243
FXUS66 KSTO 072004
AFDSTO

Area Forecast Discussion
National Weather Service Sacramento CA
104 PM PDT Mon Jul 7 2025

.DISCUSSION...

.SYNOPSIS...
Mostly dry with seasonable high temperatures today in the Valley.
Triple-digit highs in portions of the northern Sacramento Valley.
Elevated fire weather conditions from breezy southerly winds and
low daytime humidity values today for portions of the northern
Sacramento Valley. Non-zero chance for an afternoon/evening
shower/t-storm in the mountains of Shasta County today. Slight
cooldown on Tuesday, then warming trend Wednesday through the
weekend, with widespread Moderate HeatRisk Thursday - Sunday.
&&

.KEY MESSAGES...

*  Today-Wednesday:

 - Smoke from the Green wildfire visible on satellite, southerly
   winds helping move plume north of Redding this afternoon
 - Offshore low promoting periods of breezy southerly winds across
   the area today. Low daytime humidity values (15-20%) in
   portions of the northern Sacramento Valley with breezy winds
   (15-25 mph gusts) promote elevated fire weather concerns today.
   Highest threat area: Corning to Shasta Dam, along and west of
   I-5.
 - Non-zero chance (less than 5%) for an afternoon shower/t-storm
   developing in the mountains of Shasta County today. Latest high
   resolution models continue to keep the activity north of our
   area, with better chances around the Mt. Shasta region and into
   Siskiyou, Trinity, and Modoc counties as low moves inland this
   evening. RAP model soundings showing some elevated instability
   with modest CIN, so confidence on development for our area
   remains very low.
 - Brief cooldown on Tuesday, with continued dry and mostly clear
   weather. Bounce back to seasonable temperatures on Wednesday as
   high pressure begins to build in the Desert SW/Four Corners
   region.

*  Thursday - Sunday:
 - On Thursday, trough exits the area, ridge continues to build in
   the Desert SW, promotes a period of northerly winds. Current
   upper level heights/pressure gradient force not indicating an
   overly strong northerly wind setup. NBM forecast winds around
   15-25 mph, strongest in the typical wind prone areas of the
   northern Sacramento Valley.
 - Continued warming, with Moderate HeatRisk in the forecast for
   interior NorCal. Triple-digit highs in the northern and central
   Sacramento Valley and northern San Joaquin Valley Thursday-
   Sunday.
 - Cluster Analysis reveals good agreement of upper level ridging
   dominating our pattern into next week

.Changes from previous forecast...
 - No significant changes to the forecast

&&

.AVIATION...

VFR conditions across interior NorCal next 24 hours. Periods of
breezy onshore winds with gusts up to 15-25 knots in the Delta
vicinity. Breezy southerly/southwesterly wind gusts in the
Sacramento Valley and northwesterly wind gusts in the northern San
Joaquin Valley up to 15-20 kts until 06z Tuesday, and again after
18z Tuesday. Local MVFR conditions possible at times in HZ/FU
vicinity of Shasta County wildfire, including KRDD.

&&

.STO WATCHES/WARNINGS/ADVISORIES...
None.
&&

$$