623
FXUS66 KMTR 011733
AFDMTR

Area Forecast Discussion
National Weather Service San Francisco CA
1033 AM PDT Tue Oct 1 2024

...New AVIATION, MARINE...

.SYNOPSIS...
Issued at 316 AM PDT Tue Oct 1 2024

Hot and dry conditions prevail over the next several days with
dangerous heat and elevated fire weather concerns area wide. Gradual
decline in temperatures by the end of the work week, with
potentially critical fire weather conditions Wednesday and Thursday
(and beyond) across portions of the interior Central Coast.

&&

.SHORT TERM...
(Today and tonight)
Issued at 316 AM PDT Tue Oct 1 2024

Our entire forecast area is under either an Excessive Heat Warning
or Heat Advisory today. A building area of high pressure over open
water to our west will slowly migrate ESE across our area over the
next few days. Albeit light, but steady low to mid level offshore
flow today into early tomorrow will nullify any marine layer effects
allowing for many locations, including coastal areas, to realize
some of their highest temperatures of the year thus far. Overnight
lows across elevated inland areas will be unusually high with an
active thermal belt maintaining overnight temperatures in the mid
70s to mid 80s. Coastal locations will still be well above normal
too, but less impactful - mainly in the low to mid 60s by early
Wednesday morning. Temperatures on Wednesday will back off
slightly over our coastal communities from todays highs, but are
mostly higher everywhere else, thus Moderate to Extreme HeatRisk
will continue area wide into tomorrow as well. Please read the
following for heat safety information:

Heat is the number 1 weather related killer in the United States.
Unfortunately lives will be at risk 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 8pm.
-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.

&&

.LONG TERM...
(Wednesday through Monday)
Issued at 316 AM PDT Tue Oct 1 2024

As the upper ridge slowly shifts ESE farther inland by Thursday,
we`ll see a shift in the low to mid-level wind fields. Closer to the
coast, weak onshore flow will return by Thursday behind the ESE
pivoting ridge axis, providing only slight relief from the still
unusually high temps closer to the shoreline. However, the
overnight thermal belts inland and daytime downsloping winds will
keep temperatures in the mid 90s to 110 for most of our interior
locations away and/or above the rebuilding marine layer. Triple
digit heat continues for many inland locations well into the
weekend, along with increasing fire weather concerns as fuels
continue to dry and surface winds gradually increase on the back
side of the shifting dome of high pressure.

&&

.AVIATION...
(18Z TAFS)
Issued at 1032 AM PDT Tue Oct 1 2024

VFR through the TAF period for all sites but there has been some
signals for KSTS and Monterey Bay terminals to see LIFR conditions
starting between 09-12Z Wednesday. There is low confidence for these
conditions to actually occur, as models show probability less than
20%. Winds will build in the afternoon but will be relatively
moderate, with the exception of KSFO, and will diminish overnight.

Vicinity of SFO...High confidence continues for VFR through the TAF
period. Breezy W/NW winds build this afternoon with speeds near 14
knots, before returning to light this afternoon. Winds rebuild
Wednesday afternoon, but models show speeds less than 11 knots.

SFO Bridge Approach...Similar to SFO.

Monterey Bay Terminals...VFR is expected to continue through the TAF
period but there is signals for LIFR conditions between 09Z to 16Z
for both KMRY and KSNS. Confidence is low and models show
probability <20%. Therefore, LIFR conditions were left out of the
TAFs at this moment, but a FEW group was included to hint at the
possibility. S/SE winds will turn to onshore by this afternoon and
build to moderate/slightly breezy before light S/SE winds return
tonight.

&&

.MARINE...
(Today through Sunday)
Issued at 1032 AM PDT Tue Oct 1 2024

Fresh to strong northwesterly winds develop over the waters
today, creating hazardous conditions for small craft. By
Thursday, northwesterly winds will weaken to become moderate
across the waters. Significant wave heights continue to abate over
the  outer waters today but are expected to build to 10 to 13 feet
again by midweek.

&&

.FIRE WEATHER...
Issued at 1028 AM PDT Tue Oct 1 2024

Mixed bag of NEAR CRITICAL to CRITICAL fire weather conditions
across the district through late week. Hot and dry conditions
during the day combined with mild and dry conditions at night are
the main drivers of the elevated fire weather concerns. Winds were
breezy to gusty last night over the higher terrain of the N and E
Bay due to moderate offshore flow. Winds elsewhere were less, but
still had some breezy pulses. Moving forward, the offshore flow
is projected to relax easing winds over the N and E Bay. However,
winds over the Central Coast will remain stronger with several
pulses possible on Wednesday and Thursday.

Other concerns from a fire weather perspective are the fuels.
Latest observations suggest critically dry fuels. Current 100 and
1000 hr fuels are near or slightly below avg, but trending drying
Current 10 hr fuels are critically low as well. Additionally,
latest intel with Live Fuel Moisture shows values trending toward
the 60% threshold. Simply put, fuels are receptive to fire starts.

After coordinating with neighboring offices and fire weather
partners will keep the headline for for NEAR CRITICAL for Monterey
Bay northward. The Fire Weather Watch on the other hand will be
converted to Red Flag Warning(RFW) this morning. Zone 518
(Mountains of San Benito and Interior Monterey County) will also
be included with the Red Flag Warning.

Looking farther down the road isn`t that promising either. Hot Dry
Windy index highlights elevated fire weather concerns lasting
through and peaking 5-6 days out.

MM

&&

.MTR WATCHES/WARNINGS/ADVISORIES...
CA...Excessive Heat Warning until 11 PM PDT Wednesday for CAZ006-
     502>504-508-510-512>518-528.

     Heat Advisory until 11 PM PDT Wednesday for CAZ505-506-509-529-
     530.

     Fire Weather Watch from Wednesday morning through Thursday
     evening for CAZ516-517.

PZ...Small Craft Advisory from 3 PM to 9 PM PDT Wednesday for Pigeon
     Pt to Pt Pinos 0-10 nm-Pt Arena to Pt Reyes 0-10 nm.

     Small Craft Advisory from 9 PM this evening to 9 PM PDT
     Wednesday for Pt Arena to Pt Reyes 10-60 NM.

     Small Craft Advisory from 9 AM to 9 PM PDT Wednesday for Pigeon
     Pt to Pt Pinos 10-60 NM.

&&

$$

SHORT TERM...JM
LONG TERM....JM
AVIATION...SO
MARINE...Behringer

Visit us at www.weather.gov/sanfrancisco

Follow us on Facebook, Twitter, and YouTube at:
www.facebook.com/nwsbayarea
www.twitter.com/nwsbayarea
www.youtube.com/nwsbayarea