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fxus66 kmtr 141205 
afdmtr

Area forecast discussion
National Weather Service San Francisco Bay area
405 am PST Thu Nov 14 2019

Synopsis...cloudy and seasonably cool today as an upper trough
passes over the region. Another weak system will approach from the
northwest tonight into early Friday and some sprinkles or drizzle
cant be ruled out, especially for the coastal hills. Otherwise
turning partly cloudy and warmer by Friday afternoon. High
pressure builds this weekend leading to a warming trend with
mostly sunny skies. Dry pattern continues at least through early
next week.

&&

Discussion...as of 3:15 am PST Thursday...skies are mostly cloudy
early this morning and that trend will continue through much of
today as a weak and mainly dry upper trough passes over the
region. The cloud cover and light winds off the ocean have kept
temperatures mild overnight, mainly in the 50s. Temperatures wont
warm too much today, mainly due to thick cloud cover. Cool
advection with this front is not strong. In addition surface
pressure gradients remain light due to lack of a well defined
surface boundary. This along with cloud cover will keep
temperatures fairly isothermal and thus not expecting any strong
winds today. Gridded forecast will show some patchy
sprinkles/drizzle mainly along the coast and the coastal hills
from Sonoma to Santa Cruz but qpf looks to be trace amounts as the
synoptic forcing from the upper trough lifts the marine layer and
squeezes out some drizzle.

Tonight a weak shortwave moving in towards Cape Mendocino may
generate a few showers over the coastal waters and more likely for
locations north of Sonoma cnty. However, the forecast will show a
few sprinkles, mainly for northwest Sonoma County into Friday
morning. This front will wash out Friday morning leaving plenty of
residual low level clouds and morning fog along the slopes due to
the deepening of the marine layer.

Look for partly cloudy skies by Friday afternoon with temps
trending a few degrees warmer into the upper 60s and even some
lower 70s.

The weekend looks real nice as high pressure builds into norcal.
Look for plenty of sunshine with afternoon highs into the 70s.
Sunday looks to be a few degrees warmer than Saturday if you're
trying to make outdoor plans. There will be some dry northeast
winds in the hills but nothing strong and humidity values stay
moderate to keep fire danger high but not extreme. The warm ridge
looks to stay in place through Monday.

By Tuesday the ridge begins to weaken as a trough dives down from
the Pacific northwest. Solutions run wild by Wednesday but the
more likely scenario at this time is some type of a slider passing
to our east and keeping the Bay area dry. Again, that part of the
forecast is subject to change as its still a week out. As that
system passes to our east it'll carve out some type of trough
over socal or into Arizona. The end result for the Bay area would
be continued dry and seasonably warm weather for most of next
week.

Out in the ultra long range some of the pna ensembles show the
index trending negative which would support some of the
deterministic 10-15 day GFS runs that show precip some time
before Thanksgiving. Latest mjo ensembles now show it fading over
the Indian Ocean by late in the month.

&&

Aviation...as of 04:05 am PST Thursday...for 12z tafs. A weak
area of low pressure off the coast is spreading high level clouds
into the region this morning with low level stratus also
observed. Bases have lifted since yesterday with MVFR cigs at the
terminals. The marine layer per The Fort Ord profiler has deepened
to just over 3000 feet. Lifting and cool air aloft from the
trough has allowed the low stratus to become patchy with periods
of VFR mixed with MVFR this morning. Expecting cigs to remain
MVFR through the day with bases lifting to 2000-2500 feet this
afternoon. A weak frontal passage this afternoon and evening may
bring some light drizzle to the terminals but confidence was not
high enough to include in the tafs, with the exception of ksts
where -dz has been included. Light winds this morning becoming
southerly to westerly this afternoon and locally breezy. Light
winds will return this evening with MVFR cigs continuing
overnight.

Vicinity of ksfo...conditions have remained VFR overnight. High
clouds have obscured low stratus with extent difficult to discern.
At this time think periods of MVFR cigs will occur this morning,
but confidence is low. Southerly winds around 4-8 kt this morning.
Southwesterly winds will increase this afternoon to around 10 kt
with gusts to 15 kt. MVFR cigs likely to become more widspread
this afternoon as a weak front passes through. MVFR cigs
persisting overnight tonight into Friday morning.

Sfo bridge approach...similar to ksfo.

Monterey Bay terminals...patchy low clouds around this terminals
this morning. Periods of VFR mixed with MVFR will continue through
the morning and into the afternoon. MVFR cigs becoming more
widespread this afternoon as a front approaches. Light southeast
winds will continue through the morning. Breezy southwest winds
developing at kmry around 20z continuing through the early
evening. West winds around 10 kt at ksns will arrive 20-21z and
decrease early evening.



&&

Marine...as of 02:46 am PST Thursday...winds remain light and
southerly across the coastal waters. However, as a part of a front
approaching the California coast, the winds begin to switch to the
northwest Thursday night into Friday morning with increasing
winds, particularly on Friday. Expect northwest wind shift to
appear in the northern waters first before the southern waters,
due to the angle of the front. The northwest dominant swell will
remain light and continue through Thursday morning. By Thursday
night, a larger, longer period northwest swell will arrive and
continue through Friday and Saturday.

&&

Mtr watches/warnings/advisories...
...

&&

$$

Public forecast: rww
aviation: St
marine: St

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