949
FXUS66 KMTR 251148
AFDMTR

Area Forecast Discussion
National Weather Service San Francisco CA
448 AM PDT Wed Sep 25 2024

...New AVIATION, MARINE...

.SYNOPSIS...
Issued at 249 AM PDT Wed Sep 25 2024

An upper level trough off of the West Coast will bring cooler
temperatures on Wednesday with a gradual warming trend into Friday
has high pressure builds over the Desert Southwest. Temperatures
return to near seasonal averages for the upcoming weekend.

&&

.SHORT TERM...
(Today and tonight)
Issued at 249 AM PDT Wed Sep 25 2024

Widespread cloud cover with bases at between 300-1,300 feet continue
to spread inland at this hour into the coastal adjacent valleys. As
such, temperatures are expected to bottom out in the 50`s for most
locations with lower 60`s in the East Bay Valleys and Santa Clara
Valley. Cannot rule out mist or drizzle in the favored locations
across the region as an upper level low off of the coast deepens the
marine layer.

Today will mark the much anticipated cool down with temperatures
across the interior cooling between 10-20 degrees from yesterday`s
maximum temperatures and 1-10 degrees closer to the coast. This is
in response to the aforementioned upper level low which has
developed over the eastern Pacific. Breezy onshore winds are
expected this afternoon and will continue into the evening.

Tonight, expecting a 1-5 degree cool-down as temperatures cool
aloft. Look for a return of low clouds once again tonight into the
coastal adjacent valleys and much better humidity recoveries as
well. Winds diminish becoming light and variable overnight.

&&

.LONG TERM...
(Thursday through Tuesday)
Issued at 249 AM PDT Wed Sep 25 2024

More of a zonal pattern develops to our north on Thursday, while an
upper level high develops over the Desert Southwest. This will bring
temperatures back up to near seasonal averages on Thursday and above
average by Friday. Temperatures trend back to near seasonal norms for
the weekend as an upper level low to the to our southwest approaches
and an upper level trough impacts the Pacific Northwest.

From the previous forecaster: "Model output is beginning to show the
potential for light offshore flow during the night and morning hours
this weekend. However, confidence in any specific impacts are too
low to note in fire weather products at this time. CPC outlooks
continue to show a lean towards temperatures above, and
precipitation below, seasonal averages through the first week of
October."

&&

.AVIATION...
(12Z TAFS)
Issued at 448 AM PDT Wed Sep 25 2024

A deepening marine layer and onshore winds are resulting in an
inland intrusion of stratus and fog /LIFR-MVFR/. Conditions
improving to MVFR-VFR back to the coastline by late this morning
and afternoon. Coastal stratus and fog /LIFR-MVFR/ moving inland
tonight and Thursday morning.

Vicinity of SFO...MVFR ceiling to 19z today, VFR in the afternoon.
MVFR stratus ceiling returning by 03z this evening and continuing
tonight and Thursday morning. Onshore wind 5 to 15 knots.

SFO Bridge Approach...Similar to SFO.

Monterey Bay Terminals...Stratus and fog /LIFR-IFR/ this morning,
improving to MVFR-VFR by late morning and afternoon. IFR-MVFR in
stratus returning early this evening and continuing tonight and
Thursday morning. Onshore winds 5 to 12 knots.

&&

.MARINE...
(Today through Monday)
Issued at 438 AM PDT Wed Sep 25 2024

Light to gentle northwesterly breezes will continue today.
Northwesterly breezes increase to become moderate to fresh and
seas rebuild to become rough in the outer waters by Thursday.

&&

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

$$

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

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