587
FXUS66 KSTO 062118
AFDSTO

Area Forecast Discussion
National Weather Service Sacramento CA
218 PM PDT Fri Jun 6 2025


.DISCUSSION...

.SYNOPSIS...
Warm-up expected through the weekend with Moderate HeatRisk. Triple
digit temperatures and areas of Major HeatRisk expected in parts
of the northern Sacramento Valley Sunday-Monday. Periodically
breezy winds continuing into next week. Daily afternoon/evening
mountain thunderstorm chances (10-30%) will continue today and
Saturday over the High Sierra south of Highway 50. Thunderstorm
chances expand northward into Sunday into Monday. Minor cooling
expected by mid-week.

&&

.KEY MESSAGES...

* Today-Tuesday:

 -Warming trend into early next week with Moderate HeatRisk. Areas
  of areas of Major HeatRisk across the northern Sacramento Valley
  Sunday-Monday.

 -Periodically breezy onshore flow in the Delta and vicinity
  during the afternoons and evenings.

 --Probability of Valley High Temperatures > 95F:
  ---Northern/Central Sacramento Valley: 75-100%
  ---Delta, S. Sacramento Valley, N. San Joaquin Valley: 20-50%

 --Probability of Valley High Temperatures > 100F:
  ---Northern/Central Sacramento Valley: 40-90%, Saturday-Monday
   (highest chances on Sunday-Monday)

 -Chances for isolated afternoon/early evening mountain showers
  and thunderstorms:
--Today-Saturday: 15-30%, south of US 50 along the Sierra Crest
--Sunday-Monday: 10-30%, over the northern Coastal Range,
      southern Cascades and the Sierra
    --Tuesday: 10-20% across Shasta County mountains

* Wednesday-Thursday:
 -Minor cooling trend along with areas of Moderate HeatRisk
  persist across portions of the northern/central Sacramento
  Valley.
 -Periods of breezy winds, mainly in the afternoons and evenings.

.Changes from previous forecast...

 -Areas of Major HeatRisk in the northern Sacramento Valley are
  expected through Monday.
 -Mountain thunderstorm chances may linger through Tuesday
  afternoon in Shasta County.

&&

.AVIATION...
VFR conditions prevail over interior NorCal next 24 hours.
Surface winds generally below 12 kts, vicinity of the Delta where
surface winds could get up to 25 kts between 22Z Friday and 12Z
Saturday. Additionally, there is a 15-25% chance of isolated
showers or thunderstorms over the Sierra south of US 50 until 03Z
Saturday.

&&

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

$$