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fxus66 kmtr 240000 
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Area forecast discussion
National Weather Service San Francisco Bay area
500 PM PDT Sat Sep 23 2017

Synopsis...building high pressure over the eastern Pacific will
result in a gradual warming trend through much of the upcoming
workweek.

&&

Discussion...as of 12:48 PM PDT Saturday...a cool, dry air mass
remains in place over the region this afternoon with temperatures
generally only warming into the 60s and 70s. While a few spots may
top out in the lower 80s inland, temperatures remain below
seasonal averages for most locations. For tonight, temperatures
will cool back into the 40s for most inland valley locations with
light winds and a mainly clear sky. With that said, cannot rule
out a few low clouds developing off of the central coast that may
briefly push inland over the Monterey peninsula early Sunday
morning.

Daytime temperatures nudge up to near seasonal averages on Sunday as
the long-wave trough shifts eastward and a ridge of high pressure
begins to develop over the eastern Pacific. With the building ridge
off of the coast, temperatures will continue on a gradual warming
trend into early next week with very little to no coastal stratus to
speak of. By Tuesday afternoon, widespread 80s will be likely region-
wide with some of the warmest inland valley locations and higher
elevations reaching into the 90s.

The ridge axis is then forecast to shift inland across northern
California by midweek with well above average temperatures likely to
develop. In addition, weak offshore flow will be possible by midweek
which will help drive warmer conditions all the way to the coast.
Currently, Wednesday and Thursday appear to be the warmest days of
the week with mid/upper 80s possible at the coast and widespread 90s
inland. With 850 mb temperatures only forecast to warm to around 18-
19 deg c during this heat event, the heat risk will likely remain
low to potentially moderate. The dry air mass and mainly clear sky
conditions will also allow for modest cooling during the overnight
hours, further reducing any heat risks. Nonetheless, will closely
monitor model trends and adjust the forecast accordingly in the
coming days. Slight cooling is then expected by Friday of next week
as the ridge aloft weakens ahead of a mid/upper level trough to the
north. However, above average temperatures and dry weather
conditions are favored through the extended.

&&

Aviation...as of 4:40 PM PDT Saturday...VFR except patchy IFR
cigs are possible over the Monterey Bay early Sunday morning.

Vicinity of ksfo...VFR. West winds 15-20 kt til 04z this evening.

Sfo bridge approach...similar to ksfo.

Monterey Bay terminals...VFR. Some low clouds possible around
sunrise.

&&

Fire weather...as of 5:00 PM PDT Saturday...a warming and drying
trend is forecast to continue into early next week as high
pressure builds over California. Relative humidity values will
drop into the teens during the afternoon hours while overnight
humidity recoveries will only reach about 30 percent in the higher
hills. In addition, light to moderate northerly or offshore winds
are forecast to continue in the hills. Strongest winds are
expected over the North Bay hills where critical fire weather
conditions are anticipated. A red flag warning is in effect
through Tuesday morning for elevations above 1000 feet in the
North Bay hills. Locally gusty winds are expected elsewhere in
the hills, particularly in the East Bay hills. Warm and dry
conditions are forecast to persist through next week, although
winds in the hills will likely diminish after Tuesday.

&&

Marine...as of 4:36 PM PDT Saturday...high pressure offshore
will bring light to breezy north to northwest winds today and
through the coming days. The northwest swell train that first
arrived several days ago will continue to weaken into early next
week. A different northwest swell train will arrive mid week next
week.

&&

Mtr watches/warnings/advisories...
... Bay until 9 PM
Small Craft Advisory...Pigeon pt to pt pinos 0-10 nm until 9 PM
Small Craft Advisory...pt Arena to Pigeon pt 10-60 nm
Small Craft Advisory...pt pinos to pt Piedras Blancas 0-10 nm until 3 am
Small Craft Advisory...Pigeon pt to pt Piedras Blancas 10-60 nm until 3 am

&&

$$

Public forecast: rgass
aviation: canepa
marine: drp
fire weather: dykema

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