Portola, California 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

836
FXUS65 KREV 162204
AFDREV

Area Forecast Discussion
National Weather Service Reno NV
204 PM PST Tue Dec 16 2025

.KEY MESSAGES...

* Light rain and high Sierra snow showers will continue through
  Wednesday afternoon.

* Gusty to strong winds will pose impacts to travel and recreation
  tonight through Wednesday afternoon.

* Wet and windy weather resumes Friday into the weekend, with
  stronger storms possibly impacting Christmas travel.

&&

.DISCUSSION...

An approaching upper trough continues to deliver light rain showers
this afternoon, mainly across Lassen and N Washoe counties per 21Z
radar obs. Shower activity will be confined to this area until late
tonight into Wednesday morning when rain shifts southward to the
Tahoe Basin (70-90% odds of rain) and Greater Reno-Carson-Minden
area (40-60% odds). Snow levels will remain above 9000 feet when
precipitation arrives, so any snowfall will be meager and confined
to highest Sierra peaks. Rain and high elevation snow will taper off
Wednesday afternoon, leaving only light amounts in its wake.

Winds will be of greater concern this evening and most of Wednesday,
owing to a deepening surface low to our north and robust 700 mb flow
overhead. Most of Wednesday will likely be windy, but there are two
distinct timeframe when winds are favored to be strongest: 1) early
Wednesday morning, and 2) late morning to early afternoon Wednesday.
Winds begin to increase late tonight in response to the maturing
surface low, culminating in SW/W gusts of 40-50 mph across NE
California, Sierra valleys, and the Sierra Front early Wednesday
morning. While still breezy, winds briefly ease mid-morning before
increasing to similar intensity from late morning into the early
afternoon. Meanwhile, expect Sierra ridge winds to gust to 80-100
mph most of Wednesday. Winds will finally weaken for all elevations
by Wednesday evening, though ridge winds stay gusty into Thursday.

As a result, be prepared for choppy lakes, aviation impacts, and
crosswind driving hazards along north-to-south oriented roadways
such as I-580, US-395, and US-95. Low-end fire weather concerns will
also exist across lower elevations of southern Mono County where RH
reductions to 25-30% are expected.

Weak ridging will overspread the region Thursday, resulting in
mostly dry conditions save for a few light showers north of I-80.
The main belt of moisture dives southward yet again on Friday,
resulting in another afternoon of gusty winds and increasing rain
and snow chances -- although snow levels remain elevated. Minimal
change in the weather pattern will maintain daily chances of
precipitation through the weekend and into early next week. The days
leading up to Christmas still looks favorable for stronger
winter storms, which may result in holiday travel disruptions.

-Salas

&&

.AVIATION...

Mountain wave turbulence and LLWS impacts will be the primary
concern for all terminals with light rain showers periodically
lowering CIGS/VIS to MVFR conditions at Tahoe and Sierra Front
terminals tonight through Wednesday morning.

SW/W FL100 winds amplify after 00Z this afternoon and peak at 40-60
kts between 06z and 18z Wednesday. Surface winds increase in tandem
with strengthening winds aloft as SW/W gusts reach 25-35 kts at KTRK-
KTVL-KMMH and 35-45 kts at KRNO-KCXP-KMEV around 12z Wednesday.
Mountain wave turbulence and LLWS will likely be an issue to some
extent until Wednesday evening, but will be most intense from 12z to
18z when winds aloft and at the surface are strongest.

Low clouds and occasional -RA may obscure surrounding terrain at
KTRK and KTVL this afternoon before rain and periods of MVFR
conditions begin in earnest after 06z tonight. Rain showers may
sneak into KNRO-KCXP-KMEV between 08z and 14z, yielding brief MVFR
conditions and mountain obscuration.

-Salas

&&

.REV Watches/Warnings/Advisories...
NV...Wind Advisory from 10 PM this evening to 4 PM PST Wednesday
     NVZ002>005.

CA...Wind Advisory from 10 PM this evening to 4 PM PST Wednesday
     CAZ070>072.

&&

$$