Scientific Forecaster Discussion
fxus66 kmtr 280559
Area forecast discussion
National Weather Service San Francisco Bay area
959 PM PST Mon Feb 27 2017
Synopsis... dry weather will return by tomorrow for our entire
area. Dry conditions will then persist through the end of the
work week, along with a warming trend. A system moving into the
Pacific northwest this upcoming weekend may produce light rain
especially on Sunday.
Discussion...as of 9:00 PM PST Monday...no updates needed this
evening. Isolated showers over the hills from Santa Clara
southward to Monterey and San Benito ended as the sun went down
this evening and the radar has been mercifully put into clear air
Mode for the time being. Only short term concern is overnight lows
but expect readings to generally stay above freezing with
dewpoints currently in the upper 30s to around 40. This along with
some left over clouds and still some gusty NW winds on the
backside of the the low impacting Southern California will
preclude any frost or freeze headlines.
Main theme for this week is gradual and modest warming trend with
highs back into the 60s as we get towards midweek but still
seasonably cool overnight lows in the 30s and 40s.
Next chance of rain looks to be Sunday with best chances in the
North Bay. Will see what tonights Euro shows when it comes in but
GFS runs trending wetter beyond this weekend so will need to watch
long range signals closely in the coming days.
Previous discussion...as of 2:00 PM PST Monday...chilly day across
our region today with many spots only in the lower to mid 50s.
Kmux radar has indicated a few showers through the day today --
generally in Monterey and San Benito counties. Amounts have been
light for the locations that have had any tips of the bucket.
Tonight and Tuesday night will be the coolest for the week as cool
air aloft combined with fairly light winds, weak offshore flow and
light winds at the surface will allow for temperatures to drop
back into the 30s. Patchy frost will also be possible.
All signs continue to point to a substantial change in the
pattern as a ridge of high pressure builds into our region by the
middle of the week. Temperatures will warm back into the 60s for
some locations on Wednesday and most urban areas for Thursday and
Friday. Still looks like an outside shot of a lower 70 in Monterey
and san bentio counties. The ridge will flatten out on Saturday
which will lead to minor cooling.
Models are starting to trend wetter for Sunday as a longwave
trough will near the coast. GFS over the past couple of runs has
been fairly bullish with amounts and coverage while the other
models have kept more of the activity to the north with just light
amounts going through our County Warning Area. 12z European model (ecmwf) operational run does show
light rain down to slo County along with the GFS ensemble mean.
Pops were slightly increased and will be increased again tonight
if that trend continues.
Longer range outlook for next week does favor warmer than normal
temperatures along with drier than normal conditions.
Aviation...as of 9:59 PM PST Monday...VFR except patchy low
clouds, freezing fog or frost tonight into Tuesday morning.
Vicinity of ksfo...VFR. West winds generally 15 kt or less.
Sfo bridge approach...similar to sfo.
Monterey Bay terminals...VFR. West winds generally 10 kt or less becoming
mainly light southeast late tonight and Tuesday morning.
Marine...as of 8:49 PM PST Monday...gradually increasing northwest
winds tonight. Winds weaken tomorrow except along the Big Sur coast
where breezy winds will continue. Northwest winds will increase to
become moderate again Thursday through Friday. A small to moderate
northwest swell will continue to move through the coastal waters
... Pt to pt pinos 0-10 nm
Small Craft Advisory...pt Arena to Pigeon pt 10-60 nm until 3 am
Small Craft Advisory...pt pinos to pt Piedras Blancas 0-10 nm
Small Craft Advisory...pt 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 Piedras Blancas 10-60 nm
Public forecast: rww/Bell
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