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Area forecast discussion 
National Weather Service San Francisco Bay area
946 am PDT Wednesday Jul 1 2015

Synopsis...hot weather expected once again today...especially
across inland portions of the forecast area. Cooler temperatures
are anticipated Thursday through Sunday. Upper level moisture will
also make its way toward our area today and tomorrow which could
lead to a few showers and isolated thunderstorms mainly over the
mountains.

&&

Discussion...as of 09:45 am PDT Wednesday... high pressure over
the Desert Southwest states is dominating the regional weather
pattern today. Middle to high level moisture and energy rotating
around this feature are advecting into central California this
morning and will continue to do so through the day. This will lead
to increasing cloudiness from south to north through the day and
the possibility of some isolated showers and thunderstorms
over southern Monterey and San Benito counties. Forecast models
are struggling to pinpoint the exect location of these potential
showers... and it is possible some may push further northward
later this afternoon and into the evening. This afternoons forecast
package will focus on the when and where of potential convection
over the next few days.

Temperatures today are expected to be similar to yesterdays
readings... with some areas a few degrees warmer and other locations
marginally cooler. The upper high shifts downstream into the weekend
resulting in a gradual cooling trend. The marine layer will
begin to push inland Thursday night and gradually deepen into the
weekend leading to additional cooling for coastal areas.

&&

Previous discussion...as of 3:15 am PDT Wednesday...another warm day is
forecast across our area as a ridge of high pressure remains in
control. 24 hour change shows many locations a few degrees ahead
of yesterday along with generally clear skies. Synoptically only
minor changes are forecast with a ridge of high pressure (around
595 dm at 500 mb) is forecast to remain centered over northern
Nevada while 850 mb temperatures will stay in the 25 to 26c range. Temperatures
will likely be similar to values from Tuesday with highs in the
60s and 70s at the coast with many inland spots in the upper 80s
to around 100. Far inland locations will see readings back in the
100 to 108 degree range.

The position of the high will allow for moist air and a potential
easterly wave to advect in from the south with precipitable water values of 1 to
1.2 inches increasing to around 1.3 inches later today and then to
over 1.5 inches by Thursday. Similar to last night at this time
there remains disagreement with the potential for convection. 0z
NAM showed the potential for convection over the southern quarter
of the County Warning Area later today while the 06z keeps it to the east of our
area. GFS and European model (ecmwf) also keep it to the east. Will keep a mention
for showers and thunder going for southern sections to handle
model disagreement.

Temperatures will cool on Thursday as clouds increase and 850 mb readings
drop 2 to 3c. NAM continues to show instability increasing which
when combined with higher precipitable water values should lead to a better chance
for US to see convection especially for higher elevation spots.
Best chance remains for southern and eastern sections. Worth
noting that similar to today some of the models keep any showers
out of our area for Thursday.

For the remainder of the week temperatures will cool closer to normal
levels as the ridge weakens while the marine layer deepens. In
some far inland locations this will lead to temperatures dropping 20
degrees from values for today. Coastal areas will remain in the
60s and 70s.

Longer range outlook through next week shows typical dry weather
for our entire area.

&&

Aviation...as of 04:30 am PDT Wednesday... compressed marine
layer and shallow in nature will likely impact coastal terminal
and locally inland into ksns. Burn off will be early in the 16-17z
range. VFR this afternoon.

Vicinity of ksfo... VFR and moderate winds

Ksfo bridge approach... similar to ksfo.

Monterey Bay area terminals...LIFR conditions impacting kmry and
nudging toward ksns. Ceilings/fog through 17z. VFR this afternoon.

&&

Climate...record highs for July 1 for selected locations.

Sf Bay area................July 1
Kentfield.................103/1996
San Rafael.................99/1991
Napa......................103/1972
San Francisco..............92/1991
sfo Airport................99/1985
Oakland downtown...........92/1984
Oakland Airport............90/1985
Richmond...................97/1985
Livermore.................110/1950
Mountain View..............97/1985
San Jose..................102/1985
Gilroy....................108/1972

Monterey Bay area............July 1
Monterey...................96/1985
Santa Cruz.................99/1970
Salinas....................85/1996
Salinas Airport............88/1991
King City.................105/1985

&&

Marine...as of 09:26 am PDT Wednesday...light winds and small
seas will continue along central coast as high pressure remains
off the California coast. A weak disturbance will pass by on
Thursday bringing a chance of showers and thunderstorms to the
region.

&&

Mtr watches/warnings/advisories...
... Advisory...North Bay area...East Bay area... and
the Santa Clara Valley.
Small Craft Advisory...sf Bay from noon

&&

$$

Public forecast: drp
aviation: mm
marine: mm
climate: Bell



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