Scientific Forecaster Discussion
Area forecast discussion
National Weather Service San Francisco Bay area
851 PM PDT sun Mar 16 2014
Synopsis...the marine layer will deepen overnight as a dry cold
front passes over northern California. The deeper marine layer and
strengthening onshore flow will promote cooler temperatures on
Monday but the forecast remains dry through the week with temperatures
in the 60s and 70s.
Discussion...as of 8:51 PM Sunday...the final low light visible
satellite image is showing stratus beginning to impact southern
Monterey Bay this evening as well as the San Mateo coastline. The
marine layer is expected to deepen to around 1200 feet overnight
so expect a cloudy Monday morning along the coast with stratus
also expected to push into northern portions of the Salinas
valley. Current high resolution WRF forecast model shows the
stratus sticking around the Monterey Bay area through early
afternoon. These low clouds combined with light onshore flow will
result in cooler temperatures Monday with Monterey only expected
to reach a high of 62. Cooler temperates are also expected in the
San Francisco Bay area as well. The afternoon temperature at sfo
is forecast to be 66 degrees and 69 degrees in Redwood City.
The 0000z European model (ecmwf) and gfs40 have initialized well with the current
synoptic pattern and remain in good agreement into the weekend.
Both models indicate a ridge of high pressure over the eastern
Pacific Monday with a trough of low pressure pushing into the
Pacific northwest. The trough pushing into the Pacific northwest
will move into the Great Basin by late Monday morning. As this
trough exits to the east the offshore surface pressure gradient
strengthens over central California. This will result in gusty
northerly winds across the north and East Bay hills Monday night
into Tuesday morning. Generally light offshore winds are then
expected to persist into at least middle week providing warm
temperatures to the forecast area. The current forecast package
depicts this scenario well so no updates are needed at this time.
Discussion...as of 1:52 PM PDT Sunday...a sunny and warm
afternoon except right along the coast where some fog and low
clouds have lingered outside the Golden Gate and along the San
Mateo coast. A hose of moisture is pointed at the Pacific
northwest but any moisture will stay north of Cape Mendocino as a
dry front passes through northern California overnight into
Monday. The impact around here will be noticeably cooler
temperatures on Monday...especially away from the coast. Skies
will turn sunny after any morning clouds but highs generally in
the 60s on Monday afternoon.
Skies will remain clear Monday night into Tuesday with northerly
wind flow setting up. Winds in the north and East Bay hills will
increase through early Tuesday morning but not expecting any wind
advisories. Unlike last weeks event...the pattern is more
transient and not expecting the same kind of upper level support.
The airmass will be dry and expect some of the inland valley sites
to fall into the upper 30s by Tuesday morning. Readings in the
hills will stay in the 40s with strong mixing of winds.
Of course we need the rain but that's just not in the cards this
week. The pattern looks fairly non-descript with zonal flow
leading to temperatures running 4-8 degrees above normal for much
of this week. Normals are in the middle 60s and we should see plenty
of afternoons in the 70s this week. Surface gradients remain
fairly robust so no reason to expect a well defined marine layer
so plenty of sunshine through the week...even near the coast. High
confidence for dry weather at least through next Sunday.
Models are in reasonably good agreement for a possible trough by
about March 25/26 but that's 10 days out and we've seen this trend
all winter where the models hint at precipitation around day 10. The one
thing that's a positive is the pna is forecast to trend negative
and for what its Worth the European model (ecmwf) shows the mjo strengthening into
phase 2 and 3 but the predictability of those tools is marginal at
best as we head towards April.
Aviation...as of 4:45 PM PDT Sunday...there is a slight hint of
marine air noted on The Fort Ord profiler. Area metar observation do show
more sea-breezes along the immediate coastline compared to Sat
afternoon. Temperatures well inland were warm to hot.
The ocean based stratus field is more broken up compared to what it
looked like yesterday at this time. Model guidance leans toward
cloudiness for kmry and ksns. VFR is forecast elsewhere. The trough
approaching from the northwest tonight could bring in more low clouds
than presently forecast...also there's decreasing confidence in
Vicinity of ksfo...VFR. West winds below 20 knots this evening.
Ksfo bridge approach...similar to ksfo.
Monterey Bay area terminals...VFR this evening...followed by IFR
developing between 05z-06z.
Climate...record high temperatures for March 16
along with the most recent date the record occurred.
Sf Bay area
location................ sun 16
San Rafael.............. 87/1972
San Francisco........... 85/1914
sfo Airport............. 82/2004
Oakland (downtown)...... 85/2004
Oakland Airport......... 83/2004
Moffett field........... 84/2004
San Jose................ 85/2004
Monterey Bay area
location................ sun 16
Santa Cruz.............. 86/1914
Salinas Airport......... 87/2004
King City............... 91/2007
Marine...as of 4:45 PM Sunday...a high surf advisory remains in
effect through 8 am Monday morning. West facing beaches will have
an increased risk for rip currents and sneaker waves. Local
breakers around 18 feet are possible late this evening and
... Surf advisory...along the coast until 8 am Monday
Small Craft Advisory...pt pinos to pt Piedras Blancas 0-10 nm from 9 PM
Small Craft Advisory...pt pinos to pt Piedras Blancas 10-60 nm from 9 PM
Small Craft Advisory...pt Arena to pt Reyes 0-10 nm from 3 am
Small Craft Advisory...pt Reyes to Pigeon pt 0-10 nm from 3 am
Small Craft Advisory...pt Arena to pt Reyes 10-60 nm from 3 am
Small Craft Advisory...pt Reyes to Pigeon pt 10-60 nm from 3 am
Small Craft Advisory...Pigeon pt to pt pinos 10-60 nm from 3 am
Small Craft Advisory...rough bar advisory for sf bar until 3 am
Public forecast: Larry/rww
aviation: canepa marine: rgass/canepa
climate: surface observation/mm
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