Scientific Forecaster Discussion
Area forecast discussion
National Weather Service San Francisco Bay area
1026 PM PDT Tuesday Jul 22 2014
Synopsis...a gradual warming trend is expected to begin on
Thursday and continue into the upcoming weekend as high pressure
builds over the region.
Discussion...as of 9:00 PM PDT Tuesday...the middle/upper level
shortwave that caused elevated convection to develop across the
region this morning has moved into northern California. Satellites
detected several cloud-to-ground lightning strikes around the
northern sfo Bay area between 4-6 am this morning. There were
numerous reports of measured rainfall with the National Weather Service downtown San
Francisco gage receiving .04 inches.
Another shortwave is currently centered 350 miles west of San
Francisco but this system will lift northeast into northern
California. Chances of more convection are very unlikely but
there will be increasing stratocumulus clouds from the sfo Bay
area north with local drizzle possible along the coast and coastal
A strong upper level low will be moving through the Pacific
northwest Wednesday. A trailing frontal system will pass through
far northern California which will keep high temperatures near to
slightly below normal. Sea surface temperatures continue to run
in the low 60s in the northern waters and middle 60s in the central
waters and this will continue to bring mild above-normal temperatures
to the coastal areas.
The low will move inland on Thursday and an upper level high over
the southwest will build westward into the southern half of
California. This will bring 5-10 degrees of warming to the
district Thursday that will last into the weekend. Coastal
temperatures should warm into the upper 60s to lower 70s with
middle 80s to middle 90s inland and near 100 degrees over parts of the
Aviation...as of 10:15 PM PDT Tuesday...residual surface humidity
and weak low level instability resulted in some strato-cumulus cloud
development over the Bay area late this afternoon. The clouds have
dissipated over the central coast but have held together over the
Bay area for the time being. It's much drier aloft according to the
00z Oakland upper air sounding.
Vicinity of ksfo...low cloud cover persisted a little longer through
the evening but is seemingly scattering out at this time. VFR is
forecast for the period.
Ksfo bridge approach...similar to ksfo.
Monterey Bay area terminals...patches of low clouds are likely to
Marine...as of 02:15 PM PDT Tuesday...light winds over the coastal
waters will continue through tomorrow morning due to a weak
pressure gradient. Tomorrow afternoon northwest winds increase as
high pressure strengthens over the eastern North Pacific.
Public forecast: west pi
Visit US at weather.Gov/sanfrancisco
Follow US on facebook, twitter, and youtube at: