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191
FXUS66 KMTR 232011
AFDMTR

Area Forecast Discussion
National Weather Service San Francisco CA
111 PM PDT Mon Sep 23 2024

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

.SYNOPSIS...
-- Changed Discussion --
Issued at 110 PM PDT Mon Sep 23 2024

Heat Advisory in effect for the interior East Bay, South Bay, and
Santa Cruz Mountains as hot temperatures peak today. Slight cooling
tomorrow with temperatures returning to near the seasonal average on
Wednesday, slightly warming by Friday.
-- End Changed Discussion --

&&

.SHORT TERM...
-- Changed Discussion --
(This evening through Tuesday)
Issued at 110 PM PDT Mon Sep 23 2024

Today`s warm to hot weather comes courtesy of a delicate dance in
the upper levels of the atmosphere, with a ridge sliding into the
Pacific Northwest creating warm conditions up and down the West
Coast, enhanced by a subtle low pressure system retrograding
westward off Point Conception, both features combining to create
easterly flow in the upper levels, as visible earlier this morning
with the cirrus clouds streaming into the state from Nevada.

High temperatures today rise into the mid 90s to near 100 in the
inland valleys, into the mid 80s to lower 90s along the Bayshore,
and in the mid 60s to the lower 70s along the Pacific coast. Low
temperatures tonight are generally in the upper 50s to the mid 60s
in the valleys, with some cooler temperatures at the immediate coast
where the remnants of the marine layer will lie, and up to the low
to mid 70s in the higher elevations. Some cooling is expected in the
coastal regions tomorrow, with high temperatures in places like
downtown San Francisco, the Santa Cruz county coast, and the Salinas
area dropping around 5 degrees. Across the inland areas, little
cooling is expected.

A Heat Advisory is now in effect for the interior East bay, the
South Bay, and the Santa Cruz Mountains today, due to the widespread
risk for heat related illnesses for sensitive populations (children,
the elderly, pregnant women, those with certain medical conditions),
and the possibility for heat-related impacts for everyone without
adequate hydration and/or cooling. In the South Bay and the Santa
Cruz Mountains, the Heat Advisory will expire at 8 PM today, while
the Advisory continues through Tuesday night in the interior East
Bay as lingering heat sustains the risk for heat-related illnesses.
Here`s a reminder about heat safety:

* Stay hydrated and drink plenty of fluids.
* Wear lightweight, light-colored clothing.
* Reduce time spent outdoors or stay in the shade.
* Never leave people or pets unattended in vehicles.
* Use sunscreen if going to the coast or the pool.

Winds will generally be lightly onshore in the afternoon and
evening, and calm to nearly calm overnight and into the morning.
Although some weak onshore flow is possible at the higher elevations
tonight, low wind speeds and some overnight recovery keep the fire
weather concerns low.
-- End Changed Discussion --

&&

.LONG TERM...
-- Changed Discussion --
(Tuesday night through next Sunday)
Issued at 110 PM PDT Mon Sep 23 2024

The upper level ridge moves off to the east late Tuesday into
Wednesday, allowing the weak upper level low to merge into a
stronger upper level trough that sets up into the Eastern Pacific.
Temperatures across the region will cool rather dramatically, close
to or slightly below seasonal averages for this time of year. Later
on in the week, a zonal pattern towards our north and a series of
weak upper level troughs towards our south and southwest will keep
our region somewhat warm heading into the upcoming weekend, although
not as hot as the temperatures seen today. CPC outlooks keep a lean
towards temperatures above, and precipitations below, seasonal
averages through the first week of October.
-- End Changed Discussion --

&&

.AVIATION...
(18Z TAFS)
Issued at 1044 AM PDT Mon Sep 23 2024

After a pesky start to the day with VLIFR and IFR impacting
terminals all terminals as of the 18Z taf package are VFR.
Expecting VFR at all terminals outside of Monterey Bay through
the period. High pressure overhead, compressed marine layer, and
weak offshore flow will lead to less level moisture/stratus/fog
Tuesday morning. While some model guidance suggest some patchy
fog around the Bay Area current thinking is the drier offshore
flow will win out. Monterey Bay is different where enough of a
low level onshore flow will bring some fog/clouds back in again
tonight.

Vicinity of SFO...VFR. Breezy onshore flow after 23Z this
afternoon.  Winds easing overnight.

SFO Bridge Approach...similar to SFO.

Monterey Bay Terminals...VFR through 03-05Z. Will slowly introduce
fog there after with peak vis reduction late tonight/early
Tuesday. Dissipation likely before end of taf period at 18Z
Tuesday. Confidence for fog impacting MRY/SNS is about 50-60%.

&&

.MARINE...
(Today through Saturday)
Issued at 1044 AM PDT Mon Sep 23 2024

High pressure remains over the Eastern Pacific keeping
northwesterly flow over the coastal waters through at least
midweek. Northwest winds will strengthen later in the week. Seas
rebuild to become rough in the outer waters by Thursday.

&&

.MTR WATCHES/WARNINGS/ADVISORIES...
CA...Heat Advisory until 8 PM PDT Tuesday for CAZ510-515.

     Heat Advisory until 8 PM PDT this evening for CAZ512>514.

PZ...None.
&&

$$

SHORT TERM...DialH
LONG TERM....DialH
AVIATION...MM
MARINE...MM

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