156 
FXUS66 KMTR 161133
AFDMTR

Area Forecast Discussion
National Weather Service San Francisco Bay Area
433 AM PDT Sun Oct 16 2022

.SYNOPSIS...A deep marine layer brings widespread cool
temperatures and low clouds Sunday. Warming trend begins Monday
and continues through midweek, before moderating at the end of the
week. Dry conditions continue through the week. 

&&

.DISCUSSION...as of 03:49 AM PDT Sunday...Night satellite imagery
shows widespread stratus once again, reaching into higher terrain
as well. Coastal profilers earlier this afternoon were reporting 
a marine layer depth around 2500 feet, before they stopped 
reporting. A look at the 00Z KOAK sounding from this evening shows
an inversion layer around 2700 feet. Cloud bases are being 
reported mostly around 2000 feet from surface stations. As a 
result of the higher bases, not seeing reports of fog or low 
visibilities. There has also been some warming at the surface, 
with most sites reporting temperatures in the upper 50s to low 
60s, around 4 to 7 degrees warmer than 24 hours ago. The exception
to this trend is the higher elevations in the hills, which are 
now several degrees cooler from the marine layer influence.

Stratus will take a while to erode today, given the deep marine 
layer, and coastal areas may once again have a mostly cloudy day. 
While interior areas see clearing by afternoon, temperatures will be 
cool and below normal area-wide. The warmest interior locales may 
only reach the mid 70s, while along the coast 60s will be prevalent. 
Thus, similar temperatures to yesterday, or slightly cooler. The 
cooling trend is a result of the upper level ridge that was 
situated over the eastern Pacific being pushed inland by an upstream 
trough, now several hundred miles offshore. The leading edge of this 
trough is observed on water vapor imagery. As it approaches the 
coast this afternoon, we can expect increasing high level clouds. 
These clouds, along with an invading cooler airmass, will help 
moderate surface temperatures.

The incoming trough and cool air advection may help to partly 
disrupt the marine layer tonight, though ensembles and hi-res models 
still show stratus re-forming. Thus, expect another night of low 
clouds with some patchy fog possible.

The incoming trough is projected to stall before reaching the West 
Coast, and spawn a cut-off low, which will meander off the SoCal 
coast through much of the week. Meanwhile, the aforementioned upper 
level ridge will expand over the Intermountain West, leading to a 
warming trend over much of CA through midweek. Temperatures will 
likely be 5 to 15 degrees above normal by Wednesday, before 
moderating by the end of the week. Thus, expect 70s at the coast and 
80s inland, perhaps low 90s in the warmest spots Wednesday.

Global models are still projecting a trough moving down the coast 
next weekend along with some moisture. But it seems unlikely that 
it will dig deep enough to reach the Bay Area, as most ensemble 
members keep the area dry. The Euro still seems to be the most 
aggressive model for precip, but even that is not too promising.

&&

.AVIATION...As of 10:31 PM Saturday...Widespread MVFR. Clouds are
expected to last well into the late Sunday morning. Low 
confidence in exact clearing times, but terminals may see clouds 
remain past 19Z, before VFR conditions develop. Winds are light 
and breezy which will remain through Sunday afternoon. The main 
update to this TAF package in comparison to the 06Z package is 
adding cigs late on Sunday night/Monday morning for MVFR 
conditions, given that more recent hi-res models added them back 
in.

Vicinity of SFO...MVFR. Varying model runs depict clouds Clearing 
to VFR as early as 19Z and others lasting as long as 22Z The 
strongest confidence forecast was in 20Z, which was placed in the 
TAF, but there is low confidence. In fact, the 20Z FEW025 was 
updated to SCT025 to highlight that uncertainty. VFR briefly Sunday 
afternoon. High clouds move in ahead of the next upper level system. 
VFR for most of Sunday night before MVFR cigs move in.

KSFO Bridge Approach...cigs over 2000 feet prevail through the 
night, not clearing until after 20Z, otherwise similar to SFO.

Monterey Bay...MVFR. Inland clearing starts around 18Z, with coastal 
areas staying clouds through 20Z. Clear and onshore breezy Sunday 
afternoon. MVFR cigs return after 03Z.

&&

.MARINE...as of 02:32 AM PDT Sunday...Light southwesterly winds
will become occasionally breezy Sunday afternoon. Mixed
northwesterly and southerly seas prevail. Winds  become
northwesterly next week, with the chance for stronger gusts along
the immediate coast.

&&

.MTR WATCHES/WARNINGS/ADVISORIES...
     .Tday...None.

$$

PUBLIC FORECAST: Lorber
AVIATION: DK
MARINE: DK

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