High Wind Watch 1, NWS San Francisco Bay Area, CA

Area Forecast Discussion
National Weather Service San Francisco Bay Area
858 PM PST Sun Jan 30 2022

.SYNOPSIS...Dry weather conditions will continue through the week
with mild days and cool nights. Dry offshore winds will develop
late Monday through midweek across the Bay Area and Central Coast
peaks and ridges. Slight warming will be possible late week with
another bout of offshore winds possible this upcoming weekend.&&

.DISCUSSION...as of 08:33 PM PST Sunday...If one looks at the
state wide radar imagery tonight you'll notice a few showers well
to the north the CA/OR border. Sadly, that's about as far south as
they'll get. A weakening upper level shortwave ridge overhead is
helping to keep the showers to the north. What the Bay Area will
experience will be high clouds, which is already being seen on the
satellite imagery.

No update needed for the evening forecast. For forecast details
outside of wind this week see below. For some extra insight on
wind potential this week keep reading. The longwave pattern aloft
unfortunately is taking on an inside slider-ish feel. That means
less chance for precip, but additional bursts of offshore flow.
Latest guidance from the 00Z NAM and 18Z local WRF show another
robust set up for offshore wind. Offshore flow will initially re-
develop on Monday before further increasing into Tuesday. Breezy
to gusty winds will be possible over the higher terrain Tuesday.
Tuesday into Wednesday is when the offshore gradient really
intensifies. A x-section of the North Bay Mts early Wednesday
shows all the ingredients needed for mountain wave development.
The last mountain wave to develop, or at least be modeled, was
roughly 10 days ago. The end result of that offshore flow
pulse/wave were 90mph winds near Healdsburg Hills. Not saying
that same thing will happen again, but it's possible and something
that we'll be watching closely in the coming days. To add
additional support for strong winds are the HREF winds at over 60
mph and the ECMWF EFI once again highlighting how unusual winds
like this are for early February. If the guidance keeps trending
this way Wind Advisories will likely be needed and possibly
another High Wind Warning for the hills. As of now, Tuesday and
Wednesday seem to be the windiest days.

&&

.PREV DISCUSSION...as of 01:47 PM PST Sunday...After a chilly start to
the day with upper 20s to lower 30s in the region's coldest
interior valleys, afternoon temperatures have warmed into the 50s
and 60s across much of the region. Additionally, patchy fog and
low clouds over the Bay Area have since dissipated giving way to
mostly sunny conditions. This is the result of high pressure aloft
ahead of an approaching mid/upper level trough.

This mid/upper level trough is forecast to push into the Pacific
Northwest in the next 24 hours and then deepen across the
Intermountain West into midweek. This will maintain dry weather
conditions over the region and bring about another round of
offshore winds across the peaks and ridges of the Bay Area and
Central Coast. Offshore winds will first develop late Monday night
into Tuesday across the higher terrain of the North Bay and East
Bay. Winds are then forecast to strengthen Tuesday night into
Wednesday with some of the higher peaks and ridges gusting in
excess of 50 mph. While some locally stronger winds may mix down
into the valleys on Tuesday, the strongest winds are likely to
remain confined to elevations above 1,000 feet. This pattern will
also cool daytime conditions down into the upper 50s to lower 60s
(cooling of around 4- 8 deg F). Overnight temperatures will remain
on the chilly side, yet any mixing of the winds at night may
limit radiational cooling in the interior valleys. Thus, will
likely see large variability from location to location across the
region. Still, generally expecting overnight lows in the 30s to
40s through midweek and potentially into late week as well.

While wind speeds diminish late in the week, dry offshore flow is
likely to persist at times across the region. Building high
pressure over the region will also allow for slight warming of
daytime temperatures will more widespread 60s likely. Another
round of strengthening offshore flow then looks possible next
weekend which will continue to dry out fuels region-wide. With
this said, we cannot let our guard down with respect to fire
weather concerns given the little (Bay Area) to no (Central Coast)
wetting rains in the month of January and bouts of offshore
winds. Forecast ensembles indicate continued dry weather
conditions and above normal temperatures heading into middle of
February.

&&

.AVIATION...as of 8:58 PM PST Sunday...For the 06z TAFs. VFR except
patchy valley fog /VLIFR-IFR/ developing tonight and Monday morning.
Coastal Low clouds and fog /MVFR-IFR/ also developing tonight and
Monday morning. Conditions lifting to VFR by late Monday morning
and afternoon.

Vicinity of KSFO...VFR, west wind 10 to 15 knots decreasing to
near 5 knots tonight and Monday morning. Monday afternoon and
evening wind increasing to 10 knots.

KSFO Bridge Approach...Similar to KSFO.

Monterey Bay...Patchy low clouds and fog /IFR-MVFR/ developing
tonight and Monday morning. East to southeast cold air drainage
winds 5 to 10 knots developing late tonight and Monday morning.
Winds becoming variable and to locally onshore 5 to 10 knots
Monday afternoon and early evening.

&&

.MARINE...as of 08:55 PM PST Sunday...Northwesterly winds
increasing across the coastal waters through early to mid week
resulting in steep wind waves that may reach 12 to 17 feet by
Tuesday. Northwest winds likely reaching gale force Tuesday and
Wednesday, primarily in the northern outer waters,  before
diminishing at the end of the week.

&&

.MTR WATCHES/WARNINGS/ADVISORIES...
     .Tngt...SCA...Pt Pinos to Pt Piedras Blancas 0-10 nm

&&

PUBLIC FORECAST: MM/RGass
AVIATION: Canepa
MARINE: Canepa

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