Area Forecast Discussion
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FXUS66 KSTO 142222

Area Forecast Discussion
National Weather Service Sacramento CA
322 PM PDT Sat Sep 14 2019

Hot and dry weather today. Pattern change will lead to
significantly cooler temperatures and a chance of showers and
thunderstorms early next week. Another system could bring
additional mountain showers by midweek.


Hot and dry conditions continue across interior NorCal this
afternoon under upper level ridging. Afternoon temperatures are
similar to yesterday, and today`s highs will peak around 5 to 10
degrees above average, with Valley highs in the mid to upper 90s.

Significant pattern change develops Sunday into early next week as
an upper level trough deepens over the West Coast. Main impacts
will be significantly cooler temperatures, gusty winds over the
Sierra, and precipitation chances. Breezy to gusty winds will
develop ahead of the trough on Sunday, especially near the Sierra
crest with gusts in the 30 to 40 mph range. These gusty winds
could lead to enhanced fire weather concerns over the Sierra on
Sunday, though this event is anticipated to be short-lived. In
addition, the expected precipitation should help mitigate fire
weather concerns. Cooling trend begins Sunday, with daytime
temperatures around 5 to 10 degrees cooler than Saturday.

Ensemble models continue to bring precipitation over the Coastal
Range, Shasta County, and the northern Sacramento Valley by late
Sunday night/early Monday, then gradually spreading southward
during the day Monday as the trough moves inland. QPF amounts will
range from around 0.10 to 0.30 in the Valley, and up to 0.75 over
higher terrain with locally higher amounts possible. Model
guidance suggests possible thunderstorm development Monday
afternoon, mainly north of I-80. Snow levels should remain
relatively high as bulk of precip moves in during the day, though
a couple inches are possible over the higher terrain of Lassen
Park and the Central Sierra. High temperatures on Monday are
expected to be as much as 10 to 25 degrees below normal.

Precipitation activity diminishes Tuesday as the trough shifts
into the Great Basin. Tuesday high temperatures will be 5 to 15
degrees below normal, generally in the upper 70s to low 80s across
Valley locations.


It appears the period of wet weather may continue into the middle
of the week as another Gulf of Alaska system takes aim at the
West Coast. Compared to the previous couple days of model runs,
there has been a definitive southward trend favoring another round
of precipitation and cooler weather. Details will likely change
but have increased shower chances and lowered temperatures in the
forecast package. Currently expecting the best rainfall chances
over the mountains and foothills, generally north of Highway 50.
Some of this could reach the Valley, especially Tehama county
northward. Snow levels are likely to drop to around 7,500 to 8,000
feet on Thursday which could bring light accumulations to the
higher terrain. Overall temperatures will remain below average
with Valley highs in the mid to upper 70s while a warm up is
expected Friday and into the weekend. This is in response to a
building ridge along the West Coast which holds on through at
least next Saturday (Sep 21). ~BRO


VFR conditions next 24 hours. Local surface wind gusts 15-20 kts
thru 02Z northern Sacramento Valley and higher elevations northern
Sierra Nevada. &&


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