Area Forecast Discussion (glossary)
 
 FXUS65 KREV 011329 AAA
 AFDREV
 
 AREA FORECAST DISCUSSION...UPDATED
 NATIONAL WEATHER SERVICE RENO NV
 529 AM PST TUE JAN 1 2013
 
 .UPDATE...
 SOME PATCHY FREEZING FOG HAS FORMED ALONG THE SIERRA FRONT WITH A
 FEW FLURRIES. TO THE NORTH, RADAR IMAGERY SHOWS WHAT MAY BE
 HEAVIER SNOW NEAR DOYLE AND HONEY LAKE. WHILE THOSE SHOWERS ARE
 STILL RATHER LIGHT, SOME MEASUREABLE SNOW IS POSSIBLE IN THAT
 BAND. ALREADY UPDATED EARLIER FOR THE FOG AND WILL UPDATE TO ADD
 THE FLURRIES AND SNOW SHOWERS TO THE AFOREMENTIONED AREAS.
 
 LOOKING AHEAD, GIVEN THE STRONG INVERSION IN PLACE AND SOME
 LIMITED SNOW MELT IN THE VALLEYS DURING THE AFTERNOON, FREEZING
 FOG IS LOOKING MORE LIKELY THE NEXT FEW NIGHTS. WALLMANN
 
 
 .PREVIOUS DISCUSSION... /ISSUED 250 AM PST TUE JAN 1 2013/ 
 
 SHORT TERM...
 
 HIGH AMPLITUDE RIDGING CONTINUES TO BE THE MAIN FEATURE
 INFLUENCING THE OVERALL WEATHER PATTERN. THIS RIDGING, CURRENTLY
 CENTERED JUST OFF THE PACIFIC COAST, WILL CONTINUE TO BUILD AND
 EXTEND INTO THE FORECAST REGION THROUGH THE WEEKEND. ANY WAVES OF
 SIGNIFICANCE WILL BE SHUNTED WELL NORTH OF THE FORECAST REGION
 LEAVING THE REGION DRY AND SEASONABLY COOL AT LEAST INTO THE
 BEGINNING OF NEXT WEEK.
 
 ALTHOUGH GENERALLY BENIGN CONDITIONS WILL PREVAIL FOR THE NEAR
 FUTURE, THERE MAY BE SOME IMPACTS FROM FREEZING FOG ESPECIALLY
 DURING THE OVERNIGHT HOURS. HIGH LEVELS OF SURFACE MOISTURE WILL
 PERSIST DUE TO WIDESPREAD SNOW COVERAGE ACROSS THE ENTIRE FORECAST
 REGION. THIS, MOSTLY CLEAR SKIES OVER THE NEXT FEW DAYS, AND
 PERSISTENT COLD AIR LOCKED IN BENEATH SURFACE INVERSIONS, WILL
 PROVIDE IDEAL CONDITIONS FOR WIDESPREAD FREEZING FOG FORMATION. 
 
 USING MONDAY`S TEMPERATURES AS A CUE, HAVE LOWERED OVERALL
 TEMPERATURES THROUGH THURSDAY NIGHT AND SLOWED WARMING TREND. COLD
 AIR HAS BECOME LOCKED IN FOR VALLEY LOCATIONS WHERE SNOW COVER
 REMAINS. WITH SURFACE INVERSIONS STRENGTHENING, IT SEEMS PRUDENT
 TO PROCEED WITH COOLER-THAN-GUIDANCE TEMPERATURES AT LEAST UNTIL
 WE SEE A SHIFT IN TEMPERATURE TRENDS OR SIGNIFICANT SNOW MELT
 OCCURS. ALSO, SKIES WILL BECOME INCREASINGLY HAZY FOR WESTERN
 NEVADA AND SIERRA VALLEYS. AIR QUALITY MAY BECOME AN ISSUE
 ESPECIALLY FOR THE RENO METRO AREA SINCE SIGNIFICANT MIXING
 REMAINS OUTSIDE THE FORECAST PERIOD. BOYD
 
 LONG TERM...FRIDAY THROUGH MONDAY...
 
 STILL EXPECT THE MEAN UPPER RIDGE TO HOLD NEAR THE WEST COAST
 INTO EARLY NEXT WEEK. MODELS OVERALL ARE IN A LITTLE BETTER
 AGREEMENT THIS MORNING ESPECIALLY WITH REGARDS TO NEXT WEEKEND.
 GFS CONTINUES TO CUT A LOW OFF THE MEAN FLOW WELL OFF THE COAST
 WITH RIDGING HOLDING. THE EC IS DIFFERENT WITH A MUCH WEAKER CUT-
 OFF LOW AND THE MAIN TROUGH PASSING BY MORE TO THE NORTH WITH AT
 BEST A FEW LIGHT SHOWERS NEAR THE OREGON BORDER.
 
 THE MAIN ISSUE THEN WILL BE HOW LONG THE STRONG VALLEY INVERSIONS 
 WILL LAST. FOR THE GFS, THEY WILL LAST INTO NEXT WEEK WITH VALLEY 
 TEMPERATURES POSSIBLY 10-20 DEGREES COLDER THAN THE MOUNTAINS. EC 
 WOULD SUGGEST POTENTIAL INVERSION BREAKUP ON SUNDAY WITH COOLING 
 ALOFT AND MODERATE WINDS. GIVEN THE CONSISTENCY OF THE GFS SOLUTION 
 AND THE VARIABILITY OF THE EC RECENTLY WILL LEAN TOWARD THE GFS. 
 HAVE COOLED VALLEYS BELOW 5000 FEET AND WARMED MOUNTAIN LOCATIONS ON 
 AVERAGE 3-5 DEGREES FRI-MON. IF THE INVERSION HOLDS, IT IS A 
 PERSISTENCE FORECAST FOR THE VALLEYS WHILE THE MOUNTAINS WILL SEE 
 SOME SMALL VARIATION IN TEMPS BASED ON TEMPS ALOFT. AIR QUALITY
 WILL REMAIN AN ISSUE ALONG THE SIERRA FRONT WHILE FREEZING FOG MAY
 ALSO OCCUR IN MANY VALLEY LOCATIONS WITH SNOW COVER. WALLMANN
 
 AVIATION...
 VFR CONDS EXCEPT NEAR KTRK WITH FZFG THRU 18Z. FZFG AGAIN FOR KTRK 
 AFT 06Z TONIGHT, AND ALSO POSSIBLE FOR WRN NV INCLUDING KRNO WITH 
 CHANCES 20-30 PCT. WALLMANN
 
 
 .REV WATCHES/WARNINGS/ADVISORIES...
 NV...NONE.
 CA...NONE.