Scientific Forecaster Discussion

Return to Local Conditions & Forecast

Without Abbreviations
With Abbreviations

fxus66 kmtr 272338 

Area forecast discussion
National Weather Service San Francisco Bay area
438 PM PDT Thu Apr 27 2017

Synopsis...continued breezy conditions at times on Friday,
particularly near the coast and in the hills, with a gradual
warming trend. Winds will ease by Saturday morning then clear and
warm weather is forecast over the weekend and into early next week
with no rain in the extended forecast.

&& of 2:15 PM PDT Thursday...synoptic pattern today
features cyclonic flow aloft with strong onshore surface
pressure gradients that have kicked up strong afternoon northwest
winds along the coast and coastal hills.

Overnight as the main longwave trough digs over the Great Basin the
response along the California coast will be a developing thermal
trough at the surface which will push the winds to a more north or
northeast direction by Friday morning. This will bring some 35 mph
winds to the north and East Bay hills Friday morning and allow for
some favorable downslope winds. So under clear skies expect
temperatures to warm well into the 70s to wind out the work week.

Winds will ease for a time Friday afternoon, except right at the
beaches where north winds will continue. Then again Friday night
into Saturday another round of offshore winds will develop in the
hills. This time with a drier and warmer airmass in place. This will
set the stage for a magnificent Saturday morning to start out the
Bay area weekend. If you get out early enough you'll almost be able
to smell the warmth as the offshore winds usher in a drier airmass
with no marine layer to speak of. Saturday should be the warmest day
so far this year for many locations with highs climbing into the 80s
for may of the inland valleys, especially in the north and East Bay
where favorable downslope wind flow will continue.

By Sunday the offshore winds will have eased but the stage will be
set for several days of ideal Spring Time weather with clear skies
and daytime highs generally in the 70s and 80s for much of the Bay
area and likely even some near 90 degree readings for southern
Monterey County.

The earliest it looks like the ridge will break down would be around
next Thursday. Will see if we get any stratus intrusions before that
but it looks like a real nice period of warm and dry weather coming
up for the region.

&& of 4:38 PM PDT Thursday...near high confidence dry
northerly winds will keep VFR going at the terminals tonight and
Friday. Only exception is there may be a few patchy low clouds
along the immediate coastline early Friday morning, otherwise VFR
is forecast with few-sct thin cirrus.

Vicinity of ksfo...VFR. Gusty west-northwest winds near 30 knots this evening
gradually relaxes tonight, then resumes and becomes gusty from the
west-northwest again Friday.

Sfo bridge approach...VFR.

Monterey Bay terminals...VFR. Patchy IFR cigs are possible over the
southern Monterey Bay area per WRF model output, kmry tempo 12z-16z
broken 800 feet.

&& of 2:15 PM PDT Thursday...the forecast remains on
track with high pressure taking over the weather pattern. The
pressure gradient will tighten across the waters in response to
building high pressure causing northerly winds to increase over
the next couple of days. Wind gusts should reach 25 to 30 kt today
and Friday. Some isolated gale force gusts will even be possible
offshore and near coastal points. Then fresh north winds will
persist into the weekend. Seas will become quite steep due to the
winds and a mid period westerly swell will continue to impact the
waters through the weekend. The existing small craft advisories
will remain in effect.


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



Public/marine: National Weather Service Eureka
aviation: canepa

Visit US at www.Weather.Gov/sanfrancisco

National Weather Service Glossary of Abbreviations