FXUS66 KMTR 261740
AFDMTR
Area Forecast Discussion
National Weather Service San Francisco CA
1040 AM PDT Sun Apr 26 2026
...New AVIATION...
.KEY MESSAGES...
Updated at 824 AM PDT Sun Apr 26 2026
- Light rain showers Sunday morning
- 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...
(18Z TAFS)
Issued at 1040 AM PDT Sun Apr 26 2026
VFR conditions will continue to prevail across the region through
the next 24 hours, with some areas of MVFR conditions expected in
light rain. The light rain threat will decrease through the day,
but increase once again during the late overnight hours. Breezy
westerly winds will also develop in the afternoon, diminishing
overnight.
Vicinity of SFO... VFR conditions will continue through the TAF
period. Winds will pick up from the west this afternoon before
diminishing overnight. A low confidence and probability for
showers will develop late tonight into early Monday morning.
SFO Bridge Approach... Similar to SFO.
Monterey Bay Terminals... VFR conditions will prevail through
today, with the shower activity decreasing and then westerly
winds increasing this afternoon. A low confidence and probability
for showers will develop late tonight into early Monday morning.
&&
.MARINE...
(Today through Friday)
Issued at 824 AM 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...None.
&&
$$
SHORT TERM...Flynn
LONG TERM....Flynn
AVIATION...Palmer
MARINE...Flynn
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Prepared by Boulder-Creek.com Weather at: Sun Apr 26 12:30:03 PDT 2026
From the National Weather Service
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