Weather Service Report


593 
FXUS66 KSTO 151025
AFDSTO

Area Forecast Discussion
National Weather Service Sacramento CA
325 AM PDT Mon Oct 15 2018

.SYNOPSIS... 
Gusty wind with lowering humidity will continue critical fire 
weather concerns today. Dry weather with above average high 
temperatures continues this week.

&&

.DISCUSSION...
Satellite imagery indicates the area of strongest subsidence is
presently over NorCal on the backside of the upper trough digging
southward through the Great Basin toward SoCal. Northeasterly
surface pressure gradients topped out Sunday evening around 5 mbs
RDD-SAC and 12.5 mbs RNO-SAC, and have tapered a bit since.
Currently still seeing quite a few wind gusts in the 30-40 mph 
range through the foothills, Coast Range and northern Sierra with
a couple spots reporting gusts around 50 mph. Winds in the
Sacramento Valley are mostly in the 15-30 mph range.

The gusty winds will continue for several more hours before
beginning to subside after sunrise. Lighter winds are expected by
this afternoon.

Dry weather with mild days and cool nights will continue through
the week. East winds will pick up again tonight in the northern
Sierra as easterly gradients linger, but won't be as strong.

The combination of winds and low humidity has resulted in critical 
fire weather conditions. A Red Flag Warning remains in effect 
through this evening. Lighter northerly flow will continue on 
Tuesday and fire weather conditions may continue to be an issue  
with little improvement in humidity levels. This will have to be 
closely monitored.

&&

.EXTENDED DISCUSSION (Friday THROUGH Monday)
Ridge of high pressure over the eastern Pacific is anticipated to
shift onshore late this week, continuing the dry weather pattern 
across interior NorCal. Daytime temperatures will be 5-10 degrees 
above normal, with Valley highs in the 80s. Model guidance is 
suggesting the potential for unsettled weather early next week, as
an upper trough approaches the West Coast. However, confidence is
low this far out. Stay tuned.

&&

.AVIATION...
VFR conditions next 24 hours. Winds 10 to 15 knots across the 
Central Valley, with local gusts up to 20 kts mainly through 18z-
20z Monday. Local E to NE wind gusts up to 30-45 kts over higher 
terrain, decreasing to 25-30 kts after 19z Monday.

&&

.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-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-Lake County Portion of Lake-Napa-Sonoma 
Unit-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 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.

Wind Advisory until 11 AM PDT this morning for Burney Basin / 
Eastern Shasta County-Clear Lake/Southern Lake County-Motherlode-
Mountains Southwestern Shasta County to Northern Lake County-
Northeast Foothills/Sacramento Valley-Shasta Lake Area / 
Northern Shasta County-West Slope Northern Sierra Nevada-Western 
Plumas County/Lassen Park.

&&

$$

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Western Regional Climate Center, wrcc@dri.edu