000 
fxus66 kmtr 160015 
afdmtr 


Area forecast discussion 
National Weather Service San Francisco Bay area 
515 PM PDT Wed Aug 15 2018 


Synopsis...temperatures will remain near to slightly below 
seasonal averages today with widespread night/morning low clouds. 
High pressure will build toward the West Coast by late week and 
result in a gradual warming trend, especially over the interior. 
Above normal temperatures will return to the interior this Friday 
and over the weekend. 


&& 


Discussion...as of 01:46 PM PDT Wednesday...unlike yesterday 
afternoon, coastal locations are actually seeing a tad more 
sunshine this afternoon. As a result, the 24 hour trend has many 
locations running several degrees over yesterday's afternoon 
temperatures. High temperatures today will likely top out in the 
60s to low 70s along the coast and upper 70s to mid 90s inland. 


In the short term, very little change was made to the previous 
forecast. The marine layer will return again tonight along the 
coast and down the inland valleys. The longwave pattern continues 
to indicated the broad area of high pressure over the Desert 
Southwest will gradual westward over California. The building high 
pressure will possibly lead to a slight compression of the marine 
layer tonight. None the less, the depth will likely be 1800-2200 
feet deep. Similar to the last few nights mild and dry conditions 
will continue above the marine layer in the hills. 


The aforementioned high pressure will actually build westward 
through the weekend. Therefore a gradual warming trend will 
continue. Lack of strong offshore flow will keep some form of the 
marine layer in place each night and morning with patchy fog 
possible. The low clouds/fog will roll back to the coast by each 
afternoon with ample sunshine and a warming airmass across the 
interior. By Thursday, high temperatures across the far interior 
will approach 100 degrees. Friday and over the weekend highs will 
eclipse 100 degrees across the far interior. Lingering onshore 
flow will keep coastal/Bay shoreline locations in check through 
the weekend. Interior locations like San Jose, Santa Rosa, East 
Bay valleys will hit the upper 80s to 90s by the weekend thanks to 
some weak offshore flow aloft. The local WRF shows some minor 
offshore flow at 925mb Friday into Saturday. Given the slight 
offshore flow component did bump temperatures upward from previous 
forecast. Despite the warm up and temps of 100+ across the far 
interior heat risk potential is low to moderate. 


High pressure weakens Sunday into Monday as an upper low sweeps 
through the pacnw and norcal. Cooler temperatures will return 
early next week. Still no sign of any precip through the forecast 
period. 


&& 


Aviation...as of 4:58 PM PDT Wednesday...for 00z tafs. Mainly 
clear skies prevail across the region this afternoon with status 
having just cleared from the coast. A deep 2000 ft marine layer 
and a moderate onshore flow will allow widespread stratus to 
infiltrate well inland once again tonight. Breezy onshore flow of 
10 to 20 kt with gust to 25 kt over ksfo will gradually ease this 
evening to around 5 to 10 kt overnight. 


Vicinity of ksfo...VFR conditions will continue through this 
evening with MVFR cigs expected to return around 04z-05z tonight. 
Low clouds will scatter out around 19z Thursday. Breezy west 
winds around 15 to 20 kt with gusts to around 25 kt will gradually 
ease this evening to under 10 kt overnight. 


Sfo bridge approach...similar to ksfo with low clouds returning 
overnight and scattering out around 19z-20z Thursday afternoon. 


Monterey Bay terminals...VFR conditions will continue through this 
evening with IFR/MVFR cigs expected to return between 03z-05z 
this evening/tonight. Low clouds will scatter out around 17z 
Thursday morning. West winds around 10 kt will gradually ease 
this evening becoming light and variable overnight. 


&& 


Marine...as of 2:08 PM PDT Wednesday...generally light to 
moderate northwesterly winds will continue across the coastal 
waters through the end of the work week as high pressure sits over 
the eastern Pacific. Locally gusty afternoon and evening winds 
are expected in the San Francisco Bay north of the Golden Gate and 
along the Big Sur coast south of Point Sur. Look for winds to 
start to increase as we head into the weekend. Mixed northwest and 
southerly swells will remain light to moderate with a longer 
period southerly swell forecast to arrive this weekend. 


&& 


Mtr watches/warnings/advisories... 
... Bay until 9 PM 
Small Craft Advisory...mry Bay until 9 PM 
Small Craft Advisory...Pigeon pt to pt pinos 0-10 nm until 9 PM 
Small Craft Advisory...pt pinos to pt Piedras Blancas 0-10 nm until 3 am 


&& 


$$ 


Public forecast: mm 
aviation: CW 
marine: as 


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