FXUS66 KMTR 190702
AFDMTR
Area Forecast Discussion
National Weather Service San Francisco CA
1202 AM PDT Wed Aug 19 2026
...New SHORT TERM, LONG TERM...
.KEY MESSAGES...
Updated at 1201 AM PDT Wed Aug 19 2026
- Compressed marine layer today, increases Thursday into the
weekend
- Near normal temperatures today followed by a gradual cooling
into the weekend
- Elevations above about 1000 feet will have warm temperatures
and RH values in the teens this morning into the afternoon
&&
.SHORT TERM...
Issued at 1201 AM PDT Wed Aug 19 2026
(Today and tonight)
A slightly more shallow marine layer tonight resulted in a somewhat
later onset of stratus pushing inland with less extensive coverage
than what was seen last night into early Tuesday morning. Another
mild overnight into early this morning should result in stratus
retreating back to the coast an hour or two sooner than we generally
see this time of year. Todays warmup will barely be noticeable for
areas below 1000ft away from the coast, with temperatures at higher
elevations across the East Bay Hills and Santa Lucias including Big
Sur and the Timber fire, running 10 degrees or more above normal.
MinRH values will be in the teens this afternoon across those
elevated locations, fortunately light winds continue to be a
mitigating factor. The weak fetch of offshore flow above the marine
layer over the southern Central Coast will shift late tonight with
improved RH recovery expected into early Thursday, along with an
increase in the marine layer depth.
&&
.LONG TERM...
Issued at 1201 AM PDT Wed Aug 19 2026
(Thursday through Tuesday)
Troughing persists through the extended forecast with gradually
cooling setting in on Thursday and continuing through the weekend
into next week. The persistent ridging to our east increases to near
600dm by the middle of next week, while continuing steer at least a
couple of tropical waves around its perimeter well to our south. The
potential tropical system still depicted beyond the official
forecast period still appears to offer little impact for our area
while we will continue to monitor any mid-level moisture advection.
&&
.AVIATION...
(06Z TAFS)
Issued at 942 PM PDT Tue Aug 18 2026
Currently a mixed bag of LIFR-VFR. Prevailing persistence forecast
tonight with little change in the pattern or marine layer. As such,
IFR ceilings are forecast to impact all terminals tonight. If the
marine layer compresses, lower chance of it reaching LVK or SJC. VFR
expected for most by tomorrow afternoon with low stratus sticking
close to the coast. HAF will likely remain sub-VFR through the TAF
period with a low chance for ceilings to hang on at MRY and SNS
through the day. Diurnal winds will prevail.
Vicinity of SFO...Currently IFR with northwesterly flow. High
confidence in VFR prevailing by tomorrow afternoon. Diurnal winds
will prevail. Lower (40%) confidence in the return of an IFR ceiling
tomorrow night.
SFO Bridge Approach...Similar to SFO.
Monterey Bay Terminals...Currently LIFR with southwesterly flow at
MRY and IFR with northwesterly flow at SNS. SNS is expected to
further deteriorate to LIFR with LIFR-IFR conditions expected
through tomorrow morning at both terminals. Low stratus will stick
to the coast during the afternoon with another early return tomorrow
evening. Diurnal winds will prevail.
&&
.MARINE...
(Tonight through next Monday)
Issued at 942 PM PDT Tue Aug 18 2026
Moderate to fresh northwesterly breezes will prevail through
Saturday. Locally strong northwesterly breezes across the northern
outer waters and along the coastal jet regions will bring
hazardous conditions for small craft into Thursday. Rough seas in
the outer waters will abate Thursday with moderate seas
prevailing by Friday.
&&
.MTR WATCHES/WARNINGS/ADVISORIES...
CA...None.
PZ...Small Craft Advisory from 3 PM this afternoon to 3 AM PDT
Thursday for Pt Arena to Pt Reyes 0-10 nm-Pt Pinos to Pt
Piedras Blancas 0-10 nm.
Small Craft Advisory until 3 AM PDT Thursday for Pt Arena to Pt
Reyes 10-60 NM.
&&
$$
SHORT TERM...JM
LONG TERM....JM
AVIATION...Sarment
MARINE...Sarment
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Prepared by Boulder-Creek.com Weather at: Wed Aug 19 02:30:04 PDT 2026
From the National Weather Service
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