Area Forecast Discussion
Issued by NWS San Francisco Bay Area, CA
FXUS66 KMTR 311133
Area Forecast Discussion
National Weather Service San Francisco Bay Area
433 AM PDT WED AUG 31 2016
.SYNOPSIS...A broad upper level trough over the West Coast
will remain in place through late week and result in dry weather
conditions along with temperatures below seasonal averages.
.DISCUSSION...as of 3:15 AM PDT Wednesday...A weak shortwave and
associated vort max moved through the region earlier in the night
leading to a band of clouds streaming over the Bay Area. KMUX
radar even picked up a weak echo off the coast. As of now, the
band of clouds have shifted to the east and in its wake patchy
stratus is developing along the coast. Do expect stratus to
gradually fill in through sunrise, but coverage will not be
widespread. For today, do expect sunny skies once again, but
temperatures will be cooler than Tuesday. A broad upper trough
will deepen off the coast resulting in lower H5 and cooler 850mb
temps thus cooler max temps for the Bay Area. However, the warmest
locations away from the immediate coast will again eclipse 90
Very little change was made to previous forecast as the longwave
pattern changes very little through the early next week.
Synoptically speaking a broad upper level trough will remain
nearly stationary off the West Coast before shifting inland by
this weekend. For the Bay Area that means night and morning clouds
will be possible with patchy fog/drizzle. Any low clouds will peel
back to the coast each afternoon. Temperatures will be near normal
or slightly below. Highs in the 60s low 70s near the coast and 80s
and 90s inland.
A pattern shift is starting to show up on the medium range models
for the middle of next week. The slow moving trough finally
weakens and high pressure begins to re-build. The building high
pressure will lead to a more compressed marine layer with warmer
temperatures. The current forecast will reflect this with a
warming trend by next Tuesday into Wednesday. It is pretty much
fantasy land at this point, but the 240 hr model guidance from
both the GFS and ECMWF bring a tropical system to the west of
Baja. Beyond 10 days, models dissipate this system and keep most
of the moisture south of the region. A lot will likely change
between now and then, but something to watch over the next week or
.AVIATION...as of 4:30 AM PDT Wednesday...Low clouds were mixed
out by an upper trough passage has reformed off the Sonoma and San
Mateo coasts. The lack of a marine layer will only allow for
patchy low clouds into the SFO Bay Area this morning so clearing
will be early.
Vicinity of KSFO...Occasional MVFR/IFR cigs through 16Z.
West winds increasing to 20 kt with gusts to 26-28 kt after 20Z.
SFO Bridge Approach...Similar to KSFO.
Monterey Bay Terminals...Stratus formation is expected to remain
north of the MRY Bay Area. VFR.
.MARINE...as of 03:14 AM PDT Wednesday...An upper level trough
off the west coast combined with surface high pressure off the
california coast will keep moderate to strong northwest winds
through friday. gale force gusts can be expected over the southern
.Tday...SCA...Pt Arena to Pt Reyes 0-10 nm
SCA...Pigeon Pt to Pt Pinos 0-10 nm
SCA...Pt Pinos to Pt Piedras Blancas 0-10 nm
SCA...Pt Arena to Pigeon Pt 10-60 nm
SCA...Pigeon Pt to Pt Piedras Blancas 10-60 nm
SCA...SF Bay from 1 PM
PUBLIC FORECAST: MM
AVIATION: W Pi
MARINE: W Pi
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