705
FXUS66 KMTR 052352
AFDMTR

Area Forecast Discussion
National Weather Service San Francisco CA
452 PM PDT Sat Oct 5 2024

...New AVIATION...

.SYNOPSIS...
Issued at 151 AM PDT Sat Oct 5 2024

Heat peaks again today and tomorrow with widespread moderate-to-
major Heat Risk. Excessive Heat Warnings and Heat Advisories have
been extended to Sunday. Some relief is still on tap for next
week.

&&

.SHORT TERM...
(This evening through Sunday)
Issued at 152 PM PDT Sat Oct 5 2024

Widespread Moderate to Major HeatRisk continue across the region
this afternoon with isolated Extreme HeatRisk in higher elevations.
However, a very shallow marine layer continues to keep areas closest
to the coast cooler. This makes forecasting for the coast extremely
challenging! That said, have extended all heat products out to 11 PM
Sunday with the exception of San Francisco which may be allowed to
downgrade to a Heat Advisory for tomorrow. Current radar and
satellite are showing some returns of elevated showers over the
waters and well southwest of the Monterey Bay region, courtesy of
some lingering subtropical moisture around 10,000 feet. However,
this is unlikely to reach the surface with conditions extremely dry
above the marine inversion.

Tonight, temperatures are expected to stay very warm in the region`s
higher elevations with 70`s to mid 80`s expected while the valleys
and coastal areas cool into the low-to-upper 60`s with pockets
reaching as low as the mid 50`s.

Tomorrow will be equally as hot as today with slight cooling likely
near the coast as the marine layer is forecast to increase slightly.
Thus, expecting more widespread triple digit heat across the
interior, 90`s in the Bay Shoreline and other inland portions of the
region, and 70`s to 80`s near the immediate coastline.

A few interesting climate stats:

* If San Jose Airport hits 100 today, it will be the most days with
  a high of at least 100 in a calendar year on record. Currently
  tied the record, which is 5 days at or above 100 (occurred in
  several past years).

* Santa Rosa Co-op station has broken the record for the most days
  above 100 in a calendar year with 12 days so far. Old record was
  11 days in 1976 and 1917.

* San Rafael has broken the record for most days above 100 in a
  calendar year with 11 days so far (including today). Old record
  was 8 days in 1976.

&&

.LONG TERM...
(Sunday through Friday)
Issued at 151 AM PDT Sat Oct 5 2024

The onshore flow paired with falling 500 mb heights will be the
beginning of the end of this heatwave. By Monday morning, strong
northwest winds develop in a coastal jet ahead of an approaching
upper level trough. The marine layer is expected to deepen into
Tuesday, bringing much welcome relief across a much broader swath
of the region. For the latter half of the week, guidance continues
to advertise a deep trough swinging into the PNW and grazing
northern and central California. Ultimately, this would bring some
sense of rainfall to the region, but don`t hold your breath.
While ensemble members have been consistent with showing this,
they`ve also been consistent in that not very many members are on
board. Therefore, the chance still remains very low that we see
measurable rain by the end of next week in the North Bay.

&&

.AVIATION...
(00Z TAFS)
Issued at 440 PM PDT Sat Oct 5 2024

Dry airmass and offshore flow at times will lead to VFR for most
terminals through the TAF period. As noted on the previous TAF
package, Monterey Bay terminals will be the challenge. Southerly
surge battling northerly/offshore flow has kept clouds in Monterey
Bay. Once the sun sets local level flow may be enough for clouds
to sneak inland. Have higher confidence for low cigs at KSNS than
KMRY. Additionally, this onshore push would be shallow yielding
dense fog.

Vicinity of SFO...VFR.

SFO Bridge Approach...VFR.

Monterey Bay Terminals...SCT002 KMRY. Low cigs/fog will lurk
nearby for KMRY. Have CIGS and FOG moving into KSNS late tonight.
Clearing will be mid morning Sunday.

&&

.MARINE...
(Today through Thursday)
Issued at 235 PM PDT Sat Oct 5 2024

High pressure located over land continues to produce light to
moderate northerly flow over the coastal waters, which will
persist through Monday. High pressure will re-strengthen over the
Eastern Pacific on Monday, which will increase winds over the
waters. As hot conditions persist and people flock to the coast,
always remember to wear a life jacket, swim near a lifeguard, and
never turn your back on the ocean.

&&

.CLIMATE...
Issued at 906 PM PDT Fri Oct 4 2024

Record high temperatures and years of occurrence at the long term
climate stations October 5 and 6.

Station         Oct 5        Oct 6

Santa Rosa      103 1933     102 1930
Kentfield       100 1987      97 1930
Napa            101 1987      96 1930
Richmond         99 1987      91 1996
Livermore       100 1980     100 2014
San Francisco   102 1987      94 1992
SFO Airport      99 1987      92 2023
Redwood City     99 1987      99 1987
Half Moon Bay    90 2023      87 1972
Oakland museum   96 1987      93 2023
San Jose        101 1987      95 2023
Salinas Airport 105 1987      98 2023
King City       105 1933     100 1996

&&

.MTR WATCHES/WARNINGS/ADVISORIES...
CA...Excessive Heat Warning until 11 PM PDT this evening for CAZ006.

     Excessive Heat Warning until 11 PM PDT Sunday for CAZ502>504-508-
     510-512>518.

     Heat Advisory until 11 PM PDT Sunday for CAZ506-509-528>530.

PZ...None.
&&

$$

SHORT TERM...RGass
LONG TERM....Behringer
AVIATION...MM
MARINE...MM

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