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732
FXUS66 KSTO 142119
AFDSTO

Area Forecast Discussion
National Weather Service Sacramento CA
219 PM PDT Fri Jun 14 2024

.SYNOPSIS...
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Critical fire weather conditions likely Saturday night through
Sunday night across the Sacramento Valley due to gusty northerly
winds and low relative humidity. Seasonable temperatures and dry
conditions continue over the next several days.
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.DISCUSSION...

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Key Points
- A Red Flag Warning is in effect from 11 PM Saturday - 8 PM
  Sunday across the majority of the Sacramento Valley due to low
  daytime relative humidity, gusty northerly winds, and poor
  overnight recoveries.
- Northerly winds continue early next week maintaining some
  locally elevated fire weather conditions Monday and Tuesday

Short-Term Discussion (Today THROUGH Monday)...

Afternoon GOES-18 Satellite imagery reveals mostly clear skies
across interior NorCal. Temperatures are currently running in the
upper 70s to upper 80s across the Valley and mid 60s to upper 70s
in the Foothills/mountains. Temperatures are forecast to reach the
low to mid 90s for the Valley as we approach the maximum of
daytime heating. As we move into the weekend, a trough will slide
into the PacNW and introduce stronger pressure gradients around
the area, which will increase northerly wind speeds across the
Valley. The trough`s main moisture pool will be to the north of
our area, so there is no precipitation expected in our region. On
Sunday, the northwesterly flow will become stronger as the trough
phases with a closed low in Canada, where our heights will be in
a more northwesterly flow.

Critical fire weather conditions are expected to develop late
Saturday night through Sunday evening in the Valley due to gusty
northerly winds and low relative humidity (RH) values. Strongest
winds are expected in the western Sacramento Valley, where the
National Blend of Models (NBM) is projecting around 20-45%
probability of wind gusts reaching 40 mph. Recent NBM runs have
backed off slightly on the sustained and gusty winds, however low
RH values in the teens, along with poor overnight recoveries
Saturday will still lead to critical fire weather conditions.
These conditions have warranted a Red Flag Warning to be issued
from 11 PM Saturday night through 8 PM Sunday, when the gustiest
winds and lowest RH values are anticipated. Elevated fire weather
conditions will persist into Monday, as we will keep breezy
northerly winds and low RH values through the start of the work
week.

High temperatures during the short term are expected to remain
seasonal,with highs in the mid 80s to low 90s today through Monday
for the Valley. The trough aloft and onshore flow in the Delta
will promote cooling overnight in the Valley, with low
temperatures in the 50s to low 60s.
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.EXTENDED DISCUSSION (Tuesday THROUGH Friday)...

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Ensembles and clusters show upper level low gradually weakening
over the Great Basin Region through next week, bringing periods of
breezy winds at times over interior NorCal. Periods of northerly
winds may bring elevated fire weather concerns through early next
week. NBM guidance depicts Valley high temperatures gradually
climbing into the 90s mid to late next, with mid 80s to low 90s
over the foothills.
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.AVIATION...

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VFR conditions over interior NorCal next 24 hours. Southerly
surface winds up to 20 knots in the southern Sacramento Valley,
northwesterly winds up to 20 knots in the northern San Joaquin
Valley until around 06Z Saturday. Onshore surface winds of 15-25
knots in Delta with isolated gusts up to 30 knots.
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.STO WATCHES/WARNINGS/ADVISORIES...
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Red Flag Warning from 11 PM Saturday to 8 PM PDT Sunday for
Central Sacramento Valley in Glenn, Colusa, Yuba, Northern
Sutter, and Butte County Below 1000 Ft-Eastern Mendocino NF-
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.
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