Area Forecast Discussion
Issued by NWS San Francisco Bay Area, CA

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FXUS66 KMTR 261928
AFDMTR

Area Forecast Discussion
National Weather Service San Francisco Bay Area
1228 PM PDT Thu Apr 26 2018

.SYNOPSIS...Upper low off the coast will keep temperatures below
normal through the end of the work week and into the weekend. Some
coastal drizzle or very light showers possible later tonight
through early Saturday as the upper low moves onshore, however
most areas will remain dry with below normal temperatures being
the main impact. Cool and dry pattern continues into early next
week.

&&

.DISCUSSION...as of 12:28 PM PDT Thursday...The 2000+ foot marine
layer brought widespread stratus to much of the San Francisco Bay
Area and central California coast earlier today. The only
locations spared from the cloud cover were some of the higher
elevations in the region, as well as some of the interior East Bay
communities in Contra Costa County. The low clouds have mostly
mixed out as the day has progressed, though, some stubborn low
clouds remain along the coast from Point Reyes south toward the
Golden Gate and Bodega Bay, as well as near Moss Landing. By the
time the afternoon wraps up, temperatures are expected to peak in
the upper 50s to 60s near the water to as warm as the 60s and 70s
for interior locations.

An upper level low currently centered near 40N/135W, or 600 miles west
of Point Arena, is largely responsible for the deep marine layer
depth that brought about widespread cloud cover the past few
mornings. This upper level low is progged to approach the
California-Oregon border over the next few days. As it does so,
expect continued morning clouds along the coast, and perhaps some
drizzle along the immediate coastline. Parts of the North Bay
could see some light rain as this system moves onshore on Friday
night/Saturday morning, but amounts look to be very light. If
anything, this system will mostly maintain (or even enhance) the
already deep marine layer and allow for the downward trend in
temperatures to continue. Afternoon highs by Saturday are forecast
to be about 5 to 10 degrees below late April climatological
normals.

The upper level low will push northeastward into Idaho and Montana
by Sunday and Monday, though temperatures will be slow to climb
as models advertise a quick shortwave to drop from the Pacific
Northwest to the area on Monday. By the middle of next week, a
steady warming trend should commence as an amplified ridge builds
over the eastern Pacific and gradually pushes toward the
California coast.

&&

.AVIATION...As of 10:55 AM PDT Thursday...for 18z TAF. The region
is once again under the influence of a marine layer around 2,000
feet in depth. However, inland cloud cover is slowly dissipating
this morning and will do so into the early afternoon with VFR
conditions returning to most terminals. Onshore winds will
strengthen slightly for the afternoon and evening becoming breezy
to locally gusty. Winds relax slightly late this evening with the
potential for an earlier return of stratus ahead of an approaching
mid/upper level system.

Vicinity of KSFO...VFR conditions with winds becoming breezy to
locally gusty through the evening. Low clouds potentially return
earlier than previous mornings with low/moderate confidence on
timing. Once stratus returns, look for MVFR CIGS through around
18Z Friday.

SFO Bridge Approach...Similar to KSFO.

Monterey Bay Terminals...MVFR CIGS will continue to dissipate
through 19Z with VFR conditions thereafter. Onshore winds will
strengthen slightly for the afternoon and evening becoming breezy
at times. Winds diminish late this evening with low clouds
returning around or before 03Z Friday.

&&

.MARINE...as of 8:37 AM PDT Thursday...Generally light west to
northwest winds will prevail with locally breezy conditions near
the coastal gaps and prominent points this afternoon and into
Friday. Light to moderate seas will continue through the forecast
period with a mixed south and northwest swell developing late in
the week.

&&

.MTR WATCHES/WARNINGS/ADVISORIES...
     .Tngt...None.

$$

PUBLIC FORECAST: Rowe
AVIATION: RGass
MARINE: RGass

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