National Weather Service Weather Forecast Office

• Home
• Site Map
• News
• Organization
• Search for: NWS All NOAA 

000
FXUS66 KMTR 062034
AFDMTR

Area Forecast Discussion
National Weather Service San Francisco Bay Area
134 PM PDT Mon Apr 6 2020

.SYNOPSIS...An upper low moving slowly south near the California
coast will bring scattered showers and isolated thunderstorms to
the region today. Shower chances will persist across areas south
of San Jose on Tuesday and south of Monterey into Wednesday as
the upper low slowly exits the region to the south. A warming and
drying trend is forecast for the second half of the week.

&&

.DISCUSSION...as of 01:30 PM PDT Monday...Afternoon satellite
imagery shows a pinwheel of a low pressure system moving down the
coast. KMUX radar imagery continue to indicated bands of precip
rotating around the low. The low pressure is rather cold aloft
helping to destabilize the atmosphere resulting in more convective
showers and evening thunderstorms. GLM data picked up on a few
flashes in the San Joaquin Valley. The cold air aloft has also
helped to lower snow levels this afternoon with snow showing up on
the Mt Hamilton Cam. Snow is also likely falling over the higher
peaks in the Santa Lucia Mts. No real change from previous
forecast through this evening. Scattered showers, thunderstorms,
and high elevation snow showers will be possible. Thunderstorms
will be most likely south of the Golden Gate.

Latest short term and hi-res models continue to show precip
diminishing tonight as the main precip band over the region
drifts westward. The aforementioned low will continue to slowly
move southward tonight and Tuesday. Precip chances return on again
on Tuesday as bands of precip rotate around the low. Precip
chances Tuesday will likely be south of San Jose. Depending on
your model of choice a few showers continue over portions of
Monterey/San Benito Wednesday and even Thursday. Confidence is low
on Wednesday/Thursday rain chances.

As the low pressure moves farther south and ultimately east
temperatures will warm toward the end of the week. Drier and
warmer weather is expected over the weekend.

&&

.AVIATION...as of 10:39 AM PDT Monday...For 18z tafs. VFR to MVFR
conditions across the region this morning with clearer conditions
across the North Bay and lingering low clouds and showers south
of the Bay Area as an upper low slowly exits the region. Expect
showers to continue, mainly south of the SF Bay Area into tonight.
Most showers should be relatively light, though locally moderate
showers will be possible. Isolated thunderstorms cannot be ruled
out today as well, though have not seen any lightning thus far.
Should thunderstorms develop, the tafs will be amended to reflect
those conditions. VFR prevailing with occasional MVFR/IFR
conditions possible during heavier showers for SF Bay Area sites
and southward. Conditions will improve this evening and overnight

Winds have been variable given the current position of the low and
its rotation. W to NW winds anticipated this afternoon around
10-15 kt.

Vicinity of KSFO...VFR to MVFR cigs this morning expected to lift
by this evening. Showers to remain in the vicinity through the
evening. Higher res models are showing an increase in shower
activity this afternoon. Wind directions have varied this morning
and have settled at around N/NE for the moment. Winds expected to
shift out of the W/NW this afternoon around 10-15 kt.

SFO Bridge Approach...Similar to KSFO.

Monterey Bay Terminals...VFR prevailing with occasional MVFR
conditions possible during heavier showers or thunderstorms. E to
SE winds this morning to shift more W/NW this afternoon around
10-15 kt. Showers will continue into the evening and become more
isolated overnight.

&&

.MARINE...As of 8:08 AM PDT Monday...A cold mid to upper level
low will slowly move south over coastal waters today and tonight
with scattered showers and thunderstorms. Overall, winds will
remain generally light with locally breezy winds possible north of
Point Reyes this afternoon and evening. Dry weather returns to
the coastal waters and bays tomorrow. Northwest winds will
increase across the water mid-week as the upper low continues to
exit to the southeast and high pressure builds over the eastern
Pacific. A long period southwest to west swell arrives early
tomorrow morning and continues into Wednesday morning before
decreasing.

&&

.MTR WATCHES/WARNINGS/ADVISORIES...
     .Tngt...SCA...Pt Arena to Pigeon Pt 10-60 nm until 3 AM
             SCA...Pt Arena to Pt Reyes 0-10 nm until 9 PM

&&

$$

PUBLIC FORECAST: MM
AVIATION: AS
MARINE: AS

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