Scientific Forecaster Discussion
Area forecast discussion
National Weather Service San Francisco Bay area
527 PM PDT Thursday Jul 24 2014
Synopsis...a warming trend will continue across the region with
the warmest conditions expected Friday afternoon. Above average
temperatures will persist through the remainder of the
weekend...especially inland...as high pressure continues to
dominate the weather pattern.
Discussion...as of 01:45 PM PDT Thursday...clear skies prevail
across the region this afternoon as a result of the building
middle/upper level ridge across the region. In addition...the 12z Oak
sounding shows the 1000mb to 850mb layer has warmed as much as 10
degrees f compared to 24 hours ago. This has kicked off our
warming trend this afternoon with most locations running several
degrees warmer compared to yesterday at this time. The exception
is across the Monterey peninsula where cloud cover hung around a
bit longer this morning and onshore flow persists.
By tomorrow afternoon temperatures at 850mb are forecast to reach
23 to 27 degrees c. As the thermal surface trough shifts toward
the coast...inland temperatures will likely reach into the 90s
and as high as 105 in the East Bay valleys. Urban areas in the
San Francisco Bay area down to the Santa Clara Valley will range
from the upper 80s to upper 90s...the city of San Francisco will
likely warm into the lower 80s. Well above average temperatures
are also expected around the Monterey Bay...yet weak onshore flow
should keep conditions from reaching a level of major concern.
Expecting temperatures to cool slightly for the remainder of the
weekend as onshore flow increases...yet remain above seasonal
averages. Will continue to have to watch for possible middle-level
moisture that may once again advect along the back side of the
ridge over the Desert Southwest into our area late in the
weekend. Could see an increase in middle and high level clouds with
this...yet not too concerned of any convection at this point.
Something Worth keeping an eye on in the coming days.
By early next week...persistent onshore flow will likely have
cooled sea surface temperatures back to normal values and allow
for a more established marine layer to develop. Thus...overnight
and early morning low clouds will likely return and keep
conditions coolest along the coast. With the ridge aloft...inland
areas will continue at or above normal values for the end of July
and maintain dry weather conditions.
Aviation...as of 5:15 PM PDT Thursday...gradients trending more
offshore today and skies are clear over the area. VFR is expected
through Friday in the sfo Bay area but cannot rule out patchy low
clouds in mry Bay late.
Vicinity of ksfo...VFR through Friday. West winds to 25kt through
Ksfo bridge approach...similar to ksfo.
Monterey Bay area terminals...IFR ceilings returning around midnight.
Confidence is low as it could stay clear all night.
Marine...as of 2:00 PM PDT Thursday...a broad thermal trough
centered over interior California will maintain moderate
northwesterly winds across the coastal waters tonight...generating
steep choppy seas. Winds will decrease late Friday morning as the
thermal trough slides west...weakening the surface pressure
gradient. With the exception of the northern outer coastal waters
generally light winds and gentle seas are expected for the
... Bay north of the Bay Bridge until 9 PM
Small Craft Advisory...sf Bay south of the Bay Bridge until 9 PM
Small Craft Advisory...Monterey Bay until 9 PM
Small Craft Advisory...Pigeon pt to pt pinos 0-10 nm until 9 PM
Small Craft Advisory...pt Arena to pt Reyes 10-60 nm
Small Craft Advisory...pt Reyes to Pigeon pt 10-60 nm
Small Craft Advisory...pt pinos to pt Piedras Blancas 0-10 nm until 3 am
Small Craft Advisory...Pigeon pt to pt pinos 10-60 nm until 5 am
Small Craft Advisory...pt pinos to pt Piedras Blancas 10-60 nm until 5 am
Small Craft Advisory...pt Arena to pt Reyes 0-10 nm
Public forecast: rgass
aviation: west pi
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