FXUS66 KMTR 251013

Area Forecast Discussion
National Weather Service San Francisco Bay Area
313 AM PDT Tue Apr 25 2017

.SYNOPSIS...Dry weather with comfortable temperatures can be
expected today. Another chance of rain, mainly over the North
Bay, is slated for Wednesday, with dry and seasonably cool weather
expected elsewhere. Dry weather along with a warming trend is
forecast across the region from Thursday through the weekend as
high pressure builds in. Breezy conditions are likely from
Thursday and Friday, especially in the hills.


.DISCUSSION...as of 3:10 AM PDT Tuesday...Showers moved completely
out of our CWA yesterday evening with mostly clear skies now for
most the area from SF southward. Satellite does show higher clouds
over the north bay. Temperatures will be a degree or two warmer
compared to yesterday -- mostly 60s to lower 70s.

Synoptically a system will move into the Pac NW on Wednesday with
the far southern edge of moisture forecast to possibly go across
the North Bay. Guidance has been trending slightly drier compared
to yesterday with a chunk of the models keeping virtually our
entire area now dry. Amounts will be minor -- less than a tenth
for most of the North Bay with little to no accumulations
forecast for SF Bay southward. In fact, totals may be close to
what we saw from the system on Monday.

A substantial change in the pattern will begin to take shape on
Thursday as a ridge of high pressure aloft beings to build toward
the coast. At the same time off to our east the flow will become
tighter and northerly as a system drops into the central Conus
from Canada. The amplification will continue to increase Friday
into Saturday as an upper low dives into the Four Corners Region.
Winds will increase with breezy conditions likely Thursday into
Friday. Models have backed off a bit compared to previous runs, so
a little less concern for fire weather interests compared to 12
hours ago.

Closer to the surface a ridge of high pressure will move to our
region leading to warmer temperatures especially by the weekend.
Highs on Saturday and Sunday will be in the 70s to mid 80s for
most spots away from the coast. Should be enough of a sea breeze
to keep many beaches and locations right at the coast in the 60s
to lower 70s. Any rain chances will be well to our north.

The ridge will slowly advance to the coast and then flatten and
progress off to the east next work week. The storm track will stay
well to our north with warmer than normal temperatures likely.


.AVIATION...as of 10:27 PM PDT Monday...Mainly VFR reported this
evening with localized MVFR cigs holding on from the South Bay and
East Bay areas to more extensive MVFR coverage over the north Central
Coast. Sufficient surface to lower level mixing has helped lift cigs
higher over much of the Bay Area this evening. The WRF consistently
indicates lower cigs/vsbys redevelop or become reinforced along the
immediate coast with overlap continuing into the South Bay and East
Bay tonight.

VFR/MVFR cigs and VFR visibilities Tuesday. 1C-3C cooling at 925 mb
tonight will be followed by 2C-3C warming Tuesday thus along with
cloud cover it`s highly unlikely that either near surface based or
lower level (marine) inversions will develop tonight and Tuesday.
By Tuesday night into Wednesday however weak inversion redevelopment
becomes possible due to additional warming at the 925 mb and 850
mb levels accompanying the slowly eastward advancing eastern Pacific
upper level ridge.

Vicinity of KSFO...Westerly wind still could gust to 20-25 knots
overnight based on recent guidance. VFR possibly MVFR at times late
tonight/early Tuesday morning with winds gradually settling back.
VFR Tuesday with westerly wind increasing in the afternoon with
gusts to 20-25 knots.

SFO Bridge Approach...Similar to KSFO.

Monterey Bay Terminals...VFR/MVFR tonight and Tuesday morning. Lighter
westerly winds tonight. VFR forecast for most of the day Tuesday.


.MARINE...as of 02:54 AM PDT Tuesday...High pressure off the coast
will lead to breezy west to northwest winds with locally stronger
winds along the big sur coast. winds  and seas will increase
wednesday night into thursday as high  pressure strengthens over
the eastern pacific resulting in a  tighter pressure gradient
across the coastal waters.


     .Tday...SCA...Mry Bay from 9 AM
             SCA...Pigeon Pt to Pt Pinos 0-10 nm from 9 AM
             SCA...Pt Pinos to Pt Piedras Blancas 0-10 nm




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NWS MTR Office Area Forecast Discussion