NWS Forecast Area Discussion - San Francisco Area
148
FXUS66 KMTR 191135
AFDMTR
Area Forecast Discussion
National Weather Service San Francisco CA
335 AM PST Wed Feb 19 2025
...New AVIATION, MARINE...
.SYNOPSIS...
Issued at 1223 AM PST Wed Feb 19 2025
A cold front will move through today. The primary impacts will be
some light rain in the North Bay this morning, and gusty winds
throughout the cwa into Thursday. Behind the front, a dry and
warm pattern will become established, and persist through the
forecast period.
&&
.SHORT TERM...
(Today and tonight)
Issued at 1223 AM PST Wed Feb 19 2025
Prefrontal rain has reached NW Sonoma County, and will continue
to push south through the morning. KMUX returns indicate the rain
will be mostly light, as advertised. High resolution guidance
suggest the rain will continue through the early afternoon,
and a few drops may reach as far south as San Jose. The cold
front will quickly move through this afternoon, shifting the winds
back to NW and allowing the clouds to start clearing. Winds look
less concerning than a few days ago, but we are still expecting
gusts up to 30 mph along the coast and in the mountains through
Thursday night.
&&
.LONG TERM...
(Thursday through Tuesday)
Issued at 1223 AM PST Wed Feb 19 2025
We`re still expecting a warm and dry period from Friday through
at least the middle of next week. A quick look at the forecast
shows a pretty consistent message during this time, with highs in
the mid 60s along the coast to mid 70s inland. When you hear that
in February, you might assume offshore winds, but that`s not the
entire story. Behind the cold front, the air mass will start to
dry out and low-level winds will turn northerly, or slightly
offshore. You`ll notice this by the clear skies Thursday
afternoon. But that pattern doesn`t last. A low amplitude 500 mb
ridge starts building on Thursday and the axis moves through on
Friday. This will bring SW flow, allowing a subtropical air mass
to nudge its way into the Bay Area. This will usher in higher PWAT
values (more water vapor, but no rain). The biggest noticeable
difference is that clouds will return over the weekend. Don`t get
me wrong, there will still be plenty of sunshine, but there will
be some clouds mixed in, which could make for some nice sunsets.
This SW flow looks like it will stick around through Tuesday
before a cut-off low starts to approach the coast and the forecast
gets tricky. These features are notoriously hard to pin- down. To
put the uncertainty in perspective, on Wednesday the ECMWF
ensemble shows with 80% confidence that 500 mb height will be
between 5720m and 5810m, a relatively narrow 90m spread. By
Thursday, the spread jumps from 5510m to 5820m, a 310m spread.
There`s a chance we get some rain late next week, but it`s really
hard to say with any certainty. Before we get to that, enjoy the
beautiful weather coming up!
&&
.AVIATION...
(12Z TAFS)
Issued at 335 AM PST Wed Feb 19 2025
VFR conditions prevail at the terminals early this morning,
otherwise a general increase in low to mid level clouds with light
rain over the northern half of the forecast area through morning.
Clearing tonight with patchy fog and low clouds /IFR-LIFR/ forming
late tonight and Thursday morning.
Vicinity of SFO...VFR. Light rain mid to late morning. Light wind
becoming west to northwest near 10 knots later today and tonight.
SFO Bridge Approach...Similar to SFO.
Monterey Bay Terminals...VFR-MVFR today, MVFR-IFR tonight and
Thursday morning. Light southeast winds becoming west 5 to 10
knots this afternoon, then light and variable winds tonight and
Thursday morning.
&&
.MARINE...
(Today through Monday)
Issued at 329 AM PST Wed Feb 19 2025
Breezy to gusty winds and rough seas mainly over the outer
coastal waters today into early Friday. Light rain mainly over
the northern waters and the San Francisco Bay this morning. Winds
and seas diminish over the weekend.
&&
.MTR WATCHES/WARNINGS/ADVISORIES...
CA...None.
PZ...Small Craft Advisory from 9 AM this morning to 3 AM PST Thursday
for Pt Arena to Pt Reyes 0-10 nm.
Small Craft Advisory from 3 PM this afternoon to 9 PM PST
Thursday for Pt Pinos to Pt Piedras Blancas 0-10 nm.
Small Craft Advisory until 3 AM PST Friday for Pt Arena to Pt
Reyes 10-60 NM.
Small Craft Advisory from 3 PM this afternoon to 3 AM PST Friday
for Pigeon Pt to Pt Pinos 10-60 NM.
&&
$$
SHORT TERM...Flynn
LONG TERM....Flynn
AVIATION...Canepa
MARINE...Canepa
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NWS MTR Office Area Forecast Discussion