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NWS Forecast Area Discussion - San Francisco Area

307
FXUS66 KMTR 221042
AFDMTR

Area Forecast Discussion
National Weather Service San Francisco Bay Area
242 AM PST Wed Jan 22 2020

.SYNOPSIS...A few lingering showers and patchy fog will be
possible early Wednesday. Otherwise, mostly dry and warmer
conditions will return through Friday. A storm system moving into
Northern California this weekend bringing another chance for rain.

&&

.DISCUSSION...as of 02:42 AM PST Wednesday...A nearly stationary
frontal boundary remains draped over the Bay Area resulting in
lingering showers early Wednesday morning. Moist flow across the
terrain is just enough to generate light precip. KMUX radar
imagery shows the light rain has been most prevalent over the
Santa Cruz Mountains and the East Bay Hills. Rainfall amounts over
the last six hours have generally been a tenth or two, but a few
jackpots up to one half inch in the Santa Cruz Mountains. Shower
activity will continue to diminish through the early morning hours
with little to no impacts except for some damp roads. One weather
impact the could affect the morning commute will be fog. Given
the ample low level moisture automated sites around the region
have been reporting some fog with dense fog being reported at
KSTS. Therefore, forecast through the morning hours will include
fog. Besides lingering showers and fog this morning, the bigger
story will be a warming and drying trend developing this afternoon
through Friday. Highs today will approach or hit the mid 60s
across the interior. Temperatures will increase further on
Thursday and Friday with more widespread 60s and a few interior
locations in Monterey/San Benito may even approach 70 degrees -
about five degrees above normal.

No change in the 00Z model suite, rain chances look to return this
weekend as the ridge flattens with another storm system moving
into the British Columbia. The next storm system will drag another
frontal boundary through Northern California. Light rain will
return to the Bay Area Friday night over the North Bay and then
slowly move southward over the weekend. Definitely looks wetter
than the light precip from Tuesday, but as noted before not a
major soaker and heaviest rain will be north. Rain chances
linger into early next week as the tail end of additional weak
systems pass to the north. High pressure rebuilds the middle of
next week taking the storm track farther north.

Longer range outlook is definitely trending drier through the end
of next week and beyond. CPC outlooks continue the warming and
drying trend into early February.



&&

.AVIATION...as of 9:55 PM PST Tuesday...For 06z TAFs. A weak
frontal boundary continues to slide south across the forecast area
bringing lower cigs, lower vsbys, as well as light rain to the Bay
Area southward. Lingering low level moisture will keep patchy fog
over Santa Rosa through tonight. Moderate southerly winds are
expected ahead of the front. Winds will not see they typical
switch to the west or northwest behind the front but rather turn
variable or stay southerly. Winds will return to a more westerly
direction Wednesday afternoon.

Vicinity of KSFO...MVFR/VFR conditions will prevail tonight with
vcsh then tapering overnight. Moderate and locally gusty
southerly winds will ease this evening becoming light and variable
overnight then veer to the west Wednesday afternoon.

SFO Bridge Approach...Similar to KSFO.

Monterey Bay Terminals...MVFR/VFR cigs will prevail tonight with
rain showers expected by this evening then tapering overnight.
Light southeasterly winds will prevail overnight then veer to the
west Wednesday afternoon.

&&

.MARINE...as of 8:56 PM PST Tuesday...Moderate to locally gusty
southerly winds will persist ahead of a cold front that will
continue to move through the region tonight. Winds will generally
be light in wake of the frontal passage. A longer period northwest
swell will peak midweek generating hazardous seas conditions for
smaller vessels. Another long period northwest swell will then
arrive later this week.

&&

.MTR WATCHES/WARNINGS/ADVISORIES...
     .Tday...SCA...Pt Arena to Pt Reyes 0-10 nm until 3 PM
             SCA...Pt Reyes to Pigeon Pt 0-10 nm until 3 PM
             SCA...Pigeon Pt to Pt Pinos 0-10 nm until 3 PM
             SCA...Pt Pinos to Pt Piedras Blancas 0-10 nm until 3 PM
             SCA...Pt Arena to Pigeon Pt 10-60 nm until 3 PM
             SCA...Pigeon Pt to Pt Piedras Blancas 10-60 nm

&&

$$

PUBLIC FORECAST: MM
AVIATION: CW
MARINE: RGass

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NWS MTR Office Area Forecast Discussion

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