661
FXUS66 KMTR 010423
AFDMTR

Area Forecast Discussion
National Weather Service San Francisco CA
923 PM PDT Sun Jun 30 2024

...New UPDATE, FIRE WEATHER...

.SYNOPSIS...
Issued at 1235 PM PDT Sun Jun 30 2024

Significant warm up still on the way for next week after near normal
temperatures this weekend. Increased fire danger next week as well
with temperatures well above normal and dry conditions through next
weekend.

&&

.UPDATE...
Issued at 901 PM PDT Sun Jun 30 2024

Low marine stratus has begun to encroach on our coastal locations
and is expected to persist through mid/late morning tomorrow. No
significant change in the forecast for the impending heat wave
that will begin to ramp up on Tuesday. However, a Red Flag Warning
is now in effect for portions of the North Bay Interior Mountains,
East Bay Hills, Marin and Sonoma Coastal Ranges beginning
tomorrow night. Any activity that could cause an ignition should
be avoided, for example dragging trailer chains, unsecured
campfires and of course fireworks, the most obvious concern as we
move through the Fourth of July holiday and subsequent long
weekend. Another hazard more coincident with the timing of the
heat wave than the actual heat itself, is the potential for
flooding near the coast as we enter a New Moon phase. People
flocking to the water to try and escape the heat may encounter
more dangerous surf conditions than normal and potential road
closures where water spills over on to roadways.


&&

.SHORT TERM...
(This evening through Monday)
Issued at 1235 PM PDT Sun Jun 30 2024

A gorgeously warm day across the region today, and a great day to
be outside. Temps warm up a few degrees going into Monday as a
weak upper level trough degrades and moves inland. Highs Monday
look to be in the 90s across the interior, 80s for much of the Bay
shoreline, and 70s along coastal areas. If you live in the
interior, now is the time for any outdoor chores you may need to
get done before the warm up begins on Monday.

&&

.LONG TERM...
(Tuesday through next Saturday)
Issued at 1235 PM PDT Sun Jun 30 2024

Significant warmup really begins Tuesday as the very strong ridge
settles in across the West Coast. Not much change in the forecast
through the middle part of the week. Excessive Heat Warning goes
into effect Tuesday morning for interior areas, while lower
elevation locations that were once in the Watch have been
converted to a Heat Advisory given that they will cool off a
little more efficiently at night. Inland and high elevation areas
in the Warning will not see as much overnight relief through the
end of the week. Compressional heating under the ridge will warm
the airmass to near daily record territory above what little will
be left (if anything at all) of the marine layer. Guidance
continues to advertise 850 mb temps around 28 C, peaking
Wednesday. The daily max moving average this time of year is about
26.7 C, and we will be well above the 90th percentile, which is
about 23 C. Did nudge high and low temperatures up by a couple of
degrees Wednesday into the weekend as of this afternoon forecast
package. Far inland areas may actually end up with triple digits
into the weekend and the start of the next week. Left the timing
of the heat hazards as is for now (expiring Friday night), but
will definitely need to look into extending the Excessive Heat
Warning through the weekend. Cluster analysis still shows rather
high uncertainty regarding the breakdown of the ridge into next
week, hence the decision to wait on extending the hazards until
we become more confident over the next couple of days.

HEAT SAFETY AND IMPACTS:

By now youre well aware that it is going to be extremely hot next
week with well-above normal temperatures; now lets talk about the
impacts of excessive heat and actions we can take to minimize those
impacts: With extreme heat, and especially prolonged heat events, it
is a marathon, and not a sprint. Our bodies, infrastructure, pets,
and livestock will be under duress from heat over the span of days
as opposed to just a day or two. Given that there is little
overnight relief expected throughout this event, this is where it
really becomes a marathon, and precautionary measures are
necessitated in order to prevent adverse results such as heat
exhaustion and stroke. This is not just for individuals sensitive to
heat, but rather, the entire population. Heat for this duration and
at these temperatures can be dangerous for everyone. Do your body a
favor and if you can, suspend outdoors activities between the hours
of 10am and 7pm on days where Excessive Heat Watches or Warnings are
in effect. Remain in air conditioning if you have that available to
you in your residence, or seek out air conditioned environments such
as stores, movie theaters, restaurants, libraries, and cooling
shelters.

If you cannot access air conditioned environments, must be outside,
work outdoors, or otherwise, there are other precautionary measures
you can take to keep yourself and your loved ones safe (including
pets!) during excessive heat. Take frequent breaks in the shade and
ensure that you are drinking plenty of cool water, or other
hydrating beverages such as sports drinks with electrolytes. Avoid
DEHYDRATING drinks such as alcohol or caffeinated beverages. That
aside, visiting your city public pool or a lake, river, or ocean
can also help keep you cool, but dont forget the life jacket! If
planning on swimming, stick to where there is a lifeguard, and
know the ocean or river conditions before you get in. Although
outside of our area, its worth repeating: rivers can run fast and
cold with snowmelt in the Sierra Nevada mountains, and cold water
shock can set in quickly, which can lead to loss of muscle
control, and ultimately, drowning. Cold water shock can also set
in for ocean- goers. Have fun at the water, but be smart, be safe,
and Know Before You Go!

Finally, if you do not have air conditioning or cannot access it,
and also cannot access a body of water to stay cool: consider taking
cold showers or baths, turn on those sprinklers or garden hose and
have a fun time in your own makeshift water park, or lay a damp,
cool towel across your head or body. Even just dipping your hands
and feet in cool water can help to abate feelings of excessive heat.
For pets and livestock, make sure they have access to shade
structures or areas, and have clean water freely available to them
at all times. They do not have the same resources or ability to
notify of feeling heat-stressed as we do, so check in on them! If
theyre permanently outdoors, consider giving them a quick rinse-
down with the hose or set up misters, as the evaporation will help
to keep them cool as well.

&&

.AVIATION...
(00Z TAFS)
Issued at 504 PM PDT Sun Jun 30 2024

VFR through the TAF period with the exception of MRY and SNS.
Incoming high pressure has kept the marine layer fairly compressed
which should keep any stratus that does develop close to the
shoreline. The NBM leaned towards stratus filtering into portions of
the Bay Area but, given how compressed/shallow the marine layer
current is, that scenario is incredibly low confidence. Gusty W to
NW winds continue through the evening before weakening overnight.
Breezy to at times gusty W/NW winds are expected to return tomorrow
afternoon.

Vicinity of SFO...VFR through the TAF period. Gusty west to slightly
west-northwest winds continue into the evening before weakening
during the early morning. Gusts greater than 35 knots are expected
to continue until 04Z with gusts dropping down to 25 knots after.
Winds weaken significantly by the early morning before gusty
conditions return by late morning.

SFO Bridge Approach...Similar to SFO.

Monterey Bay Terminals...VFR becoming LIFR overnight. A highly
compressed marine layer will keep stratus confined to the Monterey
Bay with impacts expected at MRY and SNS. Current Fort Ord wind
profiler data shows the top of the marine layer around 600 feet with
incoming high pressure expected to compress it further. Model
consensus increased that CIGs will develop for MRY and SNS tonight
but confidence still remains higher for MRY than SNS. Any CIGs that
do develop are expected to be fairly close to the surface (given the
shallow nature of the marine layer) resulting in IFR to LIFR CIGs
and potential visibility impacts tonight. Gusty W/NW winds up to 20
knots continue through the evening before lighter, more variable
winds return overnight. Gusty conditions are likely to return again
tomorrow at SNS with gusts up to 20 knots currently expected.

&&

.MARINE...
(Tonight through next Saturday)
Issued at 504 PM PDT Sun Jun 30 2024

Strong northwesterly breezes with occasional gale force gusts
continues through the mid-week. As high pressure builds on Monday,
winds will become more northerly and widespread near-gale force
gusts will develop and spread across the waters. Significant wave
heights build to 10-12 feet generally through mid-week before
beginning to abate. Some potential for higher wave heights between
12-16 feet remains possible over portions of the northern outer
coastal waters.

&&

.FIRE WEATHER...
Issued at 901 PM PDT Sun Jun 30 2024

...A Red Flag Warning is in effect from Monday evening through
Tuesday evening for the East Bay Hills, Marin and Sonoma Coastal
Ranges, and the North Bay interior mountains Monday evening
through late Wednesday afternoon.

A Red Flag Warning has been added to the list of hazards along
with the Excessive Heat Warning which remains in place for most
of our interior locations, and a Heat Advisory for some locations
closer to the shoreline that may still see minimal influence of
the Marine Boundary Layer. Minimum RH values inland for the
upcoming week and beyond will mostly be in the teens, with some
single digit values in areas of higher elevation. Overnight RH
recover will be poor to non-existent as the heat wave persists
through the week, and potentially into next weekend. The hot and
dry conditions continue to move ERCs into the 70-80 percent range.
With the long holiday weekend, and the many outdoor activities
expected, people need to be careful with any campfires, and
fireworks should not be used. Any wildfire that ignites will have
the potential for rapid spread. Lightning is the only natural
ignition for wildfires and there are no thunderstorms in the
forecast.

&&

.MTR WATCHES/WARNINGS/ADVISORIES...
CA...Red Flag Warning from 11 PM Monday to 11 PM PDT Tuesday for
     CAZ502-503-515.

     Excessive Heat Warning from 11 AM Tuesday to 11 PM PDT Friday
     for CAZ502>504-506-510-512>518.

     Red Flag Warning from 11 PM Monday to 5 PM PDT Wednesday for
     CAZ504.

     Heat Advisory from 11 AM Tuesday to 11 PM PDT Friday for CAZ508-
     528-529.

PZ...Gale Warning until 3 AM PDT Monday for Pt Arena to Pt Reyes 0-10
     nm.

     Small Craft Advisory until 3 AM PDT Monday for Pt Reyes to
     Pigeon Pt 0-10 nm.

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

     Small Craft Advisory until 3 PM PDT Monday for Pt Arena to Pt
     Reyes 10-60 NM.

     Gale Watch from Monday afternoon through Tuesday afternoon for
     Pt Arena to Pt Reyes 10-60 NM.

     Small Craft Advisory until 3 AM PDT Tuesday for Pigeon Pt to Pt
     Pinos 10-60 NM.

&&

$$

SHORT TERM...Behringer
LONG TERM....Behringer
AVIATION...Kennedy
MARINE...Kennedy

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