Scientific Forecaster Discussion

Return to Local Conditions & Forecast

Without Abbreviations
With Abbreviations

Area forecast discussion 
National Weather Service San Francisco Bay area
459 am PST Monday Nov 24 2014

Synopsis...high pressure will bring sunny and seasonably warm
weather today through Thanksgiving day with dry weather for the
Bay area and California. The ridge will break down by Friday with
rain chances increasing north of the Golden Gate by Friday
evening. Rain chances will spread southward through the rest of
the Bay area and central coast Saturday into Sunday.

&& of 2:24 am PST Monday...quiet weather in the
short term. Skies are mostly clear early this morning with just
some thin high clouds passing overhead. The boundary layer is dry
with dew points around 40 degrees along with some light offshore
flow. This combination should keep the Bay area essentially fog
free this morning and right through midweek. High pressure building over
the region will bring strong Santa Ana winds to Southern California
but weather for the Bay area will be tranquil with seasonably warm
afternoons from the upper 60s to upper 70s through Wednesday. Right now
Tuesday and Wednesday look to be the warmest days this week with some
lower 80s possible for the interior valleys of Monterey County.
Good travel weather with no precipitation...Tule fog and marine layer
expected to impact aviation or auto travel plans right through

Main weather item of interest will become the long range forecast.
Still several days out and don't want to get too specific as daily
model changes still likely to occur. Bottom line is pretty good
consensus for rain developing in the North Bay later Friday into
early Saturday with an initial weak system. Subsequent wetter
systems then prognosticated to move onshore later Saturday into Sunday.
Only fly in the ointment could be strong southerly flow that isn't
ideal for orographics. However that's subject to change and upper jet
dynamics could be quite strong. At this time Sunday looks to be
the wetter of the two days this weekend as stronger energy moves
onshore. Still not confident enough to start advertising rain
totals and specific impacts but given the Sunday after
Thanksgiving is a busy travel day those with travel plans should
follow the forecasts as travel delays would appear likely
including aviation...wet Bay area roads and potentially
significant snow over the Sierra passes.

Models augur unsettled pattern at least through the middle of next
week. Fingers are crossed for some wet weather and long range
signals are in our favor including the pna teleconnection going
negative as well as a fairly strong mjo signal moving into phase 3
suggesting wetter than normal conditions along the West Coast
which not surprisingly is supported by the cfs v2 model as well as
the latest 6-10 and 8-14 day CPC precipitation forecasts.

&& of 5:00 am PST Monday...dry airmass will bring VFR
conditions today.

Vicinity of ksfo...VFR.

Ksfo bridge approach...similar to ksfo.

Monterey Bay area terminals...VFR.

&& of 5:00 am PST Monday...a ridge of high pressure
extends from off the California coast into the northern
California and Nevada. The high will move into the Great Basin
Wednesday as a frontal system moves into the Pacific northwest.
Light northerly winds will switch to southeast Wednesday and


Mtr watches/warnings/advisories...


Public forecast: rww
aviation: west pi
marine: canepa

Visit US at weather.Gov/sanfrancisco

Follow US on facebook, twitter, and youtube at:

National Weather Service Glossary of Abbreviations