000
FXUS66 KMTR 290049
AFDMTR

Area Forecast Discussion
National Weather Service San Francisco CA
549 PM PDT Sun May 28 2023

...New AVIATION, MARINE...

.SYNOPSIS...
Issued at 1256 PM PDT Sun May 28 2023

A cutoff low continues to drift off the coast of California,
helping to bring cooler than normal temps to the region that will
persist through the upcoming week. Low clouds/stratus will
continue to be present in coastal areas, with clearing expected in
the late afternoons, before a return into the evening.

&&

.SHORT TERM...
(This evening through Monday)
Issued at 1256 PM PDT Sun May 28 2023

Radar imagery currently shows rainshowers off of the Marin county
coastline as the center of the cutoff low spins just off the San
Mateo coast. Light rain, about 0.01" thus far, has been reported
in a few northern coastal and Bay Area locations as a result.
That being said, not expecting much more than a few hundredths in
these localized spots, and for any chances of light rainfall to
diminish by the evening.

For the far northern portions of Sonoma and Napa counties, there
does exist a slight (15%) chance of thunderstorms in the late
afternoon to early evening, so if thunder roars, go indoors.
Localized heavier rainfall, lightning, and small hail are risks
associated with these thunderstorms. The slight chances for
thunderstorms in this area look to dissipate into the night as
surface heating diminishes with sunset.

Aside from the light rainfall seen today, persistence continues
to be the name of the game. Continued troughing will keep
temperatures on the cool side the next few days, with highs in the
mid 60s for Bays, and closer to mid 70s for more interior
locations. Widespread low clouds and stratus will continue to
intrude over the bays and coastal zones potentially bringing
drizzle, then clearing in the late afternoons.

&&

.LONG TERM...
(Monday night through next Saturday)
Issued at 1256 PM PDT Sun May 28 2023

Over the next few days, the cutoff low will continue to meander
down and just off of the coast, without any steering mechanism,
before slowly exiting to the southwest towards mid to late week.
Ridging looks to build in beyond this, bringing slightly warmer
temperatures than what has been seen lately. However, longer term
model guidance suggests continued troughing and cooler than
normal temperatures to persist through the early portions of June.
Stay tuned for updates.

&&

.AVIATION...
(00Z TAFS)
Issued at 549 PM PDT Sun May 28 2023

The center of the closed upper level low pressure system is located
approx 70 miles west of San Francisco. Clouds are a mix of stratiform
and convective and it`s mainly IFR-MVFR along the coast, VFR elsewhere.
Forecast areal cloud coverage and thicknesses varying alot tonight to
predawn Monday morning subsequently varying, in many locations slowing
outgoing radiative cooling to space and further saturation and low cloud
development. On Memorial Day, clouds /IFR-MVFR/ lifting to VFR inland,
last to clear along the coast where MVFR continues to late morning or
early afternoon. Low clouds /IFR-MVFR/ moving inland Monday night and
Tuesday morning.

Vicinity of SFO...SCT vs BKN ceiling /MVFR/ and west wind near 15 knots
early evening, MVFR prevailing from 02z, IFR from 09z tonight. IFR
ceiling Memorial Day lifting to VFR late morning, west wind increasing
to near 15 knots in the afternoon.

SFO Bridge Approach...Similar to SFO.

Monterey Bay...MVFR ceilings lowering to IFR this evening, IFR tonight
and Memorial Day morning. Patchy light drizzle developing tonight. IFR
lifting to MVFR on Memorial Day by late morning or early afternoon.

&&

.MARINE...
(Tonight through next Friday)
Issued at 449 PM PDT Sun May 28 2023

Moderate northwest winds continue into Memorial Day with the
strongest winds over the northern outer waters. Winds becoming
southerly Monday, and back to northwesterly by Tuesday afternoon.
Breezy to gusty westerly winds are also expected across the San
Francisco Bay, San Pablo Bay, Suisun Bay, and the Delta each
afternoon. Longer period background southerly swell continues
through late next week.

&&

.MTR WATCHES/WARNINGS/ADVISORIES...
CA...None.
PZ...Small Craft Advisory until 9 PM PDT this evening for PZZ570.

&&

$$

SHORT TERM...AC
LONG TERM....AC
AVIATION...Canepa
MARINE...Behringer

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