Scientific Forecaster Discussion
Area forecast discussion
National Weather Service San Francisco Bay area
509 PM PDT Friday may 22 2015
Synopsis...a low pressure system will continue to exit the region
as high pressure builds. The building high pressure will result
drier conditions and a slight warming trend of through early next
Discussion...as of 2:50 PM PDT Friday...chance of precipitation
continues to diminish as a storm system exits and high pressure
builds. Drier weather expected with a slight warming trend through
early next week.
Latest surface observations and kmux radar imagery both indicate
earlier shower activity has diminished across the Bay area.
Therefore...removed any mention of showers this afternoon and early
this evening. However...the visible satellite does indicate
lingering moisture...but mainly in the form of cumulus
clouds...especially over the hills.
Expect the cumulus clouds to gradually dissipate after sunset as
daytime heating ends. High pressure currently over the epac will
slowly building through the weekend with a more Summer like
pattern. Night and morning low clouds will be common with a more
defined marine layer. Will keep the mention of drizzle early
Saturday due to the ample low level moisture. Interesting to note
as well..the NAM/GFS both show widespread very light precipitation early
Saturday. Looks very similar to what was observed on Tuesday with
many locations picking up a hundredth or two. Conf is not high
enough to put in widespread drizzle...better shot along the coast.
Despite the forecast warming trend...much of the Bay area will
still be a few degrees below normal. Highs will generally be 60s
along the coast and 60s/70s inland through.
Beyond the Holiday weekend...850mb temperatures and 500mb heights
continue to rise through much of next. As a result...the warming
trend will likely continue with near normal temperatures(80s well
inland). Night and morning clouds will remain with onshore flow.
Dry weather continues.
Aviation...as of 5:07 PM PDT Friday...there's a mix of clear skies
and areas of clouds around the region this afternoon. Generally
conditions are VFR/MVFR. Low level moisture will linger into
tonight with a few patches of drizzle becoming possible very late
at night. An upper level high over the epac will slowly edge in
from the west during the period. There's no sign of a marine
inversion yet per check of The Fort Ord and Bodega Bay profilers.
However subsidence associated with the high will result in a
gradual warming within the lower levels causing the marine layer
inversion to become re-established over the Holiday weekend. By
late Sunday night into Monday 850 mb level temperatures are predicted to
reach near 15c.
Vicinity of ksfo...MVFR ceilings with westerly winds gusty mostly holding
below 20 knots through the evening. Lighter winds expected
overnight...but a return to gusty west winds is very likely Sat
afternoon with gusts up over 20 knots.
Ksfo bridge approach...similar to ksfo.
Monterey Bay area terminals...VFR/MVFR gradually decreasing to IFR
very late. Patchy drizzle possible late. Clearing returns by late
Marine...as of 10:53 am PDT Friday...northwest winds will
increase later today as the pressure gradient tightens. Seas will
also build over the next 24 hours leading to generally
deteriorating conditions over the coastal waters into the weekend.
Unfavorable winds and seas persist through the weekend before
beginning to taper off early next week.
... Arena to pt Reyes 10-60 nm
Small Craft Advisory...pt Reyes to Pigeon pt 10-60 nm from 8 PM
Small Craft Advisory...pt Arena to pt Reyes 0-10 nm from 8 PM
Small Craft Advisory...pt Reyes to Pigeon pt 0-10 nm from 8 PM
Small Craft Advisory...sf Bay north of the Bay Bridge until 8 PM
Public forecast: mm
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