346
FXUS66 KMTR 180425
AFDMTR

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

...New UPDATE...

.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.

&&

.UPDATE...
Issued at 924 PM PDT Tue Sep 17 2024


At this hour, mid level clouds are passing through the region ahead
of our next cold front. As a result, skies are overcast across the
area, and temperatures are on the cool side sitting in the mid 50s
for most locations. Temperatures are running 1-2 degrees cooler
compared to this time yesterday in the interior regions, and
generally 1-2 degrees warmer around the bays and along the
immediate coastline.

Chances of light rain are still expected for early Wednesday
morning. Most regions will only see a few hundredths of rainfall,
with the wettest locations (generally higher elevations) only seeing
around a tenth. Isolated peaks may see amounts closer to 0.2" at
most. All for now.


&&

.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...
(00Z TAFS)
Issued at 526 PM PDT Tue Sep 17 2024

Currently a mixed bag across the board with both low clouds and high
clouds moving into the region. Another early season cold front will
traverse into the area tomorrow bringing with it chances for
precipitation and thunderstorms. The TAFs were constructed with a
four hour timeframe where probabilities of -SHRA were highest, -DZ
is possible preceding and succeeding that timeframe. Ceilings will
be transient between MVFR and VFR through the TAF period. There is
up to a 15% chance for thunderstorms tomorrow; however, confidence
was not high enough in location and/or timing to definitively
include in the TAFs at this time.

Vicinity of SFO...Currently MVFR with westerly flow. MVFR ceilings
have made an early appearance and will likely impact the terminal
through tomorrow morning. Westerly winds will prevail through the
TAF period. Best timeframe for precipitation (-SHRA) is 14Z-18Z with
-DZ possible preceding or succeeding that timeframe.

SFO Bridge Approach...Similar to SFO.

Monterey Bay Terminals...Currently MVFR with northwesterly flow at
MRY and VFR with northwesterly flow at SNS. Guidance/models are
suggesting two distinct time frames for precipitation with the first
being tonight and the second being tomorrow morning. SNS will
deteriorate to MVFR early this evening and return to VFR by tomorrow
afternoon with MRY slated to remain MVFR through the TAF period.

&&

.MARINE...
(Tonight through next Monday)
Issued at 526 PM PDT Tue Sep 17 2024

Gentle northwesterly winds with the occasional moderate gust
persist  through Wednesday morning. Hazardous seas return by late
Wednesday  as a cold front arrives and brings moderate to fresh NW
winds and  rough seas to the outer coastal waters. Strong gusts
are possible  over the far northern outer waters beginning
Thursday through the  weekend.

&&

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

$$

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

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