Scientific Forecaster Discussion
Area forecast discussion
National Weather Service San Francisco Bay area
433 am PDT Tuesday Jul 26 2016
Synopsis...a warming trend remains on track for the inland areas
beginning today and persisting through late week as high pressure
builds in from the Desert Southwest. However, typical cool Summer
conditions will prevail along coast. A cooling trend is
anticipated for the upcoming weekend as an upper level trough
develops off of the Pacific northwest coast.
Discussion...as of 3:09 am PDT Tuesday...building high pressure
is compressing the marine layer this morning as indicated by The
Fort Ord profiler which is showing a marine layer depth of just
under 1000 feet. The compressed marine layer is resulting in low
clouds, ceilings around 200 feet, along the coast and patchy
dense fog in the Monterey area. The current infrared satellite fog
product continues to Show Low clouds over the coastal waters,
stretching into the Salinas valley. The heat signature associated
with the soberanes fire is also evident on the fog product.
The 0000z European model (ecmwf) and gfs20 have initialized well with the current
synoptic weather pattern and remain in good agreement through
roughly Saturday, building The Four Corners high to 594dm. As the
high pressure builds 850mb temperatures heat up. In fact 850mb
temperatures are forecast to reach 25 to 26c today and 26 to 27c
Wednesday and Thursday. This translates to hot inland temperatures
reaching into the mid to upper 90s. The hottest areas will be in
interior Monterey and San Benito counties where low 100s will be
common. Pinnacles National Monument is expected to reach a high of
107 today and tomorrow before cooling to 106 on Thursday. In
addition to the heat the 0000z gfs20 is also indicating that some
monsoon moisture will begin to move into southern Monterey
Wednesday. At this point the atmosphere does not look unstable
enough to support convection, but we will continue to monitor this
moisture as it moves into the area. A cooling trend remains on
track for the weekend as a trough of low pressure begins to swing
into the Pacific northwest.
Aviation...as of 4:30 am PDT Tuesday...a slightly compressed
marine layer compare to 24 hours ago. Low clouds are mainly
impacting Monterey Bay. Linger smoke particulates and compressed
marine layer may have helped to produce dense fog for mry and sns.
Other locations will likely have some haze/smoke today. Current
obs show some airports reporting cigs near 8k, which is likely a
smoke layer. Overall conf is low to moderate given lingering smoke
and poss haze/smoke.
Vicinity of ksfo...will continue to forecast VFR with poss MVFR
due haze from smoke. The smoke could also have impacts on
slantwise vis in sf Bay this morning.
Sfo bridge approach...similar to ksfo.
Monterey Bay terminals...dense fog with LIFR to vlifr this
morning. MVFR/VFR this afternoon with fu poss from nearby fire.
Cigs return tonight.
Fire weather...as of 3:09 am PDT Tuesday...the marine layer has
compressed to around 900 feet this morning. Although relative
humidity recoveries have been good below a 1000 feet tonight, Max
relative humidity above 1000 feet remains poor. Surface winds over
the waters along the Big Sur coast are anticipated to be around 10
mph and out of the north. Generally light and variable winds, 4
to 8 mph, are anticipated over Santa Lucia mountain and Los Padres
National Forest. This will result in another day of smokey
conditions for the Monterey area.
Marine...as of 03:09 am PDT Tuesday...high pressure over the
eastern Pacific will maintain moderate northerly winds over the
coastal waters. Locally gusty winds will be possible over the
outer waters north of Point Reyes. Winds will gradually diminish
as the week progresses. A mixed swell will also impact the
coastal waters through the week.
... Arena to Pigeon pt 10-60 nm
Small Craft Advisory...sf Bay from 11 am
Public forecast: Larry
fire weather: Larry
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