907
FXUS65 KREV 210714
AFDREV
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE RENO NV
1214 AM PDT MON SEP 21 2026
KEY MESSAGES
* PRECIPITATION POTENTIAL RETURNS TODAY, ESPECIALLY FOR THE SIERRA
AND SOUTH OF US-50.
* WARMING UP AND GENERALLY DRY CONDITIONS ARE EXPECTED MID-WEEK
WITH TEMPERATURES 5 TO 10 DEGREES ABOVE AVERAGE.
* INCREASED WINDS AND COOLER TEMPERATURES RETURN TOWARDS THE END
OF THE WORK WEEK.
DISCUSSION
UPPER LEVEL LOW OBSERVED IN SATELLITE IMAGERY JUST OFF THE WEST
COAST IS EXPECTED TO MOVE TOWARDS THE GREAT BASIN TODAY. THIS
SYSTEM BRINGS A 20-40% CHANCE FOR SHOWERS MAINLY IN AREAS SOUTH OF
US-50 AND THE SIERRA, ESPECIALLY OVER MONO AND MINERAL COUNTIES
THIS AFTERNOON PER THE HREF AND RRFS. THE ECMWF, GFS AND NAM SHOW
MARGINAL INSTABILITY WITH MUCAPES UP TO 500 J/KG NEAR THE TAHOE
BASIN ALONG THE SIERRA CREST. THIS COULD LEAD TO A FEW ISOLATED
THUNDERSTORMS THIS AFTERNOON, BUT THUNDERSTORM CHANCES REMAIN
AT OR BELOW 10%. VERY FEW ENSEMBLE MEMBERS INDICATE THE
POSSIBILITY FOR HIGH ELEVATION MOUNTAIN SNOW MAINLY ABOVE 10500
FT. IF THERE IS ANY SNOW, IT COULD BE A TRACE UP TO 0.2 INCHES
BASED ON ENSEMBLE DATA FOR AREAS NEAR MAMMOTH LAKES. PRECIPITATION
CHANCES CONTINUE THROUGH TUESDAY, BUT UP TO 15% MAINLY OVER
LASSEN AND NORTHERN WASHOE AS THE UPPER LOW CONTINUES ITS
NORTHEASTWARD TRACK.
FOR MID-WEEK, TEMPERATURES START TO INCREASE AS WEAK RIDGING
DEVELOPS OVER THE WEST COAST. TEMPS WILL INCREASE TO 5 TO 10
DEGREES ABOVE AVERAGE WITH AFTERNOON HIGHS IN THE MID TO UPPER
90S FOR WESTERN NV, NORTHEAST CA AND SOUTHERN MONO VALLEYS, AND
MID TO UPPER 70S FOR SIERRA COMMUNITIES.
TOWARDS THE END OF THE WORK WEEK, AN UPPER LEVEL TROUGH MOVES
TOWARDS THE PACNW. THIS WILL TIGHTEN THE SURFACE PRESSURE GRADIENT
RESULTING IN SLIGHTLY STRONGER WINDS COMPARED TO EARLIER IN THE
WEEK. GUSTS ARE POTENTIALLY GOING TO BE IN THE 25-40 MPH RANGE
WITH A 20-40% CHANCE OF GUSTS GREATER THAN 35 MPH FOR WIND PRONE
AREAS ALONG THE SIERRA FRONT BOTH ON THURSDAY AND FRIDAY.
TEMPERATURES ARE ALSO EXPECTED TO START COOLING OFF AGAIN AS THIS
TROUGH BRINGS ANOTHER GENERALLY DRY COLD FRONT BY AROUND FRIDAY.
PRECIPITATION CHANCES ARE VERY UNCERTAIN AT THE MOMENT, MAYBE
LATE WEEK INTO THE WEEKEND, BUT CHANCES ARE CURRENTLY BELOW 5%.
-HC
AVIATION
MOSTLY VFR CONDITIONS ARE EXPECTED THROUGH THE NEXT 24 HRS.
EXCEPTIONS NEAR SHRA/-TSRA WHERE CIGS AND VIS COULD DROP TO MVFR,
AND IFR WITH THE STRONGEST ACTIVITY NEAR KMMH AND KHTH BETWEEN
18Z-03Z TODAY. THERE IS A 20-40% OF SHOWERS FOR THE SIERRA AND
AREAS SOUTH OF US-50. MOUNTAIN OBSCURATIONS ARE ALSO POSSIBLE
THROUGH TOMORROW.
WINDS WILL BE GENERALLY LIGHT AND VRB OVERNIGHT AND IN THE
MORNING, THEN BECOME FROM THE WEST AND SOUTHWEST WITH GUSTS UP TO
20KTS FOR KMMH/KTVL/KTRK, AND FROM THE EAST AND SOUTHEAST FOR
WESTERN NV SITES.
-HC
REV WATCHES/WARNINGS/ADVISORIES
NV...NONE.
CA...NONE.
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