National Weather Service National Headquarters

• Home
• Site Map
• News
• Organization
• Search for: NWS All NOAA 

000
FXUS66 KMTR 231144
AFDMTR

Area Forecast Discussion
National Weather Service San Francisco Bay Area
444 AM PDT Tue Jul 23 2019

.SYNOPSIS...Inland temperatures will warm to above seasonal
averages through the remainder of the week and into the upcoming
weekend as high pressure dominates the weather pattern. The
influence of a shallow marine layer and persistent onshore flow
will keep conditions seasonably mild near the coast.

&&

.DISCUSSION...as of 02:51 AM PDT Tuesday...A shallow marine layer
at about 800 feet in depth has resulted in low clouds over much
of the Monterey Bay southward into the Salinas Valley. In
addition, patchy stratus can be see on GOES-W satellite imagery
along the San Francisco Peninsula as well as offshore. These
clouds may fill in a bit through sunrise, yet will be less
widespread compared to previous mornings. In addition, mid- level
moisture rotating around the building mid/upper level high
pressure over the Desert Southwest appears to have produced an
isolated high-based shower over far eastern portion of San Benito
County, now moving across western Fresno and Merced Counties.
Overall, expecting only a few sprinkles from this if any
precipitation is reaching the surface at all. Regardless, look for
mid/high level clouds to continue to move over the interior
portion of the Central Coast through the morning.

The aforementioned mid/upper level high pressure to our east will
continue to be the dominate weather feature across the southwestern
portion of the country through the remainder of the week. However,
the ridge is forecast to be suppressed slightly over northern
California today as an upper level trough just off of the British
Columbia coast pushes into the Pacific Northwest. This will stall
the warming trend a bit today with some inland locations potentially
cooling by a few degrees. Regardless, look for widespread 80s and
90s across the interior while upper 60s to middle 70s will be common
near the coast.

The warming trend will continue on Wednesday as the ridge
strengthens over the region. Daytime temperatures will likely warm
to around 10 degrees above seasonal averages over the interior.
Meanwhile, a shallow marine layer and continued onshore flow will
maintain cooler conditions near the coast with periods of
night/morning low clouds and patchy fog. Temperatures cool slightly
across inland areas Thursday and Friday, but will remain very warm.
Look for an increase in mid/upper level clouds late in the week as
monsoon moisture advects across the region around the ridge over the
Desert Southwest. With this, will need to monitor for any potential
of high-based showers and/or thunderstorms, mainly for Thursday
night.

Longer range guidance from both the ECMWF and GFS, as well as the
ensembles, indicate the ridge of high pressure will shift westward
and over southern California during the upcoming weekend. This will
likely result in additional warming with daytime temperatures
rebounding to above seasonal averages for much of the region. Thus,
will need to monitor for increased heat risks across the interior by
the weekend.

&&

.AVIATION...as of 4:44 AM PDT Tuesday...The marine layer remains
compressed under large scale subsidence resulting in VLIFR-IFR on
the coastline and into the Salinas Valley. VFR is still reported
at KMRY, but tempo IFR remains in the forecast for a few hours
until 16z this morning. Inland it`s VFR. Similar to yesterday the
marine layer should scatter back to the coastline then return
locally inland tonight and Wednesday morning.

Vicinity of KSFO...Conditions remain favorable for VFR to prevail
through the forecast period. Onshore wind increases by early
afternoon with gusts up to 20 knots possibly a few higher gusts
up to 25 knots.

SFO Bridge Approach...Similar to KSFO.

Monterey Bay Terminals...VLIFR-IFR then clearing is anticipated
around 17z this morning. VFR late morning into the afternoon then
VLIFR-IFR returning this evening.

&&

.MARINE...as of 2:51 AM PDT Tuesday...Breezy northwest winds will
persist today across the coastal waters. Winds will increase
becoming gusty tonight and Wednesday as high pressure builds into
the Pacific Northwest and northern California. Light southerly
swell coupled with short period wind waves will continue through
the week.

&&

.MTR WATCHES/WARNINGS/ADVISORIES...
     .Tday...SCA...Pigeon Pt to Pt Pinos 0-10 nm from 9 AM
             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
             SCA...Pt Pinos to Pt Piedras Blancas 0-10 nm
             SCA...Pt Reyes to Pigeon Pt 0-10 nm
             SCA...Mry Bay from 9 AM
             SCA...SF Bay from 3 PM

&&

$$

PUBLIC FORECAST: RGass
AVIATION/MARINE: Canepa

Visit us at www.weather.gov/sanfrancisco

Follow us on Facebook, Twitter, and YouTube at:
www.facebook.com/nwsbayarea
www.twitter.com/nwsbayarea
www.youtube.com/nwsbayarea