283
FXUS66 KMTR 011614
AFDMTR

Area Forecast Discussion
National Weather Service San Francisco CA
914 AM PDT Sat Jun 1 2024

...New UPDATE...

.SYNOPSIS...
Issued at 255 AM PDT Sat Jun 1 2024

Cooler conditions today with temperatures near seasonal averages
across most of the region. Warmer to hotter temperatures return
Tuesday with moderate HeatRisk through the interior.

&&

.UPDATE...
Issued at 906 AM PDT Sat Jun 1 2024

Morning stratus is beginning to mix out across the northern SF
Bay, the western San Mateo Peninsula, and across the Central
Coast, down the Salinas Valley, and into the Gilroy-Hollister
area. The marine layer has stabilized around 1200 feet at Bodega
Bay and 2000 feet at Fort Ord, and stronger onshore gradients are
contributing to some breezy winds across the region. The forecast
remains on track with no changes at this time. Main concern
continues to be the upcoming heat event beginning next Tuesday,
which is expanded on in the previous discussion.

DialH

&&

.SHORT TERM...
(Today and tonight)
Issued at 431 AM PDT Sat Jun 1 2024

Coastal stratus and mist continue to develop due to a combination
of surface to near surface cool air advection and nocturnal
radiative cooling. The marine layer depth varies from 1200 feet
at Bodega Bay to 2000 feet at Fort Ord. Northwest and southeast
winds are juxtaposed along the coastline and inland, the northerly
ACV-SFO pressure gradient is 4.9 mb, the SMX-SFO and SNS-SJC
southerly pressure gradients are 1.6 mb and 2.1 mb respectively.

Stratus and mist will continue developing through about sunrise
then begin to mix out under diurnal surface warming as well as due
to a strengthening and gusty northerly wind overlapping the
immediate coastline later on today. Daytime highs today will be
cooler most locations except the North Bay where downsloping winds
will offset cooling. Highs today 60s/70s coastside and bayside,
inland highs in the 80s. Coastal stratus redeveloping tonight and
Sunday morning, lows cooling back to the upper 40s and 50s.

&&

.LONG TERM...
(Sunday through Friday)
Issued at 431 AM PDT Sat Jun 1 2024

Night and morning stratus likely mixing out back to near the
coastline Sunday afternoon and possibly again Monday afternoon.
By late Sunday and Monday increasing amounts of water vapor will
move across our forecast area, per comparison with Oakland upper
air early June climatology precipitable water will reach the max
moving average and may briefly exceed the early June daily maximum.
Water vapor in contact with chilly sea surface temperatures favors
stratus and we may also see light coastal drizzle.

Beginning Tuesday the weather will then become quickly influenced
by the strengthening of the subtropical high pressure system over
the Pacific. The high will strengthen while sandwiched between a
strong late season mid-latitude storm track reaching southwestern
Canada and the Pacific NW (with a soaking rain) and the seasonally
northward nudged Intertropical Convergence Zone well to our
south. Global models are in better agreement with the overall
motion of next week`s high pressure system, though there is some
difference in the strength of the high. 850 mb temps (helpful for
forecasting surface temperatures via dry adiabatic compressional
warming of air parcels to the surface) vary by a couple degrees
Celsius, these values are forecast to near the early June max
moving average, possibly exceeding the daily maximum if the ECMWF
verifies.

Expect warm to hot daytime temperatures at least during Tuesday
through Thursday, it`ll be hottest inland with 90s to lower 100s.
At the coast there may be lingering sea-breezes though the marine
layer will likely get compressed to 1000 feet or even lower, still
tough to say with certainty since this is still a few days out,
and the warm season maritime vs land temperature contrasts
naturally keeps a thermally direct circulation potential in place.
Another item to watch for, the meso to synoptic pattern may favor
a southerly wind reversal either late Wednesday or Thursday. The
PDO is still in a negative (cool phase). Hottest daytime temperatures
this week look to be Tuesday-Wednesday with carryover into Thursday,
and if the high pressure system becomes stationary then hot temperatures
will carry into late week before sea breeze relief reaches inland.
Though again, the global models do show potential for a southerly
wind reversal i.e. sea breeze before late week. Lots of factors
in the forecast next week, please stay tuned to updates. For the
time being it`s a good idea to plan on at least moderate heat risk
inland in our forecast area beginning Tuesday next week.

&&

.AVIATION...
(12Z TAFS)
Issued at 507 AM PDT Sat Jun 1 2024

Stratus continues to filter into coastal terminals this morning
bringing MVFR CIGs to Monterey Bay and KAPC. Expect stratus to begin
to mix out beyond sunrise to lead to widespread VFR conditions
through the evening. Winds will increase out of the W/NW today to
become moderate to strong, with gusts generally in the 20-25 knot
range. KSFO is likely to see higher gusts. These stronger winds
appear to last well into the nighttime, only beginning to ease in
the mid morning of Sunday. Stratus does not appear to make a return
to area terminals until winds begin to weaken in the mid morning for
most terminals, bringing MVFR conditions once more.

Vicinity of SFO...Currently VFR, though stratus has begun to creep
over the terminal. Expecting stratus to briefly form a CIG this
morning lending to MVFR conditions. In the later morning, stratus
mixes out to lead to widespread VFR as westerly winds strengthen
rapidly, gusting upwards of 35 knots into the afternoon and evening
today. It is not until close to midnight that gusts are expected to
begin to weaken. Even as gusts diminish, sustained winds will remain
breezy through the night. Stratus and MVFR CIGs make a return
towards the end of the TAF period.

SFO Bridge Approach...Similar to SFO.

Monterey Bay Terminals...Stratus has pervaded deep into the Monterey
Bay region this morning, extending far down the Salinas Valley.
Local profilers show the marine layer deepening. As a result,
stratus and MVFR conditions are not expected to clear until the late
morning to early afternoon today. VFR returns in the afternoon as
winds increase out of the W/NW and gust 20-25 knots. When stratus
returns in the evening today is a bit of a question. Models seem to
agree on a return, but have large variance in the timing of MVFR CIG
return. Moderate confidence in a return of stratus towards 06Z
Sunday. Winds slowly ease through the night.

&&

.MARINE...
(Today through Wednesday)
Issued at 849 AM PDT Fri May 31 2024

Breezy to gusty northwest winds will continue over the outer
waters into the weekend with gale force winds expected late Friday
and into Saturday. This will cause a hazardous marine environment.
Significant wave heights will reach up to about 11-12 feet Friday
afternoon, but will begin to reduce today through the remainder
of the weekend.

&&

.CLIMATE...
Issued at 127 AM PDT Sat Jun 1 2024

Record high temperatures at the long term climate stations for
June 4th and 5th:

Station             June 4th             June 5th

Santa Rosa          98 in 1949           102 in 1926
Kentfield          101 in 1981           102 in 1926
Napa               102 in 1981           105 in 1903
Richmond            90 in 1955            86 in 1983
Livermore          105 in 1960           104 in 1926
San Francisco       92 in 1949            95 in 1883
SFO Airport         92 in 1955, 1949      89 in 1972
Redwood City       100 in 1981            97 in 2002, 1972
Half Moon Bay       71 in 1955            74 in 1958
Oakland downtown    96 in 1981            87 in 2002
San Jose            98 in 1904           100 in 1926
Salinas Airport     92 in 1949            87 in 1949
King City          102 in 1981, 1957     105 in 1926

&&

.MTR WATCHES/WARNINGS/ADVISORIES...
CA...None.
PZ...Small Craft Advisory from 3 PM this afternoon to 9 PM PDT this
     evening for SF Bay N of Bay Bridge.

     Small Craft Advisory until 3 AM PDT Sunday for Mry Bay.

     Gale Warning until 3 AM PDT Sunday for Pt Arena to Pt Reyes 0-10
     nm.

     Small Craft Advisory until 3 PM PDT this afternoon for Pt Reyes
     to Pigeon Pt 0-10 nm.

     Gale Warning from 3 PM this afternoon to 3 AM PDT Sunday for Pt
     Reyes to Pigeon Pt 0-10 nm.

     Small Craft Advisory until 3 PM PDT Sunday for Pigeon Pt to Pt
     Pinos 0-10 nm-Pigeon Pt to Pt Pinos 10-60 NM-Pt Pinos to Pt
     Piedras Blancas 0-10 nm.

     Gale Warning until 3 PM PDT this afternoon for Pt Arena to Pt
     Reyes 10-60 NM.

&&

$$

SHORT TERM...Canepa
LONG TERM....Canepa
AVIATION...AC
MARINE...Murdock

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