000
FXUS66 KSTO 062056
AFDSTO

Area Forecast Discussion
National Weather Service Sacramento CA
156 PM PDT Thu May 6 2021


.SYNOPSIS...
Cooling trend through tomorrow. Increased north winds and warmer
into the weekend and early next week with elevated fire weather
concerns. Dry weather continues.

&&

.DISCUSSION...
A few high clouds are noted in the northwest portion of the CWA just
ahead of the trough this afternoon; elsewhere, mostly clear skies
prevail. Some breezy onshore winds are being seen across the area as
well, with the strongest gusts remaining in the vicinity of the
Delta. Highs will be anywhere from 5 to 10 degrees cooler than those
of yesterday.

The main trough axis passes overhead early tomorrow with even cooler
temperatures expected, although still remaining slightly above
average for early May. Winds shift to offshore tomorrow with this
pattern remaining over the weekend into next week.

The trough across the northern Rockies and Great Basin over the
weekend will (once again) act to tighten surface pressure gradients
bringing a period of gusty north to east winds to the area. The
strongest winds look to be on Saturday with gusts in the Valley
peaking from 30 to 40 mph in the morning into the afternoon. Gusty
winds continue on Sunday, although coverage may be a bit less
widespread with the strongest winds mainly in the northern and
western portions of the Sacramento Valley.

Relative humidity values will also be extremely low this weekend
with Valley locations expected to drop into the single digits. Poor
overnight recoveries will also be seen. Due to these winds, low RH
values, and dry fuels, elevated fire weather concerns will be seen
throughout the weekend into early next week. A Fire Weather Watch
has been issued beginning early Saturday. Avoid using outdoor
equipment that could create a spark and obey local burn bans.

The return of warmer temperatures is also expected this weekend as
upper level ridging moves back over Northern California.

&&

.EXTENDED DISCUSSION (Monday THROUGH Thursday)...
Ensemble guidance indicates continued breezy and dry conditions
Monday as the low pressure system that is forecast to tighten
pressure gradients this weekend moves off to our east. Thereafter,
building high pressure over the region will lead to warming
temperatures and continued dry weather. High temperatures are
expected to be 10-20 degrees above average. Also, areas along the
thermal belts in the foothills could see mild overnight
temperatures in the upper 50s to low 60s. By mid- week we could
see an increased Delta Breeze.

&&

.AVIATION...
VFR conditions next 24 hours. Surface wind gusts 15 to 20 kts
Valley terminals. Gusts 25 to 30 kts Carquinez Strait and Delta.
Winds decreasing after 6 UTC. Except, gusts 25 to 35 kts Sierra
Nevada persist into Friday.

&&

.STO WATCHES/WARNINGS/ADVISORIES...
Fire Weather Watch from Saturday morning through Monday
afternoon for Carquinez Strait and Delta-Central Sacramento
Valley in Glenn, Colusa, Yuba, Northern Sutter, and Butte County
Below 1000 Ft-Eastern Mendocino NF-Eastern Portion of
Shasta/Trinity NF-Northern Motherlode From 1000 to 3000 Ft.
Includes portions of Nevada-Yuba-Placer-Amador and ElDorado
Units-Northern Sacramento Valley to Southern Tehama County Line
Below 1000 Ft-Northern San Joaquin Valley in San Joaquin and
Stanislaus Counties Below 1000 ft-Northern Sierra Foothills from
1000 to 3000 Ft. Includes portions of Shasta-Trinity and Butte
Units-Southeast Edge Shasta-Trinity NF and Western Portions of
Tehama-Glenn Unit-Southern Motherlode From 1000 to 3000 Ft.
Includes portions of Calaveras-Tuolumne Unit-Southern Sacramento
Valley in Yolo-Sacramento Far Western Placer, southern Sutter
and Solano County Below 1000 Ft.

&&

$$