816
FXUS66 KMTR 012008
AFDMTR

Area Forecast Discussion
National Weather Service San Francisco CA
108 PM PDT Wed May 1 2024

...New SYNOPSIS, SHORT TERM...

.SYNOPSIS...
Issued at 107 PM PDT Wed May 1 2024

A ridge of high pressure will keep conditions mild to warm across
the region throughout late week. Breezy onshore winds will keep
temperatures cooler near the coast. Wet, unsettled conditions
returning Friday night into Saturday, much cooler inland Saturday.
Unseasonably cool daytime highs continuing into early next week then
gradually warming by the middle of the week.

&&

.SHORT TERM...
(This evening through Thursday)
Issued at 107 PM PDT Wed May 1 2024

Dry weather conditions prevail tonight with temperatures falling
into the mid-to-upper 40`s to lower 50`s regionwide. Only expecting
low clouds near the Monterey Peninsula, if at all, as dry conditions
remain aloft. By sunrise, any low clouds that do develop with
quickly dissipate.

Thursday will see stronger northerly winds out over the ocean, peaks
near the coast, and inland higher terrain with gusts up to 45 mph
(gale force out over the ocean). Temperatures will likely reach the
60`s near the coast with mid-to-upper 70`s to near 80F inland.
Again, clear sky conditions are expected to persist.

&&

.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...
(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.

&&

.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 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 AM PDT Thursday for Pt Arena to Pt Reyes 0-
     10 nm-Pt Pinos to Pt Piedras Blancas 0-10 nm.

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

     Gale Warning until 9 PM PDT this evening for Pt Reyes to Pigeon
     Pt 0-10 nm.

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

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

     Gale Warning until 3 AM PDT Friday for Pigeon Pt to Pt Pinos 10-
     60 NM.

&&

$$

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

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