Sebastopol, California 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

318
FXUS66 KMTR 251626 AAA
AFDMTR

Area Forecast Discussion...UPDATED
National Weather Service San Francisco CA
Issued by National Weather Service Eureka CA
926 AM PDT Fri Apr 25 2025

...New UPDATE...

.SYNOPSIS...
Issued at 124 AM PDT Fri Apr 25 2025

Cloudy and cool conditions prevail with chances for rain and
isolated thunder later today into Saturday, with the risk
concentrated across the Central Coast and adjacent offshore waters.
Dry conditions and a warming trend resume after the rain moves out
early on Sunday.

&&

.UPDATE...
Issued at 926 AM PDT Fri Apr 25 2025

Showers continue this morning, largely across the coastal waters
as ascent continues ahead of our well-anticipated upper low. Our
12 UTC sounding from KOAK indicated a good feed of moisture below
850mb with a pocket of dry air aloft. Capped off is a bit more
moistening in the mid to upper levels. This pocket of dry air will
likely minimize rain amounts at the surface and 3 to 6 hourly
rain amounts (largely under a tenth of an inch) confirm the impact
of this parched layer at the surface. Still, areas south of the
Bay Area and across the Central Coast are most probable to see
pockets of drizzle, a few sprinkles, and a few rain drops through
the rest of the morning and into the afternoon. The forecast has
been updated to expand the areal coverage of slight chance (20%)
PoPs.

The rest of the forecast remains unchanged and updates will be
shipped shortly.



&&

.SHORT TERM...
(Today and tonight)
Issued at 124 AM PDT Fri Apr 25 2025

Short Term Key Messages:
-Cool and cloudy through the day
-Rain chances arrive later today through Saturday
-Isolated thunderstorms possible in southern Monterey and San Benito
counties
-Snow possible on the peaks of the Santa Lucias and Diablo ranges

Cool and cloudy conditions are the story of the day with an upper
level low continuing to deepen and approach the state. Satellite
imagery and surface observations both support extensive and
widespread cloudiness across the region and well into the interior.
Some patches of clearing might be possible during the afternoon, but
these will be generally short-lived and will dissipate with the
approach of the low pressure system. High temperatures today and
Saturday will range from the middle 50s to the lower 60s across the
lower elevations, and the middle 40s to the lower 50s in the higher
elevations, with breezy onshore winds developing this afternoon
before a lull tonight into Saturday.

The forecast track of the low has continued to shift southwards into
San Luis Obispo and Santa Barbara Counties, with the main axis of
rainfall shifting ever so slightly southwards as a result. The main
thrust of rain is anticipated to arrive Friday evening and last into
Saturday evening. Generally beneficial rainfall is still anticipated
for the Central Coast, particularly as the region has missed out on
most of the big rainstorms during the winter storm season, with rain
totals of a tenth to a quarter of an inch in the Monterey Bay region
and the Salinas Valley, and up to half an inch in the Santa Lucias.
In Santa Cruz County and the Bay Area, rain totals are very light,
up to a tenth of an inch at most, with the region around San
Francisco and Oakland seeing a few hundredths of an inch of rain, if
any at all, from the system.

The chance for isolated convection remains across the southern
halves of Monterey and San Benito counties late on Friday into
Saturday, with the primary risk being isolated lightning strikes and
brief accumulating hail. 700-500 mb lapse rates in the core of the
upper level low will rise to around 7 to 7.5 C/km, allowing for CAPE
values of around a few hundred J/kg, although the highest CAPE
values remain displaced to SLO and Santa Barbara counties. As noted
by the previous forecaster, a more northward track to the low would
increase the risk, especially towards the northern halves of
Monterey and San Benito Counties, while a more southward track moves
the thunderstorm risk even further south.

In addition to all that, the highest peaks of the Santa Lucia and
Diablo ranges continue to see a chance for some accumulating snow,
with the blended guidance suggesting around a 50% chance of at least
2 inches of snow on the mountaintops. We do not anticipate needing
any winter weather products, as the snow accumulation remains
confined to the highest peaks.

&&

.LONG TERM...
(Saturday through Thursday)
Issued at 124 AM PDT Fri Apr 25 2025

Long Term Key Messages
-Lingering showers through Sunday morning
-Dry and warm conditions return after the showers clear.

A few lingering showers could remain across the Central Coast
through Sunday morning, with any additional accumulations limited to
a few hundredths of an inch generally, and up to a tenth of an inch
in favored mountain locations. Sunday remains rather cool, but a
drying and warming trend returns to the region as upper level
ridging returns to the western United States. The upcoming work week
should see high temperatures reach the upper 70s to the lower 80s in
the inland valleys, the upper 60s to middle 70s along the San
Francisco Bay, and the upper 50s to the middle 60s near the Pacific
coast. Longer term predictions support a lean towards temperatures
above seasonal averages into the first week of May.

&&

.AVIATION...
(12Z TAFS)
Issued at 445 AM PDT Fri Apr 25 2025

A cold core 500 mb low was located 500 miles west-northwest of the
Bay Area, with a 500 mb trough extending southeastward from the low
center toward the Bay Area and north Central Coast this morning.
Mountain top temps are in the 30s. Mt Hamilton is 32F, Chews Ridge
is 30F for example. Cold air advection with the aforementioned trough
is showing up on the Point Sur profiler. Conditions will be generally
VFR-MVFR with a few showers, with improving chances of showers later
today, tonight and Saturday with the 500 mb cold core low nearing our
coastline. Freezing levels and wet bulb zero heights will lower during
the period.

Vicinity of SFO...VFR-MVFR. A few passing light showers today and
tonight, better chances of showers Saturday. West wind near 10 knots,
southwest during the afternoon and light westerly tonight and Saturday
morning.

SFO Bridge Approach...Similar to SFO.

Monterey Bay Terminals...VFR-MVFR. A few passing light showers
today, better chances of showers tonight and Saturday. West to
southwest winds 5 to 10 knots becoming light east to southeast
tonight and Saturday.

&&

.MARINE...
(Today through Wednesday)
Issued at 842 AM PDT Fri Apr 25 2025

A chilly upper level low arriving from the northwest will result
in scattered showers across the coastal waters and bays today
through Sunday morning. Gusty northwest winds and rough seas
return across the northern outer coastal waters late Saturday. Dry
weather returns early next week due to an eastward moving high
pressure system over the Pacific.

&&

.MTR WATCHES/WARNINGS/ADVISORIES...
CA...None.
PZ...Small Craft Advisory from 3 PM to 9 PM PDT Saturday for Pt Arena
     to Pt Reyes 10-60 NM.

&&

$$

UPDATE...Bain
SHORT TERM...DialH
LONG TERM....DialH
AVIATION...Canepa
MARINE...Canepa

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