-- Discussion containing changed information from previous version are highlighted. --
683
FXUS66 KMTR 132310
AFDMTR

Area Forecast Discussion
National Weather Service San Francisco CA
410 PM PDT Thu Jun 13 2024

...New FIRE WEATHER...

.SYNOPSIS...
Issued at 247 AM PDT Thu Jun 13 2024

Quiet through the rest of the week with slight warm up on Friday
across the interior. Near normal temperatures by the weekend.
Increasing confidence for high wind potential and increased fire
danger Sunday into early next week.

&&

.SHORT TERM...
(This evening through Friday)
Issued at 207 PM PDT Thu Jun 13 2024

Zonal flow has caused some rinse and repeat for weather conditions
today, compared to yesterday. Most of the clouds have eroded back to
the coast while areas in Monterey Bay and Salinas, still remain
pretty socked in with some low clouds and is anticipated to remain
so for the rest of the day. Overnight temperatures will also be
similar to last night but a few areas in the North Bay will see 1-3
degrees warmer with minimum temperatures in the 50s, while the
remaining of the region will see upper 40s to mid 50s. As a weak
ridge moves over the region tomorrow, expect max temperatures to
become warmer compared to today with inland areas seeing mid 80s to
low 90s. Coastline remains pretty consistent with low 60s.

&&

.LONG TERM...
(Friday night through next Wednesday)
Issued at 207 PM PDT Thu Jun 13 2024

As we move into the weekend, a deep low pressure system pattern dips
down into our area bringing some cooler temperatures and some
increased winds. Max temperatures inland will reach up to mid to
high 80s Saturday, with temperatures beginning to dropping a few
degrees every day with Sunday and Monday seeing temperatures in the
low 80s and 70s. The coast will remain in the high 50 to 60s through
the weekend into the first half of next week. Overnight lows
generally will be in the 50s through most of the area. Winds will
also increase as the trough deepens into our area causing some gusty
winds throughout our region, with the highest possible winds speeds
between 30-40 mph occuring over the waters, coastal area, valleys
and inland coastal gaps.

Although we will have some moisture recovery overnight through the
weekend, there is some fire concerns Sunday into Monday, as there
have been recent drying of fine fuels and grasses. We are expecting
overall onshore winds associated with this low pressure system, but
depending on the magnitude and positioning of the trough, offshore
winds are not completely off the table. This will dry fuels out even
further. With the ensemble members showing some differences in
the magnitude of the trough, we are able to explore a best case
and worse case scenario for elevated fire concerns. The best case,
is represented by the European and GFS ensembles where it
supports a deepening of the trough, which will bring some moist
air, cooler temperatures, and stronger onshore winds, which will
alleviate some fire concerns. The worst case scenario would be if
the trough becomes weak or a short wave ridging develops. This
will bring the possibility of offshore winds, drier conditions,
and warmer temperatures, which will increase some fire weather
concerns. Therefore, we will continue to monitor the trough as it
gets closer to our region to update our forecast, as well as our
messaging.

As we move into the middle of the week, long-range models show a
possible ridging or weakening of the trough that will bring possible
warmer temperatures. Stay tuned!

&&

.AVIATION...
(18Z TAFS)
Issued at 1113 AM PDT Thu Jun 13 2024

Stratus coverage continues over MRY and SNS while satellite shows
stratus coverage dissipating over STS, APC, and OAK. The marine
layer is expected to compress tonight with less widespread stratus
than last night. Current thinking is that stratus will generally
stick closer to the coast and SF bay. Low confidence that stratus
will reach STS and APC but models indicate some lower level clouds
may be possible. Forecast vertical wind profiles show RH values
generally 50 to 60 percent so leaning towards the side that any
clouds that do develop will be on the FEW to SCT side. Light to
moderate west to northwesterly winds continue through the afternoon
with gustier conditions returning through the afternoon into the
evening. Light west to southwesterly winds return overnight for most
sites before moderate winds return after the end of this TAF period.

Vicinity of SFO...Moderate west to west-northwest winds continue
through the afternoon before lighter westerly winds return
overnight. Some uncertainty remains in wind direction but models are
in higher agreement that winds stay more W to NW. Moderate
confidence that MVFR conditions will return overnight with low
confidence that a more compressed marine layer will push ceiling
heights down into IFR territory.

SFO Bridge Approach...Similar to SFO.

Monterey Bay Terminals...Currently MVFR at MRY and SNS. Moderate
confidence that ceilings at MRY will not clear as satellite shows a
thicker layer of clouds over the area. Clearing at SNS is a little
more uncertain with models split on if ceilings will clear this
afternoon. Based on satellite trends showing stratus dissipating in
the vicinity of SNS - leaning towards stratus clearing for at least
a few hours this afternoon. Stratus will return early this evening
at SNS with MVFR to IFR CIGs expected overnight. Winds will
generally stay west to northwest with strong, gustier winds expected
during the afternoon and early evening.

&&

.MARINE...
(Today through Tuesday)
Issued at 1113 AM PDT Thu Jun 13 2024

A small craft advisory has been issued for the San Francisco Bay
north of the Bay Bridge through the San Pablo Bay, Suisun Bay, and
the West Delta for gusts up to 25 knots. Fresh to strong
northwesterly winds continue over the northern waters through the
end of the week with strong to near gale force gusts possible by
Friday. Heading into the weekend, strong north to northwesterly
winds will spread southwards over much of the coastal waters with
gale-force winds increasing in likelihood. Significant wave
heights up to around 12 to 15 feet in the outer waters and 10 to
13 feet in the inner waters continues into the weekend.

&&

.FIRE WEATHER...
-- Changed Discussion --
Issued at 408 PM PDT Thu Jun 13 2024

...Elevated Fire Weather Conditions Through The Weekend...

Elevated fire weather conditions are expected to persist through
the weekend into the beginning of next week across our area. A
lack of recent rainfall amid warmer and drier conditions has dried
fuels, especially grasses. Although temperatures have moderated
back down to around normal after the recent heat, a relatively dry
airmass associated with an upper level Pacific trough will result
in gusty surface winds mixing to the surface across our inland
locations and higher terrain. Min RH values for locations
susceptible to potential wild fires will generally be between 10
to 30 percent Friday through Monday, and possible beyond. The
public should be discouraged from activities that may spark a
wildfire, especially weekend campers with campfires.
-- End Changed Discussion --

&&

.MTR WATCHES/WARNINGS/ADVISORIES...
-- Changed Discussion --
CA...None.
PZ...Small Craft Advisory until 9 PM PDT this evening for SF Bay N of
     Bay Bridge.

     Small Craft Advisory until 3 PM PDT Friday for Pigeon Pt to Pt
     Pinos 10-60 NM-Pt Arena to Pt Reyes 0-10 nm-Pt Arena to Pt
     Reyes 10-60 NM.

     Gale Watch from Friday afternoon through late Friday night for
     Pt Arena to Pt Reyes 0-10 nm.

     Small Craft Advisory from 3 AM to 9 PM PDT Friday for Pt Reyes
     to Pigeon Pt 0-10 nm.

     Gale Watch from Friday evening through Saturday afternoon for Pt
     Reyes to Pigeon Pt 0-10 nm.

     Small Craft Advisory from 9 AM Friday to 3 PM PDT Saturday for
     Pigeon Pt to Pt Pinos 0-10 nm.

     Small Craft Advisory from 3 AM Friday to 3 AM PDT Saturday for
     Pt Pinos to Pt Piedras Blancas 0-10 nm.

     Gale Watch from Friday afternoon through Saturday afternoon for
     Pigeon Pt to Pt Pinos 10-60 NM-Pt Arena to Pt Reyes 10-60
     NM.
-- End Changed Discussion --

&&

$$

SHORT TERM...SO
LONG TERM....SO
AVIATION...Kennedy
MARINE...Kennedy

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