Area forecast discussion 
National Weather Service San Francisco Bay area 
435 PM PDT sun may 29 2016 


Synopsis...onshore flow and a deep marine layer resulted in cool 
temperatures today, especially near the coast. A warming trend is 
expected for Memorial Day and Tuesday. Warmer than normal 
temperatures will continue through the end of the week. Dry 
weather will persist. 


&& 


Discussion...as of 2:03 PM PDT Sunday...stratus continues to 
linger along portions of the coast this afternoon as well as 
across much of the coastal waters. A couple of small patches 
clings to portions of the Marin and San Mateo County coasts with 
widespread stratus coverage along the coast from Monterey Bay area 
south. The marine layer continues to deepen and currently stands 
at around 2200 feet per The Fort Ord profiler. 


Some fluctuations have been observed in the gradients this 
afternoon with current observations showing the northerly gradient 
at 4.4 mb from acv to sfo (-0.5 mb) while the onshore gradients 
from sfo to las has ramped up to 6.3 mb (+1.5 mb) over the last 6 
hours. This will keep stratus at the coast and locally inland over 
coastal valleys. 


Temperatures are running around 10 degrees cooler than yesterday 
along the coast and around 5 degrees cooler inland. Coastal 
locations reached into the low to mid 60s this afternoon with 70s 
reported around the San Francisco Bay. Inland locations are 
reporting highs in the upper 70s and 80s. 


A warming trend is on tap for Memorial Day and Tuesday as a ridge 
of high pressure builds in over the region and a surface trough 
currently situated over the interior shift west to the coast. 
This will weaken the onshore gradient and thin out the marine 
layer resulting in a quicker clearing of low clouds in the morning 
and less marine influence. Patchy low clouds along the coast may 
still be possible. 


By midweek the upper level ridge will move east over the western 
U.S. An upper level trough will develop over the eastern Pacific. 
This will result in a slight cooling trend for Wednesday and 
Thursday. Nonetheless temperatures will remain above normal for 
this time of year. Temperatures will rebound Friday as the upper 
level ridge centered over The Four Corners area amplifies 
resulting in warmer weather over the region. Models indicate 
temperatures could climb into the 80s around the Bay and low 100s 
over the warmest inland areas. 


Latest model solutions show good agreement in the upper trough 
developing a closed low off the Southern California coast through 
the later half of the week. This low is then forecast to kick out 
to the northeast by next weekend bringing a chance of precip to 
the southern portion of the forecast area on Saturday and 
potentially farther north on Sunday. 


&& 


Aviation...as of 4:30 PM PDT Sunday...coastal clouds now reach 
as far north as Point Reyes so there is a better chance for cigs 
in the sfo Bay area tonight. However the northerly component of 
the onshore flow will be strong enough to keep clouds out until 
after 07z. 


Vicinity of ksfo...MVFR after 08z. 


Sfo bridge approach...same as ksfo. 


Monterey Bay terminals...coastal clouds spreading into sns after 
02z and mry after 04-05z. 


&& 


Marine...as of 4:30 PM PDT Sunday...high pressure over the 
eastern Pacific and low pressure inland will result in gusty 
northerly winds over the coastal waters today and tonight. Winds 
will be strongest over the outer waters...especially north of 
Point Reyes. Winds will gradually decrease on Memorial Day with 
weakening high pressure. A building southerly swell is anticipated 
to arrive early next week. 


&& 


Mtr watches/warnings/advisories... 
... Arena to Pigeon pt 10-60 nm 
Small Craft Advisory...pt Arena to pt Reyes 0-10 nm until 11 PM 
Small Craft Advisory...sf Bay until 9 PM 
Small Craft Advisory...Pigeon pt to pt Piedras Blancas 10-60 nm until 2 am 


&& 


$$ 


Public forecast: CW 
aviation: west pi 
marine: Sims 




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