-- Discussion containing changed information from previous version are highlighted. --
504
FXUS66 KMTR 282321
AFDMTR

Area Forecast Discussion
National Weather Service San Francisco CA
421 PM PDT Fri Jun 28 2024

...New MARINE...

.SYNOPSIS...
Issued at 251 AM PDT Fri Jun 28 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. Pattern change causes a warm up
early next week, with monitoring potential excessive heat for the
second half of next week.

&&

.SHORT TERM...
(This evening through Saturday)
Issued at 313 PM PDT Fri Jun 28 2024

Low clouds persist along the Monterey coastline with stratus
expected to return inland overnight along the Central Coast and up
the coast of the SF peninsula. Widespread minor heat risk and
patches of moderate heat risk over the North and East Bay continue
through Saturday. Overnight temperatures Friday into Saturday will
largely be in the mid 50s to low 60s. A slight warming trend is
expected to kick off Saturday and Sunday before the more substantial
warming anticipated next week. High temperatures on Saturday will
warm slightly (2 to 4 degrees on average) with inland highs largely
in the 80s to low 90s. Favored hotspots in the North and East Bay
may reach the mid 90s. Closer to the coast, cooler temperatures
prevail with highs in the low to mid 60s. Given the long term trend
for warmer, excessively dangerous heat next week - make the most out
of these comparatively cooler temperatures and take care of any
outdoors activities you may need to do this weekend.

&&

.LONG TERM...
-- Changed Discussion --
(Saturday night through next Thursday)
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...
(18Z TAFS)
Issued at 1011 AM PDT Fri Jun 28 2024

Widespread VFR returns into the afternoon and lasts into the night.
Winds increase into the afternoon with gusty winds expected at SFO
and along the coast, while other areas stay moderate to breezy.
Winds reduce into the night as IFR/MVFR CIGs move over the coast and
Monterey Bay terminals. These CIGS look to last into late Saturday
morning as widespread moderate to breezy winds build.

Vicinity of SFO...VFR through the TAF period. Expect breezy wot
gusty winds this afternoon with gusts peaking around 24 kts. These
winds last into the evening, reducing, but staying breezy into the
late night. Breezes reduce into early Saturday, but pick up again
that afternoon.

SFO Bridge Approach...Similar to SFO.

Monterey Bay Terminals...Lingering clouds at MRY erode into the
afternoon with VFR expected afterward through the early night.
Moderate to breezy westerly winds build this afternoon, with
slightly stronger winds expected at the immediate coast. Winds
reduce the early night as IFR CIGS move inland and fill over MRY,
with SNS filling later into the night.

&&

.MARINE...
-- Changed Discussion --
(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.
-- End Changed Discussion --

&&

.FIRE WEATHER...
Issued at 322 PM PDT Fri Jun 28 2024

Temperatures will hover right around seasonal averages through the
weekend with relatively light onshore breezes. There is an
Excessive Heat Watch in effect across our area for Tuesday
through Friday of next week, encompassing the Fourth of July
holiday. Confidence is increasing for an unusually strong dome of
high pressure across our region that will produce daily maximum
temperatures well above normal and subsequently, very low min RH
values. The building heat will also result in poor overnight RH
recovery. Please plan accordingly.

&&

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

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

     Small Craft Advisory from 9 AM Saturday to 9 AM PDT Sunday for
     Pt Arena to Pt Reyes 0-10 nm.

     Small Craft Advisory from 3 PM Saturday to 9 AM PDT Sunday for
     Pigeon Pt to Pt Pinos 10-60 NM-Pt Reyes to Pigeon Pt 0-10
     nm.

     Small Craft Advisory until 9 AM PDT Sunday for Pt Arena to Pt
     Reyes 10-60 NM.

&&

$$

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

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