Wildfire in California, September 1 to 30, 2021

Area Forecast Discussion
National Weather Service Sacramento CA
158 PM PDT Tue Aug 31 2021

.SYNOPSIS...
Gusty southwest winds will result in critical fire weather
conditions over portions of the northern Sierra and southern
Cascades through tomorrow. Cooler temperatures expected through
Thursday, with a warming trend returning Friday into the weekend.

&&

.DISCUSSION...
Winds have increased early this afternoon over higher terrain with
widespread gusts ranging from 15 to 30 mph reported, locally higher.
The fire plume from the Caldor Fire is noted on radar, with visible
satellite showing a defined pyrocumulus cloud over the area. To the
north, the Dixie continues to burn hot with smoke plumes bringing
widespread smoke to areas northeast of the fire. Humidity values
this afternoon are reaching into the single digits and teens in much
of the mountains and foothills, with higher values noted in the
Valley near Delta influenced areas. A Red Flag Warning continues for
the Northern Sierra and Southern Cascades through tonight due to
these dry conditions and winds.

The trough located over British Columbia deepens slightly tonight
and tomorrow bringing continued gusty winds tomorrow, mainly in the
afternoon and evening. The strongest winds look to continue mainly
over the Northern Sierra this day, and this is where the Red Flag
Warning continues through tomorrow evening due to the potential for
the rapid spread of new of existing wildfires. Gusts tomorrow may be
slightly less than today, although still may see some gusts from 20
to 25 mph, with the highest values on ridgetops.

As for smoke, it looks to linger in portions of the northern and
central Valley through at least tomorrow, along with anywhere near
area wildfires. Winds become a bit lighter and more terrain driven
Thursday and Friday which may lead to smoke or haze in the
foothills/Valley, especially in the mornings.

Finally, temperatures cool around 8 to 12 degrees below normal
tomorrow, with only slightly warmer temperatures on Thursday. A
warming trend to slightly above normal temperatures begins on Friday
and continues into the weekend.

&&

.EXTENDED DISCUSSION (Saturday THROUGH Tuesday)...
Ensemble guidance is in decent agreement high pressure will build
over the region throughout the extended forecast period. A low
pressure area is also forecast to cut off offshore from Southern
California. This low is expected to weaken and remain offshore.
Therefore, decent confidence in a gradual warming trend into next
week is forecast over Northern California.

&&

.AVIATION...
MVFR to IFR at times for the northern Sacramento Valley terminals
next 24 hrs due to area wildfire smoke. VFR expected at other
Valley terminals. MVFR to locally IFR possible near active
wildfires, particularly over the Sierra. Gusts 15 to 30 kts
vicinity Delta and high Sierra. Elsewhere, winds generally under
12 kts.

&&

.STO WATCHES/WARNINGS/ADVISORIES...
Red Flag Warning until 11 PM PDT this evening for Burney Basin
and Northeast Plateau in Shasta County Including Northwest
Lassen NF north of Lassen NP-Eastern Portion of Shasta/Trinity
NF-Northern Motherlode From 1000 to 3000 Ft. Includes portions
of Nevada-Yuba-Placer-Amador and ElDorado Units-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-Southern
Motherlode From 1000 to 3000 Ft. Includes portions of Calaveras-
Tuolumne Unit-Stanislaus NF West of the Sierra Crest.

&&