Scientific Forecaster Discussion
Area forecast discussion
National Weather Service San Francisco Bay area
1028 PM PDT Tuesday Jul 26 2016
Synopsis...very warm conditions will persist inland through the
remainder of the work week as high pressure dominates the weather
pattern. Meanwhile, cooler temperatures will continue near the
coast as a result of weak onshore flow. Inland areas will then
cool down for the upcoming weekend as an upper level trough
develops off of the Pacific northwest coast.
Discussion...as of 8:57 PM PDT Tuesday...as anticipated
temperatures rose significantly inland this afternoon under the
influence of high pressure building over the Desert Southwest.
Afternoon highs remained cool along the coast due to the marine
influence. Temperatures warmed to around 60 degrees along the
coast while temperatures around the bays topped out around 80
degrees. Farther inland temps rose into the 90s with several
locations exceeding 100 degrees. The Hot Spot today was Bradley
hitting 110 at 4 PM this afternoon. The Pinnacles was only a
degree cooler at 109. Temperatures are expected to see very little
change Wednesday and Thursday as high pressure continues to build
over the region. The high will also continue to compress the
marine layer. The Fort Ord profiler depicts a marine layer depth
of around 800 feet at this hour. The depth of the marine layer will
fluctuate from day to day while keeping temperatures along the
coast seasonal cool.
Models continue to show a chance of mid-level moisture currently
over Mexico advecting northward toward our area Wednesday night
and Thursday. The best chance for elevated convection remains over
the interior portion of the state or in other words east of our
area. We will continue to monitor the situation closely for any
changes to the forecast.
Cooler temperatures are forecast to return to the region this
weekend as the upper level ridge weakens and is replaced by an
upper level trough developing off the Pacific northwest coast. A
deeper marine layer and cool onshore flow will result in cooler
temperatures inland Saturday and Sunday.
Aviation...as of 10:28 PM PDT Tuesday...a strong and closed mid
level high will remain nearly stationary over Nevada/Utah into Wednesday.
The western side of this high will persist over California keeping
the marine layer nearly unchanged in depth tonight and Wednesday.
Presently the marine layer depth is 500-1,000 feet. Marine based
stratus and fog persists along the immediate coast with very little
intrusion except locally into the San Francisco Bay and northern
Salinas valley. Persistent horizontal visibility restrictions
expected along the immediate coast including the vicinity of kmry,
ksns into Wednesday especially if surface winds become west-SW within
the Monterey Bay.
Vicinity of ksfo...hazy, west-northwest winds 10-15 knots. VFR/MVFR vsbys.
Sfo bridge approach...similar to ksfo.
Monterey Bay terminals...cigs/vsbys LIFR borderline vlifr tonight
under a compressed marine layer. Gradual clearing Wednesday morning
with little change, if any, in the marine layer depth with IFR
cigs/vsbys returning Wednesday evening.
Fire weather...as of 2:50 PM PDT Tuesday...warm and dry
conditions persist this afternoon, especially at elevations above
1500 feet as high pressure builds over the region. In addition,
the marine layer has mixed out this afternoon and is forecast to
recover only slightly tonight, resulting in poor humidity
recoveries. While weak onshore flow continues near the coast,
light and variable to light southerly winds remain over the Santa
Lucia mountains and Los Padres National Forest. In addition,
southerly flow just off the surface has caused smokey conditions
to persist over much of the Monterey Bay region and as far north
as the South Bay this afternoon. While surface winds are forecast
to remain light, west to northwest winds are expected to increase
slightly through late week which should help push the smoke
associated with the soberanes fire inland and south in the coming
days. Regardless, warm and dry conditions will continue to impact
firefighting efforts through late week.
Marine...as of 8:59 PM PDT Tuesday...light to moderate northerly
winds will continue over the coastal waters as high pressure
remains over the region. The strongest winds will be over the
northern outer waters and in localized areas of the northern San
Francisco Bay. Hazardous conditions from squared seas will also
be possible in the northern outer waters. Winds will taper off
through the week as a mixed swell moves through the coastal
waters. A long period southwest swell arrives later this week.
... Arena to Pigeon pt 10-60 nm
Small Craft Advisory...sf Bay until 12 am
Public forecast: CW
fire weather: rg
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