Technical NOAA Weather Discussion

FXUS66 KMTR 262335
AFDMTR

Area Forecast Discussion
National Weather Service San Francisco CA
435 PM PDT Sun Apr 26 2026

...New AVIATION, MARINE...

.KEY MESSAGES...
Updated at 428 PM PDT Sun Apr 26 2026

 - Warming and drying trend this week

 - Disturbed weather returns next week

&&

.SHORT TERM...
Issued at 824 AM PDT Sun Apr 26 2026
(This afternoon through Monday)

Light rain showers continue this morning, with most of the activity 
over Santa Cruz and Monterey Counties. We've seen a few hundredths 
since midnight, with another few hundredths expected through 
noon. All of this rain is falling from low-level clouds that are 
no more than 6,000 feet above the surface. While weaker than 
yesterday, there is still a temperature inversion preventing 
upward vertical motion and cloud formation above this layer. This 
severely limits the rainfall potential and practically eliminates
thunderstorm chances in the short term. But the radar continues 
to pick up on some light rain showers, and there are no doubt 
other showers that are hiding underneath the radar beam.

The pattern is currently dominated by a positively tilted trough 
at 500 mb. As the upper level trough axis and associated surface 
trough move through around midday today, drier air will begin to 
filter in. This will diminish the rain chances and start to mix 
out the clouds. There will much more sun breaks in the afternoon 
for most of the cwa. With cold air entrenched, this sunshine won't
be enough to warm us out of the low to mid 60s this afternoon.

&&

.LONG TERM...
Issued at 824 AM PDT Sun Apr 26 2026
(Monday night through next Saturday)

The troughing pattern sticks around Monday as a couple short wave 
troughs move through the long wave pattern. These will eventually 
become cut-off from the jet stream, leaving behind a Channel 
Island Low Tuesday through Thursday as the ridge builds to the 
North. This combination will kick off a warming and drying trend, 
and the cut-off low will likely support some nocturnal offshore 
winds through the week. The actual surface gradient doesn't look 
too impressive, however (SFO-WMC drops to -5 mb) and the offshore 
wind speeds should be moderate. As the ridge builds, the 850 mb 
temperature will climb from the 10th to 90th percentile for April 
(1.6C at 12Z this morning to roughly 15C by Thursday). Surface 
temperatures will respond by increasing a few degrees each day, 
until we see upper 70s across the interior from Wed-Fri. A marine 
layer will also redevelop under the ridge, keeping coastal areas 
significantly cooler and more humid than the interior this week.

While there was some uncertainty yesterday, it now seems likely that 
another trough will move in next Sunday or Monday. This will bring 
another round of disturbed weather with some light rain possible.
The calendar says the rainy season is nearly over, but after the 
wettest April since 2018, the weather models suggest we aren't
quite done yet.

&&

.AVIATION...
(00Z TAFS)
Issued at 435 PM PDT Sun Apr 26 2026

It's mainly VFR across the forecast area this afternoon. VFR-MVFR
conditions are forecast tonight and Monday. Onshore winds decreasing
tonight and Monday morning then strengthening Monday afternoon and
early evening.

Vicinity of SFO...VFR. West wind 14 to 20 knots decreasing to less
than 10 knots tonight and Monday morning. West wind 10 to 15 knots
Monday afternoon and evening.

SFO Bridge Approach...Similar to SFO.

Monterey Bay Terminals...VFR. VCSH late tonight and Monday morning.
Onshore winds 10 to 15 knots decreasing and becoming light and 
variable tonight and Monday morning. Onshore winds 10 to 15 knots 
Monday afternoon and early evening. 

&&

.MARINE...
(Tonight through next Friday)
Issued at 428 PM PDT Sun Apr 26 2026

Moderate west to northwest breezes persist through the middle of
the week before increasing to a fresh to strong northwest breeze
afternoon. These stronger winds will build rough seas of 8-12
feet in exposed waters Wednesday through Friday.

&&

.MTR WATCHES/WARNINGS/ADVISORIES...
CA...None.
PZ...Small Craft Advisory from 9 PM Monday to 3 AM PDT Tuesday for Pt 
     Arena to Pt Reyes 10-60 NM.

&&

$$

SHORT TERM...Flynn
LONG TERM....Flynn
AVIATION...Canepa
MARINE...Flynn

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Prepared by Boulder-Creek.com Weather at: Sun Apr 26 20:30:03 PDT 2026
From the National Weather Service