915
FXUS66 KMTR 050555
AFDMTR

Area Forecast Discussion
National Weather Service San Francisco CA
1055 PM PDT Thu Jul 4 2024

...New AVIATION...

.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.

&&

.UPDATE...
Issued at 819 PM PDT Thu Jul 4 2024

Once again, records were either tied or broken this afternoon at San
Rafael and the San Francisco International Airport (see below).
However, slight cooling was observed across the board this
afternoon. Low clouds and/or fog are widespread off of the entire
Bay Area and Central Coast and are likely to spread locally inland
tonight given the shallow marine layer.

Tonight, temperatures will lower into the mid 50`s to lower 60`s in
coastal areas and cooler interior valleys, mid 60`s in the warmer
valleys (such as the southern Santa Clara Valley), and upper 60`s to
mid 80`s in the higher terrain. Again, this will provide very little
relief from today`s heat.

...RECORD HIGH TEMPERATURES THURSDAY, JULY 4, 2024...

LOCATION                    HIGH          PREVIOUS RECORD
---------------------------------------------------------------
SAN RAFAEL                   98 (TIED)      98 IN 2013
SAN FRANCISCO AIRPORT        87             85 IN 1973

These data are preliminary and have not undergone final quality
control by the National Centers for Environmental Information.
Therefore, these data are subject to revision. Final and certified
climate data can be accessed at www.ncei.noaa.gov.

&&

.SHORT TERM...
(This evening through Friday)
Issued at 207 PM PDT Thu Jul 4 2024

The center of the dome of high pressure responsible for our extended
heat wave has begun moving onshore and will continue to gradually
shift east and south over the coming days. Today will be the
`coolest` day until possibly the middle of next week, but will offer
no relief as the high heat keeps on building, and the impacts will
only continue to compound. Elevated locations away from the
immediate shoreline are seeing little to no relief wrt overnight
temperatures with lows in the 80s, even some higher spots in the
90s. This is something campers and hikers need to be aware of as we
continue through the holiday weekend. Temperatures at or just along
the immediate shoreline will offer the best chance at beating the
heat with highs in the 60s and 70s, otherwise do everything you can
to reduce your heat risk. Read below at the bottom of the Long Term
forecast for more on how to keep yourself safe.

&&

.LONG TERM...
(Friday night through next Wednesday)
Issued at 207 PM PDT Thu Jul 4 2024

Saturday appears to be the peak of the heat wave wrt maximum
temperatures, but will still be days away from marking the end of
the event. Elevated areas across southern Monterey and San Benito
Counties will be at or slightly above 115 degrees. There is no end
in sight to heat wave in the official extended forest out to next
Thursday (July 11th), but looking out at next weekend, troughing is
established along the West Coast on the back side of the meandering
high as it moves farther inland. As heights and thickness values
gradually decrease, so will temperatures, but until then please take
note of the following information to keep yourself, family, friends
and pets safe from this historic heat wave.

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 1047 PM PDT Thu Jul 4 2024

VFR through the TAF period for all but the immediate coast and the
Monterey Bay. High pressure aloft is causing a very shallow marine
layer. The good news is this will only affect the coastal
terminals overnight, the bad news is the the terminals that do
have a ceiling roll in will see very low ceilings in the 200 ft
range and possible fog. These CIGS look to last into late Friday
morning but erode as widespread moderate to breezy winds return.
Winds reduce again into Friday evening.

Vicinity of SFO...VFR through the TAF period. Moderate winds last
into the night before reducing. Moderate westerly winds return
Friday afternoon with some infrequent breezes, but these winds
weaken into the night.

SFO Bridge Approach...Similar to SFO.

Monterey Bay Terminals...Winds reduce into the night as LIFR CIGS
move inland and fill over MRY, with SNS filling later into the
night. These CIGs erode in the mid to late morning as westerly
winds build. Winds reduce again into the evening with CIGs
returning later Friday night. There is also some visibility
reduction due to a combination of firework smoke and high pressure
that may get worse as the temperature drops and fog starts to
form.

&&

.MARINE...
(Tonight through next Wednesday)
Issued at 919 PM PDT Thu Jul 4 2024

Light to moderate winds persist for most areas until the end of
the week. Waves continue to reduce before breezy to gusty winds
build into Friday in the southern waters, causing hazardous
conditions for small craft.

&&

.FIRE WEATHER...
Issued at 819 PM PDT Thu Jul 4 2024

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
North Bay Interior Mountains, East Bay Hills, and Santa Cruz
Mountains until 9 PM Saturday. 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.

Winds have calmed since yesterday, and are now gusting in the 15-25
mph range at higher elevations. Despite the wind improvement, this
prolonged heat wave will continue to bring very low RH that will
cure and dry the fuels. ERC values are exceeding or approaching the
max moving average for a number of regions. 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.

     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 from 3 AM Friday to 9 AM PDT Saturday for
     Pt Pinos to Pt Piedras Blancas 0-10 nm.

&&

$$

SHORT TERM...JM
LONG TERM....JM
AVIATION...Flynn
MARINE...Murdock

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