491
FXUS66 KMTR 121802
AFDMTR

Area Forecast Discussion
National Weather Service San Francisco CA
1102 AM PDT Fri Jul 12 2024

...New AVIATION, MARINE...

.SYNOPSIS...
Issued at 315 AM PDT Fri Jul 12 2024

Heat highlights remain in effect through this evening. A nice cool
down this weekend, with near normal temps by early next week.
Otherwise fairly quiet weather through the forecast period.

&&

.SHORT TERM...
(Today and tonight)
Issued at 315 AM PDT Fri Jul 12 2024

The persistent high pressure responsible for all the recent heat is
currently centered over Utah and will slowly migrate east today and
tomorrow towards the Four Corners region. A weak offshore upper
level low on the eastern periphery of the high, will gradually slide
north over the next couple of days from SoCal to the Central Coast
latitude. Todays highs will continue to be well above normal with
the Excessive Heat Warning and Heat Advisories remaining intact
until 8pm later tonight. Interior temperatures will remain in the
90s to low 100s with some elevated locations approaching 110. A
welcomed cooling trend in temperatures begins on Saturday with many
interior locations seeing a 10 degrees drop in highs from today to
tomorrow afternoon. The offshore upper level low will advect cooler
low level temperatures and moisture as slowly lifts north.

&&

.LONG TERM...
(Saturday through Thursday)
Issued at 315 AM PDT Fri Jul 12 2024

The slow moving upper level low on the western periphery of high
pressure centered over the Four Corners region on Sunday, will
continue to help moderate temperatures in the wake of the recent
heat wave. Mostly zonal flow to our north will begin to buckle and
absorb the upper level low as it moves up the coast of the Pacific
Northwest for the first half of next. Unfortunately, as the upper
low/trough shifts north over water, the persistent area of high
pressure over the desert southwest begins to amplify again across
western CONUS. A warming trend can be seen for the end of next week,
and may be more pronounced than currently progged if the signal for
amplification gets stronger, which allows for the center of the high
to retrograde back to the west closer to central California.

&&

.AVIATION...
(18Z TAFS)
Issued at 1102 AM PDT Fri Jul 12 2024

VFR prevails through the afternoon today with breezy W/NW winds.
Marine stratus will make a return in the evening tonight to bring
IFR/LIFR CIGs to North Bay and Monterey Bay terminals. There does
remain some lack of confidence as to whether stratus will form a CIG
over North Bay terminals, or predominantly remain FEW-SCT low
clouds. At this moment, confidence for CIG formation over North Bay
terminals is low-moderate. High confidence in LIFR CIGs developing
at Monterey Bay terminals tonight.

Vicinity of SFO...VFR through the TAF period. Winds NW and moderate
this afternoon, but ease slightly into the late night. Stratus will
likely impact KOAK but is not expected to bring CIGs to KSFO. Winds
at KSFO turn more W/SW into the daytime Saturday as a low approaches
the region.

SFO Bridge Approach...Similar to SFO.

Monterey Bay Terminals...VFR through the late afternoon today,
though stratus will begin to make an onshore push shortly after the
00Z hour. CIGs are expected to develop by 03/04Z with LIFR
conditions lasting through the night. Towards the early morning of
Saturday, visibilities at Monterey are likely to reduce
significantly as mist and fog develops.

&&

.MARINE...
(Today through Wednesday)
Issued at 1102 AM PDT Fri Jul 12 2024

Fresh northerly winds continue over the waters today, but decrease
to become moderate Saturday. Gentle to moderate winds then persist
through much of next week, but turn to become more southerly on
Sunday as low pressure approaches the region.  Significant wave
heights between 10 to 12 ft continue over the  outer coastal
waters with peak wave heights between 12 to 14 ft  expected over
the far northern outer coastal waters.

&&

.MTR WATCHES/WARNINGS/ADVISORIES...
CA...Heat Advisory until 8 PM PDT this evening for CAZ502-503-506-508-
     512-516-528.

     Excessive Heat Warning until 8 PM PDT this evening for CAZ504-
     510-513>515-517-518.

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

&&

$$

SHORT TERM...JM
LONG TERM....JM
AVIATION...AC
MARINE...AC

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