-- Discussion containing changed information from previous version are highlighted. --
943
FXUS66 KMTR 211826
AFDMTR

Area Forecast Discussion
National Weather Service San Francisco CA
1126 AM PDT Fri Jun 21 2024

...New AVIATION...

.SYNOPSIS...
Issued at 1231 AM PDT Fri Jun 21 2024

Warm temperatures across the region today and Saturday. A Heat
Advisory comes into effect on Saturday for the interior regions with
a moderate risk of heat-related illnesses. Temperatures moderate
through the early part of next week.

&&

.UPDATE...
Issued at 845 AM PDT Fri Jun 21 2024

Low clouds across the interior are already dissipating with the
trend expected to continue. Near the coast, stratus is likely to
persist through much of the day with only brief breaks in the cloud
cover as a moderate marine layer remains in place (around 1,800 feet
at Fort Ord). With that said, the on going forecast remains on track
with no updates anticipated this morning.

&&

.SHORT TERM...
(Today and tonight)
Issued at 1231 AM PDT Fri Jun 21 2024

Marine layer stratus is developing again tonight with the Fort Ord
profiler showing a marine layer depth of 1500 feet and a robust
onshore pressure gradient, with SFO-SAC showing a +3.9 mb gradient
as of the last update. Expect the stratus to continue expanding
across the inland valleys through the night before the morning sees
the stratus pared back to the immediate coastal regions. Tonight`s
lows remain in the upper 40s to mid 50s across the lower elevations,
and into the upper 50s to lower 60s in the higher elevations.

Today sees the first day of a significant warmup in temperatures as
an upper level trough fades into a ridge moving into the western
United States. High temperatures today will range from the mid 80s
to the mid 90s in the inland valleys, perhaps close to or at 100 in
the warmest spots of the northern North Bay, eastern East bay, and
southern Central Coast. Elsewhere, expect highs near the low to mid
60s along the coast and in the 70s for the Bayshore.

We begin to see Moderate HeatRisk in some of the interior regions
today, most notably the interior East Bay, South Bay, and southern
Salinas Valley. This means 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.

&&

.LONG TERM...
(Saturday through Thursday)
Issued at 1231 AM PDT Fri Jun 21 2024

Temperatures peak on Saturday, with highs ranging from the mid 90s
to the mid 100s in the inland valleys, the mid 70s to mid 80s for
the Bayshore, and the 60s and low 70s along the Pacific coast. A
Heat Advisory will be in effect on Saturday for the interior North
Bay mountains, East Bay, South Bay, and Central Coast, where
Moderate HeatRisk continues through the day.

Sunday should be noticeably cooler with an upper level trough to our
west beginning to promote stronger onshore flow. High temperatures
will drop into the mid 80s to the low 90s in the interior valleys
(perhaps close to 100 in the warmest spots), the 70s into the lower
80s along the Bayshore, and the upper 50s to the 60s along the
coast. Expect these temperatures to continue into the next work
week. Beyond that, CPC outlooks continue to suggest chances for
temperatures above seasonal averages (around 33-50% probability) and
precipitation near or below seasonal averages into the first few
days of July.

&&

.AVIATION...
-- Changed Discussion --
(18Z TAFS)
Issued at 1057 AM PDT Fri Jun 21 2024

Deep marine layer this morning allowing ample stratus coverage.
Expecting all terminals to clear to VFR through the remainder of
the day today, with stratus returning in the evening hours for
coastal sites. Winds today follow the typical diurnal onshore
pattern. Marine layer compresses tonight and Saturday under a high
pressure ridge, leading to LIFR/IFR cigs and FG impacts at coastal
terminals early Saturday morning. All sites clear to VFR by mid
Saturday morning with high confidence of VFR through the day.

Vicinity of SFO...Clear and remaining VFR through the day. Gusty
NW winds 20-25 kts this afternoon, diminishing by about 05-06Z.
Some marine stratus will make its way into the Bay overnight.
However, not currently expecting enough coverage for a cig at the
terminal (low-medium confidence).

SFO Bridge Approach...Similar to SFO.

Monterey Bay Terminals...Clouds pulling back to the coastline and
VFR through the afternoon. Expecting IFR cigs to return between
01-03Z (medium-high confidence), lowering to LIFR during the
overnight period. Some FG impacts as well for terminals more near
the coast with vis as low as 1/4SM. Conditions are expected to
improve rapidly mid Saturday morning.
-- End Changed Discussion --

&&

.MARINE...
(Today through Wednesday)
Issued at 845 AM PDT Fri Jun 21 2024

Moderate to fresh northwesterly winds prevail into the weekend
with strong near gale forced winds over the northern outer waters.
These stronger gusts may pose hazardous 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 over
much of the waters. Light southerly swell continues to move
through the waters today, accompanied by moderate NW swell.

&&

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

PZ...Small Craft Advisory until 9 PM PDT Saturday for Pigeon Pt to Pt
     Pinos 10-60 NM-Pt Arena to Pt Reyes 10-60 NM.

&&

$$

SHORT TERM...DialH
LONG TERM....DialH
AVIATION...Behringer
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