214
FXUS66 KSTO 220910
AFDSTO

Area Forecast Discussion
National Weather Service Sacramento CA
210 AM PDT Sat Jun 22 2024

.SYNOPSIS...
Dry weather continues. The hottest temperatures of the week are
expected today with widespread triple digits, moderate HeatRisk,
and areas of Major HeatRisk. Beginning Sunday and into next week,
temperatures will cool off slightly but will remain above to
near normal.

&&

Key Points
- Widespread Moderate HeatRisk is expected today and Sunday, with
areas of Major HeatRisk today. Areas of Moderate HeatRisk remain in
the Valley Monday through Wednesday.
- A Heat Advisory is in effect from 11 am to 8 pm Saturday with
Widespread Moderate HeatRisk and areas of Major HeatRisk in the
Valley and foothills on Saturday; Highs in the triple digits.

Short-Term Discussion (Today THROUGH Tuesday)...
The upper level ridge continues to build today as it moves
eastward over the Desert Southwest, with daytime and overnight
temperatures throughout interior NorCal increasing again. Highs
in the Valley are expected to reach triple digits today, with
highs in the foothills expected to be in the 90s to low 100s, and
the 80s to 90s in the mountains. Moderate HeatRisk is expected
over the majority of the Valley, though there are some areas of
Major HeatRisk in the foothills, and portions of the central and
southern Sacramento Valley and northern San Joaquin Valley. Much
of the southern Sacramento Valley is spared from higher daytime
and overnight temperatures, and therefore HeatRisk, by onshore
flow from the Delta. Nonetheless, Moderate HeatRisk remains across
much of interior NorCal through Sunday.

A trough moving in from the Pacific will increase onshore flow and
keep temperatures somewhat moderated on Monday and Tuesday. This
leaves us with primarily Minor HeatRisk (with some areas of Moderate
HeatRisk) throughout the Valley, and Valley highs generally at or
below 100 degrees. The NBM has probabilities of hitting 100
degrees or more at the start of the week around 30-65% in the
northern and central Sacramento Valley, and 20-55% along the
eastern half of the southern Sacramento Valley and northern San
Joaquin Valley.

&&

.EXTENDED DISCUSSION (Wednesday THROUGH Saturday)...
Ensembles and Clusters indicate troughing will continue through
Friday, meaning onshore flow will continue to modulate
temperatures in locations adjacent to the Delta. Despite this, areas
of Moderate HeatRisk will cover portions of the Valley still on
Wednesday, with the NBM showing a 30 to 65% probability of
temperatures reaching or surpassing 100 degrees. On Thursday, as
the trough continues over our area, only widespread Minor HeatRisk
will remain on both Thursday and Friday. Temperatures in the
Valley will remain around the low to high 90s, and in the
foothills and mountains in the 80s and 70s respectively. On
Saturday, clusters are in some disagreement about the movement of
the trough, so NBM shows potential for temperatures falling
anywhere between below normal to well above normal over the
weekend.

&&

.AVIATION...
VFR conditions next 24 hours. Sustained wind will generally be
below 12 kts except local southwest gusts 15-25 kts vicinity west
Delta and areas of southerly gusts 15-20 kts in the Sacramento
Valley 22Z thru about 03Z Sunday.

&&

.STO WATCHES/WARNINGS/ADVISORIES...
Heat Advisory from 11 AM this morning to 8 PM PDT this evening
for Central Sacramento Valley-Motherlode-Mountains Southwestern
Shasta County to Western Colusa County-Northern Sacramento
Valley-Northern San Joaquin Valley-Southern Sacramento Valley.

&&

$$