FXUS66 KMTR 231150
AFDMTR
Area Forecast Discussion
National Weather Service San Francisco CA
450 AM PDT Thu Apr 23 2026
...New AVIATION, MARINE...
.KEY MESSAGES...
Updated at 1201 AM PDT Thu Apr 23 2026
- Seasonal temperatures and dry conditions return today
- Potential for rain/drizzle and slightly cooler temperatures
this weekend into early next week
- Warming trend begins early to mid next week
&&
.SHORT TERM...
Issued at 1201 AM PDT Thu Apr 23 2026
(Today and tonight)
KMUX has been allowed to transition back into clear air mode as
shower activity has ended across the region. Relatively moist
conditions and light winds overnight will lead to some potential for
patchy fog to develop across the valleys. Latest HRRR guidance
supports a slightly higher chance for patchy fog to develop within
the Santa Clara Valley and potentially within North Bay Valleys. Fog
development would be most likely in the early morning hours/right
around sunrise. As this may run into the early morning commute, if
you encounter fog remember to slow down and allow extra time to
reach your destination.
Morning temperatures will be seasonable with lows generally in the
40s. Portions of the Eastern Santa Clara hills, the Gabilan Range,
and the Santa Lucia Range will drop into the mid to upper 30s. High
temperatures warm up well, however, as a weak, progressive ridge
moves through southern and central California. High temperatures
will be in the low to mid 70s across the interior and 50s to 60s
along the coastline. Temperatures across the lower elevations will
be seasonal to seasonally warm while temperatures across the higher
terrain are below normal. No other concerns in the short term as dry
weather prevails. Winds remain light and onshore today with
diurnally breezy conditions expected across the valleys.
&&
.LONG TERM...
Issued at 1201 AM PDT Thu Apr 23 2026
(Friday through Wednesday)
By Friday, the upper level ridge will begin its eastward exit and
weak upper level troughing will return over the Western US. This
trough is associated with a deep upper level low that will remain
situated over Montana/the Dakotas through the weekend before exiting
the region early next week. As weak troughing returns, it will allow
a much cooler airmass to filter in over the West Coast Saturday
through early next week. Initial guidance shows 850 mb temperatures
running between 2-4 degrees Celsius which is between the 10th to
25th percentiles for 850mb temperatures recorded by OAK. For
comparison the daily mean 850 mb temperatures are closer to 7 to 8
degrees Celsius. What does that look like at the surface? High
temperatures on Friday will be fairly seasonal in the upper 60s to
low 70s across the interior and 50s to 60s along the coast. Saturday
temperatures will cool by around 5 degrees across the interior where
widespread 60s are expected (coastal temperatures remain in the 50s
to 60s). We can expect similar temperatures on Sunday before a
slight warming trend kicks off Monday as 850mb temperatures warm
(becoming more seasonal). This warming trend will see temperatures
returning to the low to mid 70s across the interior with
temperatures warming by a few degrees each day through the remainder
of the long term forecast. Overnight low temperatures remain
seasonable through the extended forecast with slightly cooler
temperatures expected across the higher elevations of the eastern
Santa Clara Hills, the Gabilan Range, and the Santa Lucia Range.
Another factor to consider in planning your weekend is the
possibility of rain. Currently, it is looking like we might get some
light rain but it will not be as impressive as the system we just
had. Ensemble guidance is alternating between drizzle to a few
tenths of an inch (0.1-0.2") possible. The higher chances for light
rain are across the Central Coast with more drizzly conditions
likely across the Bay Area. Higher precipitation totals (compared to
us) are more likely across Southern California where the main
moisture plume is oriented against. Either way, it is likely to be a
drizzly weekend but the incoming rain will be light and beneficial.
Ensembles are hinting at additional light, beneficial rain being
possible mid to late next week as the upper level pattern remains
unsettled.
&&
.AVIATION...
(12Z TAFS)
Issued at 423 AM PDT Thu Apr 23 2026
VFR is expected to prevail through today and most of tonight with
a weak fetch of offshore flow through this afternoon. There's a
chance of MVFR cigs developing early Friday morning with the
return of relatively weak onshore flow.
Vicinity of SFO...VFR is expected to prevail through the forecast
period with a weak fetch of offshore flow through this
afternoon.There's a chance of MVFR cigs developing late in the
TAF period early Friday morning with the return of weak onshore
flow.
SFO Bridge Approach...Similar as SFO.
Monterey Bay Terminals...VFR is expected to prevail through the
forecast period with a weak fetch of offshore flow through this
afternoon. There's a chance of MVFR cigs developing late in the
TAF period early Friday morning as onshore flow returns.
&&
.MARINE...
(Today through Tuesday)
Issued at 423 AM PDT Thu Apr 23 2026
Moderate north breezes this morning will develop into a northwest
breeze this afternoon. Choppy seas at times today will begin to
subside Friday and continue into the weekend.
&&
.MTR WATCHES/WARNINGS/ADVISORIES...
CA...None.
PZ...Small Craft Advisory from 3 PM this afternoon to 9 PM PDT this
evening for Pigeon Pt to Pt Pinos 0-10 nm-Pt Arena to Pt
Reyes 0-10 nm-Pt Pinos to Pt Piedras Blancas 0-10 nm-Pt
Reyes to Pigeon Pt 0-10 nm.
Small Craft Advisory until 9 AM PDT Friday for Pt Arena to Pt
Reyes 10-60 NM.
Small Craft Advisory from 3 PM this afternoon to 3 AM PDT Friday
for Pigeon Pt to Pt Pinos 10-60 NM.
&&
$$
SHORT TERM...Kennedy
LONG TERM....Kennedy
AVIATION...JM
MARINE...JM
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Prepared by Boulder-Creek.com Weather at: Thu Apr 23 08:30:03 PDT 2026
From the National Weather Service
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