Area Forecast Discussion
Issued by NWS Sacramento, CA

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FXUS66 KSTO 181059

Area Forecast Discussion
National Weather Service Sacramento CA
259 AM PST Fri Jan 18 2019

Light Showers over the Sierra this morning then light rain and
mountain snow today and Saturday mainly north of interstate 80. A
moderate storm passage through norcal Sunday then drying Monday
with dry conditions continuing through the end of the week. Valley
fog possible night and morning hours.


Scattered light showers continue this morning over the Sierra but
significant additional snowfall amounts are not expected.
Therefore, the winter storm warning will be allowed to expire.
Remainder of CWA drying out this morning although some mid cloud
cover continues to spill over the fairly flat ridge over the west
coast. Warm frontal precipitation associated with the next
upstream Pacific weather system is forecast to spread over the
forecast area later today but most precipitation should remain
north of interstate 80. Precipitation amounts should remain on the
light side with snow levels climbing to between 5000 and 6000
feet. Therefore, impacts are expected to be minimal today.

Upper ridge amplifies and moves inland on Saturday keeping any
precipitation from cold frontal portion of system north of
interstate 80 and relatively light. The upper ridge axis is
forecast to push eastward into the Great Basin Sunday allowing a
stronger and moister Pacific cold front into norcal during the day
on Sunday. Precipitation amounts in the valley are not likely
large enough to cause much problem but snowfall amounts and snow
levels below pass levels will likely make for travel impacts over
the Sierra Sunday and Sunday evening. Pressure gradients indicate
gusty south winds as well. Precipitation drops off quickly on
Monday as the main upper low shifts east of the state and high
pressure starts building over the west coast. At this time, this
building ridge looks to be the main weather influence for much of
the coming week.


Models similar in showing dry weather through the extended as high
amplitude upper ridging remains off the West Coast. Pattern will
be conducive to the formation of areas of night and morning fog
in the Central Valley and mountain valleys. Above normal daytime
highs expected Tuesday through Friday with 60s in the Central
Valley and 40s to low 60s for the mountains and foothills.



Areas of MVFR/IFR conds ovr Intr NorCal nxt 24 hrs mnly fm abt
I-80 N. Aftn lcl Sly sfc wnd gsts up to 25 kts poss in the Cntrl
Vly and Wly gusts up to 35 kts poss ovr hyr mtn trrn.

Winter Storm Warning until 4 AM PST early this morning for West
Slope Northern Sierra Nevada-Western Plumas County/Lassen Park.


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