Area Forecast Discussion
Issued by NWS Sacramento, CA

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000
FXUS66 KSTO 120934
AFDSTO

Area Forecast Discussion
National Weather Service Sacramento CA
234 AM PDT Tue Mar 12 2024

.Synopsis...
Breezy winds and isolated, light showers continue through today.
Mild and dry weather then arrives mid to late week, with a period of
strong, gusty north to east winds from Wednesday afternoon through
Friday (strongest Wednesday evening through midday Thursday). The
warming trend then continues through the weekend and into early next
week.

&&

As of early this morning, isolated to scattered light showers are
ongoing across interior NorCal. This activity looks to become more
isolated through the morning, with only a few spotty showers
possible through this afternoon. Additional precipitation through
today will be minor impact at most, with up to a few hundredths
possible throughout the Valley and foothills and up to 0.25"
possible over the Sierra. Snow levels remain fairly steady, around
4500` to 6000`, keeping additional accumulations confined to
around 5000` and above. Heaviest snowfall is expected to occur
early this morning, but despite this, snowfall totals will remain
rather light. At this time, additional snowfall accumulations of 2
to 6" will be possible, with locally higher totals at highest
peaks. A breezy south-southwesterly wind will also persist into
the afternoon, with gusts to 25 mph across the northern Sacramento
Valley and adjacent foothills, and gusts to 35 mph over the
Sierra.

Otherwise, by the afternoon, aside from a stray shower here or
there, quieter weather is expected for most, with winds trending
downward throughout the day. Mostly cloudy skies should begin to
clear by late afternoon/early evening as the system exits the region
and heights aloft begin to rise. While cloud cover will keep high
temperatures today similar to yesterday, the overnight clearing will
work to bring Wednesday morning low temperatures about 5 degrees
cooler than previous nights (Upper 30s to low 40s in the
Valley/foothills and teens to low 30s at higher elevations).

Moving into Wednesday, a bit of a pattern shift looks to build into
the region. A progressive upper trough moving through the Pacific
Northwest is expected to become sandwiched between building ridging
aloft over the southeastern CONUS and Pacific Northwest alike. This
will allow for the trough to deepen into a closed low and retrograde
through the Great Basin toward the Desert Southwest following an
"Inside Slider" pattern. While the immediate center of the system
will be more in the vicinity of NorCal, a strong, attendant mid
level jet streak on the western periphery of this system, will bring
strong wind impacts to interior NorCal.

Surface winds are expected to shift to a north to east direction
(northerly in the Valley, east-northeasterly over the
Sierra/adjacent foothills) overnight Tuesday into Wednesday morning,
increasing Wednesday afternoon and evening, peaking Thursday
morning, and gradually decreasing from Thursday afternoon through
Friday. Strongest gusts are expected over the Sierra, where
widespread gusts 55 to 65 mph (locally to 70 mph in strong wind
prone passes) will be possible overnight Wednesday through midday
Thursday. Additionally, gusts 40 to 50 mph will be possible at
elevations above 4000` along the Sierra. At Valley locations, more
northerly gusts of 30 to 40 mph are expected through the
Sacramento Valley from the I-5 corridor eastward, with gusts 40 to
50 mph possible west of the I-5 corridor and into the Delta. All
in all, probabilities of wind gusts exceeding 40 mph are in the 50
to 90% range from I-5 westward, with similar probabilities above
4000` along the Sierra. With strong winds in the forecast, take
time to prepare now for difficult driving conditions, downed tree
branches, and possible localized power outages, and be sure to
secure any loose outdoor items.

Moving into Friday, there is still some uncertainty in the forecast,
primarily regarding the evolution of the closed low. As it stands
now, still gusty (but much lesser) north to east winds are expected
through Friday, but their exact magnitude will be dependent on the
progression of the closed low. Regardless, with the upper level
ridge continuing to build in over the Pacific Northwest, heights
aloft look to increase over interior NorCal. This will lead to
warming surface temperatures into the weekend, with Valley high
temperatures in the low to mid 70s and upper 50s to mid 60s across
the foothills and mountains by Friday afternoon.

&&

.EXTENDED DISCUSSION (Saturday THROUGH Tuesday)...

Interior NorCal becomes sandwiched between upper high to the north
and upper low SE through the extended forecast period. Locally
gusty offshore wind lingers through early Saturday in portions of
the foothills/mountains then lighter wind expected. Dry weather
forecast through the weekend into early next week with high
temperatures around 10 degrees above normal.

&&

.AVIATION...

In Central Vly, mainly VFR next 24 hrs. Areas Sly sfc wind up to
15 kts thru about 21z Tue. In foothills/mountains, areas MVFR/IFR
with lcl LIFR in precip. Snow levels 4500-6000 feet. Lcl SW-NW
sfc wind gusts up to 35 kts over higher terrain.

&&

.STO WATCHES/WARNINGS/ADVISORIES...
Winter Weather Advisory until 5 PM PDT this afternoon for West
Slope Northern Sierra Nevada-Western Plumas County/Lassen Park.

&&

$$


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