-- Discussion containing changed information from previous version are highlighted. --
741
FXUS66 KMTR 290747
AFDMTR

Area Forecast Discussion
National Weather Service San Francisco CA
1247 AM PDT Sat Jun 29 2024

...New SYNOPSIS, SHORT TERM...

.SYNOPSIS...
-- Changed Discussion --
Issued at 1242 AM PDT Sat Jun 29 2024

A well established marine layer and onshore flow will keep
temperatures cool near the coast while inland areas warm to into
the 90`s throughout the weekend. Increasing confidence in a
pattern change resulting a significant warm up early next week
that will continue through late week.
-- End Changed Discussion --

&&

.SHORT TERM...
-- Changed Discussion --
(Today and tonight)
Issued at 1242 AM PDT Sat Jun 29 2024

Low clouds are spreading inland around the Monterey Bay region
this morning, into the Salinas Valley, isolated pockets along the
San Mateo coast, and portions of the coastal North Bay. Expecting
trend to continue through sunrise before retreating to the coast
thereafter. Maximum temperatures are expected to warm into the
upper 80`s to mid 90`s across the interior with 60`s and 70`s near
the coast. Tonight, expecting low clouds to return to the coast
with minimum temperatures generally in the 50`s for much of the
region.
-- End Changed Discussion --

&&

.LONG TERM...
-- Changed Discussion --
(Sunday through next Friday)
Issued at 313 PM PDT Fri Jun 28 2024

A weak warming trend continues through Sunday with temperatures
similar to Saturday in the 80s to low 90s expected. The main story
for our long term forecast: a strengthening surface high pressure
system and a large upper level ridge will move inland and bring
dangerously hot, well above average temperatures for all areas away
from the coastline in the Bay Area and Central Coast. This will be a
prolonged heat event beginning Monday and continuing through the end
of the week with widespread major to extreme heat risk expected over
the majority of the Bay Area and Central Coast. An Excessive Heat
Watch has been issued beginning Tuesday morning (when widespread
major to extreme heat develops) through Friday evening. Wondering
what an Excessive Heat Watch is? An Excessive Heat Watch is issued
when dangerous heat is possible in the coming few days. An Excessive
Heat Warning is when dangerous heat is currently occurring or about
to start occurring. For now, we are still in the watch phase but
everyone should start preparing for the excessive heat next week by
rescheduling any outdoors activities and having a way to access
somewhere that has A/C (for more ways to prepare see Heat Safety and
Impacts section below).

Getting into the gritty details of what we know so far:

High temperatures will warm into the upper 80s to upper 90s
beginning Monday with moderate heat risk expected over much of the
Bay Area and Central Coast. Tuesday will mark the beginning of
widespread excessive, dangerous heat with high temperatures
breaching the mid 90s to low 100s. Across favored hot spots in the
North/East Bay and portions of interior Monterey and San Benito
Counties high temperatures may reach up to 110 degrees with extreme
heat risk forecast for these areas. Overnight temperatures are not
spared from this warming trend with widespread overnight lows in the
upper 50s to mid 60s. In areas where extreme heat risk is expected,
overnight low temperatures will be in the upper 60s to in the 70s.
Longer term guidance (beyond this forecast period) suggests that
anomalously warm temperatures may persist past Friday into next
weekend. We will continue to monitor this as we get closer to the
event.

Daytime relative humidity values will drop beginning Tuesday through
the end of the week with widespread daytime RH values in the mid
teens to mid twenties across the interior. For most areas there will
be fair to good overnight relative humidity recoveries (60-70%)
while portions of interior North/South/East Bay and interior
Monterey/San Benito county may see locally poorer overnight relative
humidity recoveries (20-40%). This will bring elevated fire weather
concerns across interior portions of the North/East/South Bay with
emphasis placed on the interior North Bay Mountains and far interior
East Bay Hills. Remember, we have had several fires already this
fire season so fine fuels (grass, shrubs, etc.) are already dry and
ready to burn. Given that Fourth of July takes place in the middle
of this heat wave take GREAT care with any outdoor activities
involving barbecues, sparks, or any sort of flame.

One last thing to note - we are entering the King Tide cycle
beginning this week with minor coastal flooding possible in Bayside
portions of the North Bay and along the Embarcadero in San Francisco.

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.
-- End Changed Discussion --

&&

.AVIATION...
(06Z TAFS)
Issued at 1015 PM PDT Fri Jun 28 2024

IFR-LIFR ceilings across the Monterey Bay region, down the Big Sur
Coast, and into the Salinas Valley, expected to mix out late
Saturday morning. Otherwise, generally VFR through the TAF period,
although patchy stratus is possible at the immediate coast,
especially south of the Golden Gate. Some model output has ceilings
sneaking through the Golden Gate and up towards Napa Valley, but
there is very low confidence and the TAFs remain clear. Breezy
onshore winds develop Saturday afternoon and diminish late in the
evening.

Vicinity of SFO...VFR through the TAF period, with very low
confidence in the model output that places some stratus at the edge
of the terminal. Breezy west-northwest winds will become light
overnight. Gusty west to west-northwest winds gusting near 25 knots
developing Saturday afternoon and evening.

SFO Bridge Approach...Similar to SFO.

Monterey Bay Terminals...IFR-LIFR ceilings continue through the
night, clearing out later Saturday morning. Breezy onshore winds
develop Saturday afternoon. Moderate confidence that developing
stratus at the coast will remain away from the terminals until after
the end of the TAF period.

&&

.MARINE...
(Tonight through next Wednesday)
Issued at 420 PM PDT Fri Jun 28 2024

Breezy to gusty northwesterly winds continue into next week
before diminishing to more moderate winds. Significant wave
heights begin to build to 10-12 feet towards the beginning of next
week. Light southerly swell continues to move through the waters
alongside moderate northwesterly swell.

&&

.MTR WATCHES/WARNINGS/ADVISORIES...
-- Changed Discussion --
CA...Excessive Heat Watch from Tuesday morning through Friday evening
     for CAZ502>504-506-508-510-512>518-528.

PZ...Small Craft Advisory from 3 PM to 9 PM PDT Sunday for Mry Bay.

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

     Small Craft Advisory from 9 AM this morning to 9 AM PDT Monday
     for Pigeon Pt to Pt Pinos 10-60 NM-Pt Arena to Pt Reyes 0-
     10 nm.

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

     Small Craft Advisory from 9 AM Sunday to 3 AM PDT Monday for
     Pigeon Pt to Pt Pinos 0-10 nm.

     Small Craft Advisory from 9 AM Sunday to 9 AM PDT Monday for Pt
     Pinos to Pt Piedras Blancas 0-10 nm.

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

&&

$$

SHORT TERM...RGass
LONG TERM....Kennedy
AVIATION...DialH
MARINE...Sarment

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