Scientific Forecaster Discussion
Area forecast discussion
National Weather Service San Francisco Bay area
900 PM PDT Thursday may 28 2015
Synopsis...a modest warming trend remains on track through
Saturday as a ridge of high pressure continues to build along the
West Coast. This warming trend will be most apparent inland.
Cooler temperatures are expected beginning Sunday as a low
pressure system approaches the coast. There is a slight chance of
showers across the North Bay from late Sunday into Monday with
night time coastal drizzle expected.
Discussion...as of 8:58 PM PDT Thursday...temperatures finished
off several degrees warmer than yesterday with inland temperatures seeing
the greatest warming. Our warm spot today was Parkfield in
southern Monterey County with a high of 91 degrees. Coastal
locations actually experienced slightly cooler temperatures due to
coastal low clouds as well as a slightly more robust seabreeze.
The slight warming trend experienced over inland areas today was
sparked by a ridge of high pressure currently building over the
region. This high has also compressing the marine layer down to
around 1500 feet this evening. Satellite imagery continues to
Show Low clouds hugging the coast at this hour with some inland
penetration through coastal gaps and valleys. While the district
will awake to widespread stratus a shallower marine layer will
likely lead to an earlier burn off time.
Little change in the weather is expected Friday and Saturday as
the ridge remains over the region. However a change in the pattern
is on the way. Two low that are spinning near 39n 138w and 40n
150w are forecast to merge before making their way east. This
system is forecast to reach the coast Sunday bringing a chance of
showers to the North Bay. A slight chance of light showers or
drizzle is possible from the Bay area south. However showers will
likely be in the form of patchy drizzle along the coast to hit-or-
miss showers. Cooler temperatures are also in-store into early
next week as the trough passes through the region.
Forecast remains on track...no updates at this time.
Aviation...as of 4:45 PM PDT Thursday...the marine layer had
compressed slightly to about 1500 feet on Thursday afternoon and
onshore gradients had decreased a bit. However...these changes
were not enough to delay an inland influx of marine clouds.
Expect an early return to MVFR/IFR ceilings late Thursday afternoon
and early Thursday evening. The marine layer depth is expected to
continue to trend down overnight and into Friday morning...and so
expect slightly earlier clearing on Friday compared to today.
Vicinity of ksfo...MVFR ceilings by 01z...and IFR ceilings by 04z.
IFR/MVFR ceilings then persisting until 18-19z Friday. Gusty onshore
winds through middle evening...19g26kt...then decreasing overnight.
Ksfo bridge approach...similar to ksfo except MVFR ceilings developing
about an hour later than at ksfo on Thursday and clearing
slightly earlier on Friday.
Monterey Bay area terminals...widespread MVFR ceilings will develop by
02z with IFR ceilings by 04z. IFR ceilings then continuing through much of
Friday morning. Light to moderate onshore winds.
Marine...as of 08:39 am PDT Thursday...high pressure along the
California coast will result in light to locally moderate
northwest winds. The strongest wind speeds will be through the
northern San Francisco Bay...off of the Sonoma coastline and along
the Big Sur coastline. Predominately gentle seas will persist
through the forecast period.
Beaches...as of 10:50 am PDT Thursday...a westerly swell of 5 to
7 feet with a period around 14 seconds will continue to move into
the coastal waters today. The combination of this swell and
generally weak onshore winds will result in an increased risk of
strong rip currents along area beaches through this evening.
... Pinos to pt Piedras Blancas 0-10 nm
Public forecast: CW
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