-- Discussion containing changed information from previous version are highlighted. --
414
FXUS66 KMTR 011835 AAB
AFDMTR

Area Forecast Discussion...UPDATED
National Weather Service San Francisco CA
1135 AM PDT Wed May 1 2024

...New AVIATION...

.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...
-- Changed Discussion --
(18Z TAFS)
Issued at 1056 AM PDT Wed May 1 2024

VFR will prevail with the main aviation weather concern revolving
around wind (gusts and non-convective LLWS). This afternoon, wind
gusts will range between 20 and 25 knots. Tonight, winds will
subside down below 5 knots at the surface, with increased flow
between 30 and 40 knots just above the surface at a couple of
sites. At this time, the most likely terminals to be impacted by
LLWS will be APC and LVK. Winds at STS are forecast to remain
above 15 knots which should keep the LLWS potential low, however,
turbulence is probable to transpire. The LLWS potential diminishes
by mid-morning Thursday.

Vicinity of SFO...Slightly variable wind flow (E to WNW) will
continue over the next few hours. By 21Z, WNW winds will funnel in
from the San Bruno Gap and increase to near 15 knots with gusts
to near 25 knots. Crosswind calculations suggest around a 20-25
knot wind crosswind on SW to NE oriented runways which may result
in some tricky approaches. Runways should reamin usable. Winds
abate after nightfall. VFR is forecast to prevail with some high
cirrus around FL250. Thursday afternoon will feature additional NW
winds, though confidence low in model guidance thanks to
conflicting messages. Overall, the background pattern suggest a
gradual easing of the winds, but crosswind magnitudes near 25
knots may still still result in some tricky approaches. There`s a
slim chance (<10%) that MVFR stratus may attempt to creep in on
Friday morning, but that`s just beyond the current TAF cycle.

SFO Bridge Approach...Similar to SFO.

Monterey Bay Terminals...VFR is also forecast to prevail here,
though there`s a very slim (5%) chance of MVFR cigs at MRY.
Diurnal breezes are forecast through the period with gusts as
great as 20 knots. Surface winds subside below 10 knots tonight.
The greater wind magnitudes aloft (FL020) don`t appear to warrant
inclusion of LLWS in the TAFs at this time, but trends will be
monitored.
-- End Changed Discussion --


&&

.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...Bain
MARINE...RGass

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