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fxus66 kmtr 230337 
afdmtr

Area forecast discussion
National Weather Service San Francisco Bay area
837 PM PDT sun Apr 22 2018

Synopsis...dry and seasonable weather for much of the upcoming
work week. An upper low may approach Friday with a slight chance
of showers, mainly for the North Bay but most likely scenario is
all locations stay dry with a modest cooling trend by late in the
week into next weekend.

&&

Discussion...as of 8:37 PM PDT Sunday...temperatures are settling
back nicely this evening under a mainly clear sky, wrapping up a
weekend of mainly clear, mild to warm daytime weather. High pressure
remains in place keeping dry weather and warmer daytime temperatures
going through mid week. The 250 mb jet stream over the eastern Pacific
will carve out a closed mid to upper level low pressure system
later this week. Today's 12z European model (ecmwf) showed additional jet stream
energy carving out another mid to upper level low farther upstream
over the Pacific eventually being the "kicker trough" that moves
the first closed low forward to northern California and the
Pacific northwest bringing a slight chance of showers into the Bay
area later Friday night into Saturday. However, GFS output is at
odds with the European model (ecmwf) solution generally showing higher latitude
northwesterly flow and shortwave energy pouring in bringing a few
more chances of rain into early next week. Either way it looks
like some unsettled, chilly, wetter weather arriving late week and
early next week. The European model (ecmwf) solution, if verified, could tap more
in the way of subtropical moisture.

&&

Previous discussion...as of 2:05 PM PDT Sunday...skies are mostly sunny
this Sunday afternoon with just some thin high clouds over the
region. Temperatures range from around 60 at the beaches, 60s
around the Bay and mid 70s inland with lower 80s showing up
around Stockton. Current dewpoint readings in the mid 50s along
with a strong northerly gradient of nearly 6 mb. This should keep
skies mostly clear with overnight lows from the mid 40s to lower
50s most locations.

Synoptic pattern doesnt change too much through midweek so that
should give US afternoon highs generally in the 70s inland with
60s near the coast. No extreme heat, precip or cold weather under
this pattern.

Next feature we'll be tracking is a cut-off type low coming in
from the west. At the very least onshore flow will increase by
midweek into Thursday with airmass cooling aloft. This should lead
to subtle cooling by Thursday and Friday.

General model trend has been to bring the upper low onshore north
of the Golden Gate later Friday into Saturday. Right now precip
chances look slight/meager at best. However, decided to just keep
the slight chances in the forecast as we'll likely see forecast
simulations oscillate over the next few days. Either way there
does remain a slight chance of showers late in the week. Upper low
should eject inland by next Saturday or Sunday with dry and warm
weather on the backside of that. Spring appears to be here with
dry weather, cut-off lows and no storms of note in sight.

&&

Aviation...as of 4:51 PM PDT Sunday...for 00z tafs...mainly high
clouds present over the region this afternoon with a few clouds
popping up over the hills. Patchy fog possible once again Monday
morning over the North Bay valleys and in the vicinity of the
Monterey Bay. Moderate onshore flow will persist through this
afternoon then diminish this evening with light winds forecast
through tonight.

Vicinity of ksfo...VFR conditions will prevail through the period
with mainly high clouds. Moderate onshore flow of 10 to 20 kt will
persist through this evening with light winds forecast overnight
into Monday morning.

Sfo bridge approach...similar to ksfo.

Monterey Bay terminals...VFR conditions with mainly high clouds
will prevail through late tonight. IFR/LIFR cigs will return
overnight into Monday morning with clearing anticipated around 19z
Monday. Moderate onshore flow around 10 to 15 kt will persist
till this evening with light and variable winds forecast
overnight into Monday morning.

&&

Marine...as of 2:13 PM PDT Sunday...moderate northwesterly winds
will continue through this evening across the coastal waters as
high pressure resides over the eastern Pacific and a trough sits
over the California coast. Brisk winds will continue to produce
steep wind waves and fresh swell resulting in choppy seas through
this evening. Winds will diminish tonight into tomorrow.

&&

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

&&

$$

Public forecast: canepa/rww
aviation: CW
marine: as

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