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Area forecast discussion 
National Weather Service Sacramento California
427 am PDT sun Sep 21 2014

Synopsis...
lingering Sierra showers/T-storms are possible through this
evening. Otherwise, dry and warmer temperatures into early next
week. Cooler and possibly wetter weather for the middle to end of
next week.

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Discussion...
upper level closed low center now appears from satellite imagery
to be somewhere over the northern San Joaquin Valley. Infrared image
shows abundant cloudiness in the deformation zone in the northeast
section of the low. A short wave trough rotating out of this zone
and westward across north central California brought light showers
and isolated thunderstorms over the northern Sierra and westward
into the southern Sacramento Valley overnight. This disturbance
has moved westward and weakened and the showers have ended most
areas. The upper low is forecast to move rapidly to the northeast
today with the center moving into Nevada by 18z today. Instability
progs show some minor instability still over the eastern portion
of northern California today near the back side of the low so left
a slight threat of showers and thunderstorms over the east side
mountains through this evening. The remainder of the forecast area
should see clearing skies as the low continues eastward. Slightly
cooler airmass today should bring slightly cooler daytime high
temperatures. Upper level high pressure ridge sliding over the
north state will bring fair skies and warmer temperatures on
Monday. The high will shift quickly eastward on Tuesday as a low
pressure system in the Pacific moves towards the coast. Daytime
temperatures Tuesday will be similar to Monday before a bigger
cooling trend expected to begin Wednesday. Mid range models in
fair agreement in bringing a Pacific frontal system onto the north
coast sometime early Wednesday. If current models hold...parts of
the County Warning Area will be seeing light precipitation as early as mid day
Wednesday.

Extended discussion (thursday through sunday)

Extended models in fairly good agreement in moving a Pacific
frontal system across the Pacific northwest and norcal Thursday.
Nearly all of the County Warning Area will see at least a chance of precipitation.
With cloud cover and cooler airmass...daytime highs will drop to
well below normal. Extended models begin to diverge a bit by next
Friday. GFS model progresses the upper trough axis east of the
forecast area by 00z Friday while the European model (ecmwf) lingers it offshore. Gem
model takes a middle of the Road approach to the other two.
Regardless of the solution...next Friday looks to be a mainly
cloudy day with at least a threat of precipitation most areas.
Significance of model variance grows by next Saturday as GFS
would bring clearing and warming under a ridge pattern while a
less progressive European model (ecmwf) would keep showers in the region. Have kept
with the more middle of the Road Gem and kept precip threat mainly
over the eastern portions of the County Warning Area. Rap around moisture could
still be an issue for the Sierra next Sunday if European model (ecmwf) solution is
correct. GFS and Gem models show drying under a ridge of high
pressure.



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Aviation...

VFR conds nxt 24 hrs. LCL MVFR vsbys vcnty King fire near kpvf.
Isold -shra mainly ovr nrn siernev with sct thunderstorms and rain psb hyr elevs
nrn siernev aft 21z til abt 02z Mon.

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Sto watches/warnings/advisories...
none.
&&

$$

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