343
FXUS66 KMTR 140603
AFDMTR

Area Forecast Discussion
National Weather Service San Francisco CA
1103 PM PDT Thu Jun 13 2024

...New AVIATION, MARINE...

.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.

&&

.UPDATE...
Issued at 802 PM PDT Thu Jun 13 2024

The forecast remains on track this evening. Some patchy fog
overnight can be expected from the South Bay southward into the
Santa Cruz coastal region. An upper level system moving onshore
across the Pacific Northwest this weekend will bring drier air
and gusty winds, elevating fire weather concerns across our region
for the weekend into the beginning of next week. Any activities
that could spark a wildfire should be discouraged.

&&

.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...
(06Z TAFS)
Issued at 1102 PM PDT Thu Jun 13 2024

MVFR-IFR stratus is developing along the immediate coast and into
the East Bay north of OAK and across the Central Coast valleys.
Stratus coverage tonight is expected to expand slightly into the
northern SF Bay and patches of the Napa Valley. Lingering breezy
onshore winds will diminish through the rest of the night.

Stratus will clear out through Friday morning, with intensely breezy
west winds developing on Friday afternoon. Wind gusts are expected
to approach 20-30 knots at the terminals in the afternoon, with
strong gusts continuing through the evening. Model output indicates
that surface sustained winds will begin to diminish as the nocturnal
boundary layer decouples, but strong winds aloft will introduce the
risk of LLWS overnight. Model output shows signals of LLWS along the
coast, but magnitudes are not strong enough to include in the TAFs
at this time.

Vicinity of SFO... Westerly winds expected to diminish through the
night, with a moderate confidence for MVFR-IFR stratus to flow over
the terminal. OAK is just on the edge of the stratus deck, but has
consistently reported MVFR cigs which is reflected in their TAF
forecast. VFR conditions return Friday morning with strong west-
northwest winds developing Friday afternoon. Current forecast calls
for gusts around 30 knots extending late into the evening as winds
funnel through the San Bruno Gap, only coming down as the TAF period
ends. LLWS concerns develop on Friday evening but the magnitude is
marginal and confidence is low.

SFO Bridge Approach... Lower confidence for stratus impacts along
the approach path. Otherwise similar to SFO.

Monterey Bay Terminals... IFR-MVFR ceilings continue through the
night. Stratus clears out through Friday morning with low to
moderate confidence in timing at MRY. Breezy onshore winds gusting
to 15-20 knots develop Friday afternoon and last into the evening.
Model output suggests that the region remains clear through the end
of the TAF period and some portion beyond.

&&

.MARINE...
(Tonight through next Wednesday)
Issued at 1102 PM PDT Thu Jun 13 2024

Fresh to strong northwest winds persist over the northern waters
with gale force gusts expected Friday afternoon and evening.
Strong north to northwest winds will spread southwards over much
of the coastal waters late Friday into Saturday, with widespread
gale force winds anticipated. Significant wave heights up to
around 12 to 15 feet in the outer waters and 10 to 14 feet in the
inner waters continue into the weekend. Hazardous conditions for
small craft continue through the weekend and early next week.

&&

.FIRE WEATHER...
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.

&&

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

&&

$$

SHORT TERM...SO
LONG TERM....SO
AVIATION...DialH
MARINE...DialH

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