Lake Tahoe, California Weather Forecast Discussion

928
FXUS65 KREV 280918
AFDREV
Area Forecast Discussion
National Weather Service Reno NV
218 AM PDT Sun Sep 28 2025
.KEY MESSAGES...
* Scattered showers and thunderstorms are expected this afternoon
  with localized flash flooding possible.
* Strong low pressure will bring additional showers and storms,
  gusty winds, and cooler temperatures Monday through midweek.
* Unsettled weather may continue Friday into next weekend, but
  confidence is low.
&&
.DISCUSSION...
Shower and thunderstorm activity trends upward this afternoon as
large scale ascent overspreads a moist, weakly unstable airmass
residing across the region. Favored areas for initial showers and
t-storms include the Mono-S.Lyon-Mineral County vicinity northward
into the Pine Nut Mountains and Virginia Range where odds are
greatest (20-40%). Coverage of showers and t-storms will
expand/shift eastward into the W NV Basin and Range through the
afternoon before tapering off after sunset. Farther west, most
areas will remain dry today, but the environment near the Tahoe
Basin into the Greater Reno-Carson-Minden area appears to be at
least marginally supportive of a stray shower or thunderstorm
during the afternoon, especially if outflows can propagate
westward. Slower storm motions and abundant moisture will support
isolated flash flooding today, mainly across Mono, S. Lyon, and
Mineral counties where coverage/odds are greatest. Thunderstorms
will also be capable of gusty outflow winds, small hail, and
frequent lightning.
Additional showers and thunderstorms are anticipated Monday
afternoon with a few t-storms becoming strong to possibly severe
given the increasing deep-layer shear. Coverage and favored areas
has been difficult to determine due to uncertainty in the
placement  of an upper trough and if instability is too weak to
overcome wind shear. The W NV Basin and Range (east of Alt-95) has
consistently been the preferred area for thunderstorm development
in CAMs, but latest guidance hints at the possibility of storms
farther west across the Sierra and far western Nevada ahead of a
weak cold front. In any case, any thunderstorm that is able to
mature and organize will likely be capable of marginally severe
wind gusts and/or hail. Additional showers (including light snow
showers over highest Sierra peaks) or a stray t-storm will be
possible Monday night from Tahoe into NE California where the cold
front stalls. Winds will also be gusty Monday afternoon outside of
thunderstorm influence, so be prepared for choppy waters on area
lakes and impacts to travel.
A second cold front will approach the region on Tuesday,
maintaining shower chances, gusty winds, and cool temperatures
through midweek. Unsettled weather may even linger Friday into the
weekend as low pressure hangs around, but confidence is low on
exact details.
-Salas
&&
.AVIATION...
Scattered showers and thunderstorms will be the main concern
today, especially at KMMH-KHTH where odds (20-30%) are greatest.
Thunderstorms may develop as early as 18Z, but the most likely
time frame for any storm impacts at these terminals. will be
between 20Z and 02Z this afternoon. Thunderstorms will be capable
of heavy downpours and brief MVFR conditions, gusty and erratic
outflow winds, small hail, and frequent lightning.
Elsewhere, thunderstorms will likely stay east of KTRK-KTVL and
KRNO-KCXP-KMEV, but outflow winds could initiate thunderstorms
farther west near KRNO and KCXP-KMEV between 22Z and 02Z. The more
likely outcome for these terminals will be cumulus build-ups with
perhaps a stray shower or two in the afternoon.
Strong low pressure in the eastern Pacific will strengthen S/SW
FL100 winds to 25-35 kts from Tahoe northward after 06Z tonight.
This coupled with weakening surface winds may present LLWS and
mountain wave turbulence issues tonight, becoming more
pronounced/widespread on Monday as winds aloft and at the surface
increase.
-Salas
&&
.REV Watches/Warnings/Advisories...
NV...None.
CA...None.
&&
$$

NWS REV Office Area Forecast Discussion