Area Forecast Discussion
Issued by NWS Sacramento, CA

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FXUS66 KSTO 261010
AFDSTO

Area Forecast Discussion
National Weather Service Sacramento CA
310 AM PDT Tue Mar 26 2024

.Synopsis...
Dry conditions through Wednesday AM before a weather system moves
in midweek bringing mountain snow, widespread rain, breezy winds,
and thunderstorm chances.

&&

.Discussion...
Dry conditions continue today with quiet weather conditions.
Afternoon highs in the Valley will be mid 60s with 50s and 40s
across the foothills and mountains respectively. The pattern
shifts Wednesday as a weather system brings mountain snow,
widespread rain, breezy winds, and thunderstorm chances.
Precipitation begins over the mountains and Northern Sacramento
Valley Wednesday morning before pushing into the Valley later that
afternoon and evening. A Winter Storm Warning has been issued for
the Sierra from Wednesday 11 AM until Thursday 11 AM for periods
of heavy snow and gusty winds above 5500 feet. 6 to 12 inches up
to 2 feet at the highest peaks is expected with moderate travel
impacts from delays, snow-covered roads, and chain controls and
winds gusting as high as 45 MPH. Probabilities show a 30-70%
chance of at least 8 inches above 5500 feet. Snow levels start at
5000 to 6000 feet, then lower to 3500 to 4500 feet on Thursday.
This will be a low- end warning event but still could see impacts
on the commutes that evening and morning of the next day. If you
must travel, keep an extra flashlight, food, and water in your
vehicle in case of an emergency!

The National Blend of Models (NBM) indicates a 40-90% chance of
rain totals greater than 0.50" from Sacramento northward in the
Valley for Wednesday and Thursday with highest chances as you move
north in the Valley. Wednesday will see breezy south winds with
strongest winds in the northeast foothills area. Additionally,
Wednesday and Thursday brings thunderstorm chances (10-20%) to
the Valley and foothills with best chances of development north of
I-80 to Redding in the afternoon and evening hours. Forecasted
CAPE values aren`t impressive but there is some additional support
from the upper- level divergence as the jet streak and low
pressure system moves southward.

Past Thursday morning, conditions lull with lingering mountain
snow showers and minor snow accumulations. The next wave of
weather will begin late Friday morning and continue into the
weekend. This will be a similar weather impact storm as the
Wednesday-Thursday system bringing mountain snow, widespread rain,
breezy winds, and thunderstorm chances. NBM probabilities indict
a 40-60% chance of snow totals exceeding 6 inches above 5000 feet
Friday into early Saturday morning. Snow levels with this system
will be 4000 to 5500 feet. Additionally, the NBM shows a 50-70%
chance of rain totals exceeding 0.25" for that same time frame in
the Valley.

&&

.EXTENDED DISCUSSION (Saturday THROUGH Tuesday)...

Ensemble guidance and cluster analysis are generally in agreement
for the upper level low to drop down along the western US
Coastline before moving into Southern California later this
weekend or early next week. Saturday will see continued
widespread light rain, moderate to heavy mountain snow, and
breezy winds. Saturday will be the lighter portion of the weather
system with only 3-6 inches forecasted broadly over the Sierra,
heaviest south of Hwy. 50. Rain showers will be light with Valley
amounts under a quarter of an inch and an half inch in the
foothills. There is a chance for isolated thunderstorms with the
NBM showing a 10-25% chance, highest south of I-80. With any
thunderstorm development impacts include brief heavy rain showers,
lightning, gusty winds, small hail, and possible funnel clouds.
Drier conditions and northerly flow are favored by Sunday or
Monday behind the passage of this system although there is a
chance for some lingering light snow showers over the Sierra on
Sunday.

&&

.AVIATION...

General VFR conditions expected across much of interior NorCal
next 24 hours. Surface winds generally remaining below 12 knots.

&&

.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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