Area Forecast Discussion
Issued by NWS San Francisco Bay Area, CA
FXUS66 KMTR 271208 CCA
Area Forecast Discussion
National Weather Service San Francisco Bay Area
502 AM PDT FRI MAY 27 2016
.SYNOPSIS...Inland warming trend will continue today and last into
Saturday as warm north winds move into the Bay Area tonight into
Saturday. A brief cooling trend Sunday as the marine layer pushes
well inland again, then significant warming Memorial Day and
Tuesday as warm high pressure builds. Another dry upper trough may
approach later next week with a cooling trend but no rain in the
forecast the next 7 days.
.DISCUSSION...as of 3:51 AM PDT Friday...Northerly gradient
approaching 6 mb at this hour is keeping Sonoma and Marin cloud
free while some low clouds have developed in Napa county with a
2.2 mb onshore wind producing 20 mph winds in the Delta early this
morning. Farther south low clouds cover the Monterey Bay region
but will pull back to the coast by mid-morning. The northerly
gradient well help to signal a warming trend for inland areas with
temperatures forecast to warm as much as 5-10 degrees from
Thursday, so expecting more numerous readings into the 80s this
afternoon for the inland valleys.
Tonight some north winds will drop down the Sac valley and move
into the north and east bay hills after midnight. Some fire
weather concerns here with a warm night and low humidity in the
hills. In general north winds in the 20-30 mph range above 1500
feet, strongest along the Napa county line. Tonight`s wind should
erode the marine clouds and only expecting some patches from
the Monterey peninsula southward for Saturday morning. This will
set the stage for continued warming on Saturday with highs well
into the 80s and and even some 90s for the interior valleys.
NAM model suggests we`ll see a marine push Saturday night into
Sunday morning as onshore winds return. So in general expect a
cooling trend, especially near the coast and bays on Sunday but
nothing too significant inland as 850 mb temps wont change much,
hovering around 17 Celsius.
ECMWF builds a 585 dm high to our west by Memorial Day with a
thermal trough along the coast. There could be some light offshore
flow under the pattern with 850 mb temps pushing 20-21 Celsius.
This all suggests some inland warmth well into the 90s and perhaps
even some near triple digit heat for the usual hottest inland
spots. Either way Monday and Tuesday looking warm to hot inland
with minimal coastal stratus.
Next upper trough arrives by about next Thursday with perhaps some
cooling southerly winds on Wednesday ahead of the trough and
behind the departing ridge. Either way the forecast remains dry
through next week.
.AVIATION...as of 5:00 AM PDT Friday...Strong northerly flow
suppressing marine stratus north of Pt Reyes this morning. Weak
onshore gradient between Pt Reyes and Half Moon Bay limiting
intrusion into the SF Bay Area. From Half Moon Bay southward, more
favorable onshore flow allowing marine air mass to intrude inland.
Southerly flow in Santa Clara valley advecting stratus northward
from the Monterey Bay region into the San Jose region. Generally
expect mostly VFR north of the San Mateo Bridge with MVFR possible
Onshore flow increases this afternoon with sustained winds 15-20
kt with gusts 20-30 kts. For tonight, marine deck will be similar to
this morning, with mostly VFR for SF Bay and a later arrival of
MVFR/IFR for Monterey Bay.
Vicinity of KSFO...Mostly VFR with brief MVFR posbl around
sunrise. Onshore winds 15-20kt gust 25 to 30kt after in the
afternoon. VFR tonight.
SFO Bridge Approach...Similar to KSFO.
Monterey Bay Terminals...MVFR cigs will linger into the late
morning to early afternoon. MVFR/IFR cigs return overnight after
.MARINE...as of 04:56 AM PDT Friday...Strong and gusty northwest
winds will continue today as high pressure persists over the
coastal waters. gale force winds will be possible for the northern
outer waters. over the memorial day weekend this high pressure
center will gradually weaken. northwest winds will continue early
next week but are not expected to be quite as gusty.
.Tday...SCA...Pigeon Pt to Pt Pinos 0-10 nm from 9 AM
GLW...Pt Arena to Pigeon Pt 10-60 nm
SCA...Pt Pinos to Pt Piedras Blancas 0-10 nm until 9 AM
SCA...Pt Pinos to Pt Piedras Blancas 0-10 nm from 3 PM
SCA...Pt Arena to Pt Reyes 0-10 nm
SCA...Pigeon Pt to Pt Piedras Blancas 10-60 nm
SCA...Pt Reyes to Pigeon Pt 0-10 nm
SCA...Rough Bar Advisory for SF Bar
PUBLIC FORECAST: RWW
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