NWS Sacramento, CA wrote its last area forecast discussion before the first event at Feb 29, 2:00 PM PST, 10 hours earlier.
Area forecast discussion, Feb 29, 2:00 PM PST, 10 hours before
Area Forecast Discussion
National Weather Service Sacramento CA
200 PM PST Thu Feb 29 2024
.Synopsis...
Major Winter Storm impacting area today through the weekend,
bringing widespread precipitation, extremely heavy mountain snow
with blizzard conditions, strong winds, and low elevation
(1500-3000) snow accumulations.
&&
.Discussion...today through Sunday.
Key points of late week-weekend storm:
* Extremely heavy snow with BLIZZARD CONDITIONS expected in the
Sierra, heaviest this afternoon through Saturday. Storm total
snowfall into early Sunday is currently projected at 5 to 10+
feet for elevations above 5,000 feet, locally higher amounts of
12+ feet are possible at peaks, with significant disruptions to
daily life likely.
* Mountain travel will be extremely dangerous to impossible,
especially this afternoon through Saturday.
* Significant snow accumulations are expected above 3000 feet.
Cold air will drop snow levels down to 1000-2000 by the
weekend, with light accumulations possible at those levels.
* Wind gusts to 55 to 75 mph are expected over the mountains.
Expect snow rates of 2-4+" per hour. These will combine to bring
whiteout conditions with near zero visibility at times beginning
today, but especially Friday and Saturday.
* Strong winds are forecast in the Central Valley with gusts of
40 to 55 mph from Yuba City northward today, and from Modesto
northward on Friday.
---------------------------------------------------------------
Active weather prevails across interior NorCal this afternoon. At
1203 PM, a strong line of showers and thunderstorms was observed
near Redding into Red Bluff, with several observed lightning
strikes recorded and gusty winds around 50 mph. Snowfall in the
Sierra began early this morning, with several roadways requiring
chain controls this afternoon, as snowfall has continued and is
covering roadways. Conditions are expected to continue to
deteriorate as we move through the afternoon and evening.
Extremely dangerous to impossible mountain travel is expected
into the weekend. A Blizzard Warning has been issued for the
Northeast Foothills, Motherlode, Sierra, and Western Plumas/Lassen
area above 2000 feet and a Winter Storm Warning has been issued
for the Coastal Range, Shasta County Mountains, and Burney Basin.
Snow rates of 2-4+" inches are expected, with road closures,
white-out conditions and near zero visibilities at times. Very
strong winds, combined with very heavy snowfall could cause
extensive tree damage and extended power outages. Blizzard
conditions are expected through Saturday. Snow levels will start
out around 5000 to 6000 feet today, lowering to 3000 to 4500 feet
Friday, then down to 1000 to 2000 feet Saturday. Total snowfall
will be measured in feet from this event, with the National Blend
of Models (NBM) suggesting 12 feet or more of accumulating
snowfall or more in the Sierra. Afternoon model runs continue to
increase snowfall totals along the Sierra. Areas along I-5 in
Shasta County will likely see up to a foot of snow or more, so
significant travel delays and road closures are possible.
Gusty winds will also bring moderate impacts to the region through
Friday. Strongest winds will be north of Sacramento today, but
will likely spread south on Friday as the next wave moves through.
A Wind Advisory remains in effect for the central and northern
Sacramento Valley through 4AM PST Saturday morning. The Wind
Advisory will expand to include the northern San Joaquin Valley
and southern Sacramento Valley at 10 AM PST Friday through 4 AM
Saturday.
Thunderstorms have been observed with a strong line of storms from
Redding to Orland this afternoon, and will remain possible today
as the initial front moves south this afternoon and evening. The
EC Extreme Forecast Index (EFI) highlights areas in interior
NorCal for potential thunderstorm development tomorrow and
Saturday, and the NBM supports a slight chance (10-25%) for
T-storm development mainly in the Valley and Foothills in the
afternoon and evening. Hazards from any T-storms that develop will
include additional gusty winds, small hail, brief heavy rain and
lightning. Rainfall for the Valley still looks to remain below
1.50" inches, with higher amounts of 2.00 to 4.00" inches in the
Foothills and the mountains around 4.00 to 8.00" inches with
locally heavier amounts, through Saturday night.
Additional snowfall is likely after the warnings have ended Sunday
morning. We remain in west-northwesterly flow which will allow
moisture and cold air to continue to move into the area. Most of
the impacts will be felt in the Sierra, Southern Cascades, Coastal
Range, and the Foothills, with limited Valley rainfall thanks to
shadowing. Snow levels on Sunday could be as low as 1500 feet in
the Sierra, and around 1000 feet in Shasta County. Additional
snowfall may hamper blizzard recoveries.
*Mountain travel is HIGHLY discouraged while the warnings are in
effect!*
Wood
&&
.EXTENDED DISCUSSION (Monday THROUGH Thursday)...
The start of next week is looking at the passage of a secondary
storm system as a shortwave trough moves over the area. This
storm will be less impactful than the weekend storm, though
moderate snow is still expected above 3500 ft through Wednesday,
and may cause additional travel delays early next week. Currently
the NBM is projecting a 30 to 55% probability of at least 12
inches of snow between 3500 and 5000 ft, and a 55 to 65%
probability of at least 12 inches above 5000 ft between Monday and
Wednesday. Additionally, there is a 40 to 55% probability of at
least 18 inches of snow above 5000 ft during the course of the
storm.
Valley precipitation will be more limited, with most rain
occurring in the northern Sacramento Valley and northern
foothills. NBM is currently projecting a 35 to 50% probability of
0.25 inches of rain or more in the northern San Joaquin Valley and
majority of the Sacramento Valley, with a 40-70% probability of
at least a half inch in the northern Sacramento Valley. Most rain
in the Valley will occur Tuesday and Wednesday. Thursday and
beyond there is still quite a bit of uncertainty in the ensembles,
with some solutions showing a trough remaining over the area and
others showing ridging. Be sure to check back in for updates to
the forecast! //SP
&&
.AVIATION...
Widespread MVFR/IFR with areas LIFR over the mtns next 24 hrs as
Pac storm moves inland. In Central Vly, Sly sfc wind 15-30 kts
with lcl gusts up to 45 knots. Over mtns, areas SWly sfc wind
gusts 40-60 kts. Isolated -tsra possible in N San Joaquin Vly
btwn 22z-04z.
&&
.STO WATCHES/WARNINGS/ADVISORIES...
Winter Storm Warning until 10 AM PST Sunday for Burney Basin /
Eastern Shasta County-Mountains Southwestern Shasta County to
Western Colusa County-Shasta Lake Area / Northern Shasta County.
Wind Advisory until 4 AM PST Saturday for Carquinez Strait and
Delta-Central Sacramento Valley-Motherlode-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.
Blizzard Warning until 10 AM PST Sunday for Motherlode-Northeast
Foothills/Sacramento Valley-West Slope Northern Sierra Nevada-
Western Plumas County/Lassen Park.
&&