Scientific Forecaster Discussion
Area forecast discussion
National Weather Service San Francisco Bay area
1107 am PDT Wednesday Mar 12 2014
Synopsis...breezy offshore winds will continue over the area
through this afternoon. Otherwise...high pressure will continue
to build over the area into at least the first part of next week.
This will result in above normal daytime high temperatures with no
rain in sight.
Discussion...as of 09:35 am PDT Wednesday...biggest concern in
the short term will be the winds. It appears the peak of the gusty
winds have already occurred and winds are gradually decreasing.
Short term hi-res models also showing decreasing winds over the
next few hours. All that being said...winds will be gusty this
morning into early this afternoon...but not as strong as last
No update planned.
For the rest of today...dry offshore flow prevails with clear skies
and mild temperatures across the Bay area. Will monitor the high temperatures for
this afternoon. Current forecast has much of the region in the
70s with a few spots near 80 today. Given the dry airmass...clear
skies and weakening winds overnight lows will be cool the next few
nights...especially protected valleys. Will likely lower some
inland valleys into the 30s.
High and dry into the weekend. As noted previously the biggest
item of the extended will be the warm temperatures forecast over the
weekend. Currently the pattern looks favorable for record to near
record heat for Saturday and Sunday. Models put the 850mb temperatures
2-4 Standard dev above normal. That translates to highs in the 70s and
80s...may be a 90 plus reading interior. Will fine tune for the
afternoon forecast package.
Previous discussion...as of 3:37 am PDT Wednesday...
Little change is expected in the forecast through the end of the
work week as an upper low hovers around Southern California into at least
Significant warming is expected through the region over the
weekend...as upper level high pressure builds over California. 850 mb
temperatures are forecast to rise between 3 and 5 degrees c
between this afternoon and Saturday afternoon. This will result in
daytime high temperatures warming into the 70s to low
80s...between 10 and 20 degrees above normal for the middle of
March. The same can be said about Sunday...as high pressure
remains firmly in place.
As we near toward the middle of next week...the GFS and European model (ecmwf)
begin to diverge with regards to model consistency. The GFS brings
an upper low toward the northern California coast as early as Tuesday
morning...with rain impacting the North Bay by Tuesday afternoon.
However...the European model (ecmwf) has a completely different solution...with an
upper ridge firmly in place...keeping the area dry. We have
decided to keep any mention of rain out of the forecast...as
confidence is very very low.
Aviation...as of 11:00 am PDT Wednesday...a ridge of high
pressure aloft combined with significant offshore flow at the
surface will maintain clear skies through the forecast period. A
low centered over the Sierra is providing strong offshore winds
to the San Francisco Bay area this morning. The low is expected to
push southeast which will weaken the surface pressure gradient and
ultimately decrease winds by this afternoon.
Vicinity of ksfo...VFR. Strong east winds are expected to begin to
decrease by this afternoon. Currently winds are 03028g35kt and are
expected to decrease to 02020g30kt around 2200z further decreasing
to 35010kt by 0100z.
Ksfo bridge approach...similar to ksfo.
Monterey Bay area terminals...VFR. Moderate east winds are
expected to persist through early afternoon. Winds are currently
10018g23kt at kmry. East winds are expected to decrease to around
5kt by 2000z. A gentle sea breeze will be possible beginning around
Marine...as of 11:05 am PDT Wednesday...forerunner waves have
entered the coastal waters today at a height of 5 feet and a
period of 20 seconds. These fast moving waves will result in a
heightened risk of sneaker waves and strong rip currents. The
period of the waves is expected to decrease to 16 to 18 seconds
later this afternoon with waves building to around 8 feet. Waves
will subside Thursday into Friday before another moderate to long
period west swell approaches the coast Saturday evening.
Strong east winds will also result in locally rough seas. This
will be especially true near coastal gaps. East winds are expected
to decrease later this afternoon.
... Arena to pt Reyes 0-10 nm until noon
Small Craft Advisory...pt Reyes to Pigeon pt 0-10 nm until noon
Small Craft Advisory...San Francisco Bay north of the Bay Bridge
from 11 am until 2 PM
Small Craft Advisory...San Francisco Bay south of the Bay Bridge until 2 PM
Public forecast: mm
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