328
FXUS66 KMTR 081611
AFDMTR

Area Forecast Discussion
National Weather Service San Francisco CA
911 AM PDT Mon Jul 8 2024

...New UPDATE, MARINE...

.SYNOPSIS...
Issued at 111 AM PDT Mon Jul 8 2024

Day 7 of the inland heat wave. There will be a decent cooling
trend through Tuesday before temperatures increase again Wed-Fri.
More substantial cooling is on the way this weekend.

&&

.UPDATE...
Issued at 911 AM PDT Mon Jul 8 2024

Marine layer of around 1,200-1,500 feet in depth has resulted in
widespread low clouds and/or fog well inland across the Salinas
Valley, North Bay vallies, and locally inland into the East Bay
vallies this morning. Expecting conditions to mix out by afternoon
with these clouds retreating to the coast. All that said, no updates
are anticipated this morning as the forecast remains on track. For
more information, see previous forecast discussion below.

&&

.SHORT TERM...
(Today and tonight)
Issued at 111 AM PDT Mon Jul 8 2024

Inland temperatures were roughly 5-15 degrees cooler on Sunday,
compared to the peak of the heat wave on Saturday. As the ridge
continues to slide east, temperatures will continue to decrease.
Monday will be another 5 degrees cooler than Sunday was. This is
welcome relief and the HeatRisk product has moved out of the major
and extreme categories we saw for much of the last week, into
minor and moderate for Mon-Tue. As such, we have decided to
downgrade many of the Excessive Heat Warnings to Heat Advisories.
That`s the good news. The bad news is we extended many of the new
heat advisories through Friday. More information in the long term
section.

&&

.LONG TERM...
(Tuesday through Sunday)
Issued at 111 AM PDT Mon Jul 8 2024

The much anticipated cool-down will continue through Tuesday,
with inland max temperatures staying in the low to mid 90s. The
forecast gets a little more uncertain starting Wednesday. The
strong ridge will gradually flatten out as the jet stream
transitions from a very stable meridional block to more zonal
flow. While the ridge leaving is certainly a good thing to help
end this heat wave, the new pattern with higher pressure inland
could support offshore winds later in the week. Most guidance
agrees the current cooling trend will reverse, and Wednesday-
Thursday will be roughly 10 degrees warmer than Tuesday for
inland areas. This brings inland areas back to Moderate/Major
HeatRisk for the second half of the work week. Fortunately there
is a more substantial cool-down arriving next weekend, and we may
even see temperatures get close to normal by the middle of next
week. There is still a lot of model disagreement beyond the
weekend. The GFS continues cooler while ECMWF stays steady. Either
way, this week will be cooler than last week, and next week will
be cooler than this week. It`s just that after all that cooling,
we may still be above normal.

&&

.AVIATION...
(12Z TAFS)
Issued at 451 AM PDT Mon Jul 8 2024

Widespread stratus across the Bay Area and Central Coast with a mix
of LIFR to VFR conditions currently observed. Stratus is expected to
dissipate by mid to late morning at all stations. Moderate to high
confidence that stratus will return again by the late evening with
ensemble guidance suggesting stratus will return everywhere except
LVK. Slight potential (low confidence) for fog development at
STS, MRY, and SNS with 12-16Z the most likely development time
frame. Winds are generally out of the west to northwest at all
stations outside of the North Bay with moderate winds returning
during the afternoon before weakening overnight.

Vicinity of SFO...IFR conditions expected to develop by 12Z and
persist through mid morning. Onshore flow persists through the
TAF period with moderate, gusty winds returning during the
afternoon/evening before weakening overnight. Moderate confidence
that stratus will return overnight with ensemble guidance
indicating an earlier return between 04-08Z may be possible.

SFO Bridge Approach...Similar to SFO.

Monterey Bay Terminals...LIFR conditions continue at MRY and SNS
through the mid morning. Ensemble guidance indicates visibilities
between 1SM to 2SM are likely to continue through mid morning
with some models indicating potential for visibilities <1SM to
develop at both airports. Moderate confidence on timing of stratus
dissipation with ensemble guidance indicating 17-20Z as the most
likely timeframe. Moderate northwest winds return during the
afternoon before weakening overnight. LIFR conditions are
expected to return overnight.

&&

.MARINE...
(Today through Saturday)
Issued at 911 AM PDT Mon Jul 8 2024

Northwest winds persisting through the week. Widespread fresh to
strong northwest winds return across the coastal waters by
Wednesday and continue through Friday. Significant wave heights
will build to 10-14 feet across the outer waters beginning
Wednesday.

&&

.MTR WATCHES/WARNINGS/ADVISORIES...
CA...Heat Advisory until 8 PM PDT Friday for CAZ502>504-506-510-
     512>516-528.

     Heat Advisory from 11 AM Wednesday to 8 PM PDT Friday for CAZ508.

     Excessive Heat Warning until 8 PM PDT Friday for CAZ517-518.

PZ...None.
&&

$$

UPDATE...RGass
SHORT TERM...Flynn
LONG TERM....Flynn
AVIATION...Kennedy
MARINE...Canepa

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