Area Forecast Discussion
Issued by NWS Reno, NV

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FXUS65 KREV 190311
AFDREV

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE RENO NV
811 PM PDT THU SEP 18 2014

.UPDATE...
WESTERLY WINDS ARE STARTING TO DECREASE OVER WRN NV THIS EVENING
AND BEGINNING A SLOW SHIFT TO THE WNW OR NW. DURING THE LAST HOUR
VISIBILITY HAS STARTED TO IMPROVE OVER THE RENO AREA BUT REMAINS
LOW IN SOME OTHER SPOTS. THE LESSENING OF THE WINDS SHOULD HELP
THIS PROCESS AS LESS SMOKE IS ADVECTED INTO THE REGION THROUGH THE
NIGHT. CONVECTION HAS DECREASED QUITE A BIT OVER WRN NV AND
CHANGES WERE MADE TO DROP THE CONVECTION FOR NE CA LATE THIS
EVENING.

LATEST WATER VAPOR IMAGERY IS SHOWING THE UPPER LOW MAY BE TRYING
TO CLOSE OFF A LITTLE FARTHER WSW THAN ORIGINALLY FORECAST. THIS
WOULD BE IN RESPONSE TO A JET STREAK DIGGING INTO THE BACK SIDE OF
THE TROUGH. THIS WOULD MAKE THE FORECAST A BIT MORE PROBLEMATIC
OVERNIGHT. LATEST NAM STILL WANTS TO DEVELOP PCPN IN A DEFORMATION
BAND OVER WRN NV. THIS WAS MAINTAINED...BUT IF LOW CLOSES OFF
FARTHER WEST THEN WE MAY BE TOO FAR EAST TO SEE MUCH OF THIS PCPN.
AND...THIS COULD ALSO DELAY THE INCREASE IN LOW TO MID LVL EASTERLY
FLOW THAT WOULD HELP TO MOVE THE SMOKE OUT OF OUR AREA. FOR NOW
WILL BANK ON MOST OF THE SMOKE DISSIPATING BY DAYBREAK. 20

&&

.PREVIOUS DISCUSSION... /ISSUED 309 PM PDT THU SEP 18 2014/

SYNOPSIS...

SMOKE FROM THE KING FIRE WILL AFFECT PARTS OF THE REGION THROUGH
TONIGHT. AS WINDS SHIFT TO THE EAST FROM FRIDAY THROUGH THE
WEEKEND, SMOKE WILL REMAIN WEST OF THE SIERRA CREST. LOW PRESSURE
MOVING INTO NORTHERN CALIFORNIA WILL BRING A CHANCE OF
THUNDERSTORMS TODAY AND TONIGHT. THUNDERSTORM CHANCES WILL
DECREASE FRIDAY AS THIS LOW MOVES FARTHER SOUTH.

SHORT TERM...

UPPER LEVEL LOW CONTINUES TO PUSH DOWN ALONG THE CALIFORNIA COAST
THROUGH TONIGHT WITH SOUTHWEST FLOW ALOFT. TEMPERATURES WILL BE A
BIT COOLER TODAY AND FRIDAY AS THE LOW BRING DOWN TEMPERATURES
ALOFT. BY FRIDAY, THE LOW BECOMES CUT OFF FROM THE MAIN JET OVER
THE PAC NORTHWEST AND MEANDERS AROUND THE CALIFORNIA COAST THROUGH
THE WEEKEND.

SMOKE FROM THE KING FIRE WEST OF TAHOE WILL CONTINUE TO FLOW INTO
THE NORTH TAHOE AND RENO AREAS THROUGH THIS EVENING AND TONIGHT.
BY TONIGHT, WINDS WILL BEGIN TO SHIFT TO THE EAST, HELPING TO
IMPROVE THE SMOKEY SKIES FRIDAY AND SATURDAY. THERE IS MEDIUM TO
HIGH CONFIDENCE THAT THE WINDS WILL REMAIN OUT OF THE EAST THROUGH
THE WEEKEND WITH IMPROVING CONDITIONS OVER WESTERN NEVADA. AS FOR
LAKE TAHOE THIS WEEKEND, SATURDAY LOOKS PRETTY GOOD FOR EASTERLY
WINDS KEEPING SMOKE OUT OF THE BASIN, ALTHOUGH BY SUNDAY THERE MAY
BE SOME SMOKE CREEPING BACK INTO THE BASIN LATE IN THE DAY AS
LIGHT WESTERLY WINDS RETURN. THIS COULD IMPACT WEEKEND EVENTS
AROUND LAKE TAHOE

AS THE LOW CONTINUES TO DROP SOUTH, A FEW SHOWERS AND
THUNDERSTORMS ARE POSSIBLE LATE THIS AFTERNOON AND TONIGHT IN
WESTERN NEVADA. DEFORMATION ZONE OF THE LOW WILL HELP TO CREATE
SOME ADDED LIFT IN THE ATMOSPHERE. ANY PRECIPITATION FROM THESE
SHOWERS WILL ALSO HELP TO GET SOME OF THE PARTICULATES OUT OF THE
AIR AS WELL. THERE MAY BE AN AREA OF HEAVIER PRECIPITATION IN
WESTERN NEVADA TONIGHT, THE NAM AND HRRR ARE ACTUALLY STARTING TO
SHOW SOME AREAS OF HEAVIER PRECIPITATION ASSOCIATED WITH THIS
DEFORMATION ZONE OVERNIGHT. WE WILL HAVE TO KEEP A CLOSE EYE ON
THIS POTENTIAL.

BY FRIDAY AND SATURDAY, THE LOW DROPS OFF THE CA COAST SLIGHTLY, BUT
HELPS TO BRING SOUTHEAST FLOW AND INCREASED CONVERGENCE/MOISTURE OVER
THE EASTERN SIERRA. THIS WILL KEEP A CHANCE OF SHOWERS AND
THUNDERSTORMS IN THE FORECAST MAINLY SOUTH OF HIGHWAY 50 ON FRIDAY
AND CREEPING UP INTO THE TAHOE BASIN BY SATURDAY AND SATURDAY
NIGHT. HOON

LONG TERM...SUNDAY THROUGH THURSDAY...

THE MAIN CHANGE TO THE LONG TERM FORECAST WAS TO INCREASE CHANCES
FOR PRECIPITATION ON SUNDAY. THE CLOSED LOW THAT WAS SITTING OVER
SOUTHERN CALIFORNIA WILL BEGIN TO OPEN AND LIFT TOWARD THE NORTHEAST
SUNDAY INTO MONDAY. AS IT LIFTS, WRAP AROUND MOISTURE FORMS A BAND
OF PRECIPITATION ALONG A DEFORMATION AXIS IN THE NORTHEAST QUADRANT
OF THE LOW. YESTERDAY, ONLY THE EC WAS SHOWING THIS SOLUTION, AND
WHILE IT IS STILL THE MOST ROBUST, OTHER OPERATIONAL MODELS ARE NOW
COMING AROUND TO THIS SOLUTION AS WELL. THEREFORE, POPS WERE
INCREASED FOR THE PERIOD, THOUGH DEPENDING ON MODEL TRENDS, IT IS
POSSIBLE THEY WILL NEED TO BE BOOSTED FURTHER. WHILE NOT OVERLY
IMPRESSIVE, THUNDERSTORMS ARE A POSSIBILITY SUNDAY AFTERNOON DUE TO
FORCING FROM THE LOW AND MID-LEVEL INSTABILITY.

SHORTWAVE RIDGING BUILDS IN BEHIND THE EXITING LOW MONDAY INTO
TUESDAY FOR DRY AND STABLE CONDITIONS AND TEMPERATURES NEAR NORMAL.
SOUTHWEST WINDS ARE EXPECTED TO INCREASE WEDNESDAY AND THURSDAY
AHEAD OF AN APPROACHING COLD FRONT AND DEEP TROUGH. IF THE KING FIRE
IS STILL ACTIVELY BURNING, THIS WILL LIKELY BRING ANOTHER LARGE PUSH
OF SMOKE INTO THE SIERRA AND NORTHWEST NEVADA, BUT TIME WILL TELL
HOW THE FIRE EVOLVES. THERE IS DECENT LARGE SCALE MODEL AGREEMENT
WITH THE TROUGH PUSHING INTO NORTHEAST CALIFORNIA AND NORTHWEST
NEVADA ON THURSDAY WITH PRECIPITATION AND MUCH COOLER TEMPERATURES
POSSIBLE. DJ

AVIATION...

THE GREATEST AVIATION CONCERN CONTINUES TO BE SMOKE FROM THE KING
FIRE WITH MOST DRASTIC VISIBILITY RESTRICTIONS FROM THE WEST SIDE OF
TAHOE EXTENDING NORTHEAST THROUGH THE GREATER RENO AREA, PAST
PYRAMID LAKE AND INTO KWMC. BOTH KTRK AND KRNO ARE REPORTING 2SM
VISIBILITY AND WIDESPREAD TERRAIN OBSCURATION IS PRESENT THROUGHOUT
THE AREA. GUSTY SOUTHWEST TO WEST WINDS WILL BECOME MORE
NORTHWESTERLY IN THE LATE AFTERNOON WHICH COULD SHIFT SMOKE INTO
KTVL AND KCXP AS WELL. SMOKE WILL LIKELY DISSIPATE OVERNIGHT AS THE
WINDS LIGHTEN AND TURN TO THE NORTH, AND WITH EASTERLY FLOW FRIDAY
AND SATURDAY, TERMINALS WILL REMAIN SMOKE FREE.

THUNDERSTORMS ARE LOOKING LESS LIKELY THIS AFTERNOON WITH THE BEST
INSTABILITY IN NORTHEAST NEVADA. THERE IS A 15 PERCENT CHANCE AN
ISOLATED STORM COULD POP UP, BUT ANY STORMS THAT DO FORM WOULD BE
SHORT-LIVED WITH THE BIGGEST THREAT GUSTY AND ERRATIC WINDS. DJ

&&

.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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