000
FXUS66 KSTO 112023
AFDSTO

Area Forecast Discussion
National Weather Service Sacramento CA
123 PM PDT Thu Apr 11 2024

.Synopsis...
Mild and mostly dry weather continues through today. Slight chance
of isolated thunderstorms this evening with more unsettled weather
Friday through Sunday bringing light to moderate mountain snow,
rain, and gusty winds.

&&

.Discussion...
Looking at satellite late this morning, weather conditions
continue to be relatively benign outside of scattered clouds over
the Sierra and portions of the Coastal Range. Our upper-level
ridge that has provided us our recent warm, dry stretch slides
eastward as an upper-level low from the Gulf of Alaska makes its
way down towards the Central CA coast today before moving inland.
Today will the last warm day of the week with temperatures in the
low 80s across the Valley cooling to the low 60s by Sunday as more
inclement weather and cloud cover develops.

We will start seeing initial impacts from the trough today as
there is the potential for isolated thunderstorms across the
Northern Sacramento Valley, mainly east of Redding. NBM
probability shows a 10-20% chance of thunderstorm development for
areas north of Red Bluff in the Northern Sacramento Valley. There
isn`t an overwhelming amount of conditions supporting substantial
thunderstorm development with the shear profile being west-
southwesterly, and the incoming system being a drier system.
However, there may be enough moisture advection, southerly
component to the winds, and energy from the system to support
very localized showers and an isolated thunderstorm. With any
storm that develops, small hail, lighting, brief heavy rainfall,
gusty winds, and lightning are all possible impacts. Current
higher resolution models don`t indicate any impactful development
with current HRRR maintaining our drier pattern today.

With the incoming system, light to moderate snowfall is
forecasted, beginning late night Friday through Sunday morning
across the mountains. Snow levels initially will be 5000 to 6750
feet lowering to 3500 to 5000 feet by Saturday afternoon. Impacts
will be minor with NBM probability showing a 10-40% chance of
LTDAFDSTOexceeding 4 inches over the Sierra, up to 65% south of
Hwy. 50 and near the Lassen National Park Area. Heaviest snowfall
will be Saturday morning for areas south of Hwy 50. and Saturday
night into early Sunday morning for areas north of Hwy 50.

Precipitation will start along the west side of the Valley,
moving down the mountains and Valley throughout Friday evening.
Periods of light to moderate rainfall will continue through Sunday
morning but impacts will be minor. Friday brings another chance
for thunderstorm development (15-30% chance), primarily south of
I-80 and over the Coastal Range. Forecasted totals from Friday
morning to Sunday morning is 0.50-1.00" in the Valley with
0.75-1.50" over the foothills and mountains. NBM probability shows
a 10-45% chance of exceeding 0.50" with a 50-90% chance of the
foothills and mountains, highest north of I-80 and in the Northern
Sacramento Valley. Rain in the Valley tapers off Saturday
evening, with dry conditions by Sunday late morning.

Sunday will see lingering showers over the foothills and light
snowfall over the Sierra with conditions quietening by Sunday
night.

&&

.EXTENDED DISCUSSION (Monday THROUGH Thursday)...

Ensembles still point to northerly flow developing as a ridge
moves through NorCal. With this, temperatures warm with drying
conditions over the area. Monday afternoon highs warm to upper
60s, low 70s across the Valley and continue through much of next
week. Gusty north winds are expected along and west of I-5 with
gusts 15 to 35 MPH, beginning early Tuesday morning. Strongest
winds look to be Tuesday afternoon through Wednesday afternoon
before tapering off by Thursday morning. NBM probabilities show a
30 to 60 percent chance of wind gusts exceeding 40 MPH over the
Sierra and along and west of I-5, north of Sacramento Tuesday and
Wednesday.

&&

.AVIATION...

VFR conditions next 24 hours except vicinity except brief local
MVFR possible isolated showers or thunderstorms over mountains
north of KRDD 00Z-06Z Friday, and then more widespread scattered
shower potential after 12z and isolated thunderstorms after 18z.
Surface winds generally less than 12 kts through 18z Friday,
followed by breezy southerly winds 12-20 kts with gusts up to
22-30 kts.
&&

.STO WATCHES/WARNINGS/ADVISORIES...
None.
&&

$$