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Area forecast discussion 
National Weather Service Sacramento California
1015 am PDT Tuesday Aug 4 2015

Synopsis...
cooler weather early this week with temperatures below average
for early August through Wednesday. Slight chance of showers and
thunderstorms today with a better chance Thursday night into Friday.

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Discussion...
a short-wave will move across norcal today. Latest hrrr & NAM
models show forecast radar reflectivity across our County Warning Area this
afternoon. However, the reflectivity doesn't look like it will
produce much rain (generally less than 30 dbz)...perhaps some
sprinkles in the valley with some isolated mountain
thunderstorms...mainly along the coastal range. Have made a slight
modification to this morning's forecast package to remove mention
of thunderstorms in the valley and change it to sprinkles, but
will keep slight chance of thunderstorms in the mountain areas.
Otherwise, expect daytime highs to be about 5-10 degrees below
normal with much of the valley in the 80s.

The wave shifts east allowing short-wave ridging to bring warmer
and drier weather Wednesday and Thursday. Another low approaches
Thursday evening through Friday and will bring a return of shower
and thunderstorm chances along with cooler temperatures. This low is
better organized than today's short-wave so thunderstorm chances
will be more widespread across the mountains and could also impact
the valley. Jbb

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extended discussion (saturday through tuesday)

The upper trough exits on Saturday with some lingering shower and
thunderstorm activity in the mountains. By late afternoon, much of
this should be shifting out of the area with flat ridging
developing and mainly dry weather. Temperatures on Saturday should
be below normal.

Ridging develops to the east on Sunday, with drier, more stable
southwest flow over the area. There is a small possibility of some
precipitation over far northern Shasta County Sunday afternoon and
evening as a low from the Gulf of Alaska slowly drops down the
coast, but the bulk of it should stay well to the north. Where
this low ends up will determine the potential for rain next week.
The European model (ecmwf) splits of part of the trough and sends it southward as a
low sitting off the central California coast...while the GFS
gradually brings an upper low into the Pacific northwest. Will go
with a dry forecast for now, with either possibility likely
delaying precipitation into middle week. Ek

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Aviation...

Dry weather with VFR this morning. SW winds in the Delta have
decreased, but will stregthen again this evening and overnight
with peak gusts up to 25-30 kts. Some smoke near wildfires may
limit visibility. Afternoon and evening thunderstorms are possible
over the mountains. Gusty, erratic winds are the main concern
with any storms that form. Ek/jbb
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Sto watches/warnings/advisories...
none.
&&

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