862
FXUS66 KMTR 020013
AFDMTR

Area Forecast Discussion
National Weather Service San Francisco CA
513 PM PDT Sat Jun 1 2024

...New AVIATION...

.SYNOPSIS...
Issued at 109 PM PDT Sat Jun 1 2024

Cooler temperatures continue into Monday with coastal stratus
developing overnight. Significant warming begins Tuesday with
moderate HeatRisk across the interior regions through Thursday.

&&

.SHORT TERM...
(This evening through Sunday)
Issued at 109 PM PDT Sat Jun 1 2024

Coastal stratus continues to gradually erode in the western San
Mateo Peninsula and the Monterey Bay region, expected to clear
through the rest of the afternoon. Widespread marine layer stratus
is expected again across the lower elevations in the SF Bay Area and
Central Coast tonight into Sunday morning, facilitated by a deep
marine layer (2000 ft or greater as measured by the Fort Ord
profiler). This is also helping to generally moderate temperatures
from yesterday`s warm readings. The most dramatic cooldowns have
been in the interior valleys of the East Bay, South Bay, and
southern Monterey County, where temperatures are as much as 20
degrees cooler than yesterday at the same time. The North Bay has
cooled down slightly, but downsloping winds from the coastal ranges
are themselves moderating the cooling effect of the marine layer,
which is also slightly compressed compared to the situation further
south (1200 feet as measured from the Bodega Bay profiler).

All this corresponds to high temperatures extending from the upper
70s to the lower 80s for the interior valleys, with the mid to upper
80s expected in the North Bay and southern Monterey County valleys,
mid 60s to lower 70s along the Bayshore and near Santa Cruz, and the
upper 50s to lower 60s along the Pacific coast. Lows tonight are
generally in the low to mid 50s, except down into the low 40s across
the higher elevations.

&&

.LONG TERM...
(Sunday night through next Friday)
Issued at 109 PM PDT Sat Jun 1 2024

Relatively cool conditions continue into Monday. Impacts from a deep
upper-level trough impacting British Columbia will be limited, and
limited mainly to the North Bay, where the fringes of a cold front
will moderate high temperatures to the mid 70s to lower 80s in the
valleys. Any rain will be limited to the extreme northern reaches of
Sonoma County with insignificant accumulations.

The pattern changes on Tuesday with a strengthening ridge over the
Pacific migrating into the Western United States. In the interior
regions, temperatures are expected to rise into the 90s to the low
100s into Thursday with a moderate HeatRisk, meaning that there`s a
risk of heat-related illnesses for sensitive populations (children,
the elderly, pregnant women, and people without access to shade or
air conditioning). The coastal regions remain quite uncertain. The
main questions concerning the coastal forecast will any remaining
sea breezes be strong enough to outweigh the general warming trend,
how far will they travel inland, and how deep will be the remaining
marine layer be. To give just one example of the potential
uncertainty, the current forecast calls for highs in downtown San
Francisco to top out at 78, but some of the model guidance extends
into the mid 80s.

There is still a chance that the upper level trough stalls over the
West Coast, but the model ensemble clusters suggest that the most
likely outcome is that the ridge will start to build more towards
the north and bring heat impacts into the northwestern United
States. In addition, some of the global models show a southerly wind
reversal setting up sometime later on Wednesday into Thursday. With
the end of the heat still at least several days out, it`s a good
idea to stay tuned for further updates as forecast confidence
increases.

&&

.AVIATION...
(00Z TAFS)
Issued at 512 PM PDT Sat Jun 1 2024

VFR conditions at most terminals through this evening with the
exception of Monterey Bay. That last bit of cigs are finally
thinning and will allow for a few hours with no cigs before they
return early tonight. The bigger story heading into the evening
will be the increasing winds aloft leading to LLWS 1-2k ft off
the deck. Pretty low height to hit stronger winds <2k feet. As the
LLWS eases late tonight the marine layer makes a push inland.
Definitely lower confidence (40%) on marine layer details.

Vicinity of SFO...AWW remains in effect through 06z with gusts up
to 35kt. That being said, TAF still has 35kt, but latest trends
show the peak wind may have just occurred. As winds ease
overnight a shallow cig will develop lingering 17-18z Sunday.
Gusty onshore again tomorrow, but not as strong as today.

SFO Bridge Approach...Cigs will be more widespread over portions
of the approach than SFO Sunday morning, especially SE area of SF
Bay.

Monterey Bay Terminals...Cigs are thinning with VFR at MRY, but
MVFR cigs lingering at SNS. Even with thinning, expect cigs to
return early tonight lasting into Sunday afternoon.


&&

.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 until 9 PM PDT this evening for Mry Bay-SF
     Bay N of Bay Bridge.

     Small Craft Advisory from 3 PM to 9 PM PDT Sunday for Mry Bay.

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

     Small Craft Advisory until 9 PM PDT Sunday for Pigeon Pt to Pt
     Pinos 10-60 NM-Pt Pinos to Pt Piedras Blancas 0-10 nm.

     Gale Warning until 9 PM PDT this evening for Pt Arena to Pt
     Reyes 10-60 NM.

&&

$$

SHORT TERM...DialH
LONG TERM....DialH
AVIATION...MM
MARINE...Murdock

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