696
FXUS66 KSTO 072005
AFDSTO

Area Forecast Discussion
National Weather Service Sacramento CA
105 PM PDT Sun Jul 7 2024

.SYNOPSIS...
Although temperatures will remain seasonably hot, a very gradual
cooling trend is anticipated throughout the week ahead, with day to
day fluctuations in HeatRisk across the region. Dry conditions will
also result in a continuation of elevated fire weather concerns
alongside the hot temperatures.

&&

Key Points
- Long-duration, dangerous heat event persists into the week ahead,
  impacting outdoor events.
- Excessive Heat Warning remains in effect for the Valley, Delta
  and foothills through 11 PM Tuesday.
- Heat Advisory remains in effect for the Sierra, southern
  Cascades, and Burney Basin until 11 PM Tuesday.

.Discussion...
Another day of sunny skies is evident across interior NorCal on
latest GOES-West satellite imagery. Temperatures are running a few
degrees cooler than yesterday around this time, but still sit in the
90s to triple digits throughout the Valley and foothills. Generally
light winds prevail, but are expected to become breezier, especially
within the Delta and vicinity, through the afternoon and early
evening hours. This diurnal wind pattern is expected to continue to
varying degrees throughout the week and with already dry antecedent
conditions, elevated fire weather concerns remain today through the
week ahead. Otherwise, high temperatures well into the triple digits
to low 110s are expected across the Valley and foothills by the end
of the day, with 90s to low triple digits persisting along the
Sierra and Delta as well.

Moving into the early week ahead, a slowly progressing shortwave
still looks to move through the flow pattern Monday into Tuesday.
This will work to push the ridge slightly eastward, while also
flattening the ridge somewhat as well, introducing a slight
lowering of heights aloft. Additionally, this shortwave will help
reinforce slightly stronger onshore flow to the region across the
early week period. These factors together will culminate in a
brief period of comparatively cooler temperatures for interior
NorCal, most notably for the Delta, central/southern Sacramento
Valley, and northern San Joaquin Valley, where the greatest Delta
breeze influence is anticipated.

High temperatures on Monday and Tuesday generally look to fall into
the triple digits below 110F for most Valley and foothills
locations, with even some potential (30 to 60% probability) to drop
out of the triple digits entirely across the aforementioned cooler
areas by Tuesday afternoon. Attendant HeatRisk looks to drop to
Moderate in these locations and along the Sierra, with Major and
areas of Extreme HeatRisk persisting in the northern Sacramento
Valley and foothills locations. Following the early week shortwave
passage, heights look to rise once again as the ridge builds a bit
over the Great Basin. A resultant warm up is then expected across
the midweek period, with high temperatures well into the triple
digits throughout the Valley and foothills once again by Wednesday
afternoon. Corresponding areas of increasing Major HeatRisk are
expected for much of interior NorCal as areas of Extreme HeatRisk
persist in the thermal belts of the foothills as well.

&&

.EXTENDED DISCUSSION (Thursday THROUGH Sunday)...

Ensemble guidance continues to indicate rising heights aloft into
Thursday before broad troughing begins to build in from Friday
into next weekend. This will lead to another day of widespread
Valley and foothills high temperatures well into the triple
digits, with attendant widespread Major HeatRisk and areas of
Extreme HeatRisk on Thursday as well. Cluster analysis does depict
some uncertainty in the exact timing of the broad troughing
introduction and attendant eastward shift of the Great Basin ridge
on Friday. As a result, the more appreciable cool down may be
more confined to the weekend with cooler, but still above normal,
temperatures hanging on through Friday. There is then increasing
ensemble agreement on cooling temperatures through next weekend,
with generally 70 to 90% probabilities of high temperatures less
than 100F for most Valley and foothills locations outside of the
northern Sacramento Valley.

&&

.AVIATION...

VFR conditions over interior NorCal next 24 hrs. Sfc wind mainly
at or below 12 kts except south to west gusts in the afternoon for
the Valley and in the vicinity of the Delta up to 15-25 kts.

&&

.STO WATCHES/WARNINGS/ADVISORIES...
Excessive Heat Warning until 11 PM PDT Tuesday for Carquinez
Strait and Delta-Central Sacramento Valley-Motherlode-Mountains
Southwestern Shasta County to Western Colusa County-Northeast
Foothills/Sacramento Valley-Northern Sacramento Valley-Northern
San Joaquin Valley-Shasta Lake Area / Northern Shasta County-
Southern Sacramento Valley.

Heat Advisory until 11 PM PDT Tuesday for Burney Basin / Eastern
Shasta County-West Slope Northern Sierra Nevada-Western Plumas
County/Lassen Park.

&&

$$