804
FXUS66 KSTO 122016
AFDSTO

Area Forecast Discussion
National Weather Service Sacramento CA
116 PM PDT Mon May 12 2025

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

.Discussion...

.Synopsis...
A weather system will bring chances for light showers, mountain
snow showers and isolated thunderstorms through Tuesday. Drier
weather will follow with seasonable temperatures and occasionally
breezy winds. Isolated showers and thunderstorms possible over the
Sierra and southern Cascades Saturday. Gusty northerly winds and
low relative humidity may bring elevated fire weather conditions
across the Sacramento Valley late weekend into early next week.

&&

.Key Messages...

* Today-Tuesday:
 -Light showers and mountain snow showers continue as a weather
  system moves through
 -50-80% probability of rain > 0.25" mainly across northern
  Sacramento Valley, northern Sierra north of Hwy 50, and adjacent
  foothills
 -15-35% probability of isolated thunderstorms today and Tuesday,
  highest chances across north/central Sacramento Valley,
  foothills and mountains. Thunderstorm chances on Tuesday will
  be over the Sierra foothills and mountains.
 -10-50% probability of 2" snow along the Sierra above 5500 feet,
  70-90% probability in the southern Cascades/Lassen Peak

* Mid to Late Week:
 -Dry weather, seasonable temperatures and occasionally breezy
  winds
 -Light showers and isolated thunderstorms (10-20% probability)
  across the Sierra Saturday afternoon and evening.

* Sunday - Monday:
 -Elevated fire weather conditions as gusty northerly winds and
  low relative humidity overlap in the Sacramento Valley
 -Probability of gusts 40 mph or higher: 30-50% along and west of
  I-5 in the Sacramento Valley. Strongest winds on Sunday.

.Changes from previous forecast...
 -Showers and thunderstorm chances possible over the Sierra and
  southern Cascades Saturday afternoon and evening.

&&

.AVIATION...

VFR conditions across all TAF sites next 24 hours. Gusty
southerly wind gusts 25-30 kts in the lower elevations, and 30-40
kts gusts over the Sierra out of the southwest until 06z Tuesday.
There is a 10-35% chance of isolated thunderstorms across the
northern Sacramento Valley, foothills, and mountains until 06z
Tuesday and again 18z Tuesday-03z Wednesday over the foothills
and Sierra/Southern Cascades, with periods of MVFR conditions.
Gusty and erratic winds near thunderstorms.

&&

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

$$