698
FXUS66 KSTO 152047
AFDSTO

Area Forecast Discussion
National Weather Service Sacramento CA
147 PM PDT Wed Oct 15 2025

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

.KEY MESSAGES...

 - Showers have tapered off as the upper level low exits the
   region, leaving behind drier weather and well below normal
   temperatures across the region today

 - Potential for patchy fog development in the southern
   Sacramento and northern San Joaquin valleys Thursday morning

 - Slight warming and drying trend mid to late week as shortwave
   ridging moves into the area with weak northerly flow

 - A weak system passing to the north will bring chances for
   isolated showers, mainly over Lassen Peak and the northern
   mountains Sunday into Monday

 - Low confidence in breezy northerly winds early next week
   behind the passage of this weather system

.DISCUSSION...
Today...Showers have tapered off and the Winter Storm Warning
expired at 5 AM this morning. The upper level low that brought
widespread precipitation and mountain snow the past 48 hours will
continue to shift off to the east today. Drier weather has
returned to NorCal behind the storm and well below normal
temperatures are being observed, generally in the 60s in the
Valley, 50s in the foothills, and 30s to 50s in the mountains.
Current visible satellite imagery shows a swath of broken to
overcast cloud over across interior northern California this
afternoon. Cloud cover will be decreasing through the day today
and tonight.

Thursday through Saturday...There is potential for patchy fog
development Thursday morning across the southern Sacramento and
northern San Joaquin valleys as a result of the recent rain,
decreasing clouds and cooler mornings. High resolution guidance
indicates a 40-60% chance of visibilities less than a half of a
mile in those aforementioned locations for early Thursday
morning. Otherwise, weak upper level ridging will develop and move
into the region, allowing for weak northerly flow and slightly
warmer and drier weather, closer to normal for mid October
climatology. Forecast highs in the Valley are in the 70s each day.

Sunday...Ensembles and clusters are in decent agreement for an
upper trough to move across the Pacific Northwest. Some isolated
showers may clip the northern mountains and southern Cascades
Sunday and Sunday night. The most recent precipitation forecast
from WPC has trended lower and little to no impacts are expected
from this.

Monday through Tuesday...Behind the passage of this system, there
is potential for some breezy northerly winds, mainly along and
west of Interstate 5 in the Sacramento Valley and adjacent Coast
Range foothills where there is a 35-55% chance of wind gusts
greater than 30 mph on Monday. Little to no impacts are expected
at this time especially since fuels and fire weather concerns are
minimal due to recent rain. We will continue to monitor trends in
the pattern and pressure gradient in case the winds trend
stronger, as there is still a spread in the ensembles for peak
wind gusts. Northerly flow may linger into Tuesday morning as
well. /KH

.AVIATION...
General VFR conditions expected over the area over the next 24
hours. Exceptions to this are local MVFR conditions from lower
cloud ceilings possible through 02Z this evening over the northern
Sacramento Valley and the potential for patchy fog 12-18z
Thursday over the southern Sacramento Valley and northern San
Joaquin Valley, bringing IFR/LIFR. Surface winds are expected to
be generally light for TAF sites.

&&

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

&&

$$