863  
FXUS65 KREV 161004  
AFDREV  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE RENO NV  
304 AM PDT SAT OCT 16 2021  
   
SYNOPSIS
 
 
LIGHT WINDS AND DRY CONDITIONS WILL PERSIST TODAY BEFORE A DRASTIC  
CHANGE ARRIVES ON SUNDAY. A FAST-MOVING WAVE SWEEPS ACROSS THE  
REGION BRINGING CHANCES FOR RAIN AND SNOW SUNDAY NIGHT ALONG WITH STRONG,  
GUSTY WINDS. PLAN FOR TRAVEL IMPACTS ACROSS THE SIERRA SUNDAY  
NIGHT INTO MONDAY MORNING WITH A FEW INCHES OF SNOWFALL POSSIBLE.  
THE WEATHER PATTERN IS TRENDING MORE ACTIVE AND POSSIBLY WETTER  
FOR THE MIDDLE PART OF NEXT WEEK INTO THE NEXT WEEKEND.  
 

 
   
SHORT TERM
 
 
AFTER A CHILLY START, TODAY WILL BE THE WARMEST DAY OF THE WEEK WITH  
HIGHS REACHING INTO THE UPPER 60S TO LOW 70S, MOSTLY CLEAR SKIES AND  
LIGHT EASTERLY BREEZES.  
 
A FAST-MOVING SHORTWAVE WILL BARREL THROUGH THE EASTERN SIERRA AND  
WESTERN NEVADA SUNDAY INTO MONDAY BRINGING STRONG, GUSTY WINDS AND  
CHANCES FOR RAIN AND SNOW. WHILE THERE ARE CONCERNS FOR RAIN/SNOW  
FROM SUNDAY NIGHT INTO MONDAY FOR THE MORNING COMMUTE, WE ARE  
BECOMING INCREASINGLY CONCERNED WITH THE POTENTIAL FOR WIND GUSTS  
EXCEEDING 60 MPH, PARTICULARLY FOR SOUTH LAKE TAHOE, THE SIERRA  
FRONT, AND FOR THE NORTH VALLEYS (DOWNSLOPE POTENTIAL OFF  
OF PEAVINE MOUNTAIN).  
 
WIND:  
 
* IMPACTS: INCREASED POTENTIAL FOR ENHANCED FIRE DANGER DUE TO  
STRONG WINDS AND MODERATELY DRY CONDITIONS, AVIATION TURBULENCE  
AND LOW LEVEL WIND SHEAR, AREAS OF BLOWING DUST, ROUGH LAKE  
CONDITIONS, AND RESTRICTIONS FOR HIGH PROFILE VEHICLES DUE TO  
STRONG CROSS WINDS.  
 
700 MB JET ARRIVES SUNDAY AFTERNOON WITH RIDGETOP WIND GUSTS AROUND  
90-100 MPH. FOR THE SIERRA AND WESTERN NEVADA VALLEYS WIND GUSTS  
WILL BE AROUND 40-50 MPH SUNDAY AFTERNOON, BUT DOWNSLOPE ENHANCEMENT  
COULD PUSH WIND GUSTS TO 60+ MPH FOR SOME AREAS. FORECAST MODEL  
SOUNDINGS AND CROSS SECTIONS SHOW SIGNALS THAT WARRANT A HIGHER RISK  
FOR DAMAGING WIND GUSTS, I.E. (1) A STABLE LAYER JUST ABOVE  
MOUNTAIN TOP AND LESSER STABILITY ALOFT (2) A SHARP DECREASE IN  
WIND SPEED ABOVE THAT STABLE LAYER (3) STRONG COLD AIR ADVECTION  
TO THE WEST (4) AND THE ABSENCE OF A STABLE LAYER NEAR THE GROUND  
ALLOWING FOR DUCTING OF STRONG WINDS ALOFT TO THE SURFACE. THE  
STRONGEST WINDS WILL BE ALONG THE HIGHWAY 395 | INTERSTATE 580  
CORRIDOR FROM LASSEN COUNTY THROUGH RENO AND THE CARSON VALLEY AND  
INTO MONO COUNTY. MOST AREAS WILL EXPERIENCE WIND GUSTS 30 TO 40  
MPH, BUT WIND PRONE AREAS MAY REACH 60+ MPH.  
 
PRECIPITATION:  
 
* IMPACTS: SNOW-COVERED ROADS FOR THE SIERRA PASSES, WITH CHAIN- CONTROLS  
AND SLOW-DOWNS POSSIBLE. FOR LOWER VALLEY AREAS, PLAN ON SLICK  
ROADS. SET THAT ALARM A BIT EARLIER FOR MONDAY IN CASE ROADS ARE  
LESS-THAN-IDEAL FOR THE COMMUTE.  
 
SIERRA PASS SNOW: IF YOU CAN, PLAN ON LEAVING BY MIDDAY SUNDAY TO  
AVOID SNOW AND TRAVEL ISSUES ALONG THE SIERRA PASSES SUNDAY NIGHT  
AND EARLY MONDAY MORNING. SIMULATIONS HAVE TRENDED UP WITH THIS  
SYSTEM AND THERE MAY BE 2-3" OF SNOWFALL OR 6" OR MORE ALONG THE  
PASSES AS THIS POTENT SYSTEM ROLLS THROUGH THE REGION. LOCALIZED  
AREAS WITH HEAVIER ACCUMULATIONS ARE POSSIBLE DUE TO MODERATE-TO-  
STRONG 700 HPA FRONTOGENESIS AND QG-ASCENT ASSOCIATED WITH THE  
LEFT JET EXIT REGION ACROSS THE TAHOE BASIN. CONVECTIVE POTENTIAL  
REMAINS A BIT HIGHER THAN USUAL DUE TO THE PRESENCE OF 100-300  
J/KG OF SBCAPE, SO THERE MAY BE A PERIOD OF HIGHER SNOWFALL RATES,  
REDUCED VISIBILITY, AND A 5% CHANCE OF LIGHTNING AS THE COLD  
FRONTAL BAND PASSES ACROSS THE SIERRA. THERE MAY BE SOME SNOW  
SHOWERS FOR ALPINE AND NORTHERN MONO COUNTIES AS WELL, BUT THE  
BULK OF THE PRECIPITATION STAYS ALONG AND NORTH OF HIGHWAY 50.  
 
DOWN HERE AND LAKE TAHOE: SNOW SHOWERS WILL ALSO BE POSSIBLE DOWN  
TO LAKE LEVEL AS SNOW LEVELS DROP WITH ABOUT A HALF INCH TO AN  
INCH POSSIBLE. ACROSS WESTERN NEVADA VALLEYS, (MAINLY NORTH  
VALLEYS, RENO, CARSON CITY, CARSON VALLEY) WE COULD SEE A LIGHT  
RAIN/SNOW MIX BY EARLY MONDAY MORNING WITH SOME TRACE SNOW AMOUNTS  
ACROSS FOOTHILL LOCATIONS.  
 
THE SHORTWAVE QUICKLY EXITS ON MONDAY WITH A FEW RESIDUAL SNOW  
SHOWERS POSSIBLE THROUGH THE DAY. NORTH TO NORTHWEST BRISK WINDS  
WILL KEEP IT FEELING PRETTY CHILLY ACROSS WESTERN NEVADA THROUGH  
TUESDAY. HIGH TEMPERATURES WILL BE MOSTLY IN THE LOW TO MID 50S FOR  
THE LOWER VALLEYS AND 40S FOR SIERRA VALLEYS. -EDAN  
 
   
LONG TERM...TUESDAY THROUGH EARLY NEXT WEEKEND
 
 
A BREAK BETWEEN WEATHER SYSTEMS WILL OCCUR TUESDAY. WINDS WILL BE  
LIGHT OUT OF THE EAST-SOUTHEAST FOR MUCH OF THE DAY. TEMPERATURES  
WILL BE ABOUT 10 DEGREES BELOW NORMAL FOR THIS TIME OF THE YEAR,  
WHICH TRANSLATES TO UPPER-50S AND LOW-60S FOR WESTERN NEVADA AND THE  
SIERRA.  
 
A SHORTWAVE TROUGH WITH A SATISFACTORY MOISTURE PLUME SHOULD LIFT  
NORTHEASTWARD OUT OF THE EASTERN PACIFIC AND INTO THE PACIFIC  
NORTHWEST LATE TUESDAY NIGHT INTO WEDNESDAY. MOST ENSEMBLE GUIDANCE  
(ECMWF-ENS/GEFS/NBM) HAVE LIGHT RAIN AND HIGH ELEVATION SNOW SHOWERS  
FOR AREAS NORTH OF THE SIERRA FROM PLUMAS-EUREKA INTO THE SOUTHERN  
CASCADES, WITH WEAK-TO-MODERATE WARM AIR ADVECTION AND ISENTROPIC  
ASCENT TARGETING MAINLY THE WESTERN SLOPES OF THE SOUTHERN CASCADES.  
AT THIS TIME, ONLY A FEW HUNDREDTHS OF AN INCH OF RAIN LOOK  
POSSIBLE, SO NOT A STRONG SHORTWAVE BY ANY STRETCH, AS MOST OF  
NORTHEAST CALIFORNIA WILL NOT BE IN AN ENHANCED AREA OF QG-ASCENT IN  
THE RIGHT EXIT REGION OF THE UPPER-LEVEL JET. WE SHOULD SEE A BREAK  
THURSDAY BEFORE A COUPLE OF ATMOSPHERIC RIVERS LOOK TO AFFECT THE  
WESTERN COAST OF THE US, MAINLY NORTH OF 35 DEGREES NORTH LATITUDE.  
 
THE FIRST OF WHAT LOOKS TO BE TWO ARS NEXT WEEKEND AND THE EARLY  
PART OF WEEK TWO SHOULD BRING LIGHT RAIN AND MOUNTAIN SNOW SHOWERS  
TO THE NORTHERN SIERRA AND NORTHEASTERN CALIFORNIA. AT THIS POINT,  
PRECIPITATION DOES NOT LOOK TO BE HEAVY, WITH THE FIRST PACIFIC  
NORTHWEST TARGETED AR EARLY NEXT WEEKEND. BY WEEK TWO (STARTING  
OCTOBER 24TH), MANY SIMULATIONS ARE SHOWING GOOD POTENTIAL FOR  
MEANINGFUL PRECIPITATION AND STRONG WINDS MAINLY NORTH OF THE  
CENTRAL SIERRA AS ANOTHER AR MAKES LANDFALL. TIMING AND MOISTURE  
EXTENT REMAINS UNCERTAIN THIS FAR OUT, BUT WE ARE KEEPING OUR  
FINGERS CROSSED.  
 
-JOHNSTON  
 

 
   
AVIATION
 
 
* VFR CONDITIONS FOR AREA TERMINALS THROUGH TONIGHT AS HIGH PRESSURE  
MAINTAINS STABLE AND DRY CONDITIONS ACROSS THE REGION. WINDS WILL  
REMAIN MOSTLY LIGHT EXCEPT FOR THE DIURNALLY DRIVEN LOCAL FLOWS.  
 
* INCREASING SOUTHWEST UPPER LEVEL FLOW WILL BEGIN EARLY SUNDAY  
MORNING AHEAD OF AN APPROACHING SHORTWAVE TROUGH. PLAN FOR GUSTY  
CONDITIONS AT ALL TERMINALS ON SUNDAY WITH GUSTS RANGING 25-35KTS.  
THERE WILL BE INCREASING POTENTIAL FOR TURBULENCE AND LLWS FOR  
SIERRA TERMINALS, PARTICULARLY KTVL-KTRK, AS WELL AS AREAS EAST OF  
THE SIERRA CREST IN THE VICINITY KRNO-KCXP-KMEV-KRTS.  
 
* THIS POTENT SHORTWAVE IS ALSO BRINGING CHANCES FOR RAIN AND SNOW  
SHOWERS TO THE SIERRA AND WESTERN NEVADA LATE SUNDAY NIGHT INTO  
MONDAY MORNING WITH THE POSSIBILITY OF MVFR VIS/CIG CONDITIONS  
OVER KTRK AND KTVL. LIGHT ACCUMULATIONS WILL BE POSSIBLE AT LAKE  
TAHOE LEVEL BY MONDAY MORNING. RAIN/SNOW MIX WILL BE LIKELY FOR  
WESTERN NEVADA TERMINALS. -EDAN  
 

 
   
FIRE WEATHER
 
 
* STRONG AND GUSTY WINDS ARE EXPECTED SUNDAY AFTERNOON AND EVENING  
AS A LOW PRESSURE SYSTEM AND COLD FRONT PUSH THROUGH THE REGION.  
SOUTHWEST WIND GUSTS UP TO 40-50 MPH WILL BE POSSIBLE ACROSS THE  
SIERRA AND WESTERN NEVADA SUNDAY AFTERNOON AND EVENING. WIND  
PRONE LOCATIONS MAY SEE WIND GUSTS 60+ MPH, ESPECIALLY FOR  
SOUTH-NORTH ORIENTED VALLEYS. A COUPLE AREAS AT HIGHER RISK FOR  
STRONG WIND GUSTS WILL BE THE NORTH VALLEYS (DOWNWIND OF PEAVINE  
MOUNTAIN), SOUTH LAKE TAHOE, AND WIND PRONE AREAS ALONG US-395 |  
I-580.  
 
* STRONG, GUSTY WINDS MAY DOWN DAMAGED OR BURNED TREES IN RECENT  
BURN AREAS.  
 
* WHILE MODERATE HUMIDITY IS EXPECTED SUNDAY AFTERNOON ACROSS THE  
SIERRA (20-30%), AREAS ALONG THE SIERRA FRONT FROM RENO, WASHOE  
VALLEY, AND THE CARSON VALLEY COULD SEE NEAR CRITICAL CONDITIONS  
WITH RH IN THE 15-20% RANGE.  
 
* BEST POTENTIAL FOR A FEW HOURS OF CRITICAL FIRE WEATHER  
CONDITIONS WILL BE MID TO LATE AFTERNOON SUNDAY ACROSS THE  
SIERRA FRONT. WHILE THE WINDS LOOK TO PEAK LATE AFTERNOON INTO  
EARLY EVENING, RH WILL RAPIDLY BE INCREASING TO OVER 30% DURING  
THIS WINDOW AND WILL CONTINUE TO RISE THROUGH THE EVENING.  
 

 
   
REV WATCHES/WARNINGS/ADVISORIES
 
 
NV...WIND ADVISORY FROM 2 PM TO 11 PM PDT SUNDAY NVZ002-003-005.  
 
CA...WIND ADVISORY FROM 2 PM TO 11 PM PDT SUNDAY CAZ070>072.  
 
WIND ADVISORY FROM 4 PM SUNDAY TO 2 AM PDT MONDAY CAZ073.  
 

 
 

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