Portola, California 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

704
FXUS65 KREV 110843
AFDREV

Area Forecast Discussion
National Weather Service Reno NV
143 AM PDT Mon Aug 11 2025

.KEY MESSAGES...

* Heat Advisory in effect today through Wednesday morning for
  western NV and northeast CA valleys, with highs 95-105 degrees
  and Moderate to Major HeatRisk.

* Isolated thunderstorms possible Tuesday and Wednesday afternoon,
  otherwise dry weather prevails this week.

* Increasing afternoon breezes Wednesday-Thursday may bring
  elevated fire weather concerns, with a cooling trend for through
  late week and next weekend.

&&

.DISCUSSION...

A building high pressure ridge over CA/NV will bring the warmest
temperatures since mid-July for the early portion of this week.
Highs will climb to near 100 degrees for many lower elevation
sites within the Heat Advisory by this afternoon, then peak on
Tuesday with highs between 100 and 105 degrees. Areas near and
east of US-95 are most likely to see the higher end of this
temperature range. Sierra communities will get their taste of
summer heat as well, with highs near or above 90 degrees today
and Tuesday.

This period of heat will be relatively short lived as the ridge
weakens and is displaced to the Four Corners region by Wednesday,
in response to a developing trough along the west coast. The US-95
corridor in west central NV could see highs near 100 again on
Wednesday, but overall a cooling trend will take place as the
trough becomes the prevailing weather feature for CA-NV. Highs
will ease back to the upper 80s-lower 90s in lower elevations and
near 80 degrees for Sierra communities from Friday through next
weekend.

The overhead location of the ridge will only allow for flat
afternoon cumulus along the Sierra crest today, but widespread
subsidence and warm air aloft will prevent thunderstorm formation.
As this ridge shifts eastward Tuesday-Wednesday with slight
cooling aloft and some increased moisture, isolated showers or
thunderstorms (10-20% chance) may develop each afternoon. High
resolution guidance favors this potential on Tuesday over the
eastern Sierra northward across far western NV, mainly south of
I-80 and west of US-95. For Wednesday, these storm chances shift
to areas south of US-50, primarily for Mono, Mineral and southern
Lyon counties. For both days, most cells look to be pulse-type
with strong outflow gust potential (50+ mph) and brief bursts of
rain and small hail. By Thursday, the storm potential shifts
farther east to central NV, although a couple of stray cells could
pop up in far eastern Mineral County (10% chance).

We`ll also be looking at some increase in winds for the
Wednesday-Thursday time frame, although it doesn`t appear to be a
widespread strong wind event. Even so, with gusts projected near
or slightly above 30 mph across parts of western NV, especially
after following a period of hot and dry weather, elevated fire
weather conditions will likely result. From Friday through next
weekend, typical afternoon zephyr-type breezes are anticipated
with dry and cooler conditions prevailing. MJD

&&

.AVIATION...

* VFR conditions and light winds will prevail today. With well
  above average temperatures through midweek, density altitude
  concerns will increase each afternoon at all main terminals.

* For Tuesday-Wednesday, isolated high-based showers and
  thunderstorms are possible each afternoon mainly along the
  Sierra crest south of Tahoe, but a few showers or storms could
  affect the main terminals in far western NV on Tuesday. Outflow
  gusts exceeding 40 kts are possible near any cells, especially
  for lower elevations of west central NV.

* Increased winds could bring occasional gusts of 25-30 kt
  Wednesday afternoon especially from far western NV southward to
  KMMH. This will lead to periods of mountain wave turbulence and
  possible LLWS.

MJD

&&

.REV Watches/Warnings/Advisories...
NV...Heat Advisory from 11 AM Monday to 9 AM PDT Wednesday NVZ001-
     003>005.

CA...Heat Advisory from 11 AM Monday to 9 AM PDT Wednesday CAZ070-071.

&&

$$