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Area forecast discussion 
National Weather Service San Francisco Bay area
433 am PDT Thursday Oct 2 2014

Synopsis...very warm to hot weather can be expected across our
entire area through Friday as strong high pressure builds over
California and offshore flow continues. Coastal areas will
experience subtle cooling over the weekend as offshore flow
weakens...but inland areas will continue to see very warm to hot
conditions. Gradual cooling is then expected in all areas early
next week as onshore flow redevelops.

&&

Discussion...as of 3:00 am PDT Thursday...all eyes will be on the
temperatures across our area today and tomorrow as a ridge of high
pressure moves overhead along with warming aloft, a squashed
marine layer, plus an offshore flow. As expected, clear skies have
continued all night along with drying in the column. In fact, some
humidity levels are running 20% less than this time yesterday
morning and a few spots have dew points into the middle 30s.

So, the question of the day for both today and tomorrow is not
will it be warm and sunny both days, but rather just how warm will
it get. European model (ecmwf) MOS guidance just came in and it continues to
advertise a very hot event for almost all locations including San
Jose now getting into the lower 100s on Friday while upper 80s to
middle 90s make it down to many coastal spots. On the other hand,
guidance from the GFS and NAM both are continuing to depict a
less intense heat event -- in most spots they have highs 6 to 12
degrees less than the European model (ecmwf). The European model (ecmwf) numbers were a bit of a
surprise in light of the 850 mb temperature forecast for the next three
days around a degree cooler compared to yesterday's runs. What it
may be weighing in the equation is yesterday turned out to be
hotter than most of the models were projecting which would counter
the slight drop in 850 values. In the past the European model (ecmwf) has done a good job
with heat events and with the GFS showing more than a 5 mb
positive Standard deviation for 1000 mb temperatures over our waters
(thus, strongly suggesting that the heat will make it down to the
coast) feel that the very warm values we are forecasting are
justified. Day crew will want to see how the first hours after
daybreak go to get a better idea if the European model (ecmwf) is overplaying this,
or if it is on track. Will keep the heat advisory going for both
today and tomorrow for all spots.

The other difficulty with heat events around our area is the risk
of seabreeze returning since it could quickly drop temperatures near the
coast in a very quick manner which leads to forecast busts.
General consensus between the models is the best chance for the
seabreeze to kick will be down over southern portions of Monterey
Bay where the flow could Switch Back to more from the northwest.
However, for spots to the north (santa cruz up past point reyes),
winds are expected to remain either neutral or offshore. In fact,
right now 80 degrees would not be out of the question even down to near
the Point Reyes lighthouse!

Some moderation is forecast over the weekend especially near the
coast as the offshore flow switches back to a cooler onshore flow.
However, some caution with a possible cool down as the models are
stalling the eastward progression of the ridge and also bring
warmer 850 mb temperatures across our area. If the hot readings do verify
today the heat advisory will likely need to be extended through at
least Saturday for almost all inland locations. Right now enough
cooling at the coast (6-12 degrees) looks likely to keep those
spots under advisory levels. Look for a few degrees of additional
cooling on Sunday.

The ridge will slowly advance off to the east next work week as a
weak shortwave trough moves toward our area. The marine layer should
deepen once again and drizzle will be likely along the coast
Monday and Tuesday nights. Highs will still be above normal for
most locations especially for inland spots.

Dry weather continues across our entire area through all of next
week as the storm track remains diverted up to Alaska and the British Columbia
coastline.
&&

Aviation...as of 04:30 am PDT Wednesday...clear skies will
prevail across the region through the forecast period. Wind speeds
will generally be light and variable through the early
afternoon...increasing slightly during the late afternoon and
early evening. High confidence.

Vicinity of ksfo...VFR. Light winds.

Ksfo bridge approach...similar to ksfo.

Monterey Bay area terminals...VFR. Light winds.

&&

Marine...as of 3:00 am PDT Thursday...northwest winds will
continue to diminish through today and generally become light by
tonight as high pressure builds over the region. In addition...
long period southwest swell moves into the coast waters by
Thursday night.

&&

Climate...record high temperatures for Thursday through Saturday
(10/2 to 10/4) along with date or dates it occurred.

Sf Bay area
location.................10/2............10/3.............10/4...
Kentfield...............100/2012.........99/2012..........99/1987/1933
San Rafael..............106/1980........105/1980.........100/1980
Napa....................102/1980........103/1917.........100/1987
San Francisco............96/1980.........97/1985.........100/1987
sfo Airport..............96/1980.........94/1985..........95/1987
Oakland (downtown)......103/1980........100/1985..........92/1987/1985
Oakland Airport..........98/1980.........95/1985..........90/1953
Richmond................100/1980.........97/2012..........99/1987
Livermore...............106/1980........106/1980.........106/1980
Moffett field............95/2012.........97/1985..........94/1987
San Jose.................96/2012.........97/1985..........96/1987
Gilroy..................107/1980........106/1980.........103/1980

Monterey Bay area
location.................10/2............10/3.............10/4...
Monterey................101/1980.........96/1985..........94/1953
Santa Cruz..............102/1980........102/1980.........101/1987
Salinas.................100/1980.........97/1985..........98/1987
Salinas Airport.........103/1980.........99/1985.........100/1987
King City...............107/1980........102/1980.........106/1933

&&
&&

Mtr watches/warnings/advisories...
... Advisory...all locations.



&&

$$

Public forecast: Bell
aviation/marine: rgass
climate: Bell

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