693
FXUS66 KMTR 300409
AFDMTR

Area Forecast Discussion
National Weather Service San Francisco CA
909 PM PDT Sat Jun 29 2024

...New UPDATE...

.SYNOPSIS...
Issued at 1226 PM PDT Sat Jun 29 2024

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

&&

.UPDATE...
Issued at 906 PM PDT Sat Jun 29 2024

Forecast remains on track for another day of temperatures close to
or slightly above normal for Sunday. Monday will see a modest
increase in temperatures, setting the stage for the Excessive Heat
Watch beginning late morning on Tuesday, and in effect until at
least Friday evening. We will be making more focused decisions on
which locations to issue an Excessive Heat Warning or Heat Advisory
over the next 24-36 hours. The building heat will result in numerous
hazards and concerns across our region over the course of the
upcoming week. One factor 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. Of course, don`t forget about fire
weather concerns increasing as the hot and dry conditions combine
with many people camping under the warmth of camp fires, using
trailers that can cause sparks and many others using fire works.
Ultimately the use of fireworks should be strongly discouraged and
if heading out this week into next weekend, be aware of the forecast
along with your vulnerabilities to the heat, and know what you can
do to avoid sparking a wildfire.

&&

.SHORT TERM...
(This evening through Sunday)
Issued at 1226 PM PDT Sat Jun 29 2024

Warm today and tomorrow with temps near to slightly above normal.
Good onshore flow into Sunday as a weak trough sits over the West
Coast. Still warm over the next couple of days, but this weekend
will be a great time to finish up outdoor chores if you live in
interior areas before the warm up begins on Monday.

&&

.LONG TERM...
(Monday through next Friday)
Issued at 1226 PM PDT Sat Jun 29 2024

By late in the weekend, the weak trough begins to break down and
becomes replaced by a robust upper ridge that parks itself over
the western US through late week. Monday kicks off the first day
in a stretch of well above average temps. Locations far inland may
see the 100 degree mark on Monday, with an even more significant
increase on Tuesday. An Excessive Heat Watch is in effect for
inland areas away from the coast beginning Tuesday and lasting
through Friday. The whole period will be hot, but it looks like
Wednesday may be the peak just by a few degrees based on the
current forecast. Afternoon highs Wednesday are expected to be
well into the 100s for inland areas, nearing 110 for areas such as
northern Napa and Sonoma counties, eastern Contra Costa and
Alameda counties, and southern Monterey and San Benito counties.
Other urban areas can expect temps ranging from 90-100, and closer
to 80-85 for areas along the immediate Bay shoreline. Coastal
areas will continue to see temps ranging from the upper 60s to the
upper 70s. Overnight lows will be an issue with this event as
well, with elevations above about 1000 feet struggling to cool
below about 75-80 starting Tuesday morning. Lower elevations will
still see some degree of marine influence, but by Thursday
morning will only cool into the 60s. Climatologically, this event
is significant in that the forecast 850mb temps and 500mb heights
are well above the the percentile and near daily records for this
time of year based on KOAK soundings. For July 4, which is when
these values are expected to peak based on the current forecast,
the daily record max 850mb temp and 500mb height are 27.4 C and
597 dm, respectively. The forecast mean from the ECMWF ensemble
for each of these is about 28 C and 598 dm. There is considerable
uncertainty regarding the pattern after Friday, but the
possibility remains that the ridge hangs out for even longer, thus
will prompt the need to extend heat-related messaging into next
weekend.

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.

AC

&&

.AVIATION...
(00Z TAFS)
Issued at 403 PM PDT Sat Jun 29 2024

Currently VFR at all terminals with stratus hugging a majority of
the coastline. High confidence in VFR through the TAF period except
at the Monterey Bay terminals of MRY and SNS. Winds will remain
onshore through the TAF period. While below LLWS criteria, it may be
bumpy getting out of the region through tomorrow morning as winds
aloft are more northerly.

Vicinity of SFO...Currently VFR with northwesterly flow. High
confidence in VFR through the TAF period. Winds will prevail out of
the west through the TAF period with gusts up to 30 knots to be
expected through the day today as well as tomorrow afternoon and
evening.

SFO Bridge Approach...Similar to SFO.

Monterey Bay Terminals...Currently VFR with westerly flow at MRY and
VFR with northwesterly flow at SNS. Winds will prevail out of the
west for MRY and out of the northwest for SNS through the TAF
period. Moderate to high confidence in low-end IFR ceilings
returning to both terminals overnight. SNS is expected to clear by
mid-morning with MRY following suit by the afternoon.

&&

.MARINE...
(Tonight through next Thursday)
Issued at 403 PM PDT Sat Jun 29 2024

Strengthening surface high pressure over the Eastern Pacific
Ocean will be the dominating feature through the period.
Northwesterly breezes with occasional gale force gusts will
prevail through the weekend. As the pressure gradient tightens
Monday, breezes will become northerly with gale force gusts to be
expected over the outer waters through Wednesday. Significant wave
heights build to 10-15 feet through Tuesday before beginning an
abating trend towards the end of the period.

&&

.FIRE WEATHER...
Issued at 302 PM PDT Sat Jun 29 2024

Fire weather concerns will elevate this upcoming week. An
Excessive Heat Watch remains in effect for most of our area away
from the coastline for Tuesday through Friday. ERCs are quickly
shifting into the 70ish percentiles and higher in areas prone to
grass fires. The high heat and subsequent low RH values, poor
overnight RH recovery and the associated risks of fireworks with
the Fourth of July - all makes for a combustible situation,
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 from 3 PM to 9 PM PDT Sunday for Mry Bay.

     Small Craft Advisory until 3 PM PDT Sunday for Pt Arena to Pt
     Reyes 0-10 nm.

     Gale Warning from 3 PM to 9 PM PDT Sunday 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 from 9 AM to 9 PM PDT Sunday 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 Pigeon Pt to Pt
     Pinos 10-60 NM-Pt Arena to Pt Reyes 10-60 NM.

&&

$$

SHORT TERM...Behringer
LONG TERM....Behringer
AVIATION...Sarment
MARINE...Sarment

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