Diablo, California 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

957
FXUS66 KMTR 041138
AFDMTR

Area Forecast Discussion
National Weather Service San Francisco CA
338 AM PST Wed Dec 4 2024

...New AVIATION, MARINE...

.SYNOPSIS...
Issued at 139 AM PST Wed Dec 4 2024

Warm and dry conditions continue to prevail.

&&

.SHORT TERM...
(Today and tonight)
Issued at 139 AM PST Wed Dec 4 2024

Cooler and moister conditions in addition to the lack of cloud cover
is allowing for fog to be observed in greater extent than it was 24
hours ago with North Bay Valleys and Monterey Bay being the victims
thus far. Expect patchy dense fog in coastal and valley locations
through mid-morning so be sure to turn on your low-beam headlights,
drive slowly, and keep your distance from other vehicles. Above
normal temperatures and dry conditions will continue as longwave
ridging remains parked over the region. While too young to be
climate sites (less than 30 years old), STS broke and CCR and HWD
tied the records for daily maximum temperature on December 3rd. STS
reached 68 degrees breaking the previous record of 66 degrees set in
2011 and again in 2016. CCR reached 67 degrees tying the previous
record set in 2007. Similarly HWD reached 67 degrees tying the
previous record set in 2007 and again in 2014.

&&

.LONG TERM...
(Thursday through Tuesday)
Issued at 139 AM PST Wed Dec 4 2024

A weak shortwave will skirt Northern California on Thursday, with
the most likely effect being a brief pause in the warming trend due
to increased cloud cover. A Rex Block pattern will develop in the
shortwave`s wake as a ridge of high pressure noses into the Pacific
Northwest and low pressure develops over the Desert Southwest. A
second, stronger shortwave will skirt the region on Saturday
bringing an end to the warming trend with increasing cloud cover.
While PoPs (<30%) are higher with this second shortwave, the most
likely result will be coastal drizzle, particularly in locations
where orographic lift comes into play. High pressure will build yet
again into early next week. Clear skies will allow for maximum
radiational cooling and thus the return of cold and frosty
conditions, particularly interior Monterey and San Benito Counties
Sunday night through at least Wednesday night. Patchy dense fog
remains likely in coastal and valley locations during the overnight
periods.

&&

.AVIATION...
(12Z TAFS)
Issued at 337 AM PST Wed Dec 4 2024

Once patchy fog dissipates over STS, VFR conditions are forecast to
prevail through the afternoon and evening. Winds become onshore by
late morning and will continue through the afternoon before
diminishing and becoming variable overnight. Moderate confidence
for fog to return to the North Bay early Thursday morning.

Vicinity of SFO...VFR. Moderate NW winds around 10 knots return this
afternoon and continue into the evening. Winds go light and variable
into the overnight and early Thursday morning.

SFO Bridge Approach...Similar to SFO.

Monterey Bay Terminals...VFR. Light southeasterly winds prevail at
both MRY and SNS this morning and will turn to become onshore this
afternoon. Winds ease overnight and become southeast/variable.

&&

.MARINE...
(Today through Monday)
Issued at 337 AM PST Wed Dec 4 2024

Long period northwest swell, light to occasionally moderate north
winds, and wave heights between 3 to 7 feet continue through late
week. Winds look to strengthen and seas begin to build late this
weekend and continuing into next week.

&&

.MTR WATCHES/WARNINGS/ADVISORIES...
CA...None.
PZ...None.
&&

$$

SHORT TERM...Sarment
LONG TERM....Sarment
AVIATION...RGass
MARINE...RGass

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