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

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FXUS66 KMTR 181156

Area Forecast Discussion
National Weather Service San Francisco Bay Area
456 AM PDT Fri Aug 18 2017

.SYNOPSIS...Look for one more day of minor warming today as a
ridge of high pressure continues to build into our region. Minor
cooling can be expected over the weekend into next week as an
upper level low and shortwave trough move into our region.
Overnight clouds can be expected especially along the coast.

&& of 3:00 AM PDT Friday...for the first time in
quite awhile, satellite shows that clouds are fairly limited
across our region with even Monterey Bay cloud-free at this hour.
Satellite does show clouds finally advancing toward the coast and
with a westerly gradient nearly 3 MB, we should see them at least
advance to the coast before sunrise. Synoptically a ridge of high
pressure will move across our region today which will lead to a
few degrees of warming. Temperatures will be in the 60s and 70s at
the coast with 80s and 90s inland.

The ridge will be replaced by an upper level low and a shortwave
trough that will dive down from the north. This will lead to
cooling over the weekend and next week with most spots dropping 5
to 10 degrees. Clouds will also be likely each night especially
near the coast. Big question will be how much the marine layer
will change with the low overhead. Could be a case of the marine
layer mixing out. Regardless, next week is shaping up to be very
quiet with temperatures near normal.


.AVIATION...As of 4:55 AM PDT Friday...High pressure continues to
compress the marine layer this morning with tops now down to 1500
ft. The marine layer struggled to push inland overnight with MVFR
or lower cigs only at KOAK KSJC and KSFO this morning with VFR
elsewhere. Satellite imagery shows the marine layer is deepest
and most continuous across the North Bay (ie OVC004 at KSTS)
while KMRY and KSNS remain clear. Latest imagery shows the marine
layer rapidly approaching coastal Monterey Bay as of 5AM and
expect to see IFR to MVFR cigs develop there around sunrise before
mixing out early this morning. Most forecast models indicate the
stratus deck will rebound slightly tonight with a thicker depth
and more widespread coverage than this morning.

Vicinity of KSFO...Predominately VFR with brief MVFR posbl around
sunrise as marine layer reaches morning maxima. Breezy onshore
winds in the afternoon. MVFR late tonight through sunrise

SFO Bridge Approach...Similar to KSFO.

Monterey Bay Terminals...VFR through early this morning with IFR
cigs from sunrise through mid morning. Marine deck increases

&& of 04:42 AM PDT Friday...Increasing northwest winds
through the weekend as high pressure builds into the region.
Locally steep wind waves will accompany the increasing winds.






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