876
FXUS65 KREV 182220
AFDREV
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE RENO NV
220 PM PST MON NOV 18 2024
SYNOPSIS
* ISOLATED SHOWERS AND COOLER TEMPERATURES ARE EXPECTED THROUGH
TUESDAY. TUESDAY MORNING LOWS WILL BE IN THE TEENS AND LOW 20S.
* BY WEDNESDAY, SHOWER CHANCES RETURN TO TAHOE, NORTHEAST CA, AND
FAR NORTHWEST NV. PLUS GUSTY SOUTHWEST TO SOUTH WINDS ARE
EXPECTED ACROSS THE WHOLE AREA.
* A POTENTIALLY MORE SIGNIFICANT STORM ARRIVES LATE FRIDAY INTO
SATURDAY BRINGING STRONG WINDS, AND CHANCES FOR RAIN AND SNOW.
DISCUSSION
WE HAD GUSTY WINDS ALONG WITH SOME VALLEY RAIN AND MOUNTAIN SNOW
LAST NIGHT. CURRENTLY, WE HAVE MOSTLY FAIR CONDITIONS ACROSS THE
REGION, BUT WITH SOME TYPICAL BREEZES THIS AFTERNOON. THERE IS A
VERY LOW CHANCE FOR LIGHT SHOWERS NEAR THE CA/OR BORDER, NE CA AND
THE SIERRA. OTHERWISE, WE SHOULD BE DRY. CHILLY CONDITIONS PERSIST
THROUGH TOMORROW. WIDESPREAD AREAS WILL OBSERVE HARD FREEZES AGAIN
TOMORROW MORNING. THE GOOD NEWS IS THAT TEMPERATURES WILL BE SLOWLY
RISING THROUGH LATE THIS WEEK.
THE WEATHER PATTERN CHANGES ON WEDNESDAY WITH THE APPROACH OF AN
UPPER LEVEL STORM SYSTEM THAT WILL HOVER OFF THE PACIFIC NW. THIS
POSITION WILL ALLOW FOR A DEEP PLUME OF MOISTURE, AKA ATMOSPHERIC
RIVER (AR), TO BE ADVECTED TOWARDS NORTHERN CA FOR THE SECOND HALF
OF THE WEEK. THE ARRIVAL OF THIS SYSTEM BRINGS SNOW ACCUMULATIONS
FOR FAR WESTERN LASSEN AND CENTRAL PLUMAS COUNTY ABOVE 5000 FT.
THE LAST COUPLE OF MODEL RUNS HAVE INCREASED THE PRECIPITATION
AMOUNTS RESULTING IN HIGHER PROBABILITIES OF SNOW IN THE
AFOREMENTIONED AREA. THEREFORE, THERE IS ABOUT A 60-90% CHANCE OF
EXCEEDING 4 INCHES OF SNOW. FOR THE TAHOE BASIN AND NEAR THE
DONNER PASS, THE PROBABILITIES ARE 40-70% IN ELEVATIONS ABOVE 7000
FT WITH THE BEST CHANCES NEAR THE SIERRA CREST AND OVER THE WEST
SLOPES. SNOW CHANCES DIMINISH THE FARTHER SOUTH WE GO. THIS LEADS
TO THE EASTERN SIERRA ONLY HAVING A 10-40% CHANCE OF EXCEEDING 4
INCHES. THE AR BRINGS A WARMER AIR MASS, SO SNOW LEVELS WILL RISE
BY EARLY THURSDAY TO ABOUT 7-8 KFT. THIS WILL HINDER THE SNOW
ACCUMULATIONS, AND MELT SOME OF THE SNOW WHICH WILL LEAD TO
PONDING OF WATER IN LOW-LYING AREAS AND RISES IN CREEKS AND RIVERS
OVER NORTHEAST CA.
THE SECONDARY HAZARD THAT WE ARE EXPECTING ON WEDNESDAY IS GUSTY
SOUTHWEST TO SOUTH WINDS. THE UPPER LEVEL JET WILL SET IN
NORTHERN CA AND SOUTHERN OR LEADING TO AN INCREASE IN THE PRESSURE
GRADIENT NEAR THE SURFACE. THEREFORE, EXPECT GUSTS OF 30-40 MPH
IN THE VALLEYS ACROSS THE REGION AGAIN WITH GUSTS EXCEEDING 70 MPH
IN THE SIERRA CREST. NBM IS ALSO SHOWING A 30-50% CHANCE OF SEEING
50+ MPH GUSTS, WHILE ECMWF EXTREME FORECAST INDEX (EFI) IS ALSO
INDICATING AN ANOMALOUS EVENT.
TALKING ABOUT THE EFI, IT LOOKS LIKE WE HAVE ANOTHER WIND EVENT
THIS SATURDAY AFTER A BREAK ON THURSDAY AND FRIDAY WITH SLIGHTLY
WEAKER WINDS. PRETTY MUCH THIS IS WHEN THE UPPER TROUGH THAT WAS
HOVERING OFF THE PAC NW FINALLY MOVES INLAND. AGAIN EXPECT GUSTY
WINDS WITH THIS SYSTEM DURING THE AFTERNOON HOURS. BUT OF MORE
CONCERN IS THE AMOUNTS OF PRECIPITATION ASSOCIATED WITH IT AS THE
LAST OF THIS AR FINALLY PASSES THROUGH. THE PERIODS OF RAIN AND
SNOW WILL LEAD TO A 20-50% CHANCE OF GETTING AN INCH OF LIQUID IN
THE SIERRA FRONT AND 40-80% FOR THE SIERRA AND NE CA BETWEEN
FRIDAY AND SUNDAY.
-CRESPO
AVIATION
WIND GUSTS DIE DOWN THROUGH THE EVENING FOR ALL TAF SITES, AND
REMAIN LIGHT AND VARIABLE THROUGH THE PERIOD. VFR CONDITIONS
EXPECTED FOR ALL SITES EXCEPT FOR KTRK, WHERE SOME FZFG IS POSSIBLE
TONIGHT UNTIL 19/17Z AS TEMPERATURES DROP TO THE TEENS. IN ADDITION,
PERIODS OF INCREASED TURBULENCE IS EXPECTED ALONG THE SIERRA UNTIL
19/05Z.
BEYOND THAT, WE HAVE TWO SYSTEMS THIS WEEK THAT COULD BRING SNOW TO
MOUNTAIN TERMINALS AND RAIN TO VALLEY TERMINALS. THE FIRST SYSTEM
AIMS TO BRING A RAIN/SNOW MIX TO KTRK/KTVL WEDNESDAY THROUGH
THURSDAY. THE SECOND SYSTEM (FRIDAY THROUGH SATURDAY) LOOKS TO BRING
SNOW TO KMMH/KTVL/KTRK AND RAIN TO KRNO/KCXP/KMEV. FOR MORE DETAILS,
SEE THE DISCUSSION ABOVE.
-GIRALTE
REV WATCHES/WARNINGS/ADVISORIES
NV...NONE.
CA...NONE.
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