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

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FXUS66 KMTR 221805
AFDMTR

Area Forecast Discussion
National Weather Service San Francisco Bay Area
1005 AM PST Wed Jan 22 2020

.SYNOPSIS...Mostly dry and warmer conditions will return through
Friday. A storm system moving into Northern California this
weekend will bring the next chance of precipitation to the region.

&&

.DISCUSSION...as of 08:27 AM PST Wednesday...Areas of fog persist
over much of the North Bay and around the San Francisco Bay Area
this morning. While the fog has been dense at times, conditions
have been improving and will continue to do so through the morning
hours as surface temperatures begin to warm. Otherwise,
temperatures range from the middle 40s to middle 50s region-wide
at this hour. The ongoing forecast remains on track this morning
with no updates anticipated at this time. For complete forecast
details, please see the previous forecast discussion below.

&&

.PREV DISCUSSION...as of 2:42 AM PST Wednesday...A nearly
stationary frontal boundary remains draped over the Bay Area
resulting in lingering showers early Wednesday morning. Moist flow
across the terrain is just enough to generate light precip. KMUX
radar imagery shows the light rain has been most prevalent over
the Santa Cruz Mountains and the East Bay Hills. Rainfall amounts
over the last six hours have generally been a tenth or two, but a
few jackpots up to one half inch in the Santa Cruz Mountains.
Shower activity will continue to diminish through the early
morning hours with little to no impacts except for some damp
roads. One weather impact the could affect the morning commute
will be fog. Given the ample low level moisture automated sites
around the region have been reporting some fog with dense fog
being reported at KSTS. Therefore, forecast through the morning
hours will include fog. Besides lingering showers and fog this
morning, the bigger story will be a warming and drying trend
developing this afternoon through Friday. Highs today will
approach or hit the mid 60s across the interior. Temperatures will
increase further on Thursday and Friday with more widespread 60s
and a few interior locations in Monterey/San Benito may even
approach 70 degrees - about five degrees above normal.

No change in the 00Z model suite, rain chances look to return this
weekend as the ridge flattens with another storm system moving
into the British Columbia. The next storm system will drag another
frontal boundary through Northern California. Light rain will
return to the Bay Area Friday night over the North Bay and then
slowly move southward over the weekend. Definitely looks wetter
than the light precip from Tuesday, but as noted before not a
major soaker and heaviest rain will be north. Rain chances
linger into early next week as the tail end of additional weak
systems pass to the north. High pressure rebuilds the middle of
next week taking the storm track farther north.

Longer range outlook is definitely trending drier through the end
of next week and beyond. CPC outlooks continue the warming and
drying trend into early February.

&&

.AVIATION...as of 10:05 AM PST Wednesday...For 18z TAFs. Boundary
that moved through overnight has left abundant low level moisture
with low cigs and fog. Most terminals will see slow clearing
after 19-20z. Once cigs clear, light winds will remain and expect
vfr through about 04-06z this evening. Light winds, building ridge
and moist boundary layer suggest fog and low cloud potential will
return overnight and into Thursday morning.

Vicinity of KSFO...1 minute satellite shows clearing to the north
and west of SFO while low clouds are over the approach and in the
southern edge of the bay with San Mateo bridge still 3sm bkn007.
Expect vfr to persist over the terminal but less confidence for
approach. Cigs expected to return for Thursday morning.

SFO Bridge Approach....Clouds are over the approach and southern
edge of Bay. Light winds and building ridge suggest only a slow
burn through early this afternoon. San Carlos/Palo Alto and San
Mateo Bridge still reporting low cigs under 1000 feet. Best
estimate for clearing at approach will be after 20-21z.

Monterey Bay Terminals...Comms issues continue with Salinas ASOS
and FAA lines. Monterey still ovc014 with slow clearing this
afternoon. Low cigs likely to return overnight.

&&

.MARINE...as of 09:52 AM PST Wednesday...Light winds across most
of the waters through midday, with  locally breezy southeast winds
along the southern coast. Later  this afternoon and evening, winds
shift to the north and  strengthen across most of the waters
through tomorrow. A WNW swell will peak today generating hazardous
sea conditions for smaller  vessels. Another longer period WNW
swell will then arrive Thursday night into Friday.

&&

.MTR WATCHES/WARNINGS/ADVISORIES...
     .Tday...SCA...Pt Arena to Pt Reyes 0-10 nm until 3 PM
             SCA...Pt Reyes to Pigeon Pt 0-10 nm until 3 PM
             SCA...Pigeon Pt to Pt Pinos 0-10 nm until 3 PM
             SCA...Pt Pinos to Pt Piedras Blancas 0-10 nm until 3 PM
             SCA...Pt Arena to Pigeon Pt 10-60 nm until 3 PM
             SCA...Pigeon Pt to Pt Piedras Blancas 10-60 nm

&&

$$

PUBLIC FORECAST: RGass
AVIATION: RWW
MARINE: RWW

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