477
FXUS65 KREV 262117
AFDREV
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE RENO NV
117 PM PST FRI DEC 26 2025
KEY MESSAGES
* CONTINUED HEAVY SNOW IMPACTS IN THE SIERRA THROUGH THIS EVENING,
WITH LIGHT SHOWERS AND STRONG BREEZES IN WESTERN NEVADA.
* DRY BUT COLDER THIS WEEKEND WITH POTENTIAL FOR FOG.
* INITIALLY QUIET WEATHER WITH INVERSIONS AND AIR STAGNATION EARLY
NEXT WEEK, THEN POTENTIAL FOR A STORM STARTING AROUND NEW YEARS
DAY.
DISCUSSION
* ADDITIONAL PERIODS OF MODERATE-HEAVY SNOW EXPECTED THROUGH THIS
EVENING AS CONVECTION OVER THE CENTRAL VALLEY LIFTS UP INTO THE
SIERRA, PER LATEST HRRR/RRFS GUIDANCE. HAVE EXTENDED WINTER STORM
WARNINGS TO REFLECT THE LONGER DURATION IMPACT TO TRAVEL. SNOWFALL
RATES IN HEAVIEST SHOWERS GENERALLY 1-2"/HOUR AT THE PASSES AND
HIGHER TERRAIN, PER HREF 50TH-90TH PERCENTILE DATA.
* THE CURRENT STRONG SIERRA RIDGE WINDS WILL PERSIST THROUGH
MIDNIGHT THEN START TO SLACKEN, PER RRFS 700MB TRENDS. ALSO SEEING
BREEZY GUSTS IN W NEVADA VALLEYS NOW THAT WE'VE SHADOWED OUT FOR
THE MOST PART. GUSTS ON THE ORDER OF 30-45 MPH EXPECTED ESPECIALLY
IN WIND PRONE AREAS THROUGH EARLY EVENING.
* THIS WEEKEND, RIDGING DEVELOPS OFF THE COAST WITH MAINLY DRY
NORTHERLY FLOW OVER OUR REGION. THIS WILL USHER IN COLDER TEMPS,
AT LEAST COMPARED TO HOW MILD WE'VE BEEN THE LAST 3 WEEKS. WITH
FRESH SNOWCOVER, THE PROBABILITY OF SEEING SINGLE DIGIT TEMPS IN
SIERRA COMMUNITIES IS HIGH, AT LEAST 80%, WITH A GOOD CHANCE OF
SUB-ZERO AT TYPICAL COLD SPOTS LIKE TRUCKEE AIRPORT AND BODIE.
* WITH THAT COOLER AIRMASS AND RECENT MOISTURE, THAT BRINGS IN THE
PROSPECT FOR FREEZING FOG. HARD TO PIN DOWN A PROBABILITY BUT BASED
ON EXPERIENCE PLACES LIKE MONO LAKE, TRUCKEE, TAHOE, AND THE
SIERRA VALLEY HAVE 80% OR HIGHER CHANCES OF FOG EACH MORNING
THROUGH MONDAY. FOR THE RENO AREA, THAT IS TRICKIER, BUT I'D GIVE
IT A 40% PROBABILITY EACH MORNING GIVEN HOW WET THE GROUND IS
AROUND HERE.
* UPPER RIDGE WORKS IN OVERHEAD MONDAY THRU WEDNESDAY NEXT WEEK. DRY
CONDITIONS BUT CAN'T RULE OUT CONTINUED FOG IN FAVORED SPOTS PLUS
STRONG INVERSIONS. BASED ON NBM VENTILATION GUIDANCE, THIS SEEMS
LIKE A FAVORABLE SETUP FOR MID-WINTER AIR STAGNATION IN OUR LOWER
VALLEYS, LEADING TO HAZE BUILDUPS AND IMPACTS TO PRESCRIBED BURN
PLANS.
* NEXT STORM WINDOW IS ROUGHLY JAN 1-4, WITH GUIDANCE SHOWING A
SOUTHERN SYSTEM LIFTING INTO THE AREA. CONFIDENCE IS LOW-MEDIUM
WITH LARGE RANGES IN SCENARIOS, E.G. NBM SNOW LINES VARY BETWEEN
3,000 TO 8,000 FEET AT THE 10TH/90TH PERCENTILES FOR JAN 2.
-CHRIS
AVIATION
* WIND AND ROTOR IMPACTS ARE BEING FELT THIS AFTERNOON IN THE LEE OF
THE SIERRA, PER RNO PIREP REPORTS AND LOOKING OUT THE WINDOW HERE.
BASED ON MODEL TRENDS, BREEZY WINDS AND LLWS CAN BE EXPECTED
THROUGH ABOUT 6Z THIS EVENING BEFORE TAILING OFF.
* IFR/LIFR SNOW SHOWERS ARE ALSO EXPECTED THROUGH ABOUT 6Z AT TVL,
TRK, AND MMH WITH CONVECTION OVER THE CENTRAL VALLEY LIFTING OVER
THE SIERRA AS SNOW. FURTHER EAST, WE CAN'T RULE OUT LIGHT SNOW
SHOWERS AT AIRFIELDS SUCH AS RNO, CXP, AND MEV BUT PROBABILITIES
ARE LESS THAN 20% FOR MVFR CONDITIONS.
* FOG IS LIKELY TO BECOME AN ISSUE FOR SOME AIRFIELDS THIS WEEKEND
INTO EARLY NEXT WEEK, GIVEN LIGHTER WINDS, RECENT MOISTURE, AND
CLEARING SKIES. PLACES LIKE TRK ARE BASICALLY AT 100% LOCK FOR FOG
EACH MORNING AND TVL 80%. RNO IS TOUGHER BUT THE INGREDIENTS ARE
THERE FOR SOME FOG POTENTIAL, SO I'LL RATE IT AT 40%.
-CHRIS
AVALANCHE
* CONTINUED MODERATE TO HEAVY SNOW SHOWERS THROUGH MIDNIGHT THIS
EVENING, BEFORE TAPERING OFF QUICKLY OVERNIGHT. ADDITIONAL
SNOWFALL 10-20" ALONG THE CREST WITH POTENTIAL FOR 1-2"/HOUR
SNOWFALL RATES IN HEAVIER SHOWERS. ADDITIONAL SWE AMOUNTS IN THESE
AREAS ROUGHLY 0.5 TO 0.7". SNOW RATIOS GENERALLY 12-15:1.
* SOUTH/SOUTHWEST WINDS WILL INITIALLY BE STRONG THIS EVENING WITH
OBSERVED GUSTS 50-70 MPH ALONG THE SIERRA CREST. BASED ON MODEL
TRENDS THOSE WINDS WILL PERSIST THROUGH THE EVENING BEFORE
TAPERING OFF QUICKLY BY SUNRISE ON SATURDAY.
* SATURDAY IS SHOWING MAINLY LIGHT NORTH/NORTHWESTERLY FLOW WITH
PARTLY TO MOSTLY SUNNY SKIES. COULD START SEEING INVERSIONS AND
FOG DEVELOP IN FAVORED SIERRA VALLEYS SUCH AS AROUND MONO LAKE,
BRIDGEPORT, AND TRUCKEE THROUGH THE WEEKEND. MORE PRONOUNCED
INVERSION PATTERN POSSIBLE MONDAY-WEDNESDAY NEXT WEEK WITH HIGH
PRESSURE RIDGE OVERHEAD.
-CHRIS
REV WATCHES/WARNINGS/ADVISORIES
NV...WINTER STORM WARNING UNTIL 10 PM PST THIS EVENING NVZ002.
CA...WINTER STORM WARNING UNTIL 10 PM PST THIS EVENING CAZ071-072.
WINTER STORM WARNING UNTIL 1 AM PST SATURDAY CAZ073.
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