846
FXUS66 KMTR 171934
AFDMTR

Area Forecast Discussion
National Weather Service San Francisco CA
1234 PM PDT Tue Sep 17 2024

...New SYNOPSIS, SHORT TERM, LONG TERM...

.SYNOPSIS...
Issued at 1233 PM PDT Tue Sep 17 2024

The next weather system will bright light rain to parts of the
region on Wednesday and then taper off from north to south on
Thursday. A warming and drying trend is expected by this upcoming
weekend and into early next week.

&&

.SHORT TERM...
(This evening through Wednesday)
Issued at 1233 PM PDT Tue Sep 17 2024

Another upper level low will approach the coast tonight and move
across on Wednesday brining generally light rainfall to the region.
Coastal drizzle will be possible ahead of the system tonight but
transition to light rain showers throughout the day tomorrow. By
tomorrow afternoon, the greatest potential for thunderstorms will be
across the North Bay with a ~15% (a non-zero chance elsewhere).
Rainfall amounts are expected to be light, not amounting to more
than 0.10" in most locations expect for locally higher totals in the
coastal ranges or where any stronger showers develop. Lastly, winds
will not be a concern with this passing system with only 15-25 mph
onshore gusts.

&&

.LONG TERM...
(Wednesday night through next Monday)
Issued at 1233 PM PDT Tue Sep 17 2024

Rain showers will linger into Thursday morning across the Central
Coast, tapering off from north to south throughout the afternoon and
ending by the evening. Friday looks to remain cool as the mid/upper
level trough begins to exit the region but still having an
influence.

Temperatures over the weekend will trend upward towards seasonal
averages. The marine layer also looks to return as a result with
night and morning low clouds likely into next week. Low clouds will
the retreat to the coast by the afternoon each day throughout the
week.

&&

.AVIATION...
(18Z TAFS)
Issued at 1102 AM PDT Tue Sep 17 2024

Stratus is expected to clear out of most airports between 18-20Z.
Most sites should clear by 19Z but additional tempos may be needed
from 19-20Z for any lingering stratus coverage. VFR conditions are
then expected through the afternoon before MVFR CIGs return late
this evening/overnight. Stratus is expected to return earlier along
the coast with MVFR CIGs to return 00-03Z at MRY and SNS. Winds
generally stay light to moderate with southwesterly winds gradually
becoming more west to northwesterly during the afternoon/evening
throughout the Bay Area. Drizzle chances increase everywhere, except
STS and APC, after 12Z with a few sites seeing drizzle chances
starting earlier between 05-06Z. Any precipitation that makes it to
the surface will be fairly light with totals less than a few
hundredths of an inch. Drizzle chances continue through the TAF
period but likelihood will decrease heading into late Wednesday.

Vicinity of SFO...MVFR becoming VFR by 19-20Z before MVFR CIGs
return overnight. Stratus is expected to return between 02-03Z
tonight and persist through late tomorrow morning. Drizzle chances
generally increase after 12Z through the end of the TAF period.
Scattered showers may become more likely after 15-18Z tomorrow but
confidence remains too low to include in TAF. West to southwest
winds become more moderate during the afternoon/evening before
weakening overnight.

SFO Bridge Approach...Similar to SFO.

Monterey Bay Terminals...Stratus coverage is dissipating at MRY and
SNS with patchy scattered clouds showing up on satellite. Ensemble
guidance indicates an early return of stratus around 00Z but a few
scenarios leaned towards an earlier return closer to 22-23Z. CIGs
are generally expected to stay MVFR overnight but there is some
potential for CIGs to become IFR overnight. Drizzle chances
generally increase after 06Z with the highest probability of drizzle
occurring after 12Z. Light, variable winds continue through the
remainder of the morning before more moderate west to northwest
winds return this afternoon.

&&

.MARINE...
(Today through Sunday)
Issued at 900 AM PDT Tue Sep 17 2024

Seas continue to abate and light to gentle northerly winds
persist through Tuesday. Hazardous seas return Wednesday as a cold
front arrives and brings moderate to fresh NW winds and rough
seas to the outer coastal waters. Locally stronger winds are
expected over the far northern outer waters.

&&

.MTR WATCHES/WARNINGS/ADVISORIES...
CA...None.
PZ...None.
&&

$$

SHORT TERM...RGass
LONG TERM....RGass
AVIATION...Kennedy
MARINE...Kennedy

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