Area Forecast Discussion
Issued by NWS Sacramento, CA

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FXUS66 KSTO 301036

336 AM PDT Thu Oct 30 2014

Mild weather for Today under upper level high pressure. A cold
front will impact interior northern California beginning tonight
then moving through norcal on Friday. The front will bring rain
and mountain snow along with cooler temperatures, and a slight
chance of thunderstorms. Showers are expected behind the front on
Saturday. Snow levels will lower to around 4500 ft Saturday
morning. Showers ending early Sunday with drier and milder weather
early next week.


Forecast area under mainly fair skies this morning under high
pressure ridge currently over the western U.S. A Pacific frontal
system will be pushing this ridge eastward over the next few days
bringing a significant change in the weather pattern. High
cloudiness being pulled northward into the area today ahead of an
offshore cold front will bring the first signs of weather pattern
change. Daytime highs will cool slightly from Wednesday but still
remain a little above normal for this time of year. The Pacific
cold front is forecast to move into northern California on Friday
bringing rain and mountain snow and enough instability for a
slight threat of thunderstorms especially over the western half of
the CWA. Model timing of this frontal system is becoming more
consistent amongst the models with current timing putting the
frontal boundary over the central valley around 00z Friday. Not
real good timing for trick or treaters who will be under the rainy
effects of the back edge of the front early Friday evening. By 12z
Saturday morning the main frontal band should be over the Sierra.
Colder air filtering in behind this front will bring a rapid drop
in snow levels. By 12z Saturday...snow levels over the CWA should
range from 4000 to 5000 feet. Showers are likely on Saturday under
upper level cyclonic flow. Saturday afternoon highs under the
cooler airmass are forecast to come in around 10 degrees below
normal. Mid range models move the upper trough axis into the Great
Basin by 12z Sunday morning. Rebuilding high pressure will bring
an end to any precipitation threat by Sunday afternoon along with
the beginning of a warming trend.


.Extended Discussion (Monday through Thursday)

High pressure ridging along the west coast will be the dominant
weather feature through the extended period. Daytime highs will
slowly be climbing Monday through Thursday reaching to around
normal. Extended models move a weak system over the north end of
the ridge and into the Pacific Northwest around Tuesday but keep
any precipitation north of the forecast area. Therefore...extended
period remains dry for now. Extended models hinting at a return to
a wetter pattern towards the end of next week but have been rather
inconsistent both run to run and model to model so confidence in
this change not especially high at this time.



VFR conditions expected to continue the next 24 hours. A frontal
system will begin to approach the area tonight, with light showers
spreading across the Coastal Range after midnight tonight. Light
winds across the Valley this morning will become southerly up to
10 kt. Along the mountains, SW wind gusts up to 30 kt will be
possible this afternoon.



.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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