446
FXUS66 KSTO 011957
AFDSTO

Area Forecast Discussion
National Weather Service Sacramento CA
1257 PM PDT Fri May 1 2026

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

.KEY MESSAGES...

 - A weather system will bring clouds, breezy conditions, cooler
   temperatures and unsettled weather through early next week.

 - Scattered thunderstorms and thunderstorms will begins this
   evening in Shasta county and be possible most areas through
   early next week. Valley locations are not expected to see much
   precipitation.

 - Conditions will dry out and warm up starting Tuesday through
   the rest of the week.

&&

.DISCUSSION...

...Tonight...
Models indicating that best instability will be in place this
evening for this entire event mainly in far northern counties.
Lift will be limited however as the upper low just starts to set
up and slides south to our west. Most convective allowing models
are keeping it dry but may be an isolated thunderstorm this
evening/overnight but dry elsewhere.

Saturday...models again not too excited about precipitation as the
upper low is far enough west to not impact us too much except for
cooler temperatures and clouds.

Sunday...showers are likely over the higher terrain as the upper
low starts to slide east into central CA. This will create a wrap
around easterly flow aloft over the area. Modeled instability
again not too bad, but this pattern would suggest at least some
convection possibly in the valley but for now looking mostly dry
with precipitation limited to mountains and foothills. Most models
are firing stronger convection north and east of STO forecast
area.

Monday...this may end up being the day with the best chance of
showers and thunderstorms to make it to the valley as the upper
low slides across STO forecast area but overall still the biggest
impact looks to be clouds and continued cooler temperatures.

Tuesday and beyond the upper low starts to pull east with a north
flow day Tuesday and slight increase in heights through the week
for warmer but close to seasonal temperatures.
&&

.AVIATION...

VFR conditions at TAF sites next 24 hours. Light surface winds
generally 10 kts or less except in the Delta with west-southwest
winds 10 to 15 kts. Chances for -SHRA over the mountains after 00z
Saturday until 05z Saturday, mainly over the Coastal Range and
south of Hwy. 50.

&&

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

&&

$$