National Weather Service Weather Forecast Office

• Home
• Site Map
• News
• Organization
• Search for: NWS All NOAA 

472
FXUS66 KSTO 181205
AFDSTO

Area Forecast Discussion
National Weather Service Sacramento CA
405 AM PST Sun Nov 18 2018



.SYNOPSIS...
Dry with near to above normal daytime temperatures and cool
nights through early next week with smoke in the valley due to
the Camp Wildfire. Breezy northeasterly winds over the Sierra
Nevada today bringing increased fire weather concerns. Cooler
temperatures next week with a series of wet systems the middle to
end of next week. Snow over the higher elevations of the Sierra
for possible travel difficulties during Thanksgiving travel
weekend.

&&

.DISCUSSION...
High pressure ridge over the west coast bringing dry stable
conditions to the forecast area. A near 5 mb surface gradient from
Reno to Sacramento bringing localized breezy east winds to the
Sierra and foothills. Jarbo Gap in Butte county is showing gusts
up into the 20s and combined with dry conditions will create
increased fire weather concerns. Therefore, Red Flag warning for
Sierra and Foothills will remain in place today. Lighter winds in
the central valley combined with stable conditions under the
ridge allowing smoke to hang in under the valley inversion. Winds
are not expected to be very strong in the valley today so smoke
is likely to hang in much of the day. Very little change is
expected in the weather pattern on Monday as the upper ridge axis
shifts just east of the state. Winds will be light under the ridge
so smoke from the Camp fire will continue to be a issue depending
on smoke production from the fire. With ridge axis shifting east
of the region...temperatures may drop a degree or two but
otherwise little change is expected. Upper ridge axis continues to
shift eastward on Tuesday an a significant Pacific frontal system
approaches the coast. Overall airmass only changes slightly but
varying amounts of high cloud cover may bring temperature changes
Tuesday. Most significant change on Tuesday will be a shift to a
more onshore flow. With any luck this onshore flow will be strong
enough to scour out some of the valley smoke that has plagued the
valley for over a week. Initial frontal band moves onshore
Tuesday night bringing light rain to the coast range. Current
timing pushes the frontal band inland on Wednesday spreading rain
and snow across the entire forecast area during the day. Snow
levels drop low enough Wednesday afternoon that Sierra passes may
be impacted during major holiday travel.

&&
.EXTENDED DISCUSSION (Thursday THROUGH Sunday)

A major pattern change is in effect for next week with a series
of wet storms from mid to late week as the persistent high
pressure ridge is finally displaced to the east. This will bring
periods of precipitation to the area, though with some breaks at
times. This will likely cause travel problems due to wet roads,
local ponding on roads with clogged storm drains, and accumulating
snow in the mountains during the Thanksgiving travel period.
Potentially drier weather returns next weekend.
&&

.AVIATION...

Widespread MVFR with local IFR likely to continue in the Central
Valley the next 24 hours as smoke from the Camp Fire persists. VFR
conditions elsewhere. Generally light winds at TAF sites. Local
east wind gusts northern Sierra Nevada thru 18Z.
&&

.STO WATCHES/WARNINGS/ADVISORIES...
Red Flag Warning until 4 PM PST this afternoon for 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.

&&

$$