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Area forecast discussion 
National Weather Service San Francisco Bay area
253 PM PDT Tuesday Jul 28 2015

.Very warm to hot inland temperatures expected through Thursday
of this week....

Synopsis...hot temperatures are expected to continue across the inland
areas through midweek...with warm temperatures at the coast as
strong high pressure builds over the region. Temperatures cool
slightly late in the week along with increased monsoon moisture
approaching from the south. The monsoon moisture combined with
lingering instability will promote the possibility of showers and
isolated thunderstorms by the end of the week.

&&

Discussion...as of 2:54 PM PDT Tuesday...the current visible
satellite image is showing sunny skies around the forecast area
this afternoon...with the exception of the Big Sur coast and
portions of the Monterey Bay where low clouds and fog are
lingering. Under the mostly sunny skies temperatures have risen
into the upper 80s to upper 90s in the inland areas with a few
100s...keep in mind that we still have a few hours of heating left
in the day. With this in mind a few records may fall today.
Temperatures are cooler along the coast but remain fairly warm
with weather forecast office Monterey reporting a current temperature of 75...77 in
Santa Cruz and 77 at Montara.

The current satellite water vapour image is showing a ridge of
high pressure continuing to build over the eastern Pacific and
California coast with a low pressure system sliding east along the
Canadian and US border. A large area of high pressure is also
centered over the central Great Plains. Tropical depression 8 is
also speeding along...currently located around at 15 north and
129 west. The 1200z gfs40 and European model (ecmwf) have initialized well with
these synoptic features and have come into good agreement through
Tuesday.

Both of the previously mentioned models continue to build the
ridge of high pressure over California reaching about 591 dm by
tomorrow with 850mb temperatures hovering around 24 to 25 degrees
celsius Friday morning. This translates into hot temperatures at
the surface...especially for the inland areas which are expected
to reach into the upper 90s to 105 on Wednesday before cooling a
few degrees on Thursday. Offshore winds will keep the coast fairly
warm to with afternoon highs expected to be in the upper 70s to
middle 80s.

Humid conditions will return to the area Friday as monsoon
moisture pushes into California. With really hot temperatures
leading into the arrival of the monsoon moisture there will be
some instability to support showers and isolated thunderstorms
Friday afternoon. The challenge is that the forecast models have
been bouncing around with the trajectory of the moisture and
location of instability. However...the past few models runs of the
gfs40 have been generating precipitation over portions of the County Warning Area
this coming Friday and the nam12 is now also generating
precipitation over the County Warning Area Friday afternoon...adding confidence to
the possibility of showers and isolated thunderstorms for the end
of the week. At this point the exact location of showers and
thunderstorms will remain a low confidence forecast. I have
expanded the areal coverage of showers and isolated thunderstorm
in the afternoon forecast package. We will fine tune the threat
as we near Friday and the models zero in on a more defined
solution.

&&

Aviation...as of 10:45 am PDT Tuesday... widespread VFR
conditions across the area today. Brief patchy fog posbl at or
before sunrise tomorrow morning.

Vicinity of ksfo...VFR conditions will prevail through the forecast
period. Afternoon winds increasing to 15 to 20 knots.

Ksfo bridge approach...similar to ksfo.

Monterey Bay area terminals...VFR conditions will prevail through
most of the forecast period. Brief patchy LIFR ceilings/visbys from
fog at or below sunrise Wednesday. Winds 12kt or less.

&&

Climate...here are record highs for Tuesday through Thursday
across our area along with the last year the record was recorded.

Sf Bay area..............7/28............7/29............7/30
Kentfield..............98/1934........105/1954........105/1977
San Rafael............104/1980........101/1977........102/1977
Napa..................107/1954........105/1954........103/1977
San Francisco..........84/1954.........83/1977.........85/1986
sfo....................88/1954.........91/1977.........97/1977
Oakland................76/1977.........98/1977.........95/1977
Oakland Airport........96/1954.........91/1977.........95/1977
Richmond...............88/1954.........82/1967.........80/1993
Livermore.............106/1980........108/1954........107/1979
Mountain View..........93/1954.........93/1977.........97/1977
San Jose..............100/1954.........95/1977........102/1995
Gilroy................101/1995........102/1980........106/1977

Monterey Bay area........7/28...........7/29.............7/30
Monterey...............85/1954........86/1977..........91/1977
Santa Cruz.............92/1947........88/1964.........102/1977
Salinas................92/1954........95/1977..........86/1995
Salinas Airport........84/1967........92/1977..........84/1977
King City..............99/1967.......105/1977.........106/1977

&&

Marine...as of 10:37 am PDT Tuesday...northwesterly winds will
gradually decrease through the day today as the pressure gradient
weakens. Locally gusty winds will linger over the northern outer
waters through this afternoon.

&&

Mtr watches/warnings/advisories...
... Arena to Pigeon pt 10-60 nm until 3 PM
Small Craft Advisory...sf Bay until 9 PM

&&

$$

Public forecast: Larry
aviation: drp
marine: mm
climate: Bell/Benjamin



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