High Surf in California, May 1, 2024

Area Forecast Discussion...UPDATED
National Weather Service San Francisco CA
944 AM PDT Wed May 1 2024

...New UPDATE...

.SYNOPSIS...
Issued at 125 AM PDT Wed May 1 2024

High pressure brings quiet weather and slowly warming temperatures
this week. Breezy onshore winds will keep temperatures along the coast
cooler however. Wet, unsettled conditions returning Friday night and
Saturday, much cooler inland Saturday. Unseasonably cool daytime highs
continuing into early next week then gradually warming by the middle
of the week.

&&

.UPDATE...
Issued at 938 AM PDT Wed May 1 2024

The short term forecast is in good shape with just a couple of
minor tweaks the the wind grids. Northerly breezes between 15 and
20 mph with gusts to 30 to 35 mph are forecast (higher over the
marine zones) with our local WRF appearing to handle some of the
subtleties associated with the complex terrain/shorelines.
Otherwise, it should be a pleasant day with mostly sunny skies (a
few high clouds may stream in later in the day). We'll continue to
warm through the week, with a pattern change (cooler and windier)
shaping up for the weekend. More details later this afternoon.

&&

.SHORT TERM...
(Today and tonight)
Issued at 133 AM PDT Wed May 1 2024

Today's weather will be similar to Tuesday's weather, dry conditions
prevailing with high pressure over the offshore waters to far northern
California. Gusty northwest winds continuing over the coastal waters.
Forecast highs today 60s near the coast and bays to the 70s-80 inland.

&&

.LONG TERM...
(Thursday through Tuesday)
Issued at 133 AM PDT Wed May 1 2024

Dry Thursday and Friday, increasing clouds Friday night with rain
developing over the North Bay, rain spreading southeastward across
much of the rest of the forecast area Saturday. It'll turn noticeably
cooler especially inland Saturday with daytime highs Saturday 10F to
18F cooler inland compared to Friday's forecast highs.

In the last 12-24 hours global and mesoscale models are more in line
focusing on the arrival of a cold core low pressure system from the
Bering Sea/Aleutian Islands arriving in northern California Friday
night and Saturday. The southeastward trajectory takes it across
cooler than normal sea surface temperatures (negative phase PDO)
at least somewhat minimizing maritime thermal modification along
the way and for maintenance/development it'll travel through a long
wave trough on the West Coast. The low will brush by and tap higher
levels of water vapor extending far north of Hawaii, however the
low is forecast to move through our forecast area retaining a strong
mid-latitude influence. Recent precipitable water values on the GFS
have been 1.00" to 1.10" for Saturday, not far from the max moving
average on Oakland upper air sounding climatology in early May.
Model forecast rainfall amounts vary from 0.25" to 0.70" North
Bay, 0.15"-0.25" low elevations to 0.40" hills/mountains elsewhere
across the Bay Area to around 0.10" interior north Central Coast
to 0.33" Big Sur Coast. Wet and cooler weather Saturday, gusty
northwest winds over the coast temporarily subsiding with the
passage of a surface cold front/trough. Dry weather returns
Sunday. The surface pressure pattern looks favorable for gusty
northwest winds redeveloping over the coastal waters beginning
next Tuesday. Daytime highs gradually warming by the middle of
next week.

&&

.AVIATION...
(12Z TAFS)
Issued at 426 AM PDT Wed May 1 2024

Generally VFR through the TAF period with patchy stratus in the
higher elevations. LLWS concerns continue for the rest of the
morning throughout the region as light surface winds have decoupled
from strong northerly winds aloft. Northerly winds build through the
afternoon, generally gusting through 20-25 knots, with LLWS concerns
returning as the surface winds diminish in the evening.

Vicinity of SFO... VFR through the TAF period. Light onshore surface
flow tonight with strong northerly flow aloft causing LLWS.
Northwest winds build through the afternoon gusting to 20-25 knots,
before diminishing through the evening.

SFO Bridge Approach... Similar to SFO.

Monterey Bay Terminals... Patches of stratus intermittently
impacting MRY through the rest of the morning. Otherwise VFR through
the TAF period. Directional LLWS continues this morning as light
drainage flow meets northerly winds aloft. Northwest winds develop
later today with gusts up to 20-25 knots, diminishing again in the
evening with directional LLWS resuming at MRY.

&&

.MARINE...
(Today through Sunday)
Issued at 938 AM PDT Wed May 1 2024

Breezy and gusty winds continue throughout Friday, with gale
force gusts of 40 to 45 knots possible in the outer waters.
Strong winds will result in hazardous seas and steep wind waves
with significant wave heights reaching 10 to 14 feet in the outer
waters. Conditions gradually improve over the weekend and into
next week as winds begin to ease. Rain chances begin early
Saturday as a trough descends over the region.

&&

.MTR WATCHES/WARNINGS/ADVISORIES...
CA...None.
PZ...Small Craft Advisory from 9 AM to 9 PM PDT Thursday for SF Bay N
     of Bay Bridge.

     Small Craft Advisory until 9 PM PDT this evening for Mry Bay.

     Small Craft Advisory from 9 AM Thursday to 3 AM PDT Friday for
     Mry Bay.

     Gale Warning until 3 PM PDT this afternoon for Pt Arena to Pt
     Reyes 0-10 nm.

     Small Craft Advisory until 3 AM PDT Friday for Pigeon Pt to Pt
     Pinos 0-10 nm-Pt Reyes to Pigeon Pt 0-10 nm.

     Gale Warning until 3 AM PDT Thursday for Pt Arena to Pt Reyes 10-
     60 NM-Pt Pinos to Pt Piedras Blancas 0-10 nm.

     Gale Warning until 9 AM PDT Thursday for Pigeon Pt to Pt Pinos
     10-60 NM.

&&

UPDATE...Bain
SHORT TERM...Canepa
LONG TERM....Canepa
AVIATION...DialH
MARINE...RGass

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