NWS Area Weather Forecast Discussion
County Warning Area [CWA]: STO Regional NWS Weather Office: Sacramento, CA
FXUS66 KSTO 110945
Area Forecast Discussion
National Weather Service Sacramento CA
245 AM PDT Tue May 11 2021
Breezy north winds and dry conditions will lead to another day of
critical fire weather conditions. The warming trend continues
through mid- week. Lighter onshore winds and cooling temperatures
are expected for late week. Some mountain showers and
thunderstorms are possible for the weekend.
Critical fire weather conditions today and hot temperatures are
the main weather issues through the short term. The Red Flag
Warning remains in effect for the west side of the Valley and
areas below 2000 feet as breezy north winds hold and warm and dry
conditions prevail. Gusts will generally be in the 20 and 30 mph
range; however, favored gaps and canyons may observe gusts up to
35 mph at times this morning. Thankfully, the trough that brought
us gusty winds the last few days will continue to push eastward
which will allow the winds to ease.
In addition to fire weather concerns, increasing temperatures will
be observed for the first half of the week. Widespread low to mid
90s are expected for the Valley on today and Wednesday. Wednesday
should be the hottest day of the week for most areas, except for
Delta influenced locations such as the Sacramento metro area,
which could see highs a couple degrees lower than Tuesday. In
terms of Heat Risk, there are areas of orange/moderate heat risk
forecast for portions of the Valley and foothills, especially by
mid week. Be sure to practice heat safety.
Onshore flow and the Delta Breeze are anticipated to set up on
Wednesday and should bring some relief to the Delta and the
Sacramento area. Overnight temperatures there are forecast to
drop into the low to mid 50s.
By Friday guidance shows troughing setting up over the West Coast.
This should bring a reprieve in temperatures for much of northern
California. NBM guidance hints at a slight chance of showers and
thunderstorms over the mountains Friday night into Saturday.
Timing and location may change with this feature and associated
light precip, while cooler weather remains likely.
.EXTENDED DISCUSSION (Saturday THROUGH Tuesday)...
Ridging centered over the eastern Pacific forecast to weaken
briefly over NorCal on Saturday as a system quickly drops
southward. The system will close off to our south late in the
weekend and early next week as high pressure rebuilds over NorCal.
A brief cool down will be possible Saturday along with a few late
day showers and thunderstorms over the northern Sierra. Dry
weather and a little warmer temperatures return early next week.
VFR conditions next 24 hours. Local northerly surface wind gusts
15-25 kts Sacramento Valley and surrounding terrain until 20Z.
Local southwesterly surface wind gusts develop in the west Delta
after 00Z Wednesday.
Red Flag Warning until 6 PM PDT this evening for Carquinez
Strait and Delta-Central Sacramento Valley in Glenn, Colusa,
Yuba, Northern Sutter, and Butte County Below 1000 Ft-Eastern
Mendocino NF-Northern Sacramento Valley to Southern Tehama
County Line Below 1000 Ft-Northern San Joaquin Valley in San
Joaquin and Stanislaus Counties Below 1000 ft-Southeast Edge
Shasta-Trinity NF and Western Portions of Tehama-Glenn Unit-
Southern Sacramento Valley in Yolo-Sacramento Far Western
Placer, southern Sutter and Solano County Below 1000 Ft.