244
FXUS65 KREV 120900
AFDREV

Area Forecast Discussion
National Weather Service Reno NV
200 AM PDT Sat Jul 12 2025

.KEY MESSAGES...

* Dangerous heat will persist through early next week, with
  widespread Moderate to Major HeatRisk across lower elevations of
  western Nevada and northeast California.

* A low potential exists for isolated, high-based thunderstorms
  through Tuesday, with increasing chances mid to late next week.

* Strengthening southwest to west winds return mid to late next week.

&&

.DISCUSSION...

A strong and persistent ridge anchored over the Desert Southwest
will continue to support well-above-normal temperatures through at
least Tuesday. Highs will exceed 100 degrees across lower valleys in
western Nevada and northeast California, with Sierra valleys warming
into the upper 80s to low 90s. Overnight lows will remain
warmespecially in urban and lower elevation areasoffering limited
relief and contributing to sustained heat stress.

Friday afternoon, widespread cumulus castellanus were observed over
Mono County, indicative of increasing mid-level moisture and
instability. Convection-allowing models continue to show daily CAPE
values of 400800 J/kg, locally near 900 J/kg, favoring isolated,
high-based thunderstorms each afternoon through Tuesday, mainly
along the Sierra crest and adjacent terrain in western Nevada. With
limited column moisture, dry lightning and gusty, erratic outflows
remain the primary concerns.

By mid to late next week, ensemble guidance continues to trend
toward a retrograding ridge as a broad trough deepens into the
Pacific Northwest. This shift will bring modest cooling aloft and a
gradual increase in mid-level moisture. Daily thunderstorm chances
(10-20%) look to increase across the Sierra, northeast California,
and western Nevada beginning Wednesday, with potential for more
widespreadbut still primarily isolatedcoverage.

In the nearer term, prolonged hot and dry conditions will
precondition the environment ahead of increasing winds. By Tuesday
and especially Wednesday through Friday, southwest to west winds
will strengthen, with afternoon gusts of 2030 mph becoming more
common. These winds, combined with very dry conditions, may lead to
an increase in fire weather concerns mid to late next week,
particularly where receptive fuels are present. Forecast confidence
remains moderate at this range, but trends will be monitored closely.

Johnston

&&

.AVIATION...

VFR conditions will prevail this weekend. Afternoon cumulus
buildups are expected Saturday and Sunday, with a 5-10% chance of
isolated, high-based thunderstorms each day between 21- 03Z,
primarily along the Sierra crest and nearby higher terrain. Brief
outflow gusts and localized turbulence are possible near any
storms.

Elevated density altitude will continue to impact aircraft
performance, especially at Sierra terminals such as KTRK, KTVL,
and KMMH.

Winds will remain light and terrain-driven through the weekend, with
typical southwest to west gusts of 1020 kts during the afternoon
and evening.

Occasional slantwise visibility reductions are possible due to
elevated haze from wildfires in northern California and southern
Oregon, mainly during the morning and evening hours.

Johnston

&&

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

CA...Heat Advisory from 11 AM this morning to 11 AM PDT Wednesday
     CAZ070-071.

&&

$$