-- Discussion containing changed information from previous version are highlighted. --
285
FXUS66 KMTR 200751
AFDMTR

Area Forecast Discussion
National Weather Service San Francisco CA
1251 AM PDT Thu Jun 20 2024

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

.SYNOPSIS...
-- Changed Discussion --
Issued at 1251 AM PDT Thu Jun 20 2024

An eroding upper level trough is promoting a warming trend through
the weekend, with above average temperatures Friday and into the
weekend.
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&&

.SHORT TERM...
-- Changed Discussion --
(Today and tonight)
Issued at 1251 AM PDT Thu Jun 20 2024

Marine layer stratus is developing inland and is expected to expand
throughout the valleys as the nighttime progresses, aided by an
expanded marine layer of 1500-2000 feet and robust onshore pressure
gradients. This morning`s lows hover in the upper 40s to lower 50s
in the lower elevations, up to the upper 50s to near 60 in the
higher elevations.

The upper level trough that settled in and cooled us off yesterday
is beginning to erode, with a slight warmup expected today as high
temperatures rise into the upper 50s to lower 60s along the coast,
the upper 60s to mid 70s in the Bayshore, and the 80s into the lower
90s in the interior valleys. Stratus clouds will retreat to the
immediate coastal regions as breezy onshore winds set up in the
afternoon, with gusts up to 20 to 25 miles per hour through the gaps
and passes.
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&&

.LONG TERM...
-- Changed Discussion --
(Friday through Wednesday)
Issued at 1251 AM PDT Thu Jun 20 2024

The upper level trough continues to erode throughout the rest of the
week, with a weak but noticeable ridge coming by the weekend. By
Saturday, we should see high temperatures in the low 100s for the
favored warm spots, such as the northern reaches of Napa and Sonoma
Counties, eastern Alameda and Contra Costa Counties, and southern
Monterey and San Benito Counties. A Heat Advisory will be in effect
on saturday for the interior North Bay mountains, East Bay, South
Bay, and Central Coast. Moderate HeatRisk is in effect for these
areas, meaning that there is a risk of heat-related illnesses for
most people sensitive to heat, including children, the elderly,
pregnant women, those working or living outside, and those with
certain medical conditions. Here are heat safety tips:

* 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.

The heat will begin to abate during the early part of next week,
although temperatures remain warm with highs around or a few degrees
above seasonal averages. Model ensemble clusters are hinting at a
trough coming through the western US towards the end of next week,
although details remain murky.
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&&

.AVIATION...
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(06Z TAFS)
Issued at 1059 PM PDT Wed Jun 19 2024

MVFR/IFR CIGS have formed over the Coast and Bays with CIGs
continuing to move inland and are expected to affect all of the TAF
sites overnight. Pockets of fog look to form into the early morning
in the North Bay and along the coast. Winds be light to moderate
through the late morning before breezy winds arrive into the
afternoon. CIGs dissipate for all but the Monterey Bay terminals in
the mid to late morning, with those terminals seeing some brief
clearing into the afternoon. Winds reduce into Thursday evening as
MVFR and IFR CIGs begin to affect the Monterey Bay and SF Bay
terminals.

Vicinity of SFO...IFR lasts through the late morning with moderate
westerly winds. Expect CIGs to clear as a round of breezy winds
start build with peak gusts around 26 kts. IFR CIGs arrive in the
evening, with winds reducing into the night.

SFO Bridge Approach...Similar to SFO.

Monterey Bay Terminals...IFR lasts through the night and into
Thursday afternoon light to moderate winds. CIGS erode into the mid
to late morning as moderate to breezy winds arrive. Winds at the
terminals reduce into the evening as IFR CIGs move inland.
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&&

.MARINE...
(Tonight through next Tuesday)
Issued at 1059 PM PDT Wed Jun 19 2024

  Northwest winds continue, with the strongest gusts across our
northern waters. Significant wave heights of 6-8 feet will persist
until the end of the week, when they build back up to 10-12 feet
over the outer waters for the weekend, when northwest winds
increase once again.

&&

.MTR WATCHES/WARNINGS/ADVISORIES...
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CA...Heat Advisory from 11 AM to 10 PM PDT Saturday for CAZ504-510-
     513>518.

PZ...Small Craft Advisory from 3 PM this afternoon to 3 AM PDT Friday
     for Pt Arena to Pt Reyes 0-10 nm.

     Small Craft Advisory until 3 AM PDT Saturday for Pt Arena to Pt
     Reyes 10-60 NM.
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&&

$$

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

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