Area Forecast Discussion
Issued by NWS Sacramento, CA

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FXUS66 KSTO 292302
AFDSTO

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SACRAMENTO CA
402 PM PDT Wed Oct 29 2014

.Synopsis...
Mild weather into Thursday afternoon. A cold front will impact northern
interior California late Thursday into Saturday with rain and mountain
snow along, cooler temperatures, and a slight chance of thunderstorms.
Snow levels will lower to around 4500 ft Saturday morning. Drier and
milder weather early next week.

&&

.Short Term Discussion (Tonight through Saturday)...
A warm afternoon with ample sunshine as current temperatures are
running about 5 to 12 degrees warmer than 24 hours ago. Tomorrow
will be another warm and mild day, but our weather pattern will
start changing late Thursday night.

A cold front will move into the coastal range late Thursday and
track eastward, impacting NorCal into Saturday. Main impacts will
likely occur on Friday due to morning/evening commutes and the
Halloween holiday. This morning`s CNRFC forecast for liquid
equivalent of precipitation was higher than previously forecast so
we have updated rain and snow totals in the afternoon package.
Valley rain totals are now closer to 0.30-0.50" while the
foothills range between 0.50-0.75" and the higher elevations peak
between 1-1.5". Snow levels will start off around 7000 ft Friday
morning then lower to around 6000 ft by Friday evening. By
Saturday morning, snow levels will continue to lower down to about
4500 ft. For snow accumulations, the greater impacts will occur above
5000 ft from Friday afternoon into Saturday morning with 4-8" of
snow accumulation at pass levels with locally higher amounts
closer to the crest. We have issued a Winter Storm Watch for the
Sierra above 5000 ft due to hazardous winter driving conditions
from snow accumulation. With the current models: timing of the main
precipitation still shows that the Valley and including Shasta
County will have peak precipitation on Friday afternoon (before 5
pm). Precipitation will continue into the evening, but be lighter.
The Sierra precipitation will peak Friday night. But keep in mind
that if the front stalls or speeds up on Friday, then these
general timing guidelines will change.

In addition to the rain and snow impacts, there is also some
instability associated with the cold frontal passage. There is a
slight chance for thunderstorms during the day Friday into Friday
night. Although rain can dampen trick-or-treating activities,
keep an eye and ear out for thunder and lightning as this would
make outside activities more dangerous. Please seek shelter if
thunderstorms develop. JBB

&&

.Extended Discussion (Sunday through Wednesday)
Trough shifts east Sunday with ridging forecast to return into
early next week leading to a return of dry northwesterly flow for
much of interior NorCal and a retreat of precipitation chances to
around the Oregon border.

Another frontal system is perched offshore west of 130W by
Thursday. This is out past our forecast time frame, but be prepared
for another frontal system Thursday night into Friday.

JClapp


&&

.Aviation...
VFR conditions expected to continue over the next 24 hours. Winds
generally below 10 knots.

&&

.STO Watches/Warnings/Advisories...
Winter Storm Watch from Friday morning through Saturday afternoon
above 5000 feet in the west slope Northern Sierra Nevada...western
Plumas county/Lassen Park.

&&

$$







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