Area Forecast Discussion
Issued by NWS Sacramento, CA

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FXUS66 KSTO 150443

940 PM PDT Sun Sep 14 2014

Cooler temperatures for much of this work week. Valley sprinkles
and mountain showers and isolated thunderstorms will be possible
for parts of the area Monday, and again Wednesday through


.Discussion...(Tonight through Wednesday)
Max temps on Sun were some 3 to 6 degrees cooler than Sat over much
of the area except for the coastal range mtns and Shasta Co areas
where max temps were a little warmer. The approaching upper trof
over the Ern Pac shifted the hot ridge axis over Norcal Ewd. The
Delta Breeze weakened for a few hours allowing for temperatures to
make a run into the upper 90s to 100 degrees in the valley...but it
still ended up to be cooler than Sat most locations. The forecast
grads indicate the Delta Breeze will weaken overnite...but should
increase Mon afternoon as the upper trof moves inside 130W and nears
the Ore/Nrn CA coast.

The upper trof will be off the coast and lift northward staying off
the coast. The better dynamics will remain with the low but the
NAM/GFS indicate some instability/possible T-storms over the
mountains Mon afternoon north of I-80...and Nwd towards the Burney
Basin/ Lassen Park areas.   JHM

.Previous Discussion...

Cyclonic flow will remain over the area on Tuesday as a much
stronger low forms off the west coast. A decent delta breeze
should continue on Tuesday as well with some cooling over most of
the interior expected. The mountains may not have much change in
temperatures from Monday`s highs.

On Wednesday decent low will approach from the west and continued
cooling is expected. Late in the day some showers may be possible
along the coastal range per the European model but the GFS is
delaying any showers until Wednesday night.


.Extended Discussion (Thursday through Sunday)

Medium range models similar in dropping 568ish DM upper low south
along the California coast Thursday and slowly filling it.
Forecast PWS upwards of around 1.4 inches over Interior NorCal
Thursday to keep a threat of showers in portions of the lower
elevations with enough instability to support possible afternoon
mountain thunderstorms. Additional cooling Thursday will result in
below normal temperatures with mid 80s in the Central Valley and
mainly 60s to 70s for the mountains and foothills.

Models then diverge Friday into the weekend with placement of
omega upper ridge and associated trapped low. 12z GFS is more
progressive keeping the ridge axis farther downstream while 12z GEM
and ECMWF-HiRes keep it close to the West Coast. Forecast becomes
increasingly difficult as models handle placement of trapped
closed low poorly. NAEFS probability QPF keeps a dry forecast for
Interior NorCal through the remainder of the extended so will lean
towards this for now but confidence low. Will continue
advertising a warming trend with high temps rising to around 5
degrees or so above normal through next weekend.




SWly flow alf as upr low in EPAC apchs far NW ptn of CA Mon aftn.
VFR conds ovr Intr NorCal nxt 24 hrs with Sct-Bkn mid clouds with
isold tstms poss ovr Nrn intr mtns Mon aftn. Lcl SWly sfc wnd gsts
to 30 kts poss ovr hyr mtn trrn aftns into eves and in the Delta
tngt into Mon mrng.


.STO Watches/Warnings/Advisories...

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