820
FXUS66 KMTR 062333
AFDMTR

Area Forecast Discussion
National Weather Service San Francisco CA
433 PM PDT Sat Jul 6 2024

...New AVIATION, MARINE...

.SYNOPSIS...
Issued at 103 AM PDT Sat Jul 6 2024

Day 5 of the heat wave and triple digit temperatures will return
to inland areas this afternoon. A slight cool down begins Sunday,
but hot weather will continue through next week. Red Flag
Warnings remain in effect through Saturday night.

&&

.UPDATE...
Issued at 902 AM PDT Sat Jul 6 2024

Near term analysis - morning satellite imagery shows a shallow
marine layer had nosed its way inland overnight, but it`s already
retreating back the coast. Even though it`s retreating it won`t
disappear and will likely hug the coast through the day. As a
result, we`ll likely see some large temperature spreads from the
coast to the interior of 30-40 degs. Speaking of large
temperatures spreads, we`ve already seen some impressive
temperatures spreads in the vertical this morning too. Higher
elevations didn`t really cool off overnight as the marine layer
came in over lower elevations. Marin Headlands and Big Sur coast
are two great examples of temps in the 50s and 80/90s over nearby
higher elevations.

No update needed this morning...heat and fire are still the main
weather topics.

MM

&&

.SHORT TERM...
(This evening through Sunday)
Issued at 1257 PM PDT Sat Jul 6 2024

Today will mark the hottest day of the heat wave for most
locations across our area. Some of our higher elevations were
already in the 90s around 9AM this morning. The 12z KOAK sounding
measured the 6th highest H85 temperature of 30C with a chance of
breaking the all-time record this evening, with HiRes guidance
indicating around 31C around launch time. Red Flag Warnings remain
in effect for the Santa Cruz Mountains, North Bay Interior
Mountains and East Bay Hills until later this evening, as RH
values continue to be in single digits in some spots. The heat
backs off slightly tomorrow, but still well within Excessive Heat
Warning and Heat Advisory criteria.

A southern surge of low stratus can be expected again tonight as
the ridge axis continues to slowly pivot to the east of the coastline
tonight and tomorrow. Overnight lows into tomorrow morning will
also start to decline as we get on the other side of the peak
heat, with lows around our area generally 3-5 degrees cooler than
what we saw early this morning.

Please read below for tips on how to continue to beat the heat at
the end of the long term discussion.

&&

.LONG TERM...
(Sunday night through next Friday)
Issued at 1257 PM PDT Sat Jul 6 2024

Temperatures will continue to gradually trend downward but still
remain above normal through most of the extended forecast.
However, using the previously noted KOAK H85 temp as a marker, by
Tuesday evening its expected to be in the mid 20s instead of the
low 30s at that level. The cumulating impacts of the heat wave
will continue to be felt into the beginning of the work week. By
midweek the center of the persistent dome of high pressure will be
over eastern Nevada as upper level troughing works on the back
side of the ridge to lower H50 heights and thickness. As mentioned
before though, most areas inland and especially higher
elevations, will continue to see temperatures in the 90s and low
100s. All precautions to beat the heat should continue to be
taken:

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...
(00Z TAFS)
Issued at 432 PM PDT Sat Jul 6 2024

Currently VFR at all terminals with stratus hugging a majority of
the coastline. High confidence in terminals being impacted by
LIFR/IFR ceilings/visibility overnight with the exception of LVK and
SJC. Winds will remain onshore through the TAF period. Haze and
smoke may be visible from terminals, but it is not expected to
result in a reduction in flight category.

Vicinity of SFO...Currently VFR with northwesterly flow. Winds will
prevail out of the west through the TAF period. Moderate confidence
in a low-end IFR ceiling briefly impacting the terminal in the early
morning hours with VFR prevailing by late-morning.

SFO Bridge Approach...Similar to SFO.

Monterey Bay Terminals...Currently VFR with northerly 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. High confidence in the return of LIFR ceilings and reduced
visibility to both terminals tonight. VFR is expected to prevail at
both terminals by late-morning.

&&

.MARINE...
(Tonight through next Thursday)
Issued at 432 PM PDT Sat Jul 6 2024

Northwest winds prevailing over the coastal waters this weekend
and next week. By midweek, northwest winds strengthen with
moderate to fresh sustained winds and strong gusts possible across
the  coastal waters. Significant wave heights will build to 10 to
13  feet by mid to late week.

&&

.FIRE WEATHER...
Issued at 920 AM PDT Sat Jul 6 2024

Just finished up coordination calls with agency fire partners and
neighboring offices. No updates needed for ongoing fire
headlines. Red Flag Warnings remain in effect for the North Bay
Interior Mountains, East Bay Hills and Santa Cruz Mountains until
9 PM Saturday. Red Flag Warnings are also in effect for the Santa
Lucia Mountains, San Benito County, and the Southern Salinas
Valley until 9 PM Saturday as well.

Marine layer brought some overnight relief for lower elevations,
but higher elevations (specifically Red Flag Locations) saw no
relief with temps in the 80s/90s and RH less than 30 percent.
Winds are breezy at times too. Needless to say critical fire
weather conditions.

While the Red Flag Warning is set to expire this evening with
weakening winds, lack of humidity recovery tonight over higher
elevations will lead to near critical conditions.

For Sunday, areas of concern will be focused away from the coast
with another hot and dry day. Area of greatest concern will be the
East Bay were afternoon gusty pass/gap winds combined with hot/dry
conditions will lead to isolated pockets of critical fire weather.
Not widespread enough for another Red Flag, but critical
nonetheless.

MM

&&

.MTR WATCHES/WARNINGS/ADVISORIES...
CA...Excessive Heat Warning until 11 PM PDT Wednesday for CAZ502>504-
     506-510-512>518.

     Red Flag Warning until 9 PM PDT this evening for CAZ504-512-
     515>518.

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

PZ...None.
&&

$$

SHORT TERM...JM
LONG TERM....JM
AVIATION...Sarment
MARINE...Canepa

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