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000
FXUS66 KMTR 011030
AFDMTR

Area Forecast Discussion
National Weather Service San Francisco Bay Area
330 AM PDT SAT OCT 1 2016

.SYNOPSIS...Cooler than average temperatures will persist across
the region today ahead of an approaching upper level system. As
this system pushes inland on Sunday, chances for rain showers will
increase with the potential for afternoon and evening
thunderstorms, especially across the San Francisco Bay Area.
Another system will bring chances for rain showers to the region
from late Monday into Tuesday morning. Drier conditions and a
slight warming trend is then forecast for the second half of next
week.

&&

.DISCUSSION...as of 03:28 AM PDT Saturday...Mostly clear skies
prevail this morning across inland areas where temperatures range
from the upper 40s to upper 50s. Patchy low clouds can be seen on
satellite imagery just off of the coast with a few clouds
developing inland as well. Cloud cover has been less extensive as
previously thought given the well mixed marine layer. With this,
any cloud that develop through sunrise will likely burn-off
through the morning hours and give way to mostly sunny conditions
this afternoon. Temperatures today will be similar to those
yesterday afternoon as a mid/upper level trough remains off the
West Coast.

Meanwhile, off of the British Columbia coast, a mid/upper level
low continues to deepen and is forecast to drop southward down the
Pacific Northwest coast and into northern California late tonight
into Sunday morning. As this system approaches the region,
isolated to scattered rain showers will develop offshore and push
into the North Bay region by early Sunday morning. Showers will
then be possible as far south as the Monterey Bay region as the
system pushes inland to our north. The forecast models do show
enough instability to generate a few thunderstorms over the
northern half of the region as well by Sunday afternoon and
evening. Temperatures will also cool further on Sunday as the
system advects cooler air across the region. Thus, afternoon
temperatures will likely remain in the 60s for most urban areas
with cooler conditions in the hills/mountains. While lingering
showers will be possible Sunday night, most locations will see
drying conditions from Sunday night into Monday morning as the
system shifts inland.

The forecast models show another system with precipitable water
values up to around 1.25-1.50" advecting into the region as
another short-wave disturbance pushes across the region late
Monday into early Tuesday. While this system is forecast to weaken
as it approaches the coast, showers will again be possible over
the region from Monday afternoon into early Tuesday morning.

A drying and warming trend is then forecast to develop by the
middle of the upcoming week with temperatures forecast to rebound
back to near seasonal averages by Wednesday. Little change is
forecast for the latter part of next week as a weak short-wave
ridge builds along the coast. Temperatures will generally remain
near seasonal averages with ongoing dry weather conditions. Late
next week, the models do show another trough impacting the Pacific
Northwest, yet precipitation looks to stay well to our north at
this time.

&&

.AVIATION...as of 9:00 PM PDT Friday...Visible satellite shows
dry frontal system moving through the area. The marine layer has
mixed out and skies are mostly clear this evening. Northwest flow
will provide some low level moisture to allow patchy clouds to
form overnight. This will affect mainly the East Bay hills and the
MRY Bay Area. SFO and the approach looks VFR tonight.

Vicinity of KSFO...VFR. West winds to 20 kt decreasing to 15 kt
after 05Z.

SFO Bridge Approach...Patchy clouds may produce cigs over the bay
but not expected to impact the approach.

Monterey Bay Terminals...Clear skies this evening but northwest
flow should allow low clouds to form over the southern MRY Bay
after 08Z.

&&

.FIRE WEATHER...as of 03:28 AM PDT Saturday...Decent humidity
recoveries observed over much of the region this morning, with the
driest conditions over the higher peaks around the Soberanes Fire.
In addition, northwest winds remain the strongest over that region
at around 10-15 MPH with gusts around 15 MPH while wind speeds are
slightly weaker over the Loma Fire. Winds will be locally breezy
again today and on Sunday yet not as strong as those on Friday.
Meanwhile, an upper level system will push inland to our north on
Sunday and bring chances for rain showers to the region with the
potential for a few thunderstorms, mainly over the San Francisco
Bay Area. Chances for wetting rains will be best over the North
Bay with only a few hundredths of an inch or so from the Santa
Cruz Mountains southward. Another chance for showers will return
Monday night into Tuesday morning as another system impacts the
region. Cooler than average temperatures will persist through
early next week along with modest humidity recoveries.

&&

.MARINE...as of 03:28 AM PDT Saturday...An upper level trough will
move east across northern California this weekend bringing a
slight chance of showers mainly to the northern coastal waters. A
small mixed swell with a long period southerly swell will continue
through the period.

&&

.MTR WATCHES/WARNINGS/ADVISORIES...
     .Tday...SCA...Pigeon Pt to Pt Pinos 0-10 nm from 12 PM
             SCA...SF Bay from 12 PM
             SCA...Mry Bay from 12 PM
             SCA...Pt Pinos to Pt Piedras Blancas 0-10 nm

&&

$$

PUBLIC FORECAST: RGass
AVIATION: W Pi
MARINE: Canepa
FIRE WEATHER: RGass


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