Sebastopol Weather.

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Since July 1, we have had 4.50 " of rain. Average seasonal rainfall for November 19th is 5.08". We are now at 88% of our normal rainfall for this date.

Detailed Forecast
For West Sonoma County. Issued by NWS San Francisco Bay Area, CA

Today
Patchy frost before 10am. Otherwise, mostly sunny, with a high near 62. Northwest wind around 5 mph becoming calm in the morning.
Tonight
A 20 percent chance of rain after 10pm. Mostly cloudy, with a low around 47. Light and variable wind. New precipitation amounts of less than a tenth of an inch possible.
Monday
A 50 percent chance of rain, mainly before 4pm. Mostly cloudy, with a high near 64. Light and variable wind becoming southeast 5 to 10 mph in the morning. New precipitation amounts of less than a tenth of an inch possible.
Monday Night
A 20 percent chance of rain before 10pm. Mostly cloudy, with a low around 48. West northwest wind around 6 mph becoming calm in the evening.
Tuesday
Partly sunny, with a high near 72. Calm wind becoming southeast around 6 mph in the morning.
Tuesday Night
Mostly cloudy, with a low around 49.
Wednesday
Mostly sunny, with a high near 72.
Wednesday Night
Partly cloudy, with a low around 49.
Thanksgiving Day
Partly sunny, with a high near 70.
Thursday Night
A slight chance of rain. Mostly cloudy, with a low around 48.
Friday
A chance of rain. Mostly cloudy, with a high near 68.
Friday Night
A chance of rain. Mostly cloudy, with a low around 46.
Saturday
A chance of rain. Mostly cloudy, with a high near 65.

Area Forecast Discussion

Issued by NWS San Francisco Bay Area, CA
964
FXUS66 KMTR 191138
AFDMTR

Area Forecast Discussion
National Weather Service San Francisco Bay Area
338 AM PST Sun Nov 19 2017

.SYNOPSIS...Dry weather will continue through the end of the
weekend, with mild days and cool nights. The next weather system
will bring rain chances late tonight and Monday, mainly across
the North Bay. There is a slight chance of additional rainfall at
times in the North Bay for much of this week, but most of our
area is forecast to be warm and dry through Thanksgiving.

&&

.DISCUSSION...As of 3:15 AM PST Sunday...Early morning
temperatures are mostly in the mid 30s to mid 40s and are close
to where they were 24 hours ago. Patchy frost is likely for a few
hours around sunrise this morning, mainly in the North Bay Valleys
as well as the valleys of southern Monterey County.

Today`s weather is expected to be much like yesterday`s, except
for more widespread high cloud cover. Afternoon highs will be
mostly in the 60s and winds will remain light.

Early morning satellite shows a plume of moisture over the
eastern Pacific, approaching from the southwest. Precipitable water
values in this plume are in excess of 2 inches out near 30N/140W.
Meanwhile, a frontal boundary off the coast of Washington and
Oregon is sagging slowly to the southeast. This frontal boundary
is forecast to make its way into northwest California by late
tonight, but any further southward progression will be thwarted by
an upper ridge that will be building over central and southern
California. In any case, the models indicate there will be
sufficient warm advection acting on the moisture plume to produce
rainfall across the North Bay late tonight and Monday. Elsewhere
across our region, subsidence under the building upper ridge is
expected to inhibit the development of precipitation, although
isolated light rain may occur as far south as the San Francisco
Peninsula and the East Bay on Monday. Most models indicate that
rainfall totals in the North Bay through late Monday will be on
the order of a quarter of an inch or less. However, the 06Z NAM
has trended wetter and forecasts as much as 1.5 inches of rain in
northwest Sonoma County by late Monday. There certainly is
sufficient moisture approaching to produce these heavier rainfall
amounts, but given recent model trends of building the upper ridge
more strongly over California, these higher totals seem unlikely.
As is the often the case in situations such as this with moist
flow and warm advection under relatively high heights, there will
probably be a sharp gradient between soaking rains to the north
and no rain at all to the south. And that sharp precipitation
gradient will most likely set up somewhere near the
Mendocino/Sonoma County line.

Rainfall in the North Bay is expected to taper off Monday evening
and end by late Monday night. The upper ridge is forecast to
continue strengthening across the southwestern United States
through midweek. Meanwhile, moist southwesterly flow will continue
between this ridge and a deepening trough offshore near 145W. The
models agree that this moisture will remain completely north and
west of our area on Tuesday and Wednesday, and then perhaps sag
back south into the far northwest corner of our forecast area by
Thanksgiving. But for the most part, the upper ridge will maintain
dry and warm conditions across nearly all of our forecast area
from Tuesday through Thanksgiving. Widespread high temperatures in
the 70s are forecast during this period of time, with some low to
mid 80s likely from Monterey Bay southward.

The longer range models indicate the ridge will shift far enough
to the east late in the week to allow precipitation to gradually
spread into our forecast area between Thursday night and next
weekend. However, there are considerable model differences
regarding timing and location of rainfall late in the extended
forecast period.

&&

.AVIATION...As of 3:45 AM PST Sunday...Offshore flow has weakened
but airmass is still dry. High cirrus clouds will drift over the
area but conditions will be VFR.

Vicinity of KSFO...VFR.

SFO Bridge Approach...VFR.

Monterey Bay Terminals...VFR. Southeast winds to 10 kt in the
Salinas Valley from 15Z-19Z becoming light westerly in the
afternoon.


&&

.MARINE...As of 2:43 AM PST Sunday...A 1022 mb high off the coast
of Central California will bring light west to northwest winds
through today. Winds will switch to southerly Sunday night or
Monday ahead of a frontal system. Winds over the southern waters
will remain light to moderate out of the northwest. The front will
become stationary across the northern California waters through
midweek so southerly winds will persist.

&&

.MTR WATCHES/WARNINGS/ADVISORIES...
     .Tday...None.

$$

PUBLIC FORECAST: Dykema
AVIATION: W Pi
MARINE: W Pi

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Images and content John Morehead. All rights reserved.