Area Forecast Discussion
Issued by NWS Reno, NV

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000
FXUS65 KREV 230044
AFDREV

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE RENO NV
544 PM PDT MON SEP 22 2014

.UPDATE...
JUST DOING A QUICK UPDATE TO COVER SHOWERS OVER THE FAR NORTHERN
PART OF THE FORECAST AREA. ISOLATED SHOWERS ARE OCCURRING NORTH OF
GERLACH AND THIS APPEARS TO BE IN RESPONSE TO A WEAK WAVE PUSHING
THROUGH THAT AREA. THIS IS WELL AHEAD OF THE MAIN TROUGH
DEVELOPING OVER THE ERN PAC AND COULD BE MORE OF A WEAK WARM AIR
ADVECTION SIGNATURE MOVING OVER THE TOP OF THE RIDGE IN PLACE OVER
THE SRN CWA. WILL ONLY MENTION SHOWERS THIS EVENING FOR THAT AREA
AS FORCING APPEARS TO ABATE LATER THIS EVENING.

SMOKE IS RETURNING TO WRN NV NOW AFTER STAYING MAINLY IN THE
TRUCKEE AREA MOST OF THE AFTERNOON. WESTERLY WINDS ARE DRIVING
THIS SMOKE IN THE VALLEYS AND IT WILL LIKELY STAY TRAPPED HERE FOR
SOME TIME THIS EVENING. CURRENTLY THE DENSE SMOKE ADVISORY IN
EFFECT NOW RUNS UNTIL 8 PM...BUT WE WILL NEED TO LOOK AT THAT AND
MAY EXTEND IT INTO THE LATE NIGHT HOURS. TYPICALLY THE SMOKE HAS
BEEN DISSIPATED LATE IN THE EVENING AS WINDS BEGIN TO DROP OFF. 20

&&

.PREVIOUS DISCUSSION... /ISSUED 250 PM PDT MON SEP 22 2014/

SYNOPSIS...
HIGH PRESSURE WITH INCREASING SOUTHWEST FLOW WILL BRING WARM AND DRY
CONDITIONS TO THE REGION THROUGH THE MIDDLE OF THE WEEK. SMOKE AND
HAZE FROM THE KING FIRE WILL CONTINUE TO AFFECT WESTERN NEVADA AND
NORTHEAST CALIFORNIA. A LOW PRESSURE SYSTEM APPROACHING THE WEST
COAST WILL BRING INCREASING WINDS AND COOLER TEMPERATURES WITH
POSSIBLE RAIN LATER IN THE WEEK.

SHORT TERM...
MAIN CONCERNS IN THE SHORT TERM WILL BE THE CONTINUED SMOKE/HAZE
FROM THE KING FIRE AS WELL AS GUSTY WINDS AS A LOW PRESSURE SYSTEM
APPROACHES THE WEST COAST.

VISIBILITY AND AIR QUALITY CONTINUE TO BE IMPACTED BY THE SMOKE FROM
THE KING FIRE THIS AFTERNOON. WITH WEST/SOUTHWEST FLOW ACROSS THE
REGION AND AS LONG AS THE FIRE BURNS ACTIVELY, WE DO NOT ANTICIPATE
IMPROVING CONDITIONS WITH THE SMOKE AND HAZE ACROSS THE TAHOE BASIN
AND WESTERN NEVADA THROUGH WEDNESDAY. DENSE SMOKE ADVISORIES REMAIN
IN EFFECT FOR THIS AFTERNOON AND EVENING AND WE HAVE ALSO ISSUED
ANOTHER ROUND OF DENSE SMOKE ADVISORIES FOR TUESDAY. ALTHOUGH
VISIBILITIES WILL REMAIN GENERALLY ABOVE 5 MILES, THERE WILL BE
LOCALIZED CONDITIONS AND VISIBILITY DOWN TO 1 MILE AT TIMES THROUGH
THE AFTERNOONS/EVENINGS FOR THE NEXT COUPLE OF DAYS.

UPPER LEVEL SOUTHWEST FLOW WILL INCREASE TUESDAY AND WEDNESDAY AS
THE NEXT LOW PRESSURE SYSTEM APPROACHES THE WEST COAST. GUSTY
SOUTHWEST WINDS AROUND 35 MPH ALONG WITH DRY CONDITIONS WILL IMPACT
THE REGION ON WEDNESDAY INTO THURSDAY, WITH FIRE WEATHER IMPACTS
POSSIBLE. READ THE FIRE WEATHER DISCUSSION BELOW FOR DETAILS ON
WINDS AND LOW HUMIDITY.

OTHERWISE, DRY CONDITIONS WILL CONTINUE OVER THE REGION THRU
MIDWEEK. HIGH TEMPERATURES WILL BE SEVERAL DEGREES ABOVE NORMAL,
MAINLY IN THE MID TO UPPER 80S FOR WESTERN NEVADA AND MID 70S FOR THE
SIERRA VALLEYS. SLIGHT CHANCES FOR RAIN SHOWERS WILL BE POSSIBLE FOR
FAR NORTHEASTERN CALIFORNIA BY EARLY THURSDAY AHEAD OF THE NEXT
LOW PRESSURE SYSTEM. ELW

LONG TERM...THURSDAY THROUGH MONDAY...
LARGE UPPER LEVEL TROUGH WILL BE POSITIONED OFF THE WEST COAST BY
THURSDAY WITH A 110KT JET CROSSING OVER NORTHERN CALIFORNIA. THIS
SYSTEM WILL PROVIDE WINDY CONDITIONS THURSDAY AS A STRENGTHENED
SURFACE PRESSURE GRADIENT AND MIXING OF 35-40 KTS WINDS ALOFT
DEVELOPS AHEAD OF A SURFACE COLD FRONT PASSAGE LATE IN THE DAY
THURSDAY INTO EARLY FRIDAY MORNING. MOISTURE WILL INCREASE WITH THE
TROUGH SO EXPECTING INCREASES IN SURFACE HUMIDITY WHICH SHOULD HELP
MITIGATE FIRE WEATHER CONCERNS AT THIS TIME. WIND GUSTS AROUND 40-45
MPH ARE POSSIBLE WHICH MAY CREATE HAZARDOUS BOATING CONDITIONS AND
MAY IMPACT MOTORISTS IN HIGH PROFILE VEHICLES. SCATTERED SHOWERS ARE
ALSO POSSIBLE THURSDAY WITH THE BEST CHANCES ALONG THE SIERRA AND
WITH THE FRONT INTO WESTERN NEVADA MAINLY NORTH OF HWY 50.

BEHIND THE FRONT COOLER CONDITIONS WILL PREVAIL WITH HIGH
TEMPERATURES ACROSS WESTERN NEVADA ONLY REACHING THE UPPER 60S TO
LOW 70S AND LOWER 60S ACROSS SIERRA VALLEYS. TIMING DIFFERENCES STILL
EXIST BETWEEN THE EC AND GFS REGARDING HOW FAST THE UPPER LOW
DEPARTS THE REGION WITH THE GFS MAINTAINING A FASTER DEPARTURE.
LITTLE CHANGE IN THE FORECAST BEYOND FRIDAY BUT STILL EXPECTING A
PERIOD OF SHOWERS TO PERSIST AS THE COOLER TEMPS ALOFT PROMOTE
INCREASED INSTABILITY. WHETHER THE BEST POTENTIAL FOR PRECIP EXISTS
FRIDAY OR SATURDAY WILL NEED TO BE FURTHER REFINED BUT SEEMS THE GFS
HAS TRENDED MORE TOWARDS THE EC WITH A SLOWER DEPARTURE. SOME
PRECIP COULD OCCUR IN THE FORM OF SNOWFALL FOR AREAS ABOVE
8000-9000 FEET WITH 700MB TEMPS COOLING AS MUCH AS -2C. BEYOND
SATURDAY, MOST MODELS EJECT THE LOW AND WE SHOULD BEGIN A GRADUAL
WARMING AND DRYING PATTERN INTO THE START OF NEXT WEEK. FUENTES

AVIATION...
SMOKE FROM THE KING FIRE WILL CONTINUE TO BE THE MAIN ISSUE THROUGH
AT LEAST WEDNESDAY WITH SOUTHWEST FLOW ALOFT. SMOKE TRANSPORT SHOULD
INCREASE OVER THE NEXT SEVERAL DAYS WITH STRONGER WINDS EXPECTED WED
AND THU. THERE IS POTENTIAL FOR SFC VIS TO LOWER TO 1-3 MILES FOR
KRNO/KCXP/KTVL/KTRK DURING THE DAY WITH SOME IMPROVEMENT AFTER 03Z
AOA 3SM AGAIN. SLANTWISE VIS WILL ALSO BE DEGRADED WITH LESS THAN 1
SM POSSIBLE. SMOKE VIS FORECAST IS DIFFICULT AND DEPENDS LARGELY ON
FIRE BEHAVIOR. AS SUCH, VIS FORECAST CONFIDENCE IS LOW TO MEDIUM
UNTIL TRENDS CAN BE ESTABLISHED. FUENTES

FIRE WEATHER...
SOUTHWESTERLY FLOW WILL INCREASE OVER THE NEXT FEW DAYS AS A STRONG
PACIFIC TROUGH APPROACHES THE WEST COAST. THERE WILL BE A
SIGNIFICANT DRY SLOT THAT PRECEDES THE TROUGH MOVING OVER THE SIERRA
FROM THE TAHOE BASIN NORTHWARD BY TUESDAY AFTERNOON. THIS DRY SLOT
WILL REMAIN IN PLACE THROUGH WEDNESDAY BEFORE SHIFTING SOUTHEAST
INTO THE CENTRAL SIERRA AND CENTRAL NEVADA BY THURSDAY. RECOVERIES
WILL BE POOR FOR MID SLOPES AND HIGHER ELEVATIONS TUESDAY AND
WEDNESDAY NIGHTS WHILE ONLY MODERATE FOR VALLEY LOCATIONS.

MEANWHILE, WINDS WILL INCREASE EACH DAY AS THE PRESSURE GRADIENT
TIGHTENS BECOMING LOCALLY BREEZY IN NORTHEAST CALIFORNIA AND EXTREME
NORTHWESTERN NEVADA BY TUESDAY AFTERNOON. ISOLATED WIND PRONE AREAS
IN ZONE 278 AND 458 MAY BRIEFLY REACH RED FLAG CRITERIA TUESDAY
AFTERNOON, BUT THESE CONDITIONS SHOULD NOT BE VERY WIDESPREAD.
ELSEWHERE, GUSTS SHOULD MAX OUT AROUND 25 MPH LATE IN THE AFTERNOON.
WINDS INCREASE FURTHER WEDNESDAY WITH ISOLATED GUSTS TO 40 MPH AND
LOW RELATIVE HUMIDITY IN THE 10-20% RANGE. HAVE OPTED TO PUT A FIRE
WEATHER WATCH OUT FOR ZONES 270, 271, 278, AND 458 VALID WEDNESDAY
AFTERNOON AND EARLY EVENING SINCE GUSTS BECOME MORE INFLUENTIAL TO
FIRE BEHAVIOR AT 40 MPH.

WHILE WINDS CONTINUE TO INCREASE INTO THURSDAY DUE TO AN APPROACHING
JET STREAK, MOISTURE BEGINS TO MOVE INTO THE REGION AS THE PRIMARY
SHORTWAVE MOVES ONSHORE. THIS MOISTURE WILL PUSH CRITERIA BELOW RED
FLAG THRESHOLDS REMOVING NORTHWESTERN NEVADA AND NORTHEASTERN
CALIFORNIA FROM THE THREAT AREA FOR FIRE WEATHER CONCERNS. HOWEVER,
THE DRY SLOT WILL SHIFT SOUTHEASTWARD INTO THE CENTRAL SIERRA AND
CENTRAL GREAT BASIN. THE THREAT AREA FOR FIRE WEATHER CONCERNS WILL
ALSO SHIFT TO ZONES 273, 453, AND 459 ON THURSDAY. IF THESE
CONDITIONS CONTINUE TO BE PRESENTED AS DISCUSSED ABOVE, A FIRE
WEATHER WATCH WILL BE ISSUED FOR THURSDAY FOR 273, 453, AND 459.

IT SHOULD ALSO BE NOTED THAT 272 AND 450 ARE ON THE LOWER END OF
CONCERN AND WILL NOT BE INCLUDED IN THE WATCH PRODUCTS AT THIS TIME.
THE TIMING OF THE DRY SLOT COINCIDENT WITH THESE ZONES OCCUR
OVERNIGHT WHEN HUMIDITY MAXIMIZES. HOWEVER, MID SLOPE AND HIGHER
ELEVATION RECOVERIES WILL BE POOR UNTIL THE MOISTURE ARRIVES ON
THURSDAY. BOYD

&&

.REV WATCHES/WARNINGS/ADVISORIES...
NV...FIRE WEATHER WATCH FROM WEDNESDAY MORNING THROUGH WEDNESDAY
     EVENING NVZ458.

     DENSE SMOKE ADVISORY UNTIL 8 PM PDT THIS EVENING NVZ002.

     DENSE SMOKE ADVISORY FROM 11 AM TO 8 PM PDT TUESDAY NVZ002.

     DENSE SMOKE ADVISORY UNTIL 8 PM PDT THIS EVENING NVZ003.

     DENSE SMOKE ADVISORY FROM 2 PM TO 8 PM PDT TUESDAY NVZ003.

CA...FIRE WEATHER WATCH FROM WEDNESDAY MORNING THROUGH WEDNESDAY
     EVENING CAZ270-271-278.

     DENSE SMOKE ADVISORY UNTIL 8 PM PDT THIS EVENING CAZ072.

     DENSE SMOKE ADVISORY FROM 11 AM TO 8 PM PDT TUESDAY CAZ072.

&&

$$

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





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