681
FXUS66 KMTR 081159
AFDMTR

Area Forecast Discussion
National Weather Service San Francisco CA
357 AM PST Fri Nov 8 2024

...New SYNOPSIS, SHORT TERM, LONG TERM, AVIATION, MARINE, CLIMATE...

.SYNOPSIS...
Issued at 245 AM PST Fri Nov 8 2024

Dry weather lingers today. Expect chilly to cold morning low
temperatures and patchy frost in the lower elevations and valleys,
possibly nearing a record low or two, otherwise it`ll be milder
at elevation in the hills and mountains this morning. Rain returns
to the Bay Area early next week. A chance of rain also extends
southward to the north Central Coast early next week.

&&

.SHORT TERM...
(Today and tonight)
Issued at 357 AM PST Fri Nov 8 2024

Under a clear sky, light wind and low surface dewpoint temperatures
(lingering desert dry air mass, a low amount of water vapor) air
temperatures are cooling to near or below Nov 8th normal lows across
the lower elevations and valley floors. Expect additional cooling
across lower elevations and valley floors until about 7 am. Lows
may near a couple Nov 8th record lows like Oakland downtown and
Half Moon Bay, records at the long term sites are noted below. At
elevation in the hills and mountains it`s a different story, a lower
level temperature inversion under 500 mb ridging is resulting in
milder temperatures mainly in the 50s however there are a few lower
60s noted at elevation in Big Sur. After sunrise, temperatures
will warm up under a clear sky similar to Thursday`s high temps.

Chilly temperatures redeveloping in the lower elevations and valleys
tonight and Saturday morning, however high clouds possibly becomes
a factor slowing cooling overnight. HREF output shows coastal low
clouds and fog approaching from the northwest late tonight and Saturday
morning too.

&&

.LONG TERM...
(Saturday through Thursday)
Issued at 357 AM PST Fri Nov 8 2024

A progressive synoptic pattern across the Pacific and CONUS will
continue to nudge eastward the 500 mb ridge across our forecast
area today. 500 mb heights lower during the weekend with a 500 mb
trough along our coast by early Sunday morning. The GFS and ECMWF
show surface low pressure development accompanying the 500 mb level
trough, but also show dissipation of the low upon reaching the coast.
Most models are dry Sunday, except the ECMWF does show light rain
reaching Sonoma County to San Mateo County. Official forecast is
currently dry Sunday, however stay tuned to updates.

The arrival of Monday`s low pressure system brings widespread
light to perhaps moderate rain to the Bay Area with a chance of
rain extending to southern Monterey and San Benito Counties. The
next upstream low pressure system arrives mid to late week with
more wet weather at least reaching as far south as the Bay Area.
Wind modulated Pacific Decadal Oscillation (PDO) is deep in a cool
phase, October 2024 -3.81. The western Pacific warm sea surface
temperature anomalies are a source for water vapor for eastward
moving lows and fronts. The PNA teleconnection is forecast to
trend negative through mid November. It does look like a winter
season signature going forward with an expansion in the number of
north hemispheric long wave troughs, the potential is there for
more actively wet weather ahead.

&&

.AVIATION...
(12Z TAFS)
Issued at 331 AM PST Fri Nov 8 2024

VFR conditions continue at all terminals through the TAF period.
Winds for the most part will be light to moderate. Kept KHAF VFR as
well, but there is a 30-40% chc that cigs return by 12Z Saturday.
Cigs will likely be need with the next issuance of the KHAF TAF.

Vicinity of SFO...VFR. Light winds this morning then stronger
onshore winds later today.

SFO Bridge Approach...Similar to SFO.

Monterey Bay Terminals...VFR.

&&

.MARINE...
(Tonight through next Wednesday)
Issued at 236 AM PST Fri Nov 8 2024

Light to moderate winds will prevail over the coastal waters and
bays Friday and Saturday. Winds will gradually increase late this
weekend and early next week as a storm system swings through. The
passing storm system will bring rain to the region over the weekend
as well.

&&

.CLIMATE...
Issued at 138 AM PST Fri Nov 8 2024

Record lows at the long term climate stations for November 8th.

Station             Record Low

Santa Rosa          26 in 1914
Kentfield           32 in 1938, 1936, 1918
Napa                32 in 1918
Richmond            41 in 1983
Livermore           32 in 1971
San Francisco       46 in 2011, 1994, 1983, 1982, 1897
SFO Airport         42 in 1953, 1951, 1945
Redwood City        35 in 1971
Half Moon Bay       37 in 2011, 2002, 1961
Oakland downtown    44 in 2011
San Jose            34 in 1895
Salinas Airport     35 in 1938
King City           26 in 1983

&&

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

$$

SHORT TERM...Canepa
LONG TERM....Canepa
AVIATION...MM
MARINE...MM

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