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

Home | Current Version | Previous Version | Text Only | Print | Product List | Glossary On
Versions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50
FXUS66 KMTR 181729

Area Forecast Discussion
National Weather Service San Francisco Bay Area
1029 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 08:02 AM PDT Friday...Only a few minor
adjustments made to this morning`s forecast as the low clouds
have managed to progress inland. Livermore, for example, recently
transitioned from clear skies to overcast conditions. Additionally,
low clouds managed to make it to San Francisco International
Airport with BKN/OVC conditions reported over the past hour. Do
expect clearing by mid/late morning for most locations today with
mostly clear skies for the afternoon. With a building ridge just
offshore, this morning`s 12Z Oakland sounding shows increasing 500
mb heights compared to 24 hours ago. At 850 mb, temps have warmed
by about 3 deg C. As a result, this will translate to several
degrees of warming at the surface this afternoon for most interior
areas. High temperatures will be generally in the 60s and 70s
along the coast and 80s and 90s for inland communities.

For additional forecast details, please refer to the previous
discussion section.


.PREV 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 10:30 AM PDT Friday...For 18z tafs. Stratus has
begun to burn off/retreat back to the coast across most taf sites.
Expecting VFR conditions through the afternoon before the return
of low cigs late tonight/early tomorrow morning. Some uncertainty
in the extend of stratus coverage for tomorrow morning.

Vicinity of KSFO...VFR currently with westerly winds increasing
this afternoon to around 15 kt. Expecting stratus to return late
tonight with slightly lower cigs than what we saw today.

SFO Bridge Approach...Similar to KSFO.

Monterey Bay Terminals...Cigs have retreated for KSNS bringing VFR
conditions. Expecting return of low cigs this evening. Stratus
still hovering around the edge of KMRY. Possible the stratus will
clear out this afternoon although confidence is low, may bounce
between VFR and MVFR before the deck returns tonight.

&& of 08:27 AM PDT Friday...Expect increasing
northwesterly winds to continue through the weekend as high
pressure builds over the eastern Pacific. Locally steep wind waves
will also accompany the increasing winds.






Visit us at

Follow us on Facebook, twitter, and youtube at: is the U.S. government's official web portal to all federal, state and local government web resources and services.