Area Forecast Discussion
Issued by NWS San Francisco Bay Area, CA

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000
FXUS66 KMTR 280011
AFDMTR

Area Forecast Discussion
National Weather Service San Francisco Bay Area
511 PM PDT Thu Jul 27 2017

.SYNOPSIS...High pressure building over the region will result in a
slight warming trend through the weekend that will likely last
through much of next week. Inland areas can expect temperatures to
remain above seasonal averages while coastal areas remain cooler as
a result of influences from the Pacific Ocean.

&&

.DISCUSSION...as of 01:53 PM PDT Thursday...High pressure aloft
has compressed the marine layer to around 1000 feet in depth this
afternoon. With this, temperatures inland are a few to as much as
6 degrees warmer compared to 24 hours ago under sunny conditions.
Meanwhile, low clouds hug the entire coastline with temperatures
in the mid 50s to lower 60s along. Expecting low clouds to
penetrate back inland overnight, yet not as widespread as previous
nights with the marine layer to change very little. Thus, patchy
fog along with mist/drizzle will be possible along the coast
overnight and into early Friday morning as well.

As the mid/upper level ridge continues to build toward the West
Coast, inland temperatures will remain above seasonal averages
through the upcoming weekend and likely into much of next week.
While the models show 850 MB temperatures warming by a few degrees,
not expecting an extreme heat event to unfold in the coming days.
However, inland areas will see several days of afternoon
temperatures in the 90s to around 100-105 degrees in the warmest
inland locations. Meanwhile, the presence of a marine layer and weak
onshore flow will maintain cooler conditions (more typical of late
July and early August) near the coast with afternoon temperatures in
the 60s to lower 70s.

Late in the forecast period, the forecast models continue to show
the ridge building aloft with 500 MB Heights approaching 595-600
DAM. Given this, will need to closely monitor forecast temperatures
heading into next week for the potential for increased risk of heat
related illnesses. Regardless, look for above average temperatures
and dry weather conditions to persist through much of next week.

&&

.AVIATION...as of 4:40 PM PDT Thursday...For 00z tafs. A
strengthening northerly gradient has swept much of the stratus
from the coast north of the Golden Gate. Clearing is anticipated
to propagate southward with low clouds possibly returning to the
coast overnight. Cigs will like be delayed tonight over North Bay
and San Francisco Bay Area terminals as a result. A compressed
marine layer will likely result in earlier clearing times Friday
morning. Moderate and locally gusty westerly winds expected to
prevail across area terminals through this evening then diminish
overnight.

Vicinity of KSFO...VFR will prevail through late tonight with low
clouds expected to return after midnight and persist into the
early morning hours Friday. Clearing is anticipated around 16z
Friday morning. Moderate and locally gusty westerly winds expected to
prevail through this evening then diminish overnight.


SFO Bridge Approach...Similar to KSFO.

Monterey Bay Terminals...Low clouds pushing in over the Monterey
Bay will bring an early return of low clouds this evening. LIFR to
VLIFR cigs expected overnight with vsbys to 1SM possible. A
shallow marine layer will lead to an earlier burn off time around
16z Friday morning. Moderate onshore flow expected to prevail
through this evening then diminish overnight.


&&

.MARINE...as of 2:27 PM PDT Thursday...Moderate to locally strong
northwesterly winds will continue through the end of the week
across the northern waters. Gusty winds will produce steep wind
waves and fresh swell. Two tropical systems in the Pacific will
produce a long period southerly swell to arrive over the weekend.
Interaction between the northwesterly wind waves and southerly
swell will create choppy conditions across the waters.

&&

.MTR WATCHES/WARNINGS/ADVISORIES...
     .Tngt...SCA...Pt Arena to Pt Reyes 0-10 nm
             SCA...Pt Arena to Pigeon Pt 10-60 nm
             SCA...Pigeon Pt to Pt Piedras Blancas 10-60 nm from 9 PM
             SCA...SF Bay until 9 PM

&&

$$

PUBLIC FORECAST: RGass
AVIATION: CW
MARINE: AS


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