Area Forecast Discussion
Issued by NWS Sacramento, CA

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000
FXUS66 KSTO 132246
AFDSTO

Area Forecast Discussion
National Weather Service Sacramento CA
246 PM PST Mon Nov 13 2017


.SYNOPSIS...
A few lingering showers and high elevation snow through tonight.
Brief period of dry conditions Tuesday into early Wednesday. Next
system moves through Wednesday and Thursday with higher rainfall
amounts and more significant mountain snowfall.

&&

.DISCUSSION...
Shortwave currently working its way slowly across the area
afternoon, with highly scattered showers, mainly from Sacramento
north. Latest hi-res guidance not overly impressive with activity
through tonight, with hit or miss showers for most locations.
Guidance does show a weak slug of moisture around the I-80
corridor later this afternoon into evening, though only light
amounts expected. Snow levels will hover around pass levels so
could see a few inches of accumulation on roadways. Should be
minimal impact to travelers with some slick roads and maybe a few
minor delays. System moves out of the area by Tuesday morning,
with a brief break in wet weather through Tuesday night.

Focus then shifts to a stronger storm system currently brewing
in the Gulf of Alaska. This looks to be the wettest storm of the
season so far. Models in a bit better agreement this afternoon,
though the ECMWF remains a little slower. Precipitation amounts
are trending wetter and have bumped up accumulations, especially
over the Sierra. Still some uncertainty with timing and snow
levels which could have a big impact on snow accumulation
forecast. For now, looks like snow levels will be around pass
levels Wednesday as system moves in, then warm air wedges in
raising snow levels above 7500 feet sometime during the day
Wednesday into Wednesday night. Then cold air wraps in, dropping
snow levels quickly for Thursday, possibly to around 5000 feet.
Regardless, still could see significant accumulations at pass
levels, on the order of 1-2 feet, if current forecast verifies. In
addition, winds will pick up as system moves through, with some
gusts to 30 mph in the valley and 50+ mph at higher elevations.
Given potential impacts to mountain travel, winter storm watch
remains in effect for Wednesday and Thursday. Those with travel
plans should stay tuned as forecast will be better refined over
next day or so.

CEO

&&

.EXTENDED DISCUSSION (Friday THROUGH Monday)
High pressure builds Friday over NorCal after the passage of the
upper level trough on Thursday. Dry air intrusion will bring dry
weather for interior NorCal on Friday. Models are beginning to
hint at another weather system that could affect the area over the
weekend and into early next week. However, current model runs are
very inconsistent on timing and strength of the storm. For now,
if precipitation does push into NorCal on Saturday, it looks like
it will be limited to the coastal range and northern Sierra
Nevada. Precipitation could then spread southeast across the area
on Sunday and linger into Monday. HEC

&&

.AVIATION...
A Pacific storm system will continue to bring VFR/MVFR
precipitation north of I-80 this afternoon; conditions should
spread southward in the late afternoon/evening hours. Gusts up to
20 kts possible from KOVE northward through 00z Tuesday, higher
gusts over the mountains. VFR conditions should return by 12z
Tuesday for KRDD and KRBL, by 18z for other TAF stations.

&&

.STO WATCHES/WARNINGS/ADVISORIES...
Winter Storm Watch from Wednesday morning through late Thursday
night for West Slope Northern Sierra Nevada-Western Plumas
County/Lassen Park.

&&

$$


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