051  
FXUS65 KREV 291000  
AFDREV  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE RENO NV  
300 AM PDT THU SEP 29 2016  
   
SYNOPSIS
 
 
HIGH PRESSURE OVER NORTHEAST CALIFORNIA AND WESTERN NEVADA WILL  
EXIT THE REGION TODAY WITH A FEW SHOWERS POSSIBLE OVER SOUTHERN  
MONO AND WESTERN MINERAL COUNTIES. A COLD TROUGH MOVES INTO THE  
WEST COAST THIS WEEKEND BRINGING BREEZY AND MUCH COOLER  
CONDITIONS. MORE WIDESPREAD PRECIPITATION AND EVEN SOME SIERRA  
SNOW SHOWERS ARE EXPECTED SUNDAY AND MONDAY.  
 

 
   
SHORT TERM
 
 
SOME MODEST ADJUSTMENTS WERE MADE TO THE WIND FORECAST PRIMARILY  
FRIDAY EVENING INTO VERY EARLY SATURDAY MORNING. OTHERWISE,  
ADJUSTMENTS ONLY REFLECT MODEL DIFFERENCES IN TRENDS WHICH WERE  
RATHER INSIGNIFICANT FROM PREVIOUS RUNS. THE LARGEST IMPACTS FOR  
THE SHORT TERM FORECAST THROUGH SATURDAY CONTINUE TO BE BREEZY TO  
GUSTY WINDS WITH IMPLICATIONS FOR AVIATION, AREA LAKES, AND FIRE  
WEATHER CONCERNS.  
 
MODELS CONTINUE TO FAVOR ISOLATED SHOWERS AND THUNDERSTORMS FOR  
SOUTHERN MONO/MINERAL COUNTIES THIS AFTERNOON AS UPPER DUE TO  
SOME LINGERING INSTABILITY COUPLED WITH RELATIVELY WARM SURFACE  
TEMPERATURES. ELSEWHERE CONDITIONS WILL BE DRY THROUGH SATURDAY  
EVENING.  
 
THE PRESSURE GRADIENT WILL BEGIN TO TIGHTEN AS LOW PRESSURE DROPS  
DOWN THE PACIFIC COAST. UPPER LEVEL FLOW BECOMES INCREASINGLY  
AMPLIFIED INTO THE WEEKEND AS WELL. EXPECT WINDS TO BEGIN TO  
INCREASE THIS AFTERNOON WITH GUSTS AROUND 25 MPH. A FURTHER  
INCREASE ON FRIDAY IS EXPECTED WHICH CONTINUES TO BE PROJECTED AS  
THE WINDIEST DAY. GUSTS FRIDAY WILL BE GENERALLY BE 30 TO 40 MPH  
WITH SOME WIND PRONE LOCATIONS APPROACHING 50 MPH. WITH GUSTS  
AROUND 40 MPH, WE EXPECT SOME FIRE WEATHER CONCERNS FOR THE SIERRA  
FRONT AS WELL AS THE BASIN AND RANGE DESPITE HUMIDITY THAT WILL  
BE AROUND TO SLIGHTLY ABOVE CRITICAL THRESHOLDS.  
 
FORECAST WINDS WERE INCREASED OVERNIGHT FRIDAY INTO EARLY  
SATURDAY MORNING. 700 MB WIND SPEEDS REMAIN AROUND 40KTS  
SUGGESTING THAT BREEZY CONDITIONS WOULD CONTINUE FOR SIERRA  
LOCATIONS INCLUDING LAKE TAHOE AND ALONG THE SIERRA FRONT. THESE  
GUSTS WILL LIKELY CONTINUE WELL INTO THE EVENING AND INTO VERY  
EARLY SATURDAY MORNING. SATURDAY REMAINS BREEZY, BUT FIRE WEATHER  
CONCERNS WILL BE MITIGATED BY RISING HUMIDITY. BOYD  
   
LONG TERM...SUNDAY THROUGH WEDNESDAY
 
 
 
THE MAIN STORY WILL CONTINUE TO BE THE DEEP TROUGH FORECAST TO MOVE  
THROUGH SUNDAY NIGHT. AS MENTIONED EARLIER, THIS TROUGH IS NOT THAT  
UNUSUAL FOR THE TIME OF YEAR, BUT IT WILL BE THE COLDEST WE HAVE  
SEEN SO FAR THIS AUTUMN.  
 
THE MODELS HAVE CHANGED SLIGHTLY, WHICH IS EXPECTED 4 DAYS OUT.  
INSTEAD OF SHOWING A BAND OF PRECIP ALONG AND BEHIND THE MAIN COLD  
FRONT, THEY NOW SHOW IT AS MORE SHOWERY WITH THE COLD POOL OVERHEAD.  
ASIDE FROM THAT, LITTLE HAS CHANGED WITH SOME BREEZES DURING THE DAY  
SUNDAY AND GUSTS UP TO 30 MPH, STRONGER OVER RIDGES. THE GREATEST  
THREAT FOR PRECIP WILL BE LATE SUNDAY AFTERNOON INTO SUNDAY EVENING.  
I HAVE INCREASED THE POPS IN THE SIERRA TO NEAR 60% ALONG THE CREST  
FROM TAHOE NORTH AND ALSO EXPECTED THE CHANCE OF PRECIP TO INCLUDE  
ALMOST ALL OF WESTERN NEVADA SUNDAY NIGHT. THE LOW ITSELF WILL MOVE  
OVERHEAD TO THE THREAT OF LIGHT SHOWERS WILL BE PRESENT JUST ABOUT  
EVERYWHERE.  
 
AS FAR AS PRECIP AMOUNTS, THEY OVERALL LOOK TO BE LIGHT AND LESS  
THAN 1/4". SNOW LEVELS WILL START NEAR 7000 FEET SUNDAY AFTERNOON  
AND FALL TO NEAR 5000 FEET MONDAY MORNING. WITH THESE SNOW LEVELS A  
COUPLE INCHES OF WET SNOW IS POSSIBLE IN THE HIGHER ELEVATIONS ABOVE  
6000 FEET, INCLUDING AROUND LAKE TAHOE. STILL, GIVEN THE SHOWERY  
NATURE IT WON'T BE WIDESPREAD, BUT THERE ARE POSSIBLE TRAVEL IMPACTS  
OVER THE PASSES.  
 
MONDAY, THE LOW WILL SLOWLY PULL AWAY, BUT IT WILL BE COLD WITH  
HIGHS IN THE 40S AND 50S. TUESDAY MORNING COULD BE QUITE COLD WITH  
SOME HARD FREEZES POSSIBLE FOR MANY AREAS OUTSIDE OF THE MAIN URBAN  
CENTERS IN WESTERN NEVADA. TUESDAY AND WEDNESDAY WILL SEE A WARMING  
TREND, BUT IT WILL BE SLOW WITH TEMPERATURES STILL REMAINING BELOW  
AVERAGE IN THE VALLEYS DUE TO THE NORTHEAST FLOW WHILE THE MOUNTAINS  
RISE CLOSER TO AVERAGE.  
 

 
   
AVIATION
 
 
VFR CONDITIONS THROUGH FRIDAY. INCREASING SW WINDS TODAY WITH PEAK  
GUSTS TO 25 KTS NORTH OF I-80. STRONGER SW WINDS FRIDAY 18-03Z WITH  
PEAK GUSTS TO 35 KTS NORTH OF HIGHWAY 50 AND TO 25 KTS SOUTH. SOME  
MTN WAVE TURBULENCE IS POSSIBLE IN THE MORNING BEFORE MIXING HELPS  
TO ALLEVIATE SOME OF IT.  
 
FRIDAY NIGHT, MTN WAVE TURBULENCE WILL BE STRONGER AS 700 MB WINDS  
INCREASE TO 40-50 KTS. THIS COULD CREATE AREAS OF LLWS FOR HIGHER  
ELEVATION TERMINALS SUCH AS KMMH AND KTVL, WITH A LOWER PROBABILITY  
FOR KRNO/KCXP. SATURDAY'S WINDS WILL WEAKEN WITH LESS TURBULENCE  
EXPECTED. THE NEXT CHANCE OF PRECIP IS LATE SUNDAY INTO MONDAY  
MORNING WITH SOME RESTRICTIONS TO CIGS/VIS IN THE SIERRA.  
 

 
   
REV WATCHES/WARNINGS/ADVISORIES
 
 
NV...FIRE WEATHER WATCH FROM FRIDAY MORNING THROUGH FRIDAY EVENING  
NVZ450-453-458.  
 
CA...FIRE WEATHER WATCH FROM FRIDAY MORNING THROUGH FRIDAY EVENING  
CAZ272.  
 

 
 

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