969 
FXUS66 KMTR 160114
AFDMTR

Area Forecast Discussion
National Weather Service San Francisco Bay Area
614 PM PDT Sat Oct 15 2022

.SYNOPSIS...A robust marine layer continues to bring patchy fog, 
low clouds, and coastal drizzle each night and morning, while the 
interior remains dry. Some cooling this weekend brings interior 
temperatures close to or below normal, but temperatures warm up
again next week.

&&

.DISCUSSION...as of 12:15 PM PDT Saturday...

Today and Tonight: 

An amplified upper ridge will extend from the eastern subtropical 
Pacific through the Pacific Northwest States and southwest Canada. 
Meanwhile a closed upper low will move onshore over northern Baja. 
At the surface, weak upper troughing will exist just offshore from 
CA and this will induce a more southerly wind component across the 
area for today. Otherwise it's pretty much status quo from a 
forecast perspective with a robust marine layer remaining in place. 
Therefore look for clouds to gradually retreat towards the coast by 
this afternoon with plenty of interior sunshine. Despite the sun, 
inland areas should cool off a bit with the onshore flow with 
readings only in the 70s and 80s. Coastal and near-coastal areas 
will remain cool with highs mostly in the 60s. Clouds and some fog 
should return for many areas tonight with patchy drizzle along the 
coast. Lows will drop into the upper 40s (inland valleys) and 50s 
(elsewhere).

Sunday through Friday:

The previously mentioned upper low will devolve into an open-wave 
trough and eject towards the Southern Plains early in the period. 
Mid to upper ridging should then build across much of the western 
CONUS, with another trough/closed low near SoCal by late week. This 
will place our area between the influence of the large-scale ridge 
and the upper trough to our south, with increasing influence from 
the trough towards week's end. While no sensible impacts to our 
weather are anticipated, temperatures will be modulated by these 
features with a warming trend for inland locations by mid week under 
the influence of the upper ridge. Thereafter expect some cooling on 
Thursday into Friday as its influence wanes. Onshore flow should 
prevail through the period keeping coastal locations on the cool 
side.

Next Weekend:

A more progressive flow pattern should evolve aloft with upper 
troughing digging into the Pacific Northwest and Intermountain West. 
Of less confidence is whether the trough's influence could extend 
into NorCal. Based on model ensembles and clusters it appears the 
most likely forecast outcome is for our area to remain dry. However 
it's noted that a few ensemble members do bring very small rain 
chances into the Bay Area. And while this is worth watching will 
defer to the most likely forecast outcome at this time which 
suggests a continuation of dry conditions for our area. 

&&

.AVIATION...As of 6:14 PM Saturday... For the 00Z TAFs. The 
marine layer depth is 2,500 feet, coastal ceiling bases have 
increased with the marine layer depth to MVFR. Inland it's VFR. 
Onshore winds will usher stratus inland again tonight and Sunday 
morning. Patchy light drizzle tonight and Sunday morning. Surface 
to lower level cool air advection tonight and Sunday then becomes 
neutral Sunday afternoon and evening. Stratus /MVFR, possibly IFR/
returning Sunday night and Monday morning.

Vicinity of SFO...MVFR ceiling tonight and Sunday morning, west 
to southwest wind 5 to 10 knots. VFR forecast by 19z Sunday, 
continuing Sunday afternoon and early evening.

KSFO Bridge Approach...Similar to SFO. 

Monterey Bay...MVFR ceilings and west to northwest winds 5 to 10 
knots tonight and Sunday morning. Patchy light drizzle tonight and
Sunday morning. VFR from late Sunday morning to afternoon. Stratus
returning Sunday night and Monday morning.

&&

.MARINE...as of 05:09 PM PDT Saturday...Light to moderate
southwest winds are expected as mixed seas  prevail. Winds will be
locally breezy through the Golden Gate and  across the San
Francisco Bay in the afternoon and evening. Patchy fog is possible
at times in the Bays during the overnight and morning hours.

&&

.MTR WATCHES/WARNINGS/ADVISORIES...
     .Tngt...None.

$$

PUBLIC FORECAST: SPM
AVIATION: Canepa
MARINE: SPM

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