545
FXUS66 KMTR 011131
AFDMTR

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

...New SYNOPSIS, SHORT TERM, LONG TERM...

.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.

&&

.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...
(06Z TAFS)
Issued at 1119 PM PDT Fri May 31 2024

VFR persists through the TAF period for the majority of terminals
with the exception of Monterey Bay, KSFO, and KOAK where IFR
conditions are expected overnight. KSFO may see SCT low clouds
develop over the terminal this morning, later forming a CIG to usher
in IFR conditions. In the daytime, VFR will return and winds will
increase to become moderate and gusty with many coastal terminals
seeing winds reach up to 15-20 knots. Winds will be largely out of
the W, later turning to develop a slight SW component. It is not
until early Sunday that winds are expected to fully diminish.

Vicinity of SFO...Currently VFR, though low clouds will begin to
push over the terminal vicinity as stratus continues to travel north
along the CA coastline. Models do not have good agreement, but seem
to suggest intermittent CIGs forming at KSFO early Saturday morning.
Therefore, have included a TEMPO in the TAF to reflect this, though
confidence on CIG formation is low. Come the later morning, VFR is
expected to return, with winds strengthening rapidly to become
strong and gusty. Gusty winds will reach into the 30 kt range in the
afternoon, and will remain gusty through the late night.

SFO Bridge Approach...Similar to SFO.

Monterey Bay Terminals...IFR conditions last through the first
portion of the TAF period with clearing not expected until the late
morning of Saturday as stratus begins to mix out. CIGs lowering to
become LIFR this morning is not out of the question, though
confidence is currently low, therefore have kept IFR conditions in
the TAF. Winds increase in the daytime out of the W to become
moderate in the afternoon around 15 knots.

&&

.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 from 9 AM this morning to 3 AM PDT Sunday
     for Mry Bay-Pigeon Pt to Pt Pinos 0-10 nm.

     Small Craft Advisory until 9 AM PDT this morning for Pt Arena to
     Pt Reyes 0-10 nm.

     Gale Warning from 9 AM this morning to 3 AM PDT Sunday for Pt
     Arena to Pt Reyes 0-10 nm.

     Small Craft Advisory until 3 PM PDT this afternoon for Pigeon Pt
     to Pt Pinos 10-60 NM-Pt Reyes to Pigeon Pt 0-10 nm.

     Gale Warning from 3 PM this afternoon to 3 AM PDT Sunday for
     Pigeon Pt to Pt Pinos 10-60 NM-Pt Reyes to Pigeon Pt 0-10
     nm.

     Small Craft Advisory from 9 AM this morning to 9 PM PDT this
     evening for Pt Pinos to Pt Piedras Blancas 0-10 nm.

     Gale Warning from 9 PM this evening to 3 AM PDT Sunday for 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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