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Area Forecast Discussion (AFD)

Issued by San Francisco Bay Area, CA (MTR)

FXUS66 KMTR 242122

Area Forecast Discussion
National Weather Service San Francisco Bay Area
222 PM PDT Mon Jun 24 2019

.SYNOPSIS...A cooling trend will get underway today and continue 
through midweek, with temperatures forecast to cool by 10 to 20 
degrees by Wednesday. In addition, expect an increase in night and
morning low clouds over the next few days. Temperatures will warm
a bit late in the week and into next weekend, but remain slightly
below seasonal averages. 

&& of 2:22 PM PDT Monday...Visible satellite 
imagery shows some passing high clouds over the the San Francisco 
Bay Area this afternoon. Meanwhile along the immediate Pacific 
Coast, some lingering coastal stratus continues for locations such
as Point Reyes, Half Moon Bay, Moss Landing, and Pacific Grove. 
Temperatures as of 2 pm PDT this afternoon are in the 60s along 
the coast while interior communities are in the 70s and 80s. When 
compared to 24 hours ago, the present readings across the interior
have trended downward by about 4 to 8 degrees. By the time the 
afternoon wraps up, most locations will be within several degrees 
of their late June climatological normal highs.

An upper level low off the British Columbia coast is forecast to 
slide southeastward to the Pacific Northwest over the next several
days. While the stratiform rain is expected to remain far to our 
north in Oregon and Washington State, this system will promote 
further cooling for region as geopotential heights and 
temperatures aloft drop. For example, the latest NAM run has 850 
mb and 700 mb temperatures at Oakland dropping from about 20 deg C
and 10 deg C this afternoon to 7 deg C and 3 deg C, respectively,
by early Thursday morning. At the surface, this will correspond 
to high temperatures on Wednesday and Thursday in the 50s and 60s 
along the immediate coast, and 70s to isolated low 80s for the 
interior. Additionally, the trough will likely enhance the marine
layer depth over the coming days with morning low clouds.

Temperatures will begin to rebound for the Bay Area later this 
week and into the weekend as the upper low shifts eastward into 
the Northern Rockies. The long wave trough pattern over the 
eastern Pacific will try to hold on into the weekend and early 
next week as models advertise another upper level low dropping 
south from the Gulf of Alaska. Meanwhile, an upper level ridge 
will build over the Southern Plains and will gradually build 
westward toward the Desert Southwest. If this solution pans out, 
temperatures would likely continue their warming trend into the 
first week of July, particularly for the interior.

&& of 10:25 AM PDT Monday...For 18Z TAFs. VFR. Low
clouds over the region this morning have dissipated and retreated
to the coastline as of 1730Z. Look for an increase in onshore
winds this afternoon with locally gusty conditions around the Bay
Area terminals. Low clouds will spread inland once again this
evening and persist through early Tuesday morning. 

Vicinity of KSFO...VFR. W to NW winds will increase this 
afternoon to around 15 kt with gusts to 20 kt possible. Low 
clouds will return around the terminal early Tuesday morning, yet
confidence of a ceiling developing over KSFO remains low. 

SFO Bridge Approach...Similar to SFO. However, higher confidence 
of low clouds over the approach Tuesday morning.

Monterey Bay Terminals...VFR. Slight increase in onshore flow this
afternoon. Low clouds likely to return late this evening and
persist through around 17Z-18Z Tuesday.

&& of 10:25 AM PDT Monday...Gusty northwesterly winds 
will continue over the northern outer waters and along the coast 
north of Point Reyes through Tuesday as high pressure remains over
the eastern Pacific. These winds will result in steep fresh swell
creating hazardous conditions over the waters, especially for 
smaller vessels. Winds will diminish on Tuesday as high pressure 
weakens and an upper low moves offshore of the Pacific Northwest.


     .Tngt...SCA...Pt Arena to Pt Reyes 0-10 nm
             SCA...Pt Arena to Pigeon Pt 10-60 nm
             SCA...Pigeon Pt to Pt Piedras Blancas 10-60 nm
             SCA...Pt Reyes to Pigeon Pt 0-10 nm from 9 PM




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