Area Forecast Discussion
Issued by NWS Sacramento, CA

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FXUS66 KSTO 022218

318 PM PDT Tue Sep 2 2014

Cooling trend this week with near normal daytime highs Wednesday
through Saturday. Dry weather continues.


Afternoon temps were mostly running a few degrees cooler (with a few
exceptions in the central Sac Vly and Nrn San Joaquin Vly) and 8 to
13 degrees cooler in areas near the Delta. Onshore gradients began
to increase this afternoon and are forecast to increase to 3 to 4
mbs by the end of the day strengthening the Delta Breeze late this
afternoon/evening. The marine layer has also slowly deepened with
the Ft Ord profiler showing the marine layer deepening to near 2 kft
by early this afternoon. Thus...additional cooling effects from the
Delta Breeze are expected through tonite.

A positively tilted trof is forecast to move through the Pac NW and
suppress the strong ridging over Norcal leading to cooling to near
normal temps by mid week. Cyclonic flow aloft will continue for the
rest of the week as the trof expands SWwd with a possible weak low
forming over the far Nrn zones by the end of the week.

The marine layer has made a return along the coast and it looks more
promising for a stratus intrusion into the Sac Vly Wed morning as
the NAM has forecast for the past couple of days. Now that we have
seen the marine layer deepen to >=2 kft and with strengthening
onshore gradients this evening and expected onshore momentum...a
stratus intrusion into the Vly seems probable.

The Nly gradients are then forecast to increase again during the day
on Wed and continue Thu/Fri with the trof moving through the Pac NW
and offshore flow prevailing in its wake. This will suppress the
marine layer and limit the Delta Breeze Thu morning. In addition...
strong CAA from the dry NEly flow over the NErn zones should bring
some cool temps to the cooler mtn valleys/basins next couple of
overnights/early mornings.

The wind pattern will allow some smoke from the Beaver WF to affect
our Nrn zones including Shasta Co at times...but the bigger smoke
plume from the more active Happy Camp WF complex may spread over
Shasta Co Wed morning per the NAM Hysplit model run. More NEly flow
Thu/Fri mornings from higher pressures to our NE may spread the
smoke back to a SWwd trajectory during that time and sparing Shasta

With the tail end of the weak positively-tilted trof lingering over
Norcal later this week and through the weekend...max temps will be
close to normal for early Sep.   JHM

.Extended Discussion (Saturday through Tuesday)

Persistent weak troughing aloft into NorCal will bring minor
cooling...near to just below normal. We have kept the forecast
dry. Mainly onshore winds with morning marine stratus
infiltrating to I-680 and Cordelia.   JClapp



General VFR conditions with MVFR ceilings approx 015 into the
southern Sacramento Valley Wed morning. Fort Ord profiler shows
steady marine layer increase up to 2000ft and Bodega Bay is up to
1600ft as of 21z Tue. Less than 30% chance of stratus at KSCK,
but ceilings may encroach toward KSMF from SE.  JClapp


.STO Watches/Warnings/Advisories...

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