959  
FXUS65 KREV 151128  
AFDREV  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE RENO NV  
328 AM PST FRI DEC 15 2017  
   
SYNOPSIS
 
 
TEMPERATURE INVERSIONS AND REDUCED AIR QUALITY IN URBAN VALLEYS  
CONTINUE THROUGH THIS AFTERNOON, WITH A WEAK SYSTEM TONIGHT  
INCREASING SURFACE WINDS AND BRINGING IMPROVED AIR QUALITY FOR THE  
WEEKEND. INVERSIONS ARE LIKELY TO STRENGTHEN AGAIN EARLY NEXT  
WEEK BEFORE A COLD FRONT MOVES THROUGH FOR THE MIDDLE OF NEXT WEEK  
AND BREAKS THE INVERSIONS.  
 

 
   
SHORT TERM
 
 
A FAST MOVING COLD FRONT AND BAND OF PRECIPITATION WILL MOVE  
THROUGH NEVADA TONIGHT INTO SATURDAY MORNING. THESE TYPES OF LOW  
PRECIPITATION COLD FRONTS (SLIDER STORMS) CAN BE AS CHALLENGING,  
OR MORE, TO FORECAST THAN LARGE SNOW STORMS. HOWEVER, THIS STORM  
DOESN'T QUITE FIT THE PATTERN OF A CLASSIC "INSIDE SLIDER" THAT  
CAN CAUSE A HEAVY BAND OF PRECIPITATION TO MOVE INTO FAR WESTERN  
NEVADA. THIS FRONT IS FORECAST TO MOVE THROUGH THE REGION QUICKLY  
IN A SOUTHEASTERLY DIRECTION WITH THE HIGHEST PRECIPITATION  
AMOUNTS (STILL LESS THAN 0.2") LIKELY IN NORTH CENTRAL NEVADA.  
 
MOST LIKELY SCENARIO FOR FAR WESTERN NEVADA CONTINUES TO BE  
PRECIPITATION AMOUNTS IN 0.01-0.10 RANGE WITH MOST OF THE  
PRECIPITATION LIKELY FALLING AS SNOW DOWN TO VALLEY FLOORS. ISOLATED  
AREAS OF FREEZING RAIN CAN'T BE RULED OUT, BUT WINDS AHEAD OF  
THE FRONT SHOULD BE ENOUGH TO MIX OUT TRAPPED COLD AIR IN THE  
LOWER VALLEYS.  
 
EVEN THOUGH SNOW AMOUNTS FROM THIS SYSTEM ARE LIKELY GOING TO BE  
LIMITED TO LESS THAN 1/2 INCH, SOME IMPACTS TO TRAVEL SHOULD BE  
PLANNED FOR. REMEMBER, IT ONLY TAKES A LITTLE BIT OF RAIN OR SNOW  
TO CREATE SLICK ROADS AND HAZARDOUS TRAVEL CONDITIONS.  
 
ON THE UP SIDE, THIS SYSTEM SHOULD BRING ENOUGH WIND AND  
INCREASED MIXING TO PUSH OUT THE POLLUTANTS BUILT UP UNDER ONGOING  
TEMPERATURE INVERSION. TEMPERATURE INVERSIONS ARE EXPECTED TO  
BEGIN TO RE-DEVELOP BY SUNDAY NIGHT.  
 
OVERALL WIND ISN'T EXPECTED TO BE OVERLY STRONG FOR THIS SYSTEM  
WITH VALLEY GUSTS IN THE 15-20 MPH RANGE. THE EXCEPTION WILL BE AT  
THE HIGHER ELEVATIONS ALONG THE SIERRA CREST WHERE A STRONG  
TEMPERATURE GRADIENT IS EXPECTED TO SET UP WITH EAST WINDS OF  
AROUND 70 MPH OR MORE POSSIBLE SATURDAY INTO SATURDAY NIGHT AS  
COLD AIR SETTLES INTO THE GREAT BASIN. -ZACH  
 
   
LONG TERM...MONDAY ONWARD
 
 
HIGH PRESSURE RETURNS FOR EARLY NEXT WEEK RESULTING IN POOR MIXING  
AND VENTILATION MONDAY AND TUESDAY. HAZE MAY ONCE AGAIN FORM NEAR  
POPULATION CENTERS ALTHOUGH ITS SHORTER DURATION WILL PRECLUDE  
CONDITIONS GETTING AS HAZY AS RECENT DAYS.  
 
SIMULATIONS CONTINUE TO SHOW A STRONG COLD FRONT MOVING SOUTHWARD  
THROUGH THE AREA WEDNESDAY WITH SOME MUCH COLDER AIR SPREADING INTO  
THE SIERRA AND WESTERN NEVADA. CHANCES FOR SHOWERS REMAIN WEDNESDAY  
ALONG THIS FRONT, ESPECIALLY NORTH OF HIGHWAY 50 WHERE FRONTAL  
FORCING WILL ALIGN BEST WITH LARGER SCALE LIFT. AS THE BAND SHIFTS  
SOUTH, IT IS EXPECTED TO WEAKEN CONSIDERABLY AND THEREFORE MONO-  
MINERAL COUNTY WILL LIKELY SEE ONLY ISOLATED SHOWERS. THE STORM  
DOESN'T HAVE A SIGNIFICANT MOISTURE TAP, BUT IT WILL REQUIRE  
MONITORING SINCE IT WILL BE SO COLD. THE COLD NATURE OF THE STORM  
MAY RESULT IN SNOW EVEN DOWN TO VALLEY FLOORS. WHERE SNOW OCCURS, A  
COUPLE OF INCHES ARE POSSIBLE ACROSS NORTHEAST CA AND NORTHWEST NV  
WITH LESSER ACCUMULATION POTENTIAL FARTHER SOUTH.  
 
TEMPERATURES WILL BE SEASONAL MON-TUE AND THEN FALL TO BELOW NORMAL  
LEVELS BY THURSDAY. GUSTY NORTHEAST WINDS RETURN TO THE RIDGES  
WEDNESDAY NIGHT AND THURSDAY AND THESE WINDS MAY PERSIST FOR A  
COUPLE OF DAYS, POSSIBLY LONGER DEPENDING ON THE LOCATION OF THE  
MAIN RIDGE AXIS. SOME MODEL SCENARIOS KEEP THE RIDGE AXIS OVER THE  
EAST PACIFIC RATHER THAN BRINGING IT INLAND. VALLEY INVERSIONS WILL  
LIKELY RETURN BUT STRENGTH OF THE INVERSIONS WILL DEPEND ON THE  
RIDGE AXIS LOCATION AS WELL. AT THIS TIME, THE PATTERN STRONGLY  
FAVORS DRY CONDITIONS FOR THE CHRISTMAS HOLIDAY WEEKEND. HOHMANN  
 

 
   
AVIATION
 
 
VALLEY INVERSIONS WILL REMAIN STRONG TODAY, RESULTING IN SOME  
SLANTWISE VISIBILITY REDUCTIONS, ESPECIALLY IN THE RENO/SPARKS,  
CARSON CITY, AND MINDEN AREAS. INCREASED NORTHERLY WINDS TONIGHT AND  
SATURDAY MAY ALLOW SOME OF THE HAZE TO CLEAR OUT, AT LEAST FOR A DAY  
OR TWO.  
 
A COLD FRONT WILL SWEEP SOUTHEAST ACROSS THE AREA LATE TONIGHT AND  
EARLY SATURDAY MORNING AND BRING A FEW SHOWERS TO MAINLY WESTERN NV.  
BEST SHOWER COVERAGE WILL EXTEND FROM THE BASIN AND RANGE  
(KNFL/KLOL) INTO NORTHEAST NV WITH LESSER COVERAGE FARTHER WEST  
TOWARD KRNO-KXCP-KTVL-KTRK. ONLY BRIEF MVFR CONDITIONS ARE EXPECTED  
WITH THIS FAST MOVING BAND OF SHOWERS. WHILE SIGNIFICANT SNOW  
ACCUMULATIONS ARE NOT EXPECTED FOR AREA RUNWAYS, A DUSTING OF SNOW  
IS POSSIBLE, ESPECIALLY ON EXPOSED SURFACES. FOR ACCUMULATIONS UP TO  
ONE INCH...THERE IS A 10% CHANCE AT KRNO/KCXP SOUTHWARD TO ABOUT  
KBAN ALONG THE EASTERN SIERRA AND ABOUT A 20% AT KLOL/KNFL. HOHMANN  
 

 
   
REV WATCHES/WARNINGS/ADVISORIES
 
 
NV...NONE.  
CA...NONE.  

 
 

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