Scientific Forecaster Discussion
Area forecast discussion
National Weather Service San Francisco Bay area
440 am PST sun Feb 7 2016
Synopsis...strong ridge of high pressure will build today into
Monday producing offshore winds and near record warmth across the
Bay area and central coast. The ridge will weaken by midweek but
high pressure stays in control with continued dry and mild weather
heading into next weekend.
Discussion...as of 3:30 am PST Sunday...looks like the coast is
clear with 8 mb offshore gradient from the Great Basin to sfo.
This is producing some strong winds in the hills with Montana Diablo
sustained at 39 miles per hour and gusting to 46 miles per hour. Most of the strong
winds will stay in the hills above 2500 feet and not expected to
mix down to the surface. Most prone place for some morning
offshore gusts will be the East Bay hills and San Mateo coastline
along Highway 1 around Pacifica. Skies are mostly clear with the
only fog being reported so far at Santa Rosa and Novato. Will
expect some localized fog patches through sunrise but nothing
widespread. Worth noting a significant fog bank offshore of Point
Arena but with easterly flow in place not concerned about that
making a Beeline towards the beaches today.
Chamber of Commerce weather in store from the North
Bay...peninsula and South Bay all the way down to the central
coast today with unseasonably strong high pressure building.
Latest European model (ecmwf) shows 586 dm high building over County Warning Area by late this
afternoon with 850 mb temperatures near 18 celsius. This synoptic set-up
along with favorable offshore flow should set the stage for some
near record warmth this afternoon and Monday as well.
The ridge axis shifts east by Tuesday but above normal
temperatures will stay in place along with continued dry weather.
Winds will turn westerly by Tuesday afternoon and will have to
monitor for the return of some stratus to the coast.
Otherwise middle and long range models now on board in showing high
pressure along the West Coast through the end of the week and into
next weekend resulting in a prolonged period of dry conditions and
near or above normal temperatures. Suddenly...things are looking
eerily dry for February and having a hard time pin-pointing when
the next chance of significant rain returns to the forecast.
Aviation...as of 4 am PST Sunday...generally VFR conditions
prevail with mainly clear skies. Patchy shallow fog affecting sts
and will be possible at other north and East Bay terminals until
about 16z today. Continued stagnant airmass below inversion could
bring hazy conditions today...especially sjc where particulate matter is
highest and MVFR visibilities possible here...otherwise mainly VFR
Low level jet increasing across the central Bay area this morning
and moderate low level wind shear possible in the 1500-2000 foot level mean sea level this
morning into the early afternoon. Low level wind shear should diminish later in
the afternoon as stronger winds aloft shift northward...although
may continue at sts through the afternoon hours. Concern that
some mixing could allow a few gusts to around 15 knots at Oak and sfo
late morning through middle afternoon hours. Confidence is low and
will monitor conditions/pilot weather reports for verification this morning.
For Monday...offshore flow expected to continue but 00z models are
not as strong as previous runs and expect easterlies below 10 kts.
Generally clear skies expected to continue.
Vicinity of ksfo...VFR expected to prevail. Light north-northeast flow at the
surface with moderate low level wind shear expected through early afternoon. Could see
a few gusts to around 15 knots late morning through the afternoon but
confidence is low whether winds will mix down.
Sfo bridge approach...similar to ksfo.
Monterey Bay area terminals...light winds. VFR.
Beaches...as of 10:45 PM PST Friday...swells off the coast have
decreased to 7 to 8 feet tonight but the swell periods continue at
14 to 15 seconds. Although the waves are lower the longer periods
make the waves capable of generating strong rip currents and large
shore break. Additionally...water temperature is only expected to
be in the middle 50s...so those venturing into the water will also be
subject to a heightened risk of hypothermia.
Record highs for Sunday and Monday...
City name Feb 7th high and year Feb 8th high and year
Kentfield 71 in 2006 71 in 2006
San Rafael 73 in 2011 72 in 1980
Napa 79 in 2011 73 in 1987
San Francisco 73 in 2006 74 in 2006
sfo Airport 73 in 1987 73 in 2006
Oakland museum 72 in 1987 77 in 2006
Oakland Airport 69 in 1963 70 in 2006
Richmond 74 in 2015 78 in 2011
Livermore 78 in 1917 78 in 1917
San Jose 76 in 1963 75 in 1987
Gilroy 76 in 2011 78 in 1963
Monterey 85 in 1954 81 in 1954
Santa Cruz 85 in 1954 78 in 1954
Salinas 82 in 1987 83 in 2006
Salinas Airport 84 in 1954 83 in 1954
King City 85 in 1954 84 in 2006
Marine...as of 03:58 am PST Sunday...a large area of high
pressure building over the western United States will make for
light to moderate winds across the coastal waters today. Offshore
winds are forecast to develop Monday and Tuesday as the surface
thermal trough drifts off the coast. Meanwhile swell will continue
to slowly decay today but be replaced by another building swell
train on Monday. Overall the North Pacific will remain active
through the next week generating swell for late in the week.
Public forecast: r_walbrun
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