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

Current Version | Previous Version | Text Only | Print | Product List | Glossary Off
Versions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50

648
FXUS66 KMTR 132143
AFDMTR

Area Forecast Discussion
National Weather Service San Francisco Bay Area
143 PM PST Fri Dec 13 2019

.SYNOPSIS...Chances of light rain will continue tonight and
into this weekend as a disturbance moves across Northern
California. Drier and colder conditions will prevail on Sunday,
with frost possible Sunday night. An unsettled possibly wet
pattern will likely to return by the middle of next week.

&&

.DISCUSSION...As of 1:43 PM PST Friday...Under cloudy skies, area
temperatures are running cooler than yesterday at this time by
several degrees, with readings ranging from the mid 50s to the
lower 60s. Only light returns are being picked up by radar right
now, but some brief showers moved through the Bay Area earlier
today. Over the past three hours, only a few hundredths of an
inch have been picked up. Areas of light rain or drizzle will
occur overnight, and taper off by morning. Rainfall amounts are
expected to be a quarter inch or less, with the bulk of that
occurring in the coastal hills of the North Bay. A cold front will
then move across the region late in the day on Saturday. Although
this cold front will bring some light rain to the region, the
biggest impact will be with the colder and drier air moving in
behind the front. Although Sunday will be slightly cooler than
Saturday, the main impact will be on the overnight temperatures
Sunday night with frosty conditions will be possible as
temperatures fall into the lower to mid 30s across the inland
valleys.

Drier conditions are expected for early next week as high
pressure builds along the coast. Although there are still
inconsistencies amongst the model solutions, medium range models
still indicate a return to a more unsettled pattern beginning the
middle of next week with more well-defined storm systems moving
through.

&&

.AVIATION...as of 10:31 AM PST Friday...Conditions remained mixed
this morning with some of the terminals remaining in LIFR while
low clouds and fog have cleared out of others with VFR conditions.
Rain is moving across the North Bay and is expected to arrive at
the Bay Area terminals as showers around 19z. Light rain will
spread south through the day eventually impacting all terminals
late this afternoon and evening. As the rain arrives, most
locations still seeing LIFR conditions will improve to IFR or
MVFR as lifting near a weak frontal boundary increases. Showers
should diminish late this evening and overnight. Ample low-level
moisture will remain for cigs to persist overnight potentially
lowering to IFR. Some patchy fog is also possible across the North
Bay tonight. Winds will be light and variable today, becoming
predominantly northwest tonight.

Vicinity of KSFO...Conditions have improved with low clouds
clearing and visibility increased to 4 SM. Light showers will
begin to move over the terminal through the morning and into the
afternoon. Clouds should lower as the rain arrives with MVFR
conditions developing after 21-22z. Showers will decrease and end
this evening. MVFR conditions overnight potentially lowering to
IFR after 06z. Winds will be light and variable through the
evening with an increase in west-northwest winds overnight into
Saturday.

SFO Bridge Approach...Similar to KSFO.

Monterey Bay Terminals...Dense fog has ended with VFR at KMRY and
IFR cigs persisting at KSNS. Conditions will become MVFR today as
a weak front approaches. Light rain showers will develop late this
afternoon and evening and clear out overnight. Cigs lowering to
IFR overnight tonight. Winds will generally be light through the
period.

&&

.MARINE...as of 8:59 AM PST Friday...Southerly winds will persist
today ahead of a weak frontal boundary approaching the region.
Rain will fall across the waters today with showers lingering
through Saturday. Winds will switch to the northwest tonight and
increase on Saturday as a cool upper level trough passes to the
north of the area. Large long-period northwest swell will impact
the waters through Saturday.

&&

.MTR WATCHES/WARNINGS/ADVISORIES...
     .Tngt...High Surf Advisory...CAZ006-505-509-529-530
             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 Pt Reyes 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

&&

$$

PUBLIC FORECAST: Sims
AVIATION: ST
MARINE: ST

Visit us at www.weather.gov/sanfrancisco

Follow us on Facebook, Twitter, and YouTube at:
www.facebook.com/nwsbayarea
www.twitter.com/nwsbayarea
www.youtube.com/nwsbayarea



USA.gov is the U.S. government's official web portal to all federal, state and local government web resources and services.