Scientific Forecaster Discussion
fxus66 kmtr 262345
Area forecast discussion
National Weather Service San Francisco Bay area
445 PM PDT Sat may 26 2018
Synopsis...expect gradual clearing with a return to dry weather
by this afternoon as temperatures start to rebound towards
seasonal normals. Rapid warming trend develops Sunday afternoon
through Memorial Day with inland highs into the 80s to lower 90s.
Coastal cooling arrives by Tuesday with more noted cooling trend
inland by Wednesday as next dry upper trough passes over the
Discussion...as of 12:40 PM PDT Saturday...clouds are slow to
clear as low level moisture continues to wrap around the upper low
now approaching southern Nevada. As a result, current
temperatures are generally running cooler than yesterday at this
time with many readings still in the upper 50s to lower 60s. Santa
Rosa and Napa airports are exceptions, though, both warmer than
yesterday with readings in the mid and upper 60s, respectively.
Satellite imagery shows partial clearing across the eastern
portions of the County Warning Area as well as over southern Monterey and San
Benito counties. Still expecting to see more sunshine breaks as
the afternoon progresses.
High pressure aloft will begin building in over the state from
the west on Sunday for a warming trend through Monday. Onshore
flow will continue near the coast, so temperatures along the coast
are not expected to warm significantly. Much warmer temperatures
are expected across inland areas with highs warming into the mid
90s by Monday in the warmest inland inland locations.
An upper level trough approaching the coast next week will bring
a cooling trend to the area beginning on Tuesday, and more
significant by later in the week when highs will once again be in
the 60s and 70s across the district. While this trough is not
expected to bring any rain to the area, an increased marine layer
and enhanced onshore flow will likely be the outcome. Some
coastal drizzle might be possible Thursday morning when the
trough axis moves through.
Aviation...as of 4:45 PM PDT Saturday...cigs have been slow to
clear due to low level moisture on the back side of the upper low
webcams indicate sfo is finally clearing out. It will take some
time for the clouds to reform so VFR conditions are expected
through the Airport evening rush. Models indicate about a 06z
return of the stratus to the sfo Bay area. Winds become more north
to northeast overnight which should allow for an earlier burnoff
Vicinity of ksfo...MVFR cigs return after 06z. West winds gusting
25-27 kt through 04z.
Sfo bridge approach...similar to ksfo.
Monterey Bay terminals...MVFR cigs not expected to clear. Cigs may
lower to IFR range after 06z.
Marine...as of 04:31 PM PDT Saturday...building high pressure in
the eastern Pacific will allow for northwest winds to increase
throughout the coastal waters over the next 24 hours. These winds
will generate locally steep wind waves, leading to hazardous
conditions for small craft. The moderate to locally strong winds
will persist through the Holiday weekend and into early next
... Reyes to Pigeon pt 0-10 nm until 3 am
Small Craft Advisory...Pigeon pt to pt pinos 0-10 nm until 3 am
Small Craft Advisory...pt Arena to Pigeon pt 10-60 nm
Small Craft Advisory...pt pinos to pt Piedras Blancas 0-10 nm
Small Craft Advisory...Pigeon pt to pt Piedras Blancas 10-60 nm
Small Craft Advisory...pt Arena to pt Reyes 0-10 nm
Small Craft Advisory...mry Bay until 9 PM
Public forecast: Sims
aviation: west pi
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