Scientific Forecaster Discussion
Area forecast discussion
National Weather Service San Francisco Bay area
522 am PST Tuesday Feb 9 2016
Synopsis...temperatures will gradually trend cooler through the
the rest of the week. Outside of a slight chance for rain over
the far North Bay Friday and Friday night, dry weather is
forecast into at least the start of next week.
Discussion...as of 3:00 am PST Tuesday...moderate offshore flow
this morning at the surface has allowed US to start the day with
clear skies. Temperatures are running cooler than normal yesterday
partially due to calm winds. In addition, the ridge axis has
shifted a bit to our east allowing 500 mb heights to drop around
10 dm compared to yesterday plus 850 mb temperatures have lowered 1-2c.
Despite this, another round of much above normal temperatures can
be expected with wall-to-wall sunshine. Only real question is will
we break any records today? Unlike yesterday's slew of record
highs, today should be limited to just a few at best since highs
are forecast to be 3 to 6 degrees cooler in many spots. Will be
interesting to see if recent trends hold and the models
overestimate the cooling after a day of record heat. We have been
caught off-guard with a few recent events with the heat staying
one extra day. Record values are in the climate section below.
500 mb heights and 850 mb heights will slightly decrease through
the rest of the week as a longwave trough nears the coast. By Friday
the trough will advance to the coast with rain stretching from
norcal up to the British Columbia coastline. Models continue to show the
potential for light rain to move to the North Bay on Friday.
However, even that looks unlikely at best. Left probability of precipitation in the 15 to
20% range for that period. Highs will mostly be in the middle 60s to
the middle 70s.
A weak ridge of high pressure will build back toward our region
over the weekend and to the first part of next week. This will
force the storm track more to the north. Again highs will
generally be in the middle 60s to middle 70s.
Rain may return to our region by next Wednesday or Thursday as
moisture moves in from the southwest. European model (ecmwf)/GFS/Gem all indicate
rain in our County Warning Area next Wednesday/Thursday leading to a higher
confidence level in the day 8-9 time frame for the return of
moisture. Half of the GFS ensemble members also indicate rainfall
during that period.
Aviation...as of 5:20 am PST Tuesday...surface high will
continue over the Great Basin through Tuesday. Offshore flow has
weakened so winds will be light.
Vicinity of ksfo...VFR. Light winds becoming west 5-10 knots
Sfo bridge approach...similar to ksfo.
Monterey Bay area terminals...VFR.
Climate...record highs for Tuesday...
City name Feb 9th high and year
Kentfield 74 in 1945
San Rafael 70 in 2006
Napa 75 in 2006
San Francisco 74 in 2006
sfo Airport 73 in 2006
Oakland museum 74 in 2006
Oakland Airport 69 in 2006
Richmond 75 in 1988
Livermore 77 in 1917
San Jose 74 in 2006
Gilroy 78 in 2012
Santa Cruz 78 in 2006
Salinas 84 in 2006
Salinas Airport 81 in 2006
King City 86 in 2006
Marine...as of 08:43 PM PST Monday...a strong area of high
pressure over the Great Basin will maintain light southeast winds
across the coastal waters. Offshore winds will be gusty in the
vicinity of the coastal mountain gaps. Onshore flow will return
Tuesday as the high weakens.
Public forecast: Bell
aviation: west pi
marine: west pi
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