896
FXUS66 KMTR 152059
AFDMTR

Area Forecast Discussion
National Weather Service San Francisco CA
1259 PM PST Wed Jan 15 2025

...New SYNOPSIS, SHORT TERM, LONG TERM...

.SYNOPSIS...
Issued at 1256 PM PST Wed Jan 15 2025

Very quiet once again today, as will be the case through this
weekend. Potential for some local fog early this weekend around
coastal areas, and the potential for offshore winds early next
week.

&&

.SHORT TERM...
(This evening through Thursday)
Issued at 1256 PM PST Wed Jan 15 2025

Absolutely gorgeous day today under clear skies and very little
wind. A slight offshore gradient still exists where the mean flow is
easterly due to lingering high pressure over the Great Basin and a
nearly stationary upper low well off the coast of Baja. This pattern
continues tomorrow before the upper low finally starts to move
inland.

&&

.LONG TERM...
(Thursday night through next Tuesday)
Issued at 1256 PM PST Wed Jan 15 2025

A look at the long term period provides a bit more to talk about and
an frustrating level of uncertainty. Once the aforementioned upper
low moves inland, a broad upper ridge develops over the West Coast
and largely remains in place through the extended period. The
biggest question mark right now is how much a deep trough will dig
into the central US, whether or not a new cut off low will develop
from it in the Desert SW, and how strong that cut off low may be. As
it stands currently, there is considerable uncertainty in an
offshore wind event late this weekend and early next week. High
confidence that we will not see any rain, and the ridge will
dominate the pattern, but low confidence on if we will see impactful
offshore winds or not. Per latest hi-res WRF ensemble guidance,
there is a bimodal distribution after this weekend regarding the
strength of the SFO-WMC (San Francisco to Winnemucca, NV)
pressure gradient. Nearly half of ensemble members advertise a
neutral or slightly onshore gradient, whereas the other half of
members advertise an offshore gradient near the 90th percentile,
which means the potential for moderate offshore winds. Likewise,
if we zoom out to larger scale global models which include more
ensemble members, there is nearly an even distribution of
solutions varying from basically light wind and fair weather to
moderate offshore winds. Based on the lack of rain in the forecast
and the fact that the Energy Release Component of grasses and
shrubbery in the Central Coast is nearing the 80th percentile, we
will begin increasing messaging regarding the potential for at
least some fire weather impacts for southern areas next week.
However, based on the large amount of uncertainty, it would be
wise to pay close attention and stay up to date with the forecast
for the latest information.

&&

.AVIATION...
(18Z TAFS)
Issued at 945 AM PST Wed Jan 15 2025

VFR is expected to prevail through the TAF period with weak
mostly offshore flow persisting. The North Bay is expected
to see periods of LIFR fog late tonight into early Thursday
morning.

Vicinity of SFO...VFR.

SFO Bridge Approach...Similar to SFO.

Monterey Bay Terminals...VFR.

&&

.MARINE...
(Today through Monday)
Issued at 945 AM PST Wed Jan 15 2025

Light and variable winds will continue over the coastal waters
with high pressure situated to the north. Northerly winds will
eventually be more established late in the day into the evening
hours on Thursday. A further increase in northerly winds on Friday
will result in a modest building of seas for the weekend.

&&

.BEACHES...
Issued at 322 AM PST Wed Jan 15 2025

Still some energetic surf zone early on Wednesday with a moderate
period northwest swell. The northwest swell will gradually
subside later Wednesday. There is a slight risk of sneaker waves.
Remember to never turn your back on the ocean.

&&

.MTR WATCHES/WARNINGS/ADVISORIES...
CA...None.
PZ...None.
&&

$$

SHORT TERM...Behringer
LONG TERM....Behringer
AVIATION...JM
MARINE...JM

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