Shasta Lake, California 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

363
FXUS66 KSTO 222028
AFDSTO

Area Forecast Discussion
National Weather Service Sacramento CA
1228 PM PST Fri Nov 22 2024

.SYNOPSIS...
Day 3 of a strong Atmospheric River will continue to bring
moderate to heavy rain to the area through tonight. Heavy snow is
then expected over the Sierra off and on through Tuesday morning
above 6000 feet. Rain chances will slowly decrease over the valley
with dry conditions by early next week through Thanksgiving.

*Winter Storm Warning: From 4 PM Today through 4 PM Tuesday for
 elevations above 6000 feet along the Sierra/ Southern Cascades
 including Interstate 80 and Highway 50.

*Flood Watch: Through 4 AM Tonight for Valley/foothills locations
 generally north Interstate 80 and below 3000 feet.
.DISCUSSION...
The last wave of energy and moisture from the strong atmospheric
river system will continue to push across the area for the
remainder of the night into Saturday morning. The AR will stall
out a bit over the I-80 corridor late this afternoon and evening
and will likely bring some urban and small stream flooding but
overall high impacts not expected. We have issued an urban and
small stream advisory for these expected impacts. This main bulk
of rain tonight will be further south then the first 2 days of the
storm which should help with overall impacts. Also tonight as the
main push of moisture moves across snow levels will be up around
7000 feet but will quickly drop down to around 5000 feet by
Saturday morning. This snow will continue most of the day
Saturday. At lower elevations Saturday precipitation will take a
break with better chances in foothills with upslope westerly flow.

There will also likely be at least some thunderstorm activity
Saturday as we should get some clearing in the valley allowing
things to destabilize a bit. At this time looks like main threat
would remain south of Park Fire burn scar...but may have to take a
closer look tonight and tomorrow for burn scar risk.

Saturday night through Sunday...our Winter Storm Warning will
continue but we should see a break in heavier snow.

Monday...upper energy remain off shore and flow amplifies a bit to
pull some higher precipitable water northward into our area yet
again. Overall...this will result in an uptick in snow above 5500
once again.


.EXTENDED DISCUSSION (Tuesday THROUGH Friday)...

Ensembles in good agreement that last of the upper energy will
finally push across NorCal. This will result in yet another day of
higher level snow in the Sierra bringing totals generally 1 to 3
feet with around 4 at highest elevations. Significant
accumulations should remain above 6000 feet.

Wednesday and beyond NorCal will be in a general dry northwest
flow aloft which will result in dry conditions and temperatures in
the mid 50s to around 60. A mild low impact Thanksgiving looks on
track at this time. Rasch
&&

.AVIATION...
Moderate to locally heavy precipitation continues to move across
the region resulting in periods of VFR/MVFR/IFR conditions across
the Valley and foothills with areas of IFR/LIFR in the mountains.
Conditions are expected to improve after 10Z Saturday and going
into Saturday. Gusty southerly winds will continue, with gusts of
20 to 40 kts in the Valley and foothills, and 30 to 50 kts over
the Sierra. Winds are expected to decrease for the next 24 hours
but remain breezy through the day with gusts 15-30 kts in the
Valley by the evening.


&&

.STO WATCHES/WARNINGS/ADVISORIES...
Flood Watch through late tonight for Central Sacramento Valley-
Mountains Southwestern Shasta County to Western Colusa County-
Northeast Foothills/Sacramento Valley-Northern Sacramento Valley-
Shasta Lake Area / Northern Shasta County.

Winter Storm Warning from 4 PM this afternoon to 4 PM PST
Tuesday for West Slope Northern Sierra Nevada-Western Plumas
County/Lassen Park.

&&

$$