NATIONAL WEATHER SERVICE FORECAST DISCUSSION
Area Forecast Discussion
Issued by The National Weather Service
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000
FXUS66 KSTO 172221
AFDSTO

Area Forecast Discussion
National Weather Service Sacramento CA
221 PM PST Sun Jan 17 2021

.SYNOPSIS...
Above normal temperatures and dry conditions are forecast to
prevail again today. Gusty north to east winds will develop
tonight and into Monday morning. Even stronger winds are expected
Monday night and into Tuesday. Temperatures will gradually cool
through the week with a chance of light mountain precipitation
returning late week.

&&

.DISCUSSION...
Another warm afternoon is being observed over interior northern
California. Temperatures currently span the mid 60s to the mid 70s
across the Valley with most sites likely climbing a couple more
degrees. In the foothills and mountains, temperatures are warm as
well and range from the 50s to the low 70s. In terms of records,
KRBL, KSAC (71 in 2014), Downtown Sacramento (DTS) (70 in 2009),
and KSCK (68 in 2009) have a chance at tying or breaking records.
KRBL`s record is 76 set back in 2014 and they`ve already broken
the record as they`re reporting out at 79 degrees.

Moving on to the more meaty portion of the forecast, the upcoming
wind event! A dry shortwave trough will dig into northern
California tonight and then travel down the coast, while high
pressure sits to the west of it. This will lead to the tightening
of pressure gradients over the region, allowing north to east
winds to increase tonight over west side of the Valley and in the
northeast foothills and mountains. Winds will remain strong and
gusty into mid-day Monday. Guidance continues to show a brief, but
still breezy reprieve Monday afternoon and evening; however, this
will be short lived.

By Monday night, a second shortwave will dig from the
Intermountain West and slide toward the central/southern Sierra
Nevada. This will enhance the first disturbance, which will
consequently lead to even stronger winds, especially across the
Sierra Crest. Hi-res and ensemble guidance continues to show a
core of 120+ winds at the 500mb level over the Sierra. This
supports earlier thinking of enhanced winds gusts in the 55-80
mph range, locally up to 90+ for the higher and/or more exposed
ridgetops. As a result, we ended up going with a High Wind Warning
from 10PM Monday - 7PM Tuesday for Western Plumas County, Lassen
National Park, and the West Slopes of the Sierra Nevada (zones 68
and 69). For the Valley, we ended up hoisting a Wind Advisory from
4AM Monday - 7PM Tuesday. Expect to see wind gusts in the 40 to
50 mph range. For those in the foothill locations, you`re not
completely out of the boat as winds will still be breezy with
gusts ranging from the 20-40 mph range. Strongest winds for
foothill locations will be in favored canyons, gaps, and ridges.

By Tuesday evening, winds will start to decrease, especially
across the Valley. Gusty winds are expected to linger over the
Sierra Tuesday night, weakening significantly by Wednesday
morning.

Over the course the first half of the week, temperatures will
gradually cool with highs returning the low/mid 60s in the Valley
by Wednesday.

&&
.EXTENDED DISCUSSION (Thursday THROUGH Sunday)...


Confidence remains high for a pattern change for the weekend as
upper level low slides the West Coast and into NorCal Friday into
Saturday. Cooler and more seasonal weather is in store for the
region, along with the chance for some precipitation over the
mountains. NBM guidance continues to depict a reasonable shot of
light precipitation Friday into Saturday morning, mainly over the
northern and eastern foothills and mountains. Weak ridging builds
in behind this trough, with unsettled weather looking likely from
Sunday into early next week.

&&

.AVIATION...


VFR conditions are expected for the next 24 hours with the exception
being some MVFR visbys possible at SCK/MOD after 06Z. Winds will
become gusty after 04Z for northern Sacramento Valley terminals,
with gusty winds up to 35 knots for all terminals after 18Z
Monday.

&&

.STO WATCHES/WARNINGS/ADVISORIES...
High Wind Warning from 10 PM Monday to 7 PM PST Tuesday for West
Slope Northern Sierra Nevada-Western Plumas County/Lassen Park.

Wind Advisory from 4 AM Monday to 7 PM PST Tuesday for Carquinez
Strait and Delta-Central Sacramento Valley-Mountains
Southwestern Shasta County to Western Colusa County-Northeast
Foothills/Sacramento Valley-Northern Sacramento Valley-Northern
San Joaquin Valley-Shasta Lake Area / Northern Shasta County-
Southern Sacramento Valley.

&&

$$
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