953
FXUS66 KMTR 040852
AFDMTR

Area Forecast Discussion
National Weather Service San Francisco CA
152 AM PDT Thu Jul 4 2024

...New SYNOPSIS, SHORT TERM, LONG TERM...

.SYNOPSIS...
Issued at 1217 AM PDT Thu Jul 4 2024

Day 3 of the heat wave. Extremely hot conditions will continue
through the middle of next week for inland areas. Excessive Heat
Warnings, Heat Advisories, and Red Flag Warnings are in effect.

&&

.SHORT TERM...
(Today and tonight)
Issued at 1217 AM PDT Thu Jul 4 2024

Cumulative effects will begin to set in for those without access
to suitable cooling. Remember we still have a long way to go with
hot weather expected through the middle of next week. In fact this
is the longest duration Excessive Heat Warning we have ever
issued at the NWS Bay Area Office. The previous record was 162
hours (6.75 days) in September 2022. While it may still change,
our warning is currently 204 hours long (8.5 days).

A southerly surge is bringing some stratus and fog up the coast
in Monterey County and just offshore Santa Cruz, San Mateo, and
San Francisco. The Ft. Ord Profiler is showing the marine layer
has expanded to 1,000 ft as a very weak upper level disturbance
takes a temporary bite out of the ridge, and opposing southerly
flow moves up the coast. It`s hard to say how much more territory
these low clouds will gain. The HRRR has been over aggressive in
these situations before, but shows the return of low clouds this
morning along the majority of the coast and even pushing through
the Golden Gate. Even if that is too aggressive, the GOES-18 night
fog imagery continues to show the clouds gain latitude at this
time, so don`t be surprised if there`s some grey clouds along the
coast this morning.

Whether the marine layer clouds stick around past mid-day or not,
the general theme of much cooler temperatures along the coast
will continue. There is also some good news beyond the coast as
high temperatures this afternoon will be 5-10 degrees cooler than
yesterday. That`s not enough to end the heat wave, however. We
will still see temps in the upper 90s and low 100s for inland
areas today. If you want to beat the heat this holiday, the
immediate Bay Shore will be in the 70s and 80s, with the Pacific
Beaches in the 60s and 70s. With light winds, it will be a nice
day at the beach. In fact, it may even be a bit chilly at some
beaches if the clouds stick around. If you can`t make it to
cooler weather, be sure to take precautions to avoid heat illness.
Stay in the AC or shade, hydrate, take it easy, and check on your
neighbors.

It is imperative to take measures to protect yourself, loved ones,
and animals during this extreme heat. Given that today is
Independence Day, a holiday in which many activities take place
outdoors (parades, picnics, BBQs, community gatherings, fireworks
displays), extra caution is urged. For areas of Extreme Heat Risk,
consider suspending outdoor events or modifying them to take
place early in the day or indoors in an air conditioned
environment. Aside from these measures, there are many other
things you can do to protect yourself, including staying hydrated
by drinking hydrating beverages such as water or sports drinks
with electrolytes, and avoiding dehydrating beverages such as
alcohol and caffeine-laden drinks.

&&

.LONG TERM...
(Friday through Wednesday)
Issued at 1217 AM PDT Thu Jul 4 2024

Unfortunately the temperatures will rebound, and Fri-Sat look
nearly as hot as Tue-Wed. During this time, the high pressure
ridge responsible for this heat wave will be centered directly
over the Bay Area. This will bring the potential for 850 temps to
reach 30C over the weekend. This threshold has only been hit 6
times out of roughly 56,000 weather balloon observations dating
back to 1948.

There does appear to be a modest cool down to start next week and
HeatRisk starts to slide back into the moderate category. Most
inland areas will still be in the 90s, but there wont be nearly as
many thermometers reading triple digits. The ridge will gradually
flatten and slide east through next week, with more relief
expected later in the week.

Heat is the number 1 weather related killer in the United States.
Unfortunately lives will be lost during this heat wave. Follow
these tips to protect yourself, your loved ones, and your animals.

-Stay inside in an air conditioned environment between 10am and 7pm.
-Suspend unnecessary outdoor activities during the extreme heat,
 but if you must be outdoors, take frequent breaks in the shade
 or AC and drink cool water.
-Know the signs and symptoms of Heat Exhaustion vs. Heat Stroke! Heat
 Stroke can be deadly if not treated immediately by a medical
 professional. Call 911 if you suspect someone is suffering from
 Heat Stroke.
-Wear a lifejacket, swim near a lifeguard, and check conditions before
 entering the water if going to a river or ocean to cool off.
 Rivers and the ocean are extremely cold, and Cold Water Shock can
 turn into paralysis and drowning if you are not careful.
-Use a cool and damp towel on your body if you do not have AC and
 are feeling hot. Or, take a cool shower or bath.
-Do not leave kids or pets in a parked car.
-Ensure pets and livestock have access to shade and water.

&&

.AVIATION...
(06Z TAFS)
Issued at 1030 PM PDT Wed Jul 3 2024

Stratus has developed on the Big Sur coast and into parts of
Monterey Bay, with moderate confidence of LIFR stratus over the
Monterey Bay region, dissipating sometime Thursday morning. The rest
of the region remains generally VFR through the TAF period with
light winds overnight with breezy onshore winds setting up Thursday
afternoon.

Vicinity of SFO...High confidence of VFR through the TAF period.
Light winds overnight, building to a breezy west-northwest flow
Thursday afternoon with wind speeds at 10-15 knots. Low confidence
in model output that shows some chance of stratus through the Golden
Gate Thursday night into Friday morning.

SFO Bridge Approach...Similar to SFO.

Monterey Bay Terminals...Stratus is already building into the region
with moderate confidence that it extends into MRY and SNS. Expect
the stratus to clear out sometime on Thursday morning although
timing remains a bit uncertain. Breezy onshore flow sets up Thursday
afternoon followed by a chance for stratus to return to MRY in the
evening, although confidence is low.

&&

.MARINE...
(Tonight through next Tuesday)
Issued at 907 PM PDT Wed Jul 3 2024

Light moderate winds continue into the weekend with possible
gusty and strong winds in the northern outer waters that will pose
hazardous to small crafts into tonight before easing. Waves start
to diminish Thursday morning, bringing relatively calm conditions
over the waters into Friday.

&&

.FIRE WEATHER...
Issued at 257 PM PDT Wed Jul 3 2024

Red Flag Warnings are in effect for the North Bay Interior
Mountains, East Bay Hills, and Santa Cruz Mountains until 9 PM
Saturday. Red Flag Warnings are in effect for the Marin and Sonoma
Coastal Range until 5 AM Friday. Red Flag Warnings are in effect
for the Santa Lucia Mountains, San Benito County, and the Southern
Salinas Valley from 9 AM Friday through 9 PM Saturday.

This heat wave will bring very low RH and the long duration will
cure and dry the fuels. ERC values are exceeding or approaching
the max moving average for a number of regions. Thankfully the
winds won`t be very strong, but with such high temps, low RH and
critically dry fuels, it only takes 6-11 mph winds to trigger RFW
criteria. Conditions are dangerous, and we urge extreme caution.
Please rethink the use of any fireworks this year, including the
safe and sane, or even those seemingly-innocuous sparklers and
pop-its. Perhaps consider not lighting them off at all this year,
and instead enjoy a professional display in your community, or
even on TV. Its not worth the risk. Don`t Be the Spark!

&&

.BEACHES...
Issued at 1224 AM PDT Wed Jul 3 2024

Beaches will be a popular destination over the Holiday and as one
of the few places to escape the oppressive inland temperatures.
Fortunately the waves are relatively low energy, but that doesn`t
alleviate all beach safety concerns. Ocean temperatures are in
the mid-50s. This cold water may catch some off-guard. Cold water
shock can set in very quickly. Wear a life jacket, dress
appropriately, limit time in the water, swim near a lifeguard and
follow their instructions.

&&

.MTR WATCHES/WARNINGS/ADVISORIES...
CA...Coastal Flood Advisory until 5 AM PDT Friday for CAZ006-506-508.

     Heat Advisory until 7 PM PDT this evening for CAZ006.

     Excessive Heat Warning until 11 PM PDT Wednesday for CAZ502>504-
     506-510-512>518.

     Red Flag Warning until 5 AM PDT Friday for CAZ502-503.

     Red Flag Warning until 9 PM PDT Saturday for CAZ504-512-515.

     Heat Advisory until 11 PM PDT Wednesday for CAZ508-528-529.

     Red Flag Warning from 9 AM Friday to 9 PM PDT Saturday for
     CAZ516>518.

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

&&

$$

SHORT TERM...Flynn
LONG TERM....Flynn
AVIATION...DialH
MARINE...Behringer

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