Area Forecast Discussion
Issued by NWS San Francisco Bay Area, CA

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000
FXUS66 KMTR 300354
AFDMTR

Area Forecast Discussion
National Weather Service San Francisco Bay Area
854 PM PDT Mon May 29 2017

.SYNOPSIS...Continued seasonably cool and breezy through midweek
with a slight chance of showers late Tuesday night into Wednesday
as an upper trough moves through. A drying and warming trend
Thursday into next weekend.

&&

.DISCUSSION...as of 9:00 PM PDT Monday...An upper level trough
will be moving through northern California tonight. Strong
onshore flow kept low clouds around the SF Bay and southern MRY
Bay Area through much of the day. Ft Ord Profiler shows the marine
layer is around 2000 feet deep and has trended a little deeper
this evening. This will produce patchy drizzle along the coast and
the coastal mountains overnight.

As this trough moves inland on Tuesday a second upper trough
approaches. This trough is a little deeper and will further cool
the airmass aloft. The WRF and GFS show a line of light showers
from the SFO Bay Area to Monterey County developing over the area
early Wednesday morning. The ECMWF does not show this while the NAM
shows a disorganized line of spotty showers. Given that the
cooler airmass aloft will destabilize the atmosphere the forecast
calls for a slight chance of showers late Tuesday night and early
Wednesday morning.

Temperatures will contiue to run 5 to 10 degrees below normal
through Wednesday before slowly returning to normal later in the
week as weak upper level ridging builds over southern California.
Medium range models indicate an upper level low deepening in the
Gulf of Alaska with strong ridging building over the west. This
could result in significant warming early next week.

&&

.AVIATION...4:49 PM PDT Monday for 00Z TAFs...While most of the
stratus has scattered out across the region this afternoon a
couple of stubborn patches of stratus have maintained borderline
MVFR/IFR cigs over the Monterey and San Francisco Bay terminals.
Partial/temporary breaks in the clouds are possible this
afternoon/evening however these terminals will likely fill back
in early this evening. Elsewhere stratus is forecast to return
around 05z-06z tonight. Moderate and locally gusty onshore flow
will persist through this evening then gradually diminish
overnight. Tuesday will likely be a repeat of today with regard to
cigs with some locations only seeing partial clearing if any.

Moderate confidence.

Vicinity of KSFO...MVFR cigs will prevail through late tonight
with cigs dropping to IFR after 10z Tuesday morning. Cigs are
anticipated to lift to MVFR after 19z Tuesday however only
partial or temporary clearing is expected if any. Moderate to
locally strong and gusty westerly winds will persist through this
evening then diminish slightly overnight to around 10 to 15 kt
sustained.

SFO Bridge Approach...A line of clouds around 1200 feet stretched
out across the bay from KSFO to KOAK will prevail through this
evening then gradually fill in across the bay overnight. Clouds
over the approach are anticipated to scatter out around 21z
Tuesday afternoon.

Monterey Bay Terminals...MVFR cigs will quickly drop to IFR after
02z-03z this evening. Cigs over KMRY will likely drop to LIFR
around 400 ft after 10z tonight. Cigs over KMRY are anticipated
to lift to MVFR after 18z Tuesday however only partial or
temporary clearing is expected if any. Cigs over KSNS will scatter
out around 19z. Moderate westerly winds will persist through this
evening then gradually diminish overnight.

&&

.MARINE...as of 2:26 PM PDT Monday...Strong and gusty northerly
winds will generate steep wind waves and fresh swell...making for
adverse and hazardous seas through at least Tuesday night for the
coastal waters. Winds are forecast to decrease Wednesday as a
weak front moves through the area and the surface pressure
gradient weakens.

&&

.MTR WATCHES/WARNINGS/ADVISORIES...
     .Tngt...SCA...Pt Arena to Pt Reyes 0-10 nm
             SCA...Pt Reyes to Pigeon Pt 0-10 nm
             SCA...Pigeon Pt to Pt Pinos 0-10 nm
             SCA...Pt Pinos to Pt Piedras Blancas 0-10 nm
             SCA...Pt Arena to Pigeon Pt 10-60 nm
             SCA...Pigeon Pt to Pt Piedras Blancas 10-60 nm
             SCA...Mry Bay
             SCA...SF Bay

&&

$$

PUBLIC FORECAST: W Pi
AVIATION: CW
MARINE: BAM


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