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

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FXUS66 KMTR 232033
AFDMTR

Area Forecast Discussion
National Weather Service San Francisco Bay Area
133 PM PDT Tue Oct 23 2018

.SYNOPSIS...Seasonably cool conditions will persist through midweek
as an upper level trough pushes inland over the Pacific Northwest
and northern California. A warming trend is then likely late in the
week and into Saturday as high pressure builds over California.
Temperatures trend downward early next week as another upper level
system pushes inland north of the region. Dry weather conditions are
likely to prevail through the forecast period.

&&

.DISCUSSION...as of 1:33 PM PDT Tuesday...Morning low clouds
dissipated and gave way to a mix of sun and upper level clouds
this afternoon. The upper level clouds are associated with a cold
front and upper trough. One of the more notable weather items in
CA is a weak cold front moving into far Northern California
bringing light rain to the OR/CA border. Temperatures this
afternoon are actually running a few degrees warmer than yesterday
despite some high level clouds. The warmer temperatures are
likely due to the earlier burn off of the low level clouds this
morning.


The longwave pattern over the next few days will be an upper level
trough moving inland today with ridging to follow. Locally that
will translate to a gradual warming trend through Thursday with
more widespread warming on Friday and Saturday. Night and morning
low clouds will remain, but become less widespread into the
weekend. In fact, some of the model guidance even suggests weak
offshore flow given high pressure building across the interior
and a trough of low pressure along the coast. 925mb winds on the
local WRF models become N to NE by Thursday and remain into
Friday. Regarding temperatures - the latest ensemble guidance
backed slightly from the upper end of the envelop (was low 90s and
is now upper 80s) for Friday/Saturday. Despite this trend will
keep current forecast on the mild side with temps in the 80s
across the interior and 60s/70s at the coast. In short, it should
be a pleasant end to the work week and nice start to the weekend.

Upper level ridging shifts eastward on Sunday as an another trough
approaches far NorCal. The shifting of the ridge will initiate a
cooldown for the beginning of next week. Still no sign of precip
for the Bay Area.

&&

.AVIATION...as of 10:50 AM PDT Tuesday...For 18z TAFs. Low clouds
are rapidly eroding at this hour with only a few lingering
patches over inland valleys and the bays. High cloud ahead of an
approaching frontal boundary will continue to stream across the
region today. The front will not bring any precip to area
terminals however will disrupt the stratus pattern and make for a
difficult forecast tonight and Wednesday. Have included cigs for
select terminals tonight however confidence is low as this
boundary moves across Northern California and high pressure begins
to fill in behind it. Generally light winds will prevail with the
typical diurnal increases during the afternoon.

Low Confidence with respect to cigs returning tonight.

Vicinity of KSFO....VFR conditions will prevail across area
terminals through late tonight. MVFR cigs possible after midnight
tonight however, confidence is low. Onshore winds this afternoon
around 15 kt.

SFO Bridge Approach...Similar to KSFO.

Monterey Bay Terminals...VFR conditions will prevail across area
terminals through late tonight. MVFR/IFR cigs possible after
06z tonight however, confidence is low. Onshore winds this
afternoon around 12 kt.

&&

.MARINE...as of 10:38 AM PDT Tuesday...Generally light winds will
continue through much of the week as high pressure builds. Expect
locally gusty northwest winds along  the Big Sur coast through
Wednesday evening. Mixed moderate period northwest swell and a
longer period southerly swell will continue through the forecast
period.

&&

.MTR WATCHES/WARNINGS/ADVISORIES...
     .Tngt...SCA...Pt Pinos to Pt Piedras Blancas 0-10 nm

&&

$$

PUBLIC FORECAST: MM
AVIATION: CW
MARINE: AS/CW

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