Scientific Forecaster Discussion
fxus66 kmtr 240635
Area forecast discussion
National Weather Service San Francisco Bay area
1035 PM PST Fri Feb 23 2018
Synopsis...mostly sunny skies will prevail around the Bay area
today. Another very cool night is forecast for Friday night. Dry
weather and slightly warmer temperatures are expected over the
weekend. Cooler, unsettled weather is expected to return by early
next week with another system bringing rain to the area later next
Discussion...as of 9:15 PM PST Friday...cold northerly flow
aloft continues over the area. Another cold night is expected
tonight due to clear skies, light winds, and low dew points. A
freeze warning is issued for the interior of Monterey and San
Benito counties from midnight through 9 am Saturday for
temperatures dropping into the 20s. Interior locations of the sfo
Bay area will also be cold enough for patchy frost.
Dry weather continues through Sunday as the next system drops into
the Great Basin. Rain will stay east of the district but there may
be some cumulus clouds during the day Saturday. The coldest air
will shift further to the east so overnight lows for Saturday
night will be about 3-5 degrees warmer.
Model runs from the past few days have been advertising an
increasing chance of rain late Sunday night and Monday as the
next system drops south along the West Coast picking up more
overwater trajectory. Rainfall amounts are expected to range from
one-tenth inch in the valleys to one-quarter inch in the hills.
Snow levels will initially be around 2500 feet then drop during
the day Monday so we could see snow on the highest peaks.
Medium range models show a wet pattern finally setting up off the
West Coast next week. Synoptically the polar low over the Hudson
Bay which has kept the ridge over US has been displaced
temporarily and this will allow troughs to set up over the
eastern Pacific. The next chance of rain will be Thursday.
Aviation...as of 10:34 PM PST Friday...VFR. Light onshore wind will
tend to shift to a light land breeze tonight as air temperatures over
land become colder, more dense compared to relatively milder, less
dense air temperatures over the ocean and bays. Lingering snow cover
enhancing radiative cooling in the mountains of the central coast may
add to east-southeast cold air drainage winds overnight into Saturday morning
in the Salinas valley.
Vicinity of ksfo...VFR. Light to calm wind tonight, becoming westerly
10-15 knots Saturday afternoon and evening.
Sfo bridge approach...similar to ksfo.
Monterey Bay terminals...VFR, winds becoming east-southeast tonight, possibly
gusty in the Salinas valley overnight into Saturday morning.
Here are the record low temperatures and the years they occurred for
Saturday, February 24.
Sf Bay area
Healdsburg 29 in 1944
Santa Rosa 28 in 1920
Calistoga 29 in 1982
Kentfield 29 in 1955
San Rafael 34 in 2017
Napa 30 in 1919
San Francisco 40 in 1891
sfo Airport 35 in 1955
Half Moon Bay 33 in 2017
Oakland Airport 36 in 2015
Richmond 36 in 1955
Livermore 29 in 1987
Moffett field 34 in 2017
San Jose 26 in 1897
Gilroy 28 in 1960
Monterey Bay area
Santa Cruz 29 in 1925
Salinas 31 in 1982
Salinas Airport 30 in 1953
Monterey 37 in 1955
King City 24 in 1982
Marine...as of 10:28 PM PST Friday...gusty north to northwest winds
will continue across the coastal waters through the weekend as high
pressure sits over the eastern Pacific. On Monday an upper level low
pressure system will move south bringing a cold front over the waters
resulting in increasing winds, fresh swell, and scattered showers.
... Warning...San Benito and interior Monterey counties
Small Craft Advisory...pt Arena to Pigeon pt 10-60 nm
Small Craft Advisory...Pigeon pt to pt Piedras Blancas 10-60 nm
Small Craft Advisory...pt Arena to pt Reyes 0-10 nm
Small Craft Advisory...pt Reyes to Pigeon pt 0-10 nm
Public forecast: west pi
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