North San Juan, California 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

525
FXUS66 KSTO 071003
AFDSTO

Area Forecast Discussion
National Weather Service Sacramento CA
303 AM PDT Mon Oct 7 2024

.Synopsis...
Hot weather continues today for the region, along with a slight
(5-15%) chance of showers along the Sierra Crest. Temperatures
begin to gradually cool tomorrow, with continued cooling through
the week. Chance of showers across the area late week and into the
weekend.

.Discussion...
Temperatures are still relatively warm across the area at the time
of this discussion, with low to mid 70s currently observed. Hot
weather is expected once again today around interior NorCal, as
upper level ridging will dominate the synoptic pattern today. High
temperatures will be in the upper 90s to triple digits with
widespread Moderate to Major HeatRisk across the Valley and
Foothills. With the oppressive heat continuing, we have extended
the Heat Advisory to continue today until 11 PM. A weak embedded
trough will also move through the area later today, which will
promote around a 5-15% chance of showers across the higher
elevations of the Sierra, mainly along and south of I-80. With the
weak trough`s arrival this evening, we will start to see
temperatures slightly falling on Tuesday, with highs in the mid to
upper 90s across the Valley and 80s for the higher elevations.
Offshore troughing will begin to develop, and the Delta Breeze
and its cooling affect will make a triumphant return Tuesday
evening, helping lower overnight temperatures and reducing the
HeatRisk for Tuesday.

Wednesday, the upper level pattern flattens out into a more
westerly component, with weak troughing in SoCal, which will
further allow onshore flow to help cool the areas that experienced
the early October heat. High temperatures will struggle to hit 90,
as the NBM is advertising around a 10-20% chance of hitting 90,
with the highest probabilities in the northern Sacramento Valley.
While the cooling on Wednesday will be welcomed, the temperatures
will still be 5-10 degrees warmer than climatologically normal for
early October in NorCal. Daytime humidity values will also
recover thanks to onshore flow, with values in the upper 20s to
mid 30s on Wednesday.

Continued cooling is expected on Thursday, where widespread 80s
are forecast for the Valley. In fact, the NBM suggest less than 5%
chances across the entire warning area of temperatures less than
90. With the continued cooling, the area will finally start to see
close to normal Fall temperatures. Our heights will continue to
lower, as troughing in the PacNW begins to move south and the
ridge that was responsible for our summer like temperatures will
no longer be impacting the weather pattern.

&&

.EXTENDED DISCUSSION (Friday THROUGH Monday)...

Ensemble guidance and cluster analysis continues to show a trough
from the eastern Pacific approaching on Friday. This will bring
relatively cooler temperatures, near to slightly above normal for
Friday, then slightly below normal to normal on Saturday. Sunday
could see some temperatures trending a little warmer, but there is
significant uncertainty in how quickly the trough will exit or
weaken. The track and timing of the trough also impacts the
potential for precipitation over the areas. Overall, The latest
National Blended Model (NBM) is showing the potential for
precipitation (15-30% chance) gradually spreading into the
northern Coastal Range late Friday and reaching as far south as
I-80 by Saturday morning. Generally light precipitation is
expected. The best potential (25-35% chance) for rain total
amounts of 0.10" of more is over the northern Coastal Range and
the Shasta County. There is 15-25% chance over the rest of the
Sacramento Valley down to the Sacramento metro area and for the
Delta and the Sierra north of I-80. Dry weather is currently
projected to return by late Saturday night.

Breezy northerly winds are possible at times, but increased
humidity with the trough should act to limit fire weather
concerns.

&&

.AVIATION...

VFR conditions are expected over interior northern California for
the next 24 hours with surface winds are generally below 12
knots.
&&

.STO WATCHES/WARNINGS/ADVISORIES...
Heat Advisory until 11 PM PDT this evening for Carquinez Strait
and Delta-Central Sacramento Valley-Motherlode-Northern San
Joaquin Valley-Southern Sacramento Valley.

&&

$$