901  
FXUS65 KREV 250309  
AFDREV  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE RENO NV  
809 PM PDT SAT JUN 24 2017  
   
UPDATE
 
 
ISOLATED STORMS FORMED ON OUR SIDE OF THE SIERRA CREST FROM MONO  
COUNTY TO JUST SOUTH OF TAHOE. OTHER STORMS FIRED JUST WEST OF THE  
CREST FROM SIERRA CITY TO LASSEN PARK. OVERALL THE STORMS HAVE  
DIMINISHED, BUT A FEW SHOWERS REMAIN WEST OF THE CREST SOUTH OF  
HIGHWAY 50. EXPECT AN OVERALL QUIET NIGHT, BUT THE WAVE MENTIONED  
EARLIER, THERE WILL LIKELY BE SOME ACCAS AFTER SUNRISE NORTH OF  
TAHOE. THE WAVE AND UPPER LEVEL LAPSE RATES OVER 7.5 C/KM WOULD  
SUPPORT THIS. IT DOESN'T APPEAR STRONG ENOUGH FOR ANY DECENT  
CONVECTION, BUT AN ISOLATED STRIKE OR TWO DURING THE MORNING HOURS  
IS NOT OUT OF THE QUESTION. THIS IS HANDLED WELL OVERALL BY THE  
PREVIOUS FORECAST SO NO UPDATES ARE ANTICIPATED AT THIS TIME.  
 

 
   
PREVIOUS DISCUSSION
 
/ISSUED 143 PM PDT SAT JUN 24 2017/  
 
SYNOPSIS...  
 
WELL ABOVE AVERAGE TEMPERATURES CONTINUE THROUGH THE WEEKEND WITH  
SOME COOLING BY EARLY NEXT WEEK. ISOLATED THUNDERSTORMS ARE  
POSSIBLE NEAR THE SIERRA THIS EVENING, SPREADING INTO PARTS OF  
WESTERN NEVADA AND NORTHEAST CALIFORNIA SUNDAY. CRITICAL FIRE  
WEATHER CONDITIONS ARE POSSIBLE MONDAY AS VERY DRY AIR COMBINES  
WITH GUSTY WINDS. AFTER A BRIEF COOL DOWN TO NEAR NORMAL  
TEMPERATURES, A BUILDING RIDGE WILL BRING ANOTHER ROUND OF WELL  
ABOVE NORMAL TEMPERATURES TO THE REGION STARTING FRIDAY. FLOODING  
WILL CONTINUE FOR THE CREEKS IN MONO COUNTY AND PORTIONS OF THE  
WALKER RIVER.  
 
DISCUSSION...  
 
ISOLATED CONVECTION IS POSSIBLE INTO THE EARLY EVENING HOURS ALONG  
THE SIERRA FROM MONO COUNTY NORTH TO AROUND EL DORADO COUNTY. THE  
LATEST HRRR GUIDANCE IS LESS ROBUST OF THE EAST SIDE OF THE  
SIERRA...KEEPING MUCH OF THE ACTIVITY WEST OF THE CREST. BUT THE  
HRRR DOES HOLD OUT SOME SLIGHT CHANCES FOR THE ALPINE COUNTY AREA.  
FOR THE TIME BEING WE WILL NOT REDUCE THUNDERSTORM COVERAGE...BUT  
WE BE A LITTLE OVER DONE.  
 
ATTENTION TURNS TO A MID LEVEL SHORT WAVE LIFTING NORTHEAST ACROSS  
THE REGION SUNDAY. MODELS HAVE BEEN TRENDING DOWN IN TERMS IN  
THUNDERSTORM COVERAGE WITH THIS FEATURE. TIMING IS CRITICAL AS A  
MORNING PASSAGE WOULD TEND TOWARD LESS COVERAGE OVERALL. RIGHT  
NOW IT APPEARS THE BEST CHANCE FOR INCREASED COVERAGE WILL BE  
NORTH OF I-80 AND WEST OF A LINE FROM CEDARVILLE TO GERLACH. A  
POTENTIAL VORTICITY MAXIMUM WILL BE LIFTING ACROSS NORTHEAST  
CALIFORNIA BY LATE AFTERNOON...BUT THIS APPEARS TO BE THE ONLY  
MID/UPPER LEVEL SUPPORT. LAPSE RATES ALOFT ARE NOT IMPRESSIVE AND  
THERE IS LITTLE IN THE WAY OF JET SUPPORT. WHILE THE CONVECTION  
SHOULD BE ROOTED IN A DEEP...WELL MIXED BOUNDARY LAYER...THE LACK  
OF UPPER LEVEL SUPPORT WILL LIMIT ORGANIZATION AND COVERAGE.  
STILL...WITH INCREASING INSTABILITY IT IS NOT OUT OF THE REALM OF  
POSSIBILITY THAT WE WILL SEE EARLY DEVELOPMENT AND CONTINUAL  
CYCLING OF STORMS FROM LATE MORNING INTO THE AFTERNOON. ANY STORMS  
THAT DEVELOP WOULD BE MOVING FAST ENOUGH TO LIMIT PRECIPITATION  
POTENTIAL AND PRODUCE DRY LIGHTNING STRIKES. SHOWERS LINGER INTO  
LATE SUNDAY NIGHT AND EARLY MONDAY MORNING OVER THE FAR NORTH.  
 
DRIER AIR MOVES INTO THE REGION AND BREEZY WINDS DEVELOP MONDAY  
AND TUESDAY. MONDAY LOOKS LIKE THE DAY WITH THE BEST POTENTIAL FOR  
CRITICAL FIRE WEATHER CONDITIONS. SEE THE FIRE WEATHER DISCUSSION  
FOR MORE DETAILS. IN THE WAKE OF THE SHORT WAVE TROUGH...HEIGHTS  
FALL AND TEMPERATURES MONDAY AND TUESDAY WILL DROP BACK TO JUST  
SLIGHTLY ABOVE NORMAL. THIS WILL SLOW SNOWMELT A BIT IN THE  
HIGHER ELEVATIONS.  
 
ANOTHER TROUGH WILL SLIDE TOWARD THE REGION FROM THE NORTHWEST  
WEDNESDAY. THIS TROUGH SHOULD BRING MAINLY AN INCREASE IN CLOUDS  
AS LOW LEVEL MOISTURE IS LACKING FOR SHOWERS. NORTHWEST FLOW ALOFT  
AND LOW NORTHEAST DEVELOPS IN ITS WAKE THURSDAY.  
 
BY FRIDAY A RIDGE STARTS TO BUILD BACK INTO THE REGION. THIS WILL  
BRING A RETURN TO WELL ABOVE NORMAL TEMPERATURES AND POSSIBLY  
ENOUGH INSTABILITY FOR ISOLATED CONVECTION ALONG THE SIERRA. FOR  
NOW WE WILL LEAVE MENTION OF THUNDERSTORMS OUT OF THE FORECAST FOR  
FRIDAY AND SATURDAY...BUT THEY MAY NEED TO BE ADDED IN A FEW DAYS.  
 
AVIATION...  
 
ISOLATED STORMS ALONG THE SIERRA SHOULD BE THE ONLY AVIATION  
CONCERN FOR THE FIRST 12 HOURS OF THE FORECAST. A MID LEVEL TROUGH  
OF LOW PRESSURE LIFTING NORTHEAST ACROSS THE REGION SUNDAY WILL  
BRING AN INCREASE IN COVERAGE FOR STORMS. THE BEST CHANCE FOR  
STORMS IS ACROSS NORTHEAST CALIFORNIA AND FAR WESTERN NEVADA...BUT  
WE COULD SEE ISOLATED STORMS ALL ALONG THE SIERRA.  
 
AS THE TROUGH LIFTS OUT LATE SUNDAY NIGHT A FEW SHOWERS WILL  
LINGER NORTH OF SUSANVILLE. THEN...BREEZY WINDS WILL DEVELOP FOR  
MONDAY WITH SURFACE GUSTS APPROACHING 30-35 KTS IN MANY LOCATIONS.  
BREEZY CONTINUES CONTINUE INTO TUESDAY...BUT THE GUSTS WILL BE A  
LITTLE LESS THAN MONDAY.  
 
FIRE WEATHER...  
 
TEMPERATURES HAVE WARMED INTO THE UPPER 90S WITH LOW 100S STILL  
LIKELY FOR THE DAILY HIGH FOR MANY LOCATIONS IN WESTERN NEVADA  
TODAY. RECOVERIES WERE MODERATE TO GOOD IN THE SIERRA LAST NIGHT  
WITH POOR TO MODERATE FOR WESTERN NEVADA. WITH TEMPERATURES RUNNING  
WARMER TODAY, EXPECT SLIGHTLY POORER RECOVERIES OVERNIGHT INTO  
SUNDAY WHICH WILL HEAT BACK TO THE UPPER 90S TO LOW 100S AGAIN.  
 
MEANWHILE, TOWERING CUMULUS AND A FEW THUNDERSTORMS HAVE FORMED IN  
THE SIERRA AND ALONG THE LONG VALLEY CALDERA RIM IN SOUTHERN MONO  
COUNTY. EXPECT THUNDERSTORMS TO CONTINUE TO FORM ALONG OUTFLOW  
BOUNDARIES AND HIGHER TERRAIN OF THE SIERRA MAINLY SOUTH OF THE  
TAHOE BASIN THROUGH THE REST OF THE AFTERNOON. GUSTS IN VALLEYS  
COULD BE STRONG WITH SLIGHT POTENTIAL FOR A STRAY DRY LIGHTNING  
STRIKE.  
 
MAIN CHANGES TO THE ONGOING FORECAST HAVE BEEN TO TRIM THUNDERSTORM  
CHANCES DOWN SLIGHTLY FOR SUNDAY AS MODELS CONTINUE TO SHOW AN  
EARLIER PASSAGE OF A DESTABILIZING UPPER WAVE. WITH THIS WAVE  
PASSING EARLIER SUNDAY MORNING, INSTABILITY ALOFT WILL BE UN-  
PHASED FROM HIGHEST SURFACE INSTABILITY. STILL, CHANCES OF  
ISOLATED THUNDERSTORMS COVER A MUCH LARGER AREA THAN RECENT  
ACTIVITY. ANY STORMS THAT FORM WILL BE CAPABLE OF PRODUCING STRONG  
GUSTS AND DRY LIGHTNING STRIKES, ESPECIALLY IF THEY MOVE OVER  
WESTERN NEVADA VALLEY LOCATIONS. JUST A FEW STRIKES ALONG THE  
SIERRA FRONT WOULD LIKELY BE ENOUGH TO ALLOW FOR NEW FIRE STARTS  
SINCE DRIED GRASSES ARE NEARLY CONTINUOUS.  
 
FINALLY, AN UPPER LOW MOVES INTO NORTHERN CALIFORNIA MONDAY INCREASING  
WINDS ACROSS THE REGION. EXPECT CRITICAL FIRE WEATHER CONDITIONS  
FOR WESTERN NEVADA AS WINDS GUST AROUND 35MPH. AS SUCH, A FIRE  
WEATHER WATCH REMAINS IN EFFECT FOR PORTIONS OF WESTERN NEVADA  
INCLUDING THE SIERRA FRONT, NORTHERN LYON COUNTY, AND  
CHURCHILL/PERSHING COUNTIES. WINDS DROP OFF BELOW CRITICAL  
THRESHOLDS TUESDAY AND WEDNESDAY, BUT WOULD STILL BE ABLE TO DRIVE  
ANY GRASS FIRES THAT MAY OCCUR.  
 
GRASSES EAST OF HIGHWAY 395 IN CALIFORNIA, MAINLY IN LASSEN COUNTY,  
HAVE MOSTLY CURED AND COULD PROPAGATE FIRE. WHILE THIS ZONE IS NOT  
TECHNICALLY FIRE READY, IT'S SOMETHING TO PREPARE FOR. IT SHOULD  
ALSO BE NOTED THAT SAGEBRUSH IN WESTERN NEVADA VALLEYS IS BEGINNING  
TO SHOW SIGNS THAT IT IS BECOMING DRY ENOUGH TO CARRY FIRE; IT MAY  
NOT CONTRIBUTE TO EXPLOSIVE FIRE GROWTH, BUT IT WILL BE AVAILABLE TO  
BURN. BOYD  
 

 
   
REV WATCHES/WARNINGS/ADVISORIES
 
 
NV...FIRE WEATHER WATCH FROM MONDAY AFTERNOON THROUGH MONDAY EVENING  
NVZ450-453.  
 
CA...NONE.  

 
 

 
 
FOR MORE INFORMATION FROM THE NATIONAL WEATHER SERVICE VISIT...  
HTTP://WEATHER.GOV/RENO  
 
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