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Area forecast discussion 
National Weather Service San Francisco Bay area
854 PM PDT Wednesday Jul 1 2015

Synopsis... showers and an isolated thunderstorm will remain
possible overnight into Thursday morning. A cooling trend will
begin tomorrow and continue into the weekend as temperatures
approach normal values.

&&

Discussion...as of 8:54 PM PDT Wednesday...it has been an
interesting weather day around the County Warning Area. In the North Bay...East
Bay and Santa Clara Valley temperatures were running in the upper
90s with Livermore reporting a high of 105 and Morgan Hill
reaching 102. Temperatures along the coast were more comfortable
but still relatively warm with Monterey reaching a high of
77...Santa Cruz 82 and San Francisco Airport 74. The other weather
phenomena of interest was an upper level circulation...a vorticity
maximum...which interacted with monsoon moisture and elevated
instability to trigger some showers and even a few thunderstorms
around the forecast area.

The current satellite water vapour image continues to show a dome
of high pressure centered over the south western states with
another round of monsoon moisture pushing into Southern
California. A low pressure system is also present in the Gulf of
Alaska pushing into northwestern Canada. The 1800z gfs40 and 1200z
European model (ecmwf) have initialized well with the current synoptic pattern and
remain in good agreement through the forecast period. Both models
shift the position of the dome of high pressure...which will
result in a cooling trend for the forecast area...bringing
temperatures back to normal through the weekend.

In the near term the 1800z nam12 is showing some elevated
instability and moisture working its way into the forecast area
overnight tonight which will support the possibility of showers
and even an isolated thunderstorm around the forecast area
tonight. Over the past several runs the European model (ecmwf) and gfs40 have also
been suggestion convective precipitation for our forecast area
tonight...adding confidence to the forecast. By Thursday morning
this threat begins to diminish for most of the area with the
exception of portions of the Los Padres National Forest and
portion of San Benito County which could see showers and isolated
thunderstorms into the afternoon and early evening hours.

&&

Aviation...as of 4:56 PM PDT Wednesday...for 00z tafs. Showers
and isolated T-storms are rotating offshore over Monterey County
at this time but isolated activity remains possible for areas
south of San Jose. Hard to get a gage on the marine layer but it
appears very shallow offshore at this time. Low confidence on
return but for now will show some late night stratus at Bay area
terminals with expectation that any morning ceilings will mix out
by 16-17z.

Vicinity of ksfo... VFR with high clouds this evening and a
light to moderate westerly seabreeze. Low confidence for ceilings
returning by morning.

Ksfo bridge approach...similar to ksfo.

Monterey Bay area terminals...isolated showers and T-storms this
evening then some low stratus to push back inland overnight.

&&

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 4:41 PM PDT Wednesday...high pressure across the
coastal waters will maintain light winds and seas through the
forecast period. A weak disturbance will pass by on Thursday
bringing southwesterly winds and a chance of showers and
thunderstorms to the region.

&&

Mtr watches/warnings/advisories...
...

&&

$$

Public forecast: Larry
aviation: rww
marine: CW
climate: Bell



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