-- Discussion containing changed information from previous version are highlighted. --
951
FXUS66 KMTR 100610
AFDMTR

Area Forecast Discussion
National Weather Service San Francisco CA
1110 PM PDT Sun Jun 9 2024

...New AVIATION...

.SYNOPSIS...
Issued at 107 PM PDT Sun Jun 9 2024

Warmer temperatures are in store Monday-Wednesday before a return
to seasonal averages late week.

&&

.UPDATE...
Issued at 855 PM PDT Sun Jun 9 2024

The short term forecast is in really good shape, with just some
cosmetic changes to the wind/wind gust and weather grids. A
consensus of the latest high-resolution short term forecast seems
matches the best with the latest observations across the East Bay
and SF Peninsula wind wise. As we`ve seen over the past few
nights, winds will accelerate through the rest of the evening into
before easing through the pre-dawn hours on Monday across these
locales. Peak gusts will average between 20 and 30 mph across the
SF Peninsula to 30 to 40 mph across the East Bay Hills/Mountains.

Regarding the fog potential---dewpoint depressions will approach
1-2 degrees across the the marine zones to a few miles inland
along the coastline. While the PBL may remain somewhat overturned
and result in a bit more in the way of low stratus, the signals
from some of the short-term guidance suggests that patchy to even
areas of fog may transpire for areas along the San Francisco
Peninsula (Pacific Side) down toward Half Moon Bay, Santa Cruz,
Monterey Bay, and down to Point Sur. Mariners and motorists should
be aware of limited visibility late tonight and into early Monday
morning.

Otherwise, the most dominant weather headlines will be the above
normal temperatures and hot conditions, especially on Tuesday.
The current Heat Advisory appears to be in good shape, though
we`ll need to keep an eye on Wednesday across parts of the area.

&&

.SHORT TERM...
-- Changed Discussion --
(This evening through Monday)
Issued at 107 PM PDT Sun Jun 9 2024

One more pleasant day before the heat returns.

A short wave trough axis at 500 mb is now directly above the Bay
Area. This is evident in the convective clouds over the Sierra
moving to the NE and the stratocumulus over the ocean moving the
the S. Locally, satellite imagery that shows most clouds have
cleared, with the exception of the SF Peninsula coastline. The
Ft. Ord profiler is measuring the marine layer at 2,100 ft deep.
This is helping keep temperatures in the 60s along the coast and
adjacent valleys. Inland areas are in the upper 70s, and will take
advantage of the clear skies to get into the mid-80s later this
afternoon. Onshore winds will also begin to increase as the higher
surface temperature allows more downward momentum transfer.

The short wave trough will continue to amplify and become a cut-
off low west of the Channel Islands by Monday morning. This will
allow a high pressure ridge to move in north of the low. This
ridge will warm the air mass through both normal subsidence and
by interacting with the cut-off low to generate some weak
offshore flow around 700 mb. This effect is most evident in the
North Bay where a tongue of higher thickness values will spill
over from Nevada. Monday is the first day of the heat spell, with
temperatures expected to reach the high 80s and lower 90s inland.
-- End Changed Discussion --

&&

.LONG TERM...
(Monday night through next Saturday)
Issued at 107 PM PDT Sun Jun 9 2024

Temperatures will cool off quite a bit Monday night, retreating
back to near normal values in the 50s. This will be a theme of the
event with high afternoon temperatures, but good relief overnight.
Unlike the worst heat waves, there will be an opportunity to open
the windows after dinner.

Tuesday looks to be the hottest day and has most of our attention.
Mid to upper 90s are expected for inland areas, as well as low
100s in the northern portions of Sonoma and Napa counties, the
southern Salinas valley and San Benito county, and more generally
along the easternmost portions of counties bordering the Central
Valley. Warm temperatures persist into Wednesday, but begin to
drop by a few degrees, with high temps largely similar to those on
Monday. Coastal areas throughout this event will remain
relatively cool in the mid to upper 60s, perhaps touching the
lower 70s on Tuesday as onshore flow helps maintain more
comfortable temperatures. As it currently stands, models continue
to show light onshore flow persisting at the surface.

With these warmer temperatures comes increased HeatRisk. While
Monday and Wednesday see largely Minor HeatRisk for the majority of
our area, Tuesday will have many inland locations achieving Moderate
levels of HeatRisk while coastal areas remain in the Minor category.
This moderate category indicates a level of heat that affects most
individuals sensitive to heat, such as those that are ill, elderly,
very young, or without shelter or a means to cool themselves such as
air conditioning. As we draw nearer to this event, keep in mind that
even if only Minor HeatRisk is indicated, that heat related illness
and impacts can affect anyone, especially when heat is prolonged.
Its never a bad idea to make sure you are staying adequately
hydrated during times of warmer temperatures, taking breaks in the
shade if working outdoors, and to check in on loved ones who perhaps
fall into the demographics of those sensitive to heat. Additionally,
if planning to visit the coast or a body of water to cool off, make
sure you wear a life jacket, swim near a lifeguard, and be aware
of the risks of cold water shock.

By Thursday, high temperatures decrease and begin to cool off as
troughing resumes and the cutoff low rejoins upper level flow and
lifts out to our east. Sweet relief.

&&

.AVIATION...
-- Changed Discussion --
(06Z TAFS)
Issued at 1109 PM PDT Sun Jun 9 2024

IFR CIGs are moving inland and have already filled over the SF Bay
and Monterey Bay. STS and APC are expected to form CIGS later into
the night. Cigs are expected to erode in the mid to late morning.
Winds stay light to moderate through the morning before increasing
this afternoon, with gusty winds along the immediate coast and at
SFO. Expect winds to reduce into monday evening stratus begins to
move inland. This will offer IFR/MVFR CIGs along the coast and
affecting MRY. Additional overnight and early morning CIGs will form
around the North Bay Terminals. Pockets of mist and drizzle will be
possible along the coast overnight as well.


Vicinity of SFO...MVFR/IFR CIGs linger into the mid morning before
clearing. Winds stay moderate through the night but decrease into
the mid morning. Breezy westerly winds arrive Monday afternoon with
peak gusts around 20 kts. Gusts taper off into the late evening.

SFO Bridge Approach...Similar to SFO.

Monterey Bay Terminals...IFR/MVFR CIGS last with light to moderate
winds last into the late morning. Expect more moderate to breezy
winds to arrive as CIGs thin. Winds become light into Monday evening
and CIGs approach the terminals.
-- End Changed Discussion --

&&

.MARINE...
(Tonight through next Saturday)
Issued at 847 PM PDT Sun Jun 9 2024

The pressure gradient between subtropical high pressure over the
Eastern Pacific Ocean and low pressure over the West is
supporting fresh to strong northwesterly breezes and rough seas.
The overall pattern will remain fairly stable over the next week
although the high pressure will meander closer to the coast at
times, bringing periods of near gale force winds and very rough
seas. The first push is expected mid-week, with another over the
upcoming weekend.

&&

.MTR WATCHES/WARNINGS/ADVISORIES...
-- Changed Discussion --
CA...Heat Advisory from 11 AM to 8 PM PDT Tuesday for CAZ504-506-510-
     513>515-518.

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

     Small Craft Advisory until 9 AM PDT Monday for Pigeon Pt to Pt
     Pinos 0-10 nm-Pt Pinos to Pt Piedras Blancas 0-10 nm-Pt
     Reyes to Pigeon Pt 0-10 nm.

     Small Craft Advisory until 9 AM PDT Tuesday for Pt Arena to Pt
     Reyes 10-60 NM.
-- End Changed Discussion --

&&

$$

SHORT TERM...Flynn
LONG TERM....Flynn
AVIATION...Murdock
MARINE...Sarment

Visit us at www.weather.gov/sanfrancisco

Follow us on Facebook, Twitter, and YouTube at:
www.facebook.com/nwsbayarea
www.twitter.com/nwsbayarea
www.youtube.com/nwsbayarea