFTERNOON
EXPECTED FOR THE SIERRA AND WESTERN NV.

FOR SUNDAY NIGHT-MONDAY, THE GFS ENSEMBLE CONTINUES TO SUPPORT A
NORTHERLY JET DROPPING SOUTH OVER THE SIERRA WHILE THE ECMWF
CONTINUES TO FORECAST THE JET FARTHER EAST. THE GFS FORECAST SHOWS
BETTER POTENTIAL FOR A THERMAL GRADIENT ACROSS THE SIERRA FRONT RANGE
AND THUS STRONGER NORTHWESTERLY WINDS ACROSS WESTERN NV. FOR NOW THE
CURRENT FORECAST IS A COMPROMISE BETWEEN THE TWO MODELS.

FOR TUESDAY-WEDNESDAY, THE MODEL CONSENSUS IS FOR INCREASING HIGH
PRESSURE ALOFT, LIGHT EASTERLY WINDS AND A SLOW WARMING TREND. JCM

&&

.AVIATION...
TYPICAL WESTERLY WINDS WITH GUSTS UP TO 20KT EXPECTED THIS EVENING
FOR WESTERN NEVADA AND SIERRA TERMINALS. ALSO EXPECT ISOLATED
SHOWERS AND THUNDERSTORMS THIS EVENING SOUTH OF HIGHWAY 50. MAIN
THREATS NARY ANY THUNDERSTORMS ARE LIGHTNING, SFC WND GUSTS TO 45
KTS AND SMALL HAIL. JCM

&&

.FIRE WEATHER...
A TROUGH OF LOW PRESSURE WILL SHIFT THROUGH THE NORTHWEST ON
FRIDAY BACKED BY A 90 MPH JET STREAM. RIDGE LEVEL WINDS BEGIN TO
INCREASE BY EARLY FRIDAY MORNING, BECOMING STRONGEST FRIDAY
AFTERNOON FROM HIGHWAY 50 NORTH. THESE MID LEVEL WINDS COINCIDE
WITH A STRENGTHENING SURFACE GRADIENT BRINGING GUSTS OF 30 TO 40
MPH ACROSS NORTHEAST CALIFORNIA AND NORTHWEST NEVADA FRIDAY
AFTERNOON. THERE IS A FAIRLY SIGNIFICANT DRY SLOT MOVING IN BEHIND
THE LOW AND THIS DRIER AIR WILL LIKELY MIX DOWN TO THE SURFACE
BRINGING 10 TO 15 PERCENT RELATIVE HUMIDITY VALUES TO THE DESERTS
OF EXTREME NORTHEAST CALIFORNIA AND NORTHWEST NEVADA. THE
COMBINATION OF GUSTY WINDS AND LOW HUMIDITY MAY LEAD TO CRITICAL
FIRE WEATHER CONDITIONS AND A FIRE WEATHER WATCH HAS BEEN ISSUED
FOR NORTHEAST CALIFORNIA, THE SIERRA FRONT, NORTHERN WASHOE
COUNTY, AND THE WEST CENTRAL BASIN AND RANGE.

LIGHT NORTHEAST WINDS WILL RESULT AS THE LOW SHIFTS EASTWARD ON
SATURDAY BEFORE BREEZY WEST WINDS RETURN SUNDAY INTO MONDAY AS
A SECONDARY SHORTWAVE MOVES THROUGH THE NORTHWEST. DJ

&&

.REV WATCHES/WARNINGS/ADVISORIES...
NV...FIRE WEATHER WATCH FROM FRIDAY MORNING THROUGH FRIDAY EVENING
     NVZ450-453-458.

CA...FIRE WEATHER WATCH FROM FRIDAY MORNING THROUGH FRIDAY EVENING
     CAZ270-278.

&&

$$

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



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