776
FXUS66 KSTO 032037
AFDSTO

Area Forecast Discussion
National Weather Service Sacramento CA
137 PM PDT Sun Aug 3 2025

.DISCUSSION...

.SYNOPSIS...
Chances for afternoon and evening thunderstorms continue today
over the Shasta County mountains. Near to slightly below normal
temperatures are expected early this week with breezy winds. A
warming and drying trend is then anticipated from mid week onward
with areas of Moderate HeatRisk returning by late next week.

&&

.KEY MESSAGES...

* Today:
 - Thunderstorm chances around 5-15% over the Shasta County
   mountains this afternoon/evening.
 - Main threats include lightning, brief heavy rain, gusty winds,
   small hail, and possible fire starts. Short term models show
   convection initiating around 3 PM until 7 PM. Trends indicate
   storms remaining north of Shasta County, but an isolated shower
   or thunderstorms is still possible in our area.
 - Elevated fire weather conditions are expected in the mountains
   due to the lightning and gusty outflow wind threat and any
   strikes outside the main precipitation cores will pose the
   threat for fire starts.
 - Increased westerly flow through gaps and canyons in the Coastal
   Range for only a few hours this afternoon with gusts 20-30 mph.
 - Breezy onshore flow expected during the afternoons and
   evenings.
 - Probability of south to west wind gusts across the Delta and
   adjacent Valley > 30 mph: 60-90%
 - Afternoon highs in the 90s throughout the Valley.


* Monday-Thursday:
 - Temperatures cool down slightly on Monday as a quick moving
   system exists the region.
 - Gradual warming and drying trend expected mid to late week as
   Desert Southwest ridging amplifies.
 - Periodically breezy onshore flow looks to continue as split
   flow aloft persists over interior NorCal.
 - High temperatures trend slightly above normal by the end of the
   week, with 90s to lower triple digits through the Valley,
   Delta, and foothills resulting in areas of Moderate HeatRisk.

.Changes from previous forecast...
 - Increased westerly winds over the Coastal Range and Sierra
   this afternoon and early evening, 40-60% chance of gusts > 30
   mph.



&&


.AVIATION...
Generally VFR conditions expected to prevail next 24 hours across
interior NorCal. MVFR/IFR possible due to a slight (5-10%) chance
for isolated mountain showers/thunderstorms across Shasta County
mountains today until around 03Z Monday. Increased breezy onshore
surface winds up to 12 kts expected through Valley and Delta with
gusts 15 to 20 kts in the Valley until 08Z Monday and up to 25 kts
in the Delta and vicinity area through 18Z Monday. Westerly winds
over the Coastal Range and Sierra are expected to gust up to 25
kts until around 10Z Monday.

&&

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

$$