FXUS66 KSTO 012023
AFDSTO

Area Forecast Discussion
National Weather Service Sacramento CA
123 PM PDT Sun Sep 1 2024

.SYNOPSIS...
Breezy to locally gusty winds, dry conditions, and seasonable
temperatures persist through Labor Day with a rapid warm up to
above normal temperatures and Moderate to locally Major HeatRisk
through Thursday. A late week disturbance then brings a slight
cool down and possibly some increasing precipitation potential
moving toward next weekend.

&&

.Discussion...
GOES-West satellite imagery as of early this afternoon shows
mostly clear skies once again across interior NorCal, with a thin
layer of smoke aloft still lingering. Additionally, a closed low
can be seen gradually moving eastward just off the shore of
northwestern California. Further inspection of low and mid level
water vapor imagery though indicates a distinct lack of moisture
advection toward interior NorCal at this time, which will limit
shower and thunderstorm potential. Rather, the primary impacts
will be from a few different periods of breezy to locally gusty
winds as the system progresses.

As the trough moves nearer to the coastline today, increasing
south to west winds are expected across the Valley and foothills
through early this evening. Gusts of 15 to 25 mph will be
possible, with a 40% to 70% probability of gusts to 30 mph across
the northern Sacramento Valley. The strongest wind potential then
shifts toward the Sierra crest as the trough progresses eastward
on Labor Day. As a result, wind gusts of 30 to 40 mph will be
possible along the Sierra crest on Labor Day, with attendant 40%
to 70% probabilities of gusts to 45 mph. As the trough continues
to eject eastward out of the region on Tuesday, surface winds are
expected to shift to a northerly direction across the Valley and
foothills. While the period of gustier northerly winds is expected
to be brief (under 6 hours), occasional gusts of 15 to 25 mph
will be possible from mid Tuesday morning through the mid
afternoon hours. Despite some moisture recovery across the region
tonight into Monday, generally dry conditions persist, with
potential for further lowering daytime humidities as the northerly
winds are induced on Tuesday. As a result, periods of locally
elevated fire weather conditions will be possible the remainder of
today through Tuesday.

Attendant temperatures will remain near to slightly below normal
through Labor Day as the aforementioned system moves through. The
exiting trough will then be rapidly followed by pronounced ridging
aloft building in by the middle of the week. This, in conjunction
with the typically warming northerly winds on Tuesday, will
result in high temperatures jumping to about 10 degrees warmer
than Monday, with an additional 4 to 7 degree rise on Wednesday.
Current probabilities of high temperatures exceeding 100F for
Valley and foothills locations on Tuesday sit around 20% to 40%
before rising to 60% to 80% on Wednesday. As a result, widespread
Moderate HeatRisk is expected, with some areas of Major HeatRisk
cropping up for the northern San Joaquin Valley and foothills
thermal belts by Wednesday.

&&

.EXTENDED DISCUSSION (Thursday THROUGH Sunday)...
Ensemble guidance continues to indicate ridging aloft persisting
into Thursday. As a result, another day of high temperatures in
the upper 90s to low triple digits is expected for the Valley and
foothills, with corresponding Moderate and areas of Major HeatRisk
remaining as well. There is now increasing confidence in broad
troughing building into the region by Friday as the ridge pushes
off to the east. While a pronounced cool down is not expected on
Friday, high temperatures do look to trend toward near normal
values by next weekend. Some precipitation activity may be
possible (primarily along the high elevation of the Sierra) as
well Friday into the weekend, but there remains a high degree of
uncertainty on the details of potential moisture advection at this
time.

&&

.AVIATION...
Clear skies and VFR conditions are expected across interior
Northern California over the next 24 hours. Southerly winds in the
Sacramento Valley will be at or slightly below 12 kts with gusts
15-25 kts between 21z-04z today. Sustained southwesterly winds
through the Delta will be 12-16 kts with gusts 20-30 kts through
20z Monday. There is also a 30-50% chance of ceilings less than
2000 ft in the Delta & Sacramento Valley between 09-16z tomorrow
morning.

&&

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

$$