362  
FXUS65 KREV 221121  
AFDREV  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE RENO NV  
321 AM PST TUE JAN 22 2019  
   
SYNOPSIS
 
 
QUIET WEATHER WITH MOSTLY CLEAR SKIES, GENERALLY LIGHT WINDS, AND  
ABOVE AVERAGE TEMPERATURES EXPECTED THROUGH THE END OF JANUARY.  
 

 
   
DISCUSSION
 
 
THE MAIN WEATHER STORY THIS MORNING IS A SIGNIFICANT PATTERN  
CHANGE THAT IS CURRENTLY UNDERWAY. HIGH PRESSURE AND QUIET  
WEATHER EXPECTED FOR THE WESTERN U.S. LIKELY LASTING THROUGH END  
OF THE JANUARY, AND POSSIBLY LONGER. AN AMPLIFIED PATTERN IS  
DEVELOPING AROUND A STRONG LOW PRESSURE ANOMALY NEAR THE HUDSON  
BAY, WITH A LARGE SCALE TROUGH EAST OF THE ROCKIES, AND STRONG  
RIDGING ALONG THE WEST COAST AND EASTERN PACIFIC. THIS WILL LIKELY  
KEEP THE REGION IN A DRY PATTERN THROUGH THE NEXT 10 DAYS OR SO,  
AFTER WHICH PREDICTABILITY IS TOO LOW TO SPECULATE. FORTUNATELY,  
ACTIVE WEATHER IN EARLY JANUARY HAS PUSHED THE SNOWPACK TO AROUND  
130% OF NORMAL.  
 
CURRENTLY, CLEAR SKIES THROUGH MOST OF THE REGION ARE ALLOWING  
FOR STRONG RADIATIVE COOLING. THE COLDEST TEMPERATURES IN THE  
FORECAST PERIOD ARE EXPECTED THIS MORNING WITH TEENS IN MANY AREAS  
AND SINGLE DIGITS IN COLDER SIERRA VALLEYS. THE VERY COLD SURFACE  
TEMPERATURES SHOULD ALLOW FOR FOG TO FORM IN TYPICALLY FOG PRONE  
AREAS, BUT DRY EASTERLY FLOW SHOULD KEEP IT FROM BEING VERY  
WIDESPREAD.  
 
NORTHEAST GRADIENT WINDS HAVE FORMED ALONG THE SIERRA CREST WITH  
SPEEDS CURRENTLY 60-70 MPH AND MAY STRENGTHEN A BIT MORE OVER THE  
NEXT FEW HOURS BEFORE SLOWLY SUBSIDING DURING THE DAY TOMORROW.  
TEMPERATURES ALONG THE CREST ARE CURRENTLY IN THE SINGLE DIGITS,  
AND FOR ANYONE WHO IS WONDERING, THAT PUSHES THE WIND CHILL TO  
AROUND -20 DEGREES. SO, BRRR.  
 
WARM AIR MOVING IN ALOFT TODAY WILL BRING STABLE CONDITIONS WITH  
RELATIVELY STRONG LOW LEVEL INVERSIONS TONIGHT. A DISTURBANCE  
MOVING THROUGH THE PACIFIC NORTHWEST WILL ALLOW FOR SOME MIXING  
THE FOLLOWING FEW DAYS AND KEEP STRONGER INVERSIONS AT BAY UNTIL  
THE END OF THE WEEK, WHEN A STRONGER RIDGE IS EXPECTED TO BUILD  
OVER THE REGION.  
 
RIDGING OVER THE WEEKEND WILL ALLOW FOR TEMPERATURES TO PUSH BACK  
INTO THE 50S IN WESTERN NEVADA AND WITH UPPER 40S IN THE SIERRA.  
GENERALLY LIGHT WINDS CAN BE EXPECTED WITH RELATIVELY STRONG  
OVERNIGHT INVERSIONS POSSIBLE FRIDAY AND SATURDAY NIGHT. MAIN  
CHANGES OVERNIGHT WERE TO WARM AND DRY UPPER ELEVATIONS AS  
WARMER AND DRY AIR IS EXPECTED TO BUILD IN ALOFT. -ZACH  
 

 
   
AVIATION
 
 
BUILDING HIGH PRESSURE SHOULD LEAD TO A PERIOD OF VFR CONDITIONS  
ACROSS THE FORECAST AREA THAT EXTENDS THROUGH MUCH OF THE WEEK. THE  
ONLY EXCEPTION TO VFR IS LIKELY TO BE FREEZING FOG IN SOME OF THE  
SIERRA VALLEYS THIS MORNING...AND AGAIN WEDNESDAY MORNING AND  
THURSDAY MORNING...REDUCING VISIBILITIES BELOW 1 MILE. THE TERMINAL  
WITH HIGHEST PROBABILITY OF FREEZING FOG IS KTRK; FOG HAS ALREADY  
FORMED THERE THIS MORNING.  
 
SURFACE WINDS REMAIN LIGHT THROUGH MUCH OF THE WEEK. WINDS ALOFT  
WILL DECREASE TODAY. THERE ARE SOME RESIDUAL GUSTS OVER THE SIERRA  
RIDGES FROM THE EAST-NORTHEAST THIS MORNING. THESE WILL SUBSIDE AS  
THE RIDGE BUILDS ALOFT. TURBULENCE IS STILL A POSSIBILITY THIS  
MORNING OVER AND WEST OF THE RIDGE LINES. THAT WILL BE THE MAIN  
FLIGHT LEVEL HAZARD TODAY.  
 

 
   
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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