083
FXUS66 KSTO 141755
AFDSTO
Area Forecast Discussion
National Weather Service Sacramento CA
1055 AM PDT Tue Jul 14 2026
For additional details on weather and expected impacts over the
next 7 days, please visit weather.gov/sto/briefing.
.KEY MESSAGES...
- Elevated Fire Weather conditions due to mountain thunderstorm
chances today.
- Widespread Moderate HeatRisk today and Wednesday, then cooler
temperatures in most of the Valley beginning Thursday.
- Monsoonal moisture and thunderstorm chances return this weekend.
&&
.DISCUSSION...
500mb pattern aloft continues to bring southerly flow through
California increasing our moisture aloft and elevated
instability. HIRES guidance shows the development of thunderstorms
in the Coastal Range, Shasta county, southern Cascades, and
through the Sierra this afternoon and evening. Likely timeframe of
development and chances are 20z through 5z where elevated
instability is highest. A majority of the thunderstorms will be
wet, but a few could be dry. Inverted "V" soundings within the
mountains through the 700mb level show the potential for those dry
thunderstorms. Fuel conditions and stronger winds bring the
elevated chance for fire weather concerns for the mountains due to
the dry thunderstorm chances. There is a chance a few storms may
be on the stronger side producing gusty outflow winds, small hail,
frequent lightning, and in some cases brief heavier rainfall. A
few storms may develop in the northern Sacramento Valley into the
foothills as well, but chances are less than 20 percent at this
time. Guidance continues to trend downward on the threat of
nocturnal thunderstorms with chances less than 10 percent for the
mountains tonight into Wednesday morning. Instability is lacking
in the overnight hours to help fuel continuing thunderstorm
chances.
We will continue with the elevated fire weather concerns today due
to the dry thunderstorm chances in the mountains. There is further
chances for elevated fire weather concerns on Wednesday in
portions of the southern Sacramento Valley and northern San
Joaquin Valley due to increased winds through the terrain coupled
with the low RH values.
There does exist the chance for further thunderstorm chances in
the Sierra Wednesday afternoon and evening from lingering
moisture and elevated instability. Chances are less than 20
percent at this time. A few of the storms could be dry and we will
continue to monitor closely. Otherwise, we will see widespread
moderate HeatRisk today and tomorrow across the area, with areas
seeing triple digit heat.
Thursday and Friday, onshore flow will increase helping to cool
conditions off for parts of the Valley. Temperatures are expected
to be in the upper 80s to 90s Thursday through Friday, with the
warmest conditions in the northern Sacramento Valley.
Further into the weekend, we may see additional monsoonal moisture
surges into the area, with PWAT values approaching roughly 160
percent of normal by Saturday. With a ridge developing near the
Four Corners region by the weekend, this setup will once again
favor afternoon/evening mountain precipitation chances. Elevated
instability in the mountains brings the chance for thunderstorms
as well over the weekend. We will continue to monitor for the
chance of a few dry thunderstorms during this time, and how far
into the Valley the thunderstorms develop.
&&
.AVIATION...
VFR conditions prevail through the TAF period, with FEW to SCT
clouds moving in this afternoon and evening. Chance for VCTS or
isolated thunderstorms around RBL and RDD this afternoon and
evening, but chances are less than 15 percent. Onshore flow later
this evening and overnight for the Sacramento sites, MOD, and
SCK. Clearing conditions overnight and into tomorrow morning, with
light and variable winds.
&&
.STO WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
