976
FXUS66 KSTO 292030
AFDSTO

Area Forecast Discussion
National Weather Service Sacramento CA
130 PM PDT Tue Jul 29 2025

For additional details on weather and expected impacts over the
next 7 days, please visit weather.gov/sto/briefing.

.DISCUSSION...

.SYNOPSIS...
Chances for afternoon and evening mountain thunderstorms this
week, with the highest chances overnight tonight through Wednesday
evening along the Sierra/southern Cascades and northeast
foothills. Otherwise, near normal temperatures expected this week
as periodically breezy onshore winds persist.

&&

.KEY MESSAGES...

* Today-Thursday:
 - Isolated thunderstorm chances around 10% along Sierra crest
   this afternoon/evening. Thunderstorm chances then increase to
   15-30% overnight through Wednesday evening with highest
   chances expected along the Sierra/southern Cascades and into
   the northeast foothills.
 - Decreasing thunderstorm chances around 10% across Shasta County
   mountains for Thursday afternoon/evening.
 - Main storm hazards include lightning, brief heavy rain, gusty
   winds, small hail, and possible fire starts.
 - Elevated fire weather conditions are expected in the mountains
   due to the lightning threat and any strikes outside the main
   precipitation core will pose the threat for fire starts.
 - Afternoon highs in the 80s and 90s throughout the Valley as
   high temperatures remain seasonable.
 - Periodically breezy onshore flow expected during the afternoons
   and evenings.

* Friday-Next Weekend:
 - Isolated mountain thunderstorm chances less than 10% through
   the weekend.
 - Periodically breezy onshore flow persists, with a slight uptick
   in wind speed possible by Sunday. Probability of south to west
   wind gusts > 30 mph on Sunday: 30-50%
 - Near to slightly below normal temperatures expected to
   continue.

.Changes from previous forecast...
 - Isolated to scattered mountain thunderstorms across the
   Sierra/southern Cascades and northeast foothills overnight
   tonight into Wednesday morning and again Wednesday
   afternoon/evening.

&&

.AVIATION...
Generally VFR conditions expected to prevail next 24 hours across
interior NorCal. MVFR/IFR possible in isolated mountain
thunderstorms and showers from 21z today through 18z Wednesday
with a lull in activity during the late evening hours along the
Sierra crest. Otherwise, breezy onshore surface winds up to 12 kts
expected through Valley and Delta, with lighter terrain driven
winds at higher elevations. Gusts 20-25 kts in Delta and vicinity
from 00-12z Wednesday, decreasing in the morning.

&&

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

$$