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000 
FXUS66 KSTO 202329
AFDSTO

Area Forecast Discussion
National Weather Service Sacramento CA
329 PM PST Wed Nov 20 2019


.SYNOPSIS... 
Breezy winds and isolated mountain showers in to the overnight.
Quieter weather to end the week into the weekend. 

&&

.DISCUSSION...
The upper level low is currently located over SoCal and is slowly
pushing off to the east. The current SAC to MFR gradient is 
around 12 mb and we are seeing breezy winds with gusts up to 45 
mph down the Valley and in some of the higher elevations. The 
breezy winds will continue for the next few hours but we will 
start to see them let up some this evening as the gradient 
weakens. 

Easterly flow and upper level energy are bringing some light
showers to the east slope of the Sierra and the Sierra crest south
of I-80. The majority of the showers will stay off to our east but
some light activity will continue to be possible into the
overnight mainly along the crest.  

Quieter weather will set in by Thursday afternoon as a ridge 
builds in. Highs will be near to a bit above average the next few
days. 

-CJM

&&

.EXTENDED DISCUSSION (Sunday THROUGH Wednesday)...

A broad east-west oriented ridge will remain overhead for Sunday
ensuring another day of mild, dry conditions. High temperatures
across the Valley and Delta should reach the mid/upper 60s with
even a couple low 70s toward Red Bluff and Redding. This is
approximately 6 to 12 degrees above typical late November
climatology. At night, high pressure will ensure calm winds which
supports optimal radiational cooling effects. This will take lows
into the 30s and low 40s over the Valley, foothills, and Delta.

Global ensembles continue to advertise a pair of systems to impact
the region during the Monday through Wednesday (November 25-27)
timeframe. To start the week, another amplified shortwave is
expected to move from the Pacific Northwest into the central
Rockies. This setup would enhance height/pressure gradients
allowing for a period of dry, northerly winds on Monday into early
Tuesday. Given extremely dry fuels, elevated fire weather concerns
will need to be monitored.

Moving into the Tuesday/Wednesday period, model guidance continues
to advertise an upper trough tracking into the West Coast. With
the stagnant ridge over the east Pacific retrograding west, this
may allow the trough to bring well needed precipitation back to
the region. Ensemble spread is around average with some dry
members keeping the precipitation to the north. Based on the
latest models, have maintained cooling temperatures along with
increasing precipitation chances. This includes mountain snows
which will continue to be monitored given busy Thanksgiving travel
over the major thoroughfare. ~BRO

&&

.AVIATION...

VFR conditions expected the next 24 hours with gusty winds 
continuing into the evening. KRDD and KRBL can expect the
strongest northerly wind gusts, generally around 25-35 knots
through 03Z Thursday, with breezy conditions into the Sacramento
area. The northern San Joaquin Valley TAF sites could see gusts 
of 15-20 knots through 00Z Thursday. Lighter overnight winds may
bring local MVFR visibilities after 14Z to KSCK and KMOD. ~BRO

&&

.STO WATCHES/WARNINGS/ADVISORIES...
Red Flag Warning until 7 AM PST Thursday for Central Sacramento 
Valley in Glenn, Colusa, Yuba, Northern Sutter, and Butte County 
Below 1000 Ft-Eastern Mendocino NF-Eastern Portion of 
Shasta/Trinity NF-Lake County Portion of Lake-Napa-Sonoma Unit-
Northern Sacramento Valley to Southern Tehama County Line 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)-
Southeast Edge Shasta-Trinity NF and Western Portions of Tehama-
Glenn Unit-Southern Sacramento Valley in Yolo-Sacramento Far 
Western Placer, southern Sutter and Solano County Below 1000 Ft.

Wind Advisory until 10 PM PST this evening for Central 
Sacramento Valley-Clear Lake/Southern Lake County-Mountains 
Southwestern Shasta County to Northern Lake County-Northeast 
Foothills/Sacramento Valley-Northern Sacramento Valley-Shasta 
Lake Area / Northern Shasta County-Southern Sacramento Valley-
Western Plumas County/Lassen Park.

Winter Weather Advisory until 7 PM PST this evening for West 
Slope Northern Sierra Nevada.

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