877
FXUS66 KMTR 201103
AFDMTR

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

...New AVIATION, MARINE...

.SYNOPSIS...
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.

&&

.SHORT TERM...
(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.

&&

.LONG TERM...
(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.

&&

.AVIATION...
(12Z TAFS)
Issued at 402 AM PDT Thu Jun 20 2024

CIGs have filled across the region. Pockets of fog look to form into
the early morning in the North Bay and along the coast. Winds will
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. Expect widespread CIGs again late Thursday
night as stratus pushes well inland.


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 late
morning and early afternoon as moderate to breezy winds arrive.
Winds at the terminals reduce into the early evening as IFR CIGs
move inland.

&&

.MARINE...
(Today through Tuesday)
Issued at 402 AM PDT Thu Jun 20 2024

  Breezy to gusty northwest winds continue, with the strongest
gusts across over the northern waters causing hazardous conditions
for small craft. Significant wave heights of 6-8 feet will
persist until the end of the week, then build back up to 10-12
feet over the outer waters for the weekend, when northwest winds
increase once again.

&&

.MTR WATCHES/WARNINGS/ADVISORIES...
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.

&&

$$

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

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