Red Flag Warning 4, NWS Sacramento, CA

667 
WWUS86 KSTO 051030
RFWSTO

URGENT - FIRE WEATHER MESSAGE
National Weather Service Sacramento CA
330 AM PDT Thu Sep 5 2019

CAZ213-214-263-266-268-279-051130-
/O.CAN.KSTO.FW.W.0004.000000T0000Z-190905T1800Z/
Eastern Portion of Shasta/Trinity NF-
Burney Basin and Northeast Plateau in Shasta County Including
Northwest Lassen NF north of Lassen NP-Southeast Edge Shasta-
Trinity NF and Western Portions of Tehama-Glenn Unit-
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)-Eastern Mendocino NF-
330 AM PDT Thu Sep 5 2019

...RED FLAG WARNING IS CANCELLED FOR LIGHTNING FOR FIRE WEATHER 
ZONES 213, 214, 263, 266, 268, AND 279...

The National Weather Service in Sacramento has cancelled the Red
Flag Warning. 

Isolated thunderstorms accompanied by wetting rain will be
possible this morning.

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$$

Area Forecast Discussion
National Weather Service Sacramento CA
335 AM PDT Wed Sep 4 2019

.SYNOPSIS...
Afternoon mountain thunderstorms possible today and Thursday.
Above normal temperatures today and Thursday. followed by near or
below normal temperatures late this week into next week

&&

.DISCUSSION...
Upper flow over Norcal becoming more southerly today as an upper
low over the eastern Pacific digs towards the coast. Isolated
monsoon type thunderstorms formed over the Sierra just south of
the CWA on Tuesday so a chance of showers or thunderstorms over
the northern Sierra today looks good as upper flow shifts.
Shortwave disturbances pivoting northward in this southerly flow
may bring isolated showers or thunderstorms over the coast range
today as well. Moisture progs indicate that main moisture is still
above 700 mb so rainfall with any thunderstorms will be limited.
RH values are expected to remain moderate and thunderstorm
coverage will be limited so fire impacts should be limited as
well. Not expecting a significant change in airmass today so
expect daytime highs should come in similar to Tuesday with
daytime highs a few to several degrees above normal.

Instability shifts northward tonight and Thursday so shower and
thunderstorm threat shifts northward as well bringing a
thunderstorm threat to the Shasta county mountains. This threat
will continue through the day Thursday as the offshore upper low
shifts to the northeast towards the Pacific Northwest. Thursday
will likely see a little cooling most places but highs will still
remain above normal.

Flat upper ridging returns on Friday for a temporary end to the
mountain shower threat and a little more cooling. Another Pacific
trough approaches the north coast on Saturday bringing daytime
highs down to below normal for the first time in a quite a while.
Could see a few showers over the Shasta county mountains Saturday
night as this system clips through Norcal.

&&

.EXTENDED DISCUSSION (Sunday THROUGH Wednesday)...

Troughing will bring cooler weather to the region on Sunday, in
addition to isolated showers and thunderstorms over northern
Sierra and Cascades. Deterministic models aren't the most excited
about this opportunity, but ensemble guidance remains persistent.
At this time, we've opted to keep the precip chance as showers
instead of thunderstorms, but as we get closer to the day there's
a chance we could see more favorable convective parameters.

Beyond Sunday and into early next week, high temperatures are
forecast to be below normal.

&&

.AVIATION...

Mainly VFR conditions are expected across northern California
today. There will be chances for showers and thunderstorms in the
mountains this afternoon and evening, which may drop ceilings and
visibility at times. Some vicinity showers and/or thunderstorms
could reach KRDD and KRBL.

&&

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