FXUS66 KMTR 190809
AFDMTR

Area Forecast Discussion
National Weather Service San Francisco CA
109 AM PDT Sun Jul 19 2026

...New SHORT TERM, LONG TERM...

.KEY MESSAGES...
Updated at 120 PM PDT Sat Jul 18 2026

 - Near or slightly below normal temperatures and higher humidity
   through the first half of the upcoming week.

 - The marine layer and mid to upper level cloud cover will
   continue to help keep temperatures cooler under building high
   pressure.

&&

.SHORT TERM...
Issued at 109 AM PDT Sun Jul 19 2026
(Today and tonight)

Onshore winds are ushering stratus inland. Onshore winds continue
due to a 2.9 mb SFO-SAC pressure gradient. A few patches of mist/fog
may additionally develop through daybreak. High clouds are extending
far north-northeast of tropical storm Elida located 1000 miles south-
southwest of Point Conception. Elida is forecast to essentially move
northward, get drawn into the westerlies and weaken to a post tropical
remnant low by 5 am PDT Tuesday, July 21st per latest from the NHC.

Strong (warm core) high pressure remains located over the interior
west, land locked as typically this time of year due to high sun 
angle surface heating. The high is surrounded by a mix of cold 
core (mid-latitude) and warm core (tropical) low pressure systems 
of varying strength. Upward vertical motion/expansion (lows) has 
to return downward/compression (highs) somewhere via continuity. 
Upper level troughing generally remains located over the eastern 
Pacific. Daytime highs today will be about the same it was on 
Saturday, varying from the mid to upper 60s along the coast to the
70s bayside to the 80s and 90s well inland. Tonight lows will 
cool to the 50s except in the 60s in the hills and mountains.

&&

.LONG TERM...
Issued at 109 AM PDT Sun Jul 19 2026
(Monday through Saturday)

As mentioned, current tropical storm Elida is forecast to move
generally northward, get drawn into the westerlies and weaken to 
a post tropical/remnant low by early Tuesday. Tropical cyclones 
depend on a minimum of 80F or warmer sea surface temperatures. With
less heat flowing into northward moving tropical cyclones the 
thermodynamic system diminishes. Not to mention northward moving 
tropical cyclones eventually encounter the westerlies, wind shear,
drier air (destructive to convection), but may temporarily form in
to a hybrid system or become an extra-tropical cold core system 
tapping energy transformation from warm/cold air temperature 
advection. As of current time, the GFS and ECMWF for example 
forecast the remnant low to pass ~ 500 miles to our west early-mid
week, rain is forecast to fall from the low, but of course it'll 
be too far to our west to benefit from it. Good news so far, based
on the forecast low trajectory and most model forecasts, there is
minimal convective potential over our forecast area early-mid week.
Of course as always stay tuned to the latest updates.

&&

.AVIATION...
(06Z TAFS)
Issued at 952 PM PDT Sat Jul 18 2026

Stratus is pushing in to the Bay Area and Central Coast with most 
sites reporting IFR ceilings. Confidence is increasing that LIFR 
CIGs will develop, at least, along the coast with some potential 
across interior sites. Confidence remains low that fog will develop 
but cannot rule out patchy fog within the North Bay valleys and 
along the coast. Conditions improve by mid to late morning with 
stratus returning early tomorrow evening. Diurnally breezy onshore 
winds continue.

Vicinity of SFO...Stratus is working its way into SFO with the site 
currently bouncing between IFR and VFR conditions. IFR conditions 
are expected to prevail for much of tonight with clearing by late 
morning. Stratus looks to return tomorrow evening but confidence is 
low to moderate on the current timing of stratus return. Diurnally 
breezy onshore winds continue.

SFO Bridge Approach...Similar to last night, stratus may take longer 
to fill in over the SF Bay/bridge approach than over the SFO 
terminal. Otherwise, similar to SFO.

Monterey Bay Terminals...IFR-LIFR overnight with some potential for 
fog during the early morning hours. CIGs have continued to lower at 
MRY which is increasing confidence that LIFR CIGs will be observed 
overnight. Model guidance supports widespread LIFR CIGs and the 
potential for reductions in visibility tonight. LIFR CIGs may make 
the chances for reduced visibility tonight higher than it was the 
previous night. Moderate confidence that stratus will clear by the 
late morning before an early evening return.&&

.MARINE...
(Tonight through next Friday)
Issued at 952 PM PDT Sat Jul 18 2026

Winds continue to decrease overnight with a moderate northwesterly
breeze to prevail into next week. Moderate seas prevail through
the forecast. Moderate southerly swell will increase from
tropical cyclone activity across the eastern Pacific through next
week.

&&

.MARINE...
(Tonight through next Friday)
Issued at 952 PM PDT Sat Jul 18 2026

Winds continue to decrease overnight with a moderate northwesterly
breeze to prevail into next week. Moderate seas prevail through
the forecast. Moderate southerly swell will increase from
tropical cyclone activity across the eastern Pacific through next
week.

&&

.FIRE WEATHER...
Issued at 120 PM PDT Sat Jul 18 2026

Cooler than normal temperatures with assistance from onshore flow 
and relatively normal diurnal intrusion of the marine layer will 
continue through the weekend into next week. RH recovery will be 
excellent for coastal areas and valleys, and moderate to good 
farther inland. However weak offshore flow/thermal belting will 
result in poor RH for higher elevations, especially above 1500-
2000ft across the East Bay Hills and Santa Lucias.

&&

.MTR WATCHES/WARNINGS/ADVISORIES...
CA...None.
PZ...Small Craft Advisory until 3 AM PDT Sunday for Pt Arena to Pt 
     Reyes 10-60 NM.

&&

$$

SHORT TERM...Canepa
LONG TERM....Canepa
AVIATION...Kennedy
MARINE...Kennedy

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Prepared by Boulder-Creek.com Weather at: Sun Jul 19 04:30:04 PDT 2026