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
000
FXUS66 KMTR 211135
AFDMTR

Area Forecast Discussion
National Weather Service San Francisco Bay Area
335 AM PST Wed Feb 21 2018

.SYNOPSIS...A couple of weak weather system will impact the region
today though Thursday night with chances for a few showers and
lowering snow levels. Blustery conditions are likely on Thursday
with colder temperatures Friday morning. Dry weather and slightly
warmer daytime conditions are likely for the weekend with cooler,
unsettled conditions potentially returning early next week.

&&

.DISCUSSION...as of 03:30 AM PST Wednesday...Increasing cloud
cover ahead of an approaching weather system has kept temperatures
up slightly compared to 24 hours ago. This will limit widespread
freezing conditions this morning, yet many of the region`s
typically cooler spots have fallen into the lower 30s so far this
morning. The aforementioned weather system will drop down the
coast today with a few showers potentially impacting the North Bay
and points southward down the coastline. However, widespread
precipitation is unlikely from this passing system.

A second short-wave disturbance is then forecast to move over the
region on Thursday with additional chances for showers over portions
of the region. Both systems will advect reinforcing shots of colder
air across the region with daytime temperatures generally in the 50s
and overnight lows in the 30s. Snow levels will fall a bit lower to
around 1,500 feet with the Thursday system with light snow
accumulation possible in the higher peaks across the region.
However, as with the first system, precipitation will be spotty
Thursday into Thursday night. Blustery conditions will also develop
with this system as northeasterly winds increase region-wide,
strongest along the coast and in the hills with gusts upwards of 40
MPH. As winds subside and sky conditions clear late Thursday night
into Friday morning, temperatures will fall into the 30s for most
locations with the potential for another widespread freeze across
inland areas. Will need to continue to monitor in the coming days.

Drier conditions are then anticipated from Friday into Saturday as a
weak short-wave ridge builds over the region. Look for daytime
temperatures to rebound to near seasonal averages for the upcoming
weekend with continued cool overnight conditions under a mainly
clear sky.

Medium to longer range models indicate the weather pattern over much
of the West Coast will be dominated by a broad mid/upper level
trough with systems passing over the region early next week.
However, confidence remains low at this time with respect to
precipitation chances over the region. Regardless, cool and
unsettled weather conditions are likely to persist into early next
week, yet widespread beneficial rainfall is not expected.

&&

.AVIATION...as of 3:30 AM PST Wednesday for 12Z TAFs. Infrared
satellite shows increasing mid-level clouds across northern
California that will extend southward through the rest of the
morning. The challenge will be the how low the cloud bases will
actually go. Currently think most terminals will be primarily VFR
this morning with ceilings dropping as low as 3-5k ft. Another
system will drop south at the tail end of the TAF period, and will
bring another shot of increasing cloud cover as well as breezy
west to northwest winds.

Vicinity of KSFO...SCT/BKN cloud cover this morning, with cloud
bases generally around around 4-5k ft. Generally light easterly
winds in the morning will become west around 10 kt in the
afternoon, with even stronger winds by the end of the TAF period.

SFO Bridge Approach...Similar to KSFO.

Monterey Bay Terminals...VFR with increasing mid and high clouds
through the day.

&&

.CLIMATE...

Here are record low temperatures and the years they occurred for
Wednesday.

Location          Wednesday

SF Bay Area

Healdsburg        28 in 1929
Santa Rosa        26 in 1913
Calistoga         25 in 2006
Kentfield         29 in 1953
San Rafael        33 in 1955
Napa              29 in 1955
San Francisco     36 in 1890
SFO Airport       34 in 1955
Half Moon Bay     31 in 2006
Oakland Airport   33 in 1955
Richmond          35 in 1981
Livermore         27 in 1955
Moffett Field     32 in 1955
San Jose          25 in 1897
Gilroy            31 in 1976

Monterey Bay Area

Santa Cruz        30 in 1955
Salinas           31 in 1970
Salinas Airport   30 in 1953
Monterey          36 in 1952
King City         23 in 1953

&&

.MARINE...as of 03:30 AM PST Wednesday...Generally light winds
this morning are forecast to gradually increase this afternoon and
overnight as the next system impacts region. These gusty
northerly winds will produce hazardous sea conditions with steep
wind waves and fresh swell.

&&

.MTR WATCHES/WARNINGS/ADVISORIES...
     .Tday...SCA...Pt Arena to Pigeon Pt 10-60 nm from 2 PM

&&

$$

PUBLIC FORECAST: RGASS
AVIATION: Rowe
MARINE: Rowe

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


USA.gov is the U.S. government's official web portal to all federal, state and local government web resources and services.