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

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663
FXUS66 KMTR 190034
AFDMTR

Area Forecast Discussion
National Weather Service San Francisco Bay Area
434 PM PST Thu Jan 18 2018

.SYNOPSIS...The cold front continues to make its way southward
bringing light precipitation to the area. Light rainfall is still
expected for the southern half of the region late this afternoon
and this evening. Scattered showers will follow in the wake of the
frontal passage tonight and tomorrow as colder air settles aloft.
This will bring slight chances of thunderstorms over the coastal
waters and parts of the North Bay coast. A few lingering showers
possible Saturday morning, but otherwise dry. The next system is
set to move in late Sunday into Monday.

&&

.DISCUSSION...As of 1:40 PM PST Thursday...Current KMUX radar
imagery showing a few echos across the region. Cigs remain low
enough, that most precip has not been visible on the radar.
Precipitation is slowly making its way southward with areas just
south of the SF Peninsula now having received at least a few
hundredths of an inch and some of the higher peaks breaching a
tenth of an inch. Over the past six hours Middle Peak appears to
have the highest rainfall amounts at 0.53 inches. Rainfall is
still expected to reach the southern portion of the region later
this afternoon into this evening.

As the front passes, rain will transition to convective showers
and 850 mb temps will drop to around -2 degrees C. All information
continues to indicate a slight chance of thunderstorms tonight
and tomorrow over the coastal waters and coastal areas of the
North Bay. Cooling aloft in the wake of the frontal passage will
also lower snow levels to around 3000-3500 ft bringing the
potential for a light dusting of snow to some of the higher peaks
tomorrow afternoon and evening.

There may be a few lingering showers on Saturday morning, but
otherwise expect a fairly dry start to the weekend. Another
system is still set to move into the region Sunday afternoon into
Monday. There is very little model consensus on the QPF from this
next system. This will continue to be monitored over the coming
days.

&&

.AVIATION...as of 4:00 PM PST Thursday...for 00Z TAFs. MVFR to
VFR cigs anywhere from 1000 ft to 4000 ft will continue through
tonight as rain showers continue through much of the forecast
period. Cigs will be jumping between categories as showers move
across area terminals. West winds of 10 kt or less will prevail.

Vicinity of KSFO...MVFR cigs will prevail across area terminals as
showers continue to move across the region. Showery conditions
will persist through much of the forecast period therefore have
kept -SHRA and VCSH in the forecast. West winds around 10 kt.

SFO Bridge Approach...Similar to KSFO.

Monterey Bay Terminals...MVFR to VFR cigs will prevail across
area terminals as showers continue to move across the region.
Showery conditions will persist through much of the forecast
period therefore have kept -SHRA and VCSH in the forecast. Light
winds.

&&

.MARINE...as of 2:06 PM PST Thursday...A large, long period west
swell will continue to impact the waters overnight and into
Friday, bringing hazardous seas throughout the coastal waters.
Additionally, the coastline will see large  breaking waves and
high surf associated with the large swell. A  cold front will
slowly pass through the waters through the evening and overnight
hours, bringing with it a chance of rain.

&&

.MTR WATCHES/WARNINGS/ADVISORIES...
     .Tngt...High Surf Warning...Entire coast
             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...Rough Bar Advisory for SF Bar
             SCA...Mry Bay

&&

$$

PUBLIC FORECAST: AS
AVIATION: CW
MARINE: Rowe

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