Area Forecast Discussion
Issued by NWS Sacramento, CA

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FXUS66 KSTO 262043
AFDSTO

Area Forecast Discussion
National Weather Service Sacramento CA
143 PM PDT Tue Mar 26 2024

.Synopsis...
Dry conditions through Wednesday AM before the first of two
weather systems bring periods of mountain snow, widespread rain,
breezy winds, and thunderstorm chances. The first storm is
expected Wednesday into Thursday morning, and the second from
Friday into Saturday morning.

&&

.Discussion...
Today and tomorrow, the currently dry and calm conditions will
continue, with highs expected to reach the mid 60s in the Valley,
and into the 50s in the foothills, and 50s in the mountains.
Beginning Wednesday, unsettled weather returns, bringing mountain
snow, widespread rain, breezy winds, and potential for thunderstorms
with it. Earliest precipitation will occur in the morning over
the northern Sacramento Valley, followed by the mountains in the
late morning/early afternoon, and eventually the remainder of the
Valley. Moderate to heavy snow is expected overnight in the
mountains at elevations above 5500 ft.

To this point, we have issued a Winter Storm Warning for areas above
5500 ft in the Sierra and southern Cascades from 11 AM Wednesday to
11 AM Thursday. Moderate to heavy snow and gusty winds are expected
during this time period, with snow totals around 6 to 12 inches (2
ft at highest peaks). While this is a low-end Warning event,
moderate travel impacts are still to be expected due to snow-covered
roads, chain controls, and winds gusting up to 45 mph. Be sure to be
prepared if you must travel during this time period! Pack your car
with an extra flashlight, food, and water in case of an emergency.
The National Blend of Models (NBM) is currently showing a 30 to 70%
probability of at least 8 inches of snow above 5500 ft between
Wednesday and Thursday. As for rainfall totals, the WPC is
currently projecting somewhere between 0.25 inches (50 to 80%
probability) and 0.5 inches (20 to 60% probability) for most of
the Valley, with Shasta County and the foothills and mountains
below snow level expecting closer to 1 inch (50 to 90%
probability) to 1.5 inches (25 to 65% probability). Additionally,
thunderstorm chances return with this system (10-20% probability),
primarily between I-80 and Redding in the Valley and foothills.

After a brief respite on Thursday afternoon from the rain and snow,
Friday morning will see additional widespread precipitation. Snow
rates over the course of Friday will be similar to those that occur
overnight on Wednesday into Thursday, and weekend travel will once
again be impacted by the effects of the storm. Given that this
weekend is also a holiday weekend and a larger number of people may
try to travel , it is especially important to use caution if you
must travel through the mountains. Currently, the WPC is
predicting a 40 to 65% probability of at least 8 inches of snow
above 5000 ft on Friday, with some additional snow expected on
Saturday. Lower elevations can expect Friday rainfall totals to
fall somewhere between 0.25 inches (60 to 85% probability) and
0.75 inches (20 to 70% probability), with highest totals occurring
in Shasta County as well as the foothills and lower elevations in
the mountains. //SP

&&

.EXTENDED DISCUSSION (Saturday THROUGH Tuesday)...
Ensembles and clusters show an upper level low dropping southward
along the coast and moving into SoCal late weekend into early
next week. Moderate to heavy snow will persist through Saturday
morning, with snowfall rates up to 1" at times. By Saturday
afternoon, lighter snowfall accumulations are expected with
generally 3-6 inches of snow over the Sierra. Isolated
thunderstorms are possible on Saturday, as depicted by the EFI
signal and NBM probabilities (15-25% chance in the Valley and
foothills). Best chances are expected from I-80 southward. Main
storm hazards are brief heavy rain, lightning, gusty winds, and
small hail. Lingering light showers are anticipated on Sunday,
mainly over the foothills and mountains with little to no impacts.
Drier conditions and northerly flow are favored by early next
week behind the passage of this system. A gradual warming trend is
expected early next week, with Valley high temperatures reaching
into the mid 60s by Monday and upper 60s to low 70s by Tuesday.

&&

.AVIATION...
Scattered MVFR in diurnal cumulus throughout the Valley into this
evening becomes predominantly VFR overnight. Weather system
arriving Wednesday then brings lowering cigs early Wednesday
morning through 18z Wednesday. Light winds, less than 12 kts,
prevail today, becoming more southerly and sustained by early
Wednesday morning. Gusts to 20 to 25 kts then anticipated at RDD
and RBL after 12z.

&&

.STO WATCHES/WARNINGS/ADVISORIES...
Winter Storm Warning from 11 AM Wednesday to 11 AM PDT Thursday
for West Slope Northern Sierra Nevada-Western Plumas
County/Lassen Park.

&&

$$


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