Area Forecast Discussion
Issued by NWS Sacramento, CA
FXUS66 KSTO 242254
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SACRAMENTO CA
354 PM PDT Fri Oct 24 2014
Wet and windy weather moves in later tonight into Saturday as an
upper level trough and associated front move into the area.
Thunderstorms with heavy rain, accumulating small hail and gusty
winds and maybe even a weak tornado are possible on Saturday.
Snow levels will come down to below Sierra passes Saturday night.
Decreasing winds are expected Saturday evening and precipitation
will taper off Sunday. A brief break Monday will be followed by a
chance of rain over areas north of Sacramento Tuesday and
Wednesday. This precipitation threat will drop southward bringing rain or
mountain snow over much of NORCAL for the end of the next week.
Upper level trough offshore of the West Coast will move into
Northern California tonight into Saturday bringing a change to wet
and windy weather. Increasing clouds and precipitation moving into the
Coastal range and Shasta County around midnight and spread
southeast across interior northern California Saturday. Southerly
winds will increase late tonight into Saturday as the cold front
and trough move inland. This will bring breezy and gust winds with
southerly winds 15 to 30 mph with gusts to around 40 mph in the
Valley...strongest in the Sacramento Valley and up to 70 mph over the
ridges. Holiday decorations should be secured with the gusty
winds and high profile vehicles should use caution. Winds should
be decreasing Saturday evening. Shasta County mountains could see
up to 2 inches of precipitation by Sunday morning with good
orographics with the southerly winds. Snow levels will be around
8000 ft Saturday morning and drop down to around 5000 to 6000 ft
on Sunday morning. Snow accumulations up to 10 inches are possible
on Mt Lassen and up to 4 inches possible over the higher Sierra
passes. Motorists should be prepared for possible winter driving
conditions in the mountains this weekend. Good instability and
shear on Saturday will bring a threat of thunderstorms and
possibly weak tornadoes. Precipitation will taper off on Sunday
with showers mainly lingering over the Shasta County and down the
Sierra. High temperatures this weekend will be in the mid 60s to
low 70s in the Valley and mid 30s to low 50s in the mountains.
Monday will be a drier and warmer day with ridge building into
the area as trough shifts east.
.Extended Discussion (Tuesday through Friday)
Flat high pressure over the southwest U.S will keep at least the
southern half of the forecast area dry Tuesday. The northern
portions of the forecast area will see a continued threat of light
rain. Daytime high temperatures under mainly cloudy skies are
expected to come in a few to several degrees below normal. Another
cool low pressure system dropping out of the Gulf of Alaska will
bring precipitation chances southward Wednesday through Friday.
Significant model differences exist in the Wednesday-Friday time
frame. The European model is much deeper and brings deeper
moisture into Norcal versus the drier GFS. Have opted for a blend
of solutions but forecast confidence not high during this time
High thin clouds with winds from the south between 10-15 mph in
the afternoon. A system spreads in late tonight and Saturday bringing
chances of rain and increasing winds. Wind gusts to 45 mph will be
possible after 12z especially over the northern valley.
wind advisory from 5 am to 8 pm pdt saturday central sacramento
valley...northern sacramento valley...southern sacramento valley.