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

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659
FXUS66 KMTR 241142
AFDMTR

Area Forecast Discussion
National Weather Service San Francisco Bay Area
342 AM PST Tue Jan 24 2017

.SYNOPSIS...Isolated showers likely to linger this morning across
the region and give way to clearing skies this afternoon and
evening. Dry weather conditions return region-wide into Wednesday
before a passing system brings a slight chance of precipitation to
the northern portion of the region Wednesday night into Thursday.
Otherwise, dry weather conditions likely into the upcoming
weekend.

&&

.DISCUSSION...as of 02:46 AM PST Tuesday...Showers persist early
this morning over the Monterey Bay and off of the San
Francisco/San Mateo coast as well as the North Bay coast. These
lingering showers are in response to the back end of the mid/upper
level trough pushing inland. Given the cold and unstable air mass
aloft, showers that pushed inland early in the night continued to
produce small hail and KMUX 88D Radar indicated weak rotation with
some of the cells off of the coast. However, does appear these
cells have weakened over the past hour or so. In addition, snow
levels have been around or slightly below 3,000 ft through the
night with snow showers likely impacting the higher elevations
across the region.

Showers are forecast to diminish in coverage through the morning
with clearing skies by this afternoon/evening as a weak short-wave
ridge builds aloft. With clearing skies overnight, colder
temperatures are likely into Wednesday morning with patchy fog
possible in the North Bay and East Bay valleys. Should see most
areas fall into the 30s by sunrise Wednesday with lower 30s in the
coldest, inland valley locations. Meanwhile, around the San
Francisco Bay upper 30s to lower 40s are expected.

By Wednesday night, a weak system is forecast to past inland
north of the region and bring a slight chance of precipitation to
the northern portion of the region. Overall, rainfall will be
limit with this system and most locations across the region will
remain dry. By Thursday morning, a few lingering showers will be
possible along the coast and into the coastal hills. Otherwise,
the ridge will build in stronger over the region through late week
and maintain dry weather conditions.

The ridge will then build inland further and aid in warming
temperatures region-wide this upcoming weekend. Could see
afternoon temperatures warm above seasonal averages by Saturday
and Sunday. The ridge will likely hold in place even to early next
week with many areas warming into the 60s. The forecast models
continue to hint at the ridge breaking down and troughing
returning to the West Coast by the middle of next week. Thus,
precipitation may return to the central California coast late in
the forecast period, however confidence remains low at this time.

&&

.AVIATION...As of 3:42 AM PST Tuesday...Scattered showers will
gradually diminish as a low pressure system continues to slide
south down the coast. The departing low will take the mid-level
cigs with it leading to mostly clear skies this afternoon.
Conditions will continue to improve through today as this system
exits the region and high pressure builds in. Moderate to high
confidence.

Vicinity of KSFO....Mostly VFR conditions expected. A stray
shower cannot be ruled out this morning. Light offshore winds will
veer onshore once again this afternoon. Moderate confidence.

SFO Bridge Approach...Similar to SFO.

Monterey Bay Terminals...Mostly VFR cigs and vsby expected through
the period. A stray shower cannot be ruled out this morning.
Light offshore winds will veer onshore once again this afternoon.
Moderate confidence.

&&

.MARINE...as of 3:00 AM PST Tuesday...Scattered showers and
isolated thunderstorms will continue to diminish this morning as a
low pressure system continues to slide south down the coast and
through our coastal waters. Large westerly swell will persist
through tonight. Another long period swell will move into our
region on Wednesday.

&&

.MTR WATCHES/WARNINGS/ADVISORIES...
     .Tday...High Surf Advisory...CAZ006-505-509-529-530
             SCA...Pigeon Pt to Pt Pinos 0-10 nm
             SCA...Pt Pinos to Pt Piedras Blancas 0-10 nm
             SCA...Pigeon Pt to Pt Piedras Blancas 10-60 nm
             SCA...Mry Bay
             SCA...Pt Arena to Pt Reyes 0-10 nm
             SCA...Pt Reyes to Pigeon Pt 0-10 nm
             SCA...Pt Arena to Pigeon Pt 10-60 nm
             SCA...Rough Bar Advisory for SF Bar

&&

$$

PUBLIC FORECAST: RGass
AVIATION/MARINE: CW


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