Scientific Forecaster Discussion
fxus66 kmtr 281740
Area forecast discussion
National Weather Service San Francisco Bay area
1040 am PDT sun may 28 2017
Synopsis...dry weather and seasonable temperatures are forecast for
the remainder of the Holiday weekend. Slight cooling is expected for
inland areas on Tuesday and Wednesday, but otherwise little
change is forecast through the week.
Discussion...as of 10:10 am PDT Sunday...widespread clouds at
the coast and adjacent inland locations are expected to burn-off
to the water later in the day. Due to most areas will be a bit
warmer than yesterday -- 70s and 80s inland with upper 50s to near
70 at the coast. Look for clouds to return tonight along with
some patchy drizzle.
Overall, very quiet week shaping up. No major updates planned.
Previous discussion...the marine layer has been rather ill-
defined overnight and low clouds have been slow to develop,
especially from Santa Cruz County southward. However, satellite
currently shows that low clouds have filled in around most of San
Francisco Bay and are gradually developing elsewhere.
Low clouds are expected to clear from inland areas by late this
morning, but only partial afternoon clearing is likely at the
coast. The airmass above the marine boundary layer has warmed
since yesterday and this will translate into warmer afternoon
highs for most inland areas. Temperatures in coastal areas today
will probably be similar to yesterday.
The upper ridge currently centered over California is forecast to
shift gradually eastward over the next few days. This is expected
to result in at least modest cooling in coastal areas on Memorial
Day. But temperatures for inland areas are forecast to hold
steady. The upshot is that our area can expect only minor changes
for the remainder of the Holiday weekend, with areas of night and
morning low clouds continuing. Temperatures will remain slightly
cooler than normal in coastal areas and near normal inland.
A weak upper trough is forecast to gradually develop near the West
Coast by Tuesday. This should result in at least modest cooling on
Tuesday and Wednesday, especially inland, as a cooler airmass
overspreads our area. However, model guidance, especially the
ECMWF, indicate very little change in temperatures as we move
through the week.
The models forecast periodic isolated light precipitation across
northern California from late Monday through Wednesday as the
upper trough settles in. Nearly all of this precipitation is
expected remain over the higher mountains to our north and east.
However, the 00z European model (ecmwf) shows isolated light precipitation across
portions of our area on Wednesday as a shortwave trough moves
through. Forecast confidence is not yet high enough to add rain
chances to the forecast. However, patchy drizzle is certainly
possible at times in coastal areas, particularly from late Monday
night through Wednesday morning.
Aviation...as of 10:40 am PDT Sunday...the marine layer
thickened somewhat so burn-off times might be a little later at
sfo. Expect VFR by noon at all airports. Cigs are expected to
Vicinity of ksfo...MVFR cigs clearing 18-19z. Cigs return
Sfo bridge approach...similar to ksfo.
Monterey Bay terminals...IFR to MVFR cigs this am. Clearing
Marine...as of 10:36 am PDT Sunday...northerly winds will
increase across all waters today as high pressure builds off the
West Coast. The gusty winds will produce hazardous conditions
with steeper wind waves and fresh swell. Winds will decrease
Tuesday night as a weak frontal system moves through the coastal
... Arena to pt Reyes 0-10 nm
Small Craft Advisory...pt Reyes to Pigeon pt 0-10 nm
Small Craft Advisory...Pigeon pt to pt pinos 0-10 nm
Small Craft Advisory...pt pinos to pt Piedras Blancas 0-10 nm
Small Craft Advisory...pt Arena to Pigeon pt 10-60 nm
Small Craft Advisory...Pigeon pt to pt Piedras Blancas 10-60 nm
Small Craft Advisory...mry Bay
Small Craft Advisory...sf Bay from 12 PM
Public forecast: Bell/dykema
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