177
FXUS66 KSTO 282141
AFDSTO

Area Forecast Discussion
National Weather Service Sacramento CA
241 PM PDT Mon Sep 28 2020


.SYNOPSIS...
Critical fire weather conditions continue through this evening due
to dry weather and breezy winds. Above normal temperatures and dry
conditions continue through much of the week, although smoke may
make a return due to new wildfire starts.

&&

.DISCUSSION...
Gusty winds continue this afternoon with the western side of the
Valley seeing some gusts up to 25 mph and the eastern foothills
seeing gusts from 20-35 mph (with the strongest gust noted at Jarbo
Gap at 49 mph early this afternoon). These winds are expected to
decrease later this evening, although some locally breezy winds will
continue across the eastern foothills through the early morning
hours. With the extremely dry conditions and gusty winds, critical
fire weather conditions and the Red Flag Warning will persist
through the evening.

A high amplitude ridge will remain over the West Coast through the
week bringing above average temperatures to much of the Valley and
surrounding foothills. Highs each afternoon are forecast to be
roughly 10-15 degrees above normal for late September/early October.
Areas of moderate heat risk are expected each afternoon though
Thursday. The one hindrance could be the return of wildfire smoke
due to onshore winds returning and new wildfires across the area.
HRRRx guidance supports the return of smoke and haze in the Valley
which, if dense, may bring high temperatures down a few degrees or
more.

&&

.EXTENDED DISCUSSION (Friday THROUGH Monday)...
Dry weather and a cooling trend are expected Friday into the
weekend. Upper ridging overhead Friday slowly weakens through the
weekend as mesoscale offshore upper low approaches California
Sunday and lingers along the coast early next week. Friday looks
to be the warmest day with Valley highs still in the mid to upper
90s, cooling to the low 90s and upper 80s Saturday and Sunday.
Mountain highs generally remain in the 70s. With some new
wildfires early in the week, highs may be impacted by any local
dense smoke.

&&

.AVIATION...
VFR conds ovr intr NorCal nxt 24 hrs exc lcl MVFR conds in HZ/FU
poss vcnty of wild fires. Nly sfc gsts up to 30 kts poss in Cntrl
Vly mnly N of KSMF tda til abt 02z. Lcl of N-E sfc wnd gsts up to
30 kts poss in fthls/mtns, mnly I-80 N, til 06z Tue.


&&

.STO WATCHES/WARNINGS/ADVISORIES...
Red Flag Warning until 9 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-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-Northern Sierra
Including Lassen NP and Plumas and Lassen NF/S West of the
Sierra Crest (West of Evans Peak-Grizzly Peak-Beckworth Peak)-
Northern Sierra Including the Tahoe and ElDorado NF/S West of
the Sierra Crest-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-Stanislaus NF
West of the Sierra Crest.

&&

$$