Technical NOAA Weather Discussion

FXUS66 KMTR 231557
AFDMTR

Area Forecast Discussion
National Weather Service San Francisco Bay Area
857 AM PDT Tue Oct 23 2018

.SYNOPSIS...Seasonably cool conditions will persist through midweek 
as an upper level trough pushes inland over the Pacific Northwest 
and northern California. A warming trend is then likely late in the 
week and into Saturday as high pressure builds over California. 
Temperatures trend downward early next week as another upper level 
system pushes inland north of the region. Dry weather conditions are 
likely to prevail through the forecast period. 

&&

.DISCUSSION...as of 08:58 AM PDT Tuesday...Interesting visible 
satellite this morning as low clouds blanket much of the interior 
valleys, but mid-high levels are streaming in from the north over 
the low clouds. The marine layer depth has deepened is now close 
to 2,000 feet per the Ft Ord profiler. The increasing mid-high 
level clouds are associated with a cold front and upper level 
trough nosing into far NorCal. These two features are helping to 
disrupt the marine layer and mixing it out in parts of the Bay 
Area. The cold front is also bringing a slight chance of rain to 
areas north of the Bay Area. KBHX radar is currently showing rain 
off the CA/OR. Sadly, the tail end of the frontal boundary fizzles
out and is not expected to bring any rain to the North Bay. 
Otherwise, seasonably cool temperatures today as many locations 
will be a few degrees below normal.

Not a fan of the clouds and cooler weather? Trends for later in
the week continue to show less clouds and possibly above normal
temperatures.

No update is planned. 

&&

.PREV DISCUSSION...as of 03:21 AM PDT Tuesday...

The marine layer is forecast to mix out some by Wednesday as high 
pressure begins to build over the region. This should result in less 
widespread cloud cover late tonight into Wednesday morning and a 
slight warming trend by Wednesday afternoon. The ridge of high 
pressure out over the eastern Pacific will build further into the 
region late in the week and into Saturday. With this, temperatures 
will warm back to above seasonal averages by Friday with coastal 
areas warming into the 70s while the interior will see widespread 
80s. Weak offshore flow at times will keep mild/warm temperatures 
region-wide into Saturday with less widespread coastal stratus as 
well. 

Temperatures level off on Sunday and begin to cool early next week 
as the ridge flattens ahead of another approaching mid/upper level 
trough.  The latest forecast models are in a good agreement with 
this cooling trend and also keep any precipitation well north of the 
region. Thus, dry conditions are likely to persist through the 
forecast period. 

&&

.AVIATION...as of 04:29 AM PDT Tuesday...For 12z tafs. Satellite
imagery shows stratus along the coast with patches of low clouds inland.
Can also see high clouds approaching from the west. A boundary
offshore stretching from southern Marin County through Monterey 
County appears to be breaking up the stratus along the coast. This
will make for a difficult cig forecast for Bay Area taf sites. 
MVFR cigs expected through the morning (~16Z-18Z) with periods of
clearing for sites near the boundary. Once the stratus clears, 
expect VFR conditions before potential patchy stratus development
tonight.

Vicinity of KSFO....VFR prevailing with periods of MVFR cigs
through the early morning. A boundary offshore appears to be
breaking apart the stratus before it reaches the airport. Still
possible the clouds will fill back in, but confidence is low. VFR
this afternoon and evening. Onshore winds this afternoon around 15
kt.

SFO Bridge Approach...Similar to KSFO.

Monterey Bay Terminals...MVFR/IFR cigs through late morning. VFR
this afternoon before stratus returns this evening.

&&

.MARINE...as of 03:21 AM PDT Tuesday...Generally light winds will
continue through much of the week as high pressure builds. Expect
locally gusty northwest winds along the Big Sur coast through 
Wednesday evening. Mixed moderate period northwest swell and a 
longer period southerly swell will continue through the forecast 
period.

&&

.MTR WATCHES/WARNINGS/ADVISORIES...
     .Tday...SCA...Pt Pinos to Pt Piedras Blancas 0-10 nm

&&

$$

PUBLIC FORECAST: MM/RG
AVIATION: AS
MARINE: AS

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Prepared by Boulder-Creek.com Weather at: Tue Oct 23 10:30:02 PDT 2018
From the National Weather Service