Area forecast discussion 
National Weather Service San Francisco Bay area 
904 PM PDT Wednesday Jul 27 2016 


Synopsis...very warm conditions will persist inland through the 
remainder of the week as high pressure remains over the west. 
Meanwhile, cooler temperatures will continue near the coast as a 
result of weak onshore flow. Slight cooling is expected over the 
weekend as an upper level trough develops off of the Pacific 
northwest coast. 


&& 


Discussion...as of 9:04 PM PDT Wednesday...high pressure that 
encompasses much of the state continues to drive hot temperatures 
across the region. Highs finished off with mid 50s and 60s along 
the coast, 70s around the Bay, 80s and 90s inland. Warmest inland 
valleys warmed into the low 100s with Bradley coming in as our Hot 
Spot today at 111 degrees. Little change is expected Thursday in 
the overall weather pattern therefore anticipate similar 
conditions to today. Smoke from the soberanes fire continue to 
impeded the heating potential of this heat wave and as a result 
temperatures actually cooled a bit over yesterdays highs. 


As mentioned over the last few days we will continue to see minor 
fluctuations in the marine layer through the end of the week as 
high pressure remains in control. The inversion appears to be 
around 1200 feet at this hour per The Fort Ord profiler...however 
the marine layer will likely compress to around 800 feet by 
morning. Latest satellite imagery shows status has fill back into 
the coast this evening. With a slightly deeper marine layer than 
previous evenings low clouds have moved farther inland but are 
expected to remain confined mainly to the coast and coastal 
valleys. 


Water vapor imagery depicts an increase in moisture across the 
region. There has been some concern with moisture to the south 
advecting northward resulting in elevated convection. Model tend 
to agree that the best chance of convection remains over the 
Sierra during the afternoon. We will continue to monitor the 
situation closely. 


From previous discussion...the interaction of the hot, dry 
stagnant air mass of the ridge with the soberanes smoke is leading 
to poor to unhealthy air quality for a large number of communities 
in and around California today. Be sure to visit 
http://www.Airnow.Gov for additional air quality readings for your 
local zip code. The marine layer will continue to be suppressed by 
the ridge into tonight and will not provide much support to 
firefighting efforts. 


The high pressure ridge is expected to weaken and dissipate late 
in the week allowing increased onshore flow and a gradual cooling 
trend for the region. The pattern will shift to become more of a 
mean quasizonal flow by the weekend and into early next week 
heralding a return towards near normal conditions. A weak 
disturbance passing to the north after the weekend should help to 
deepen the marine layer and promote additional cooling. No 
precipitation is expected locally through the next several days, 
however, for those travelling to the Sierra Nevada, there could be 
some isolated high base thunderstorms as monsoonal moisture 
rotates around the ridge Thursday into the weekend. 


&& 


Aviation...as of 4:46 PM PDT Wednesday...IFR ceilings and visibilities 
due to stratus and fog along the immediate coast will move locally 
inland tonight into Thursday morning. Fresh onshore breezes are 
helping to keep visibilities good in the vicinity of San Francisco 
Bay, but generally increasingly hazy and smokey conditions exist 
from the inland valleys southward to the north central coast. 


Vicinity of ksfo...VFR. Northwest-west winds under 20 knots this evening. 


Sfo bridge approach...similar to ksfo. 


Monterey Bay terminals...VFR followed by IFR cigs/vsbys developing 
in the 01z-05z time-frame. IFR tonight into Thursday morning, partial 
clearing returning by late Thursday morning. 


&& 


Fire weather...as of 8:05 PM PDT Wednesday...warm and dry 
conditions will continue through Thursday, especially at 
elevations above 1500 feet as high pressure remains over the 
region. Weak onshore flow will persist along the coast with light 
and variable to light southerly winds over the Santa Lucia 
mountains and Los Padres National Forest overnight and through the 
morning becoming westerly in the afternoon. Winds aloft will 
remain out of the south which will transport the smoke associated 
with the soberanes fire to the north over the Monterey Bay and 
across the Bay area. Warm and dry conditions will continue to 
impact firefighting efforts through late week. 


&& 


Marine...as of 08:02 PM PDT Wednesday...moderate to locally gusty 
northwest winds will persist over the coastal waters as high 
pressure remains over the eastern Pacific with the strongest 
across the northern outer waters and north of the Bay Bridge. 
Winds will then diminish later this week while a mixed swell moves 
into the coastal waters. A long period southwest well arrives 
later in the week. 


&& 


Mtr watches/warnings/advisories... 
... Arena to Pigeon pt 10-60 nm 
Small Craft Advisory...sf Bay until 3 am 


&& 


$$ 


Public forecast: CW 
aviation: canepa 
marine: rgass 
fire weather: CW 




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