Scientific Forecaster Discussion
Area forecast discussion
National Weather Service San Francisco Bay area
1037 am PDT Tuesday Sep 2 2014
Synopsis...the area will see a cooling trend beginning today as a
low pressure trough approaches the coast. Dry conditions will
persist through the period.
Discussion...as of 8:20 am PDT Tuesday...some cooling for today
compared to yesterday as the marine layer has increased to over
1500 feet with a stronger onshore surface gradient compared to
yesterday. Forecast calls for sunny conditions for almost all
locations by afternoon although will keep a close eye on that if
the burn-off doesn't go as planned. Highs will generally be in the
middle 60s to middle 70s at the coast with upper 70s to around 90 well
inland. This will average out to a 5 to 10 degree drop for inland
locations with a small change expected near the water.
Looks very quiet through the forecast period with a longwave trough
advance to our area and then becoming fairly stationary at least
through the weekend. Outside of some coastal drizzle, no
precipitation is expected.
Previous discussion...with a marine layer depth of around 1200
feet...the satellite infrared fog product imagery is showing coastal
stratus extending from Point Reyes south...and pushing into the
Salinas valley. Expect cooler temperatures today across the
district as an upper level trough approaches the coast. This
trough is prognosticated to remain over the eastern Pacific resulting in
continued cooling through about middle to late in the week. Night and
morning coastal low clouds are expected as well as possible
drizzle right at the immediate coast during the early morning
hours. High temperatures are expected to remain around or slightly
below normal through the latter part of the week and into next
weekend as onshore flow persists.
Aviation...as of 10:30 am PDT Tuesday...northwest flow through the
Golden Gate is making stratus at Oak unusually persistent while
mry Bay area terminals will be slow to burn off as well. Should see
full clearing by at least afternoon. Stratus likely to be more
widespread tonight as the marine layer deepens.
Vicinity of ksfo...VFR today. Light to moderate onshore winds.
Stratus late evening.
Ksfo bridge approach...similar to ksfo.
Monterey Bay area terminals...northwest flow will keep ceilings at mry through
at least the rest of the morning with early return. Sns to burn
off within the next hour followed by early return this afternoon.
Marine...as of 5:00 am PDT Tuesday...high pressure continues off
the Pacific northwest coast. A thermal trough will shift to the
coast resulting in decreasing winds over the area except for the
outer waters north of Point Reyes.
... Arena to pt Reyes 10-60 nm
Small Craft Advisory...pt Reyes to Pigeon pt 10-60 nm until 3 PM
Small Craft Advisory...sf Bay north of the Bay Bridge from 1 PM
Public forecast: Bell/Sims
marine: west pi
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