511
FXUS66 KMTR 301117
AFDMTR

Area Forecast Discussion
National Weather Service San Francisco CA
417 AM PDT Tue Apr 30 2024

...New AVIATION, MARINE...

.SYNOPSIS...
Issued at 133 AM PDT Tue Apr 30 2024

High pressure brings quiet weather and slowly warming temperatures
this week. Breezy onshore winds will keep temperatures along the
coast cooler however. Cooler and more unsettled conditions return
this weekend into next week with light rain chances in the forecast.

&&

.SHORT TERM...
(Today and tonight)
Issued at 203 AM PDT Tue Apr 30 2024

Dry conditions prevailing with high pressure from the offshore
waters to far northern California and the Pacific Northwest.
Gusty northwest winds continue over the coastal waters. Forecast
highs today 60s near the coast and bays to the 70s inland.

&&

.LONG TERM...
(Wednesday through Monday)
Issued at 203 AM PDT Tue Apr 30 2024

Dry conditions prevailing through mid-week. A slowly retrograding
long wave trough along the West Coast varies in strength late
week and early next week. There is a large difference between
recent GFS (wet) and ECMWF (not nearly as wet as the GFS) in
calculating the trajectory/progression of a low pressure system
moving through the long wave trough, now well within 120 hours (5
days) forecast. QPF differences are showing up in the GEFS and EPS
as well, though recent EPS have increased a little. As of current,
it remains a low confidence forecast from a global model forecast
perspective. Given the model forecast trajectory of the low pressure
system is from near the Bering Sea/Aleutians southeastward across
the Pacific (and surface high pressure over the Pacific retrogrades)
where below normal sea surface temperatures exist including a
negative phase Pacific Decadal Oscillation (PDO) i.e. the potential
forward slowing due to local surface heating is reduced therefore
the quicker arriving QPF in the GFS solution may not be that far
off if development much closer to our forecast area verifies. The
northern hemispheric pattern remains active with the current number
of long wave troughs reflecting a winter-like circulation.

Stay tuned to latest forecast updates, as currently advertised
the official forecast shows potential for showery, cool weather
this weekend. Planning travel to the mountains? This pattern has
potential for snow accumulations, it`s a good idea to monitor the
latest forecasts. Per 30 year climatology we are of course past
peak cool season rainfall, however it can still rain in May in the
Bay Area and north Central Coast. Recalling a Lead Forecaster here
years ago mentioned it`s always a good idea to carry chains in case
needed (for Sierra Nevada travel) through Memorial Day.

July climatologically is our driest time of year since by then the
jet stream has reliably weakened and returned northward and high
pressure often sets up.

&&

.AVIATION...
(12Z TAFS)
Issued at 416 AM PDT Tue Apr 30 2024

Generally VFR through the TAF period with patchy stratus in the
higher elevations. Breezy westerly winds building through the day
with gusts somewhat less intense than seen yesterday. LLWS concerns
start to emerge early Wednesday morning, towards and after the end
of the TAF period, primarily for the East Bay and eastern North Bay.

Vicinity of SFO... VFR through the TAF period. Breezy west-northwest
winds building through the day. As of now, winds expected to gust up
to 30 knots this afternoon and evening. Not expecting gusts above 35
knots at this time, but will monitor the evolution of the situation.

SFO Bridge Approach... Similar to SFO.

Monterey Bay Terminals... Not expecting any more ceilings to develop
at MRY for the rest of the morning, and a low confidence (10-20%
probability) that a patch of MVFR stratus forms over the northern
Santa Lucias late this evening into Wednesday morning and then
impacts the terminal. Otherwise, generally VFR through the region
with breezy onshore flow developing this afternoon and evening.

&&

.MARINE...
(Today through Sunday)
Issued at 416 AM PDT Tue Apr 30 2024

A strong northerly pressure gradient continues to produce
hazardous gale force wind gusts through early Friday. Gale force
gusts of 40 to 45 knots are possible over the outer waters and
portions of the immediate coast near Point Reyes and Point Sur.
The strong winds will result in fresh steep wind waves with
heights reaching 10 to 12 feet. Conditions will gradually improve
late in the week into next week.

&&

.MTR WATCHES/WARNINGS/ADVISORIES...
CA...None.
PZ...Small Craft Advisory from 3 PM this afternoon to 3 AM PDT
     Wednesday for SF Bay N of Bay Bridge.

     Small Craft Advisory from 9 AM this morning to 3 AM PDT
     Wednesday for Mry Bay.

     Small Craft Advisory from 9 AM to 9 PM PDT Wednesday for Mry Bay.

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

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

     Small Craft Advisory from 3 PM to 9 PM PDT Wednesday for Pigeon
     Pt to Pt Pinos 0-10 nm-Pt Reyes to Pigeon Pt 0-10 nm.

     Gale Warning until 9 PM PDT Wednesday for Pt Pinos to Pt Piedras
     Blancas 0-10 nm.

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

&&

$$

SHORT TERM...Canepa
LONG TERM....Canepa
AVIATION...DialH
MARINE...DialH

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