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Area forecast discussion 
National Weather Service Sacramento California
214 PM PDT Wed Sep 17 2014

Synopsis...
temperatures cooling to below normal Thursday with a chance of
showers and thunderstorms. Warmer and drier weather returns for
the weekend. High uncertainity towards middle week but at least
some indications of a possible system Wednesday or Thursday.

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Discussion...
somewhat active but fairly low impact short tern forecast with 3
key things to concentrate on. Upper trough will into area late
tonight and across the area Thursday. This wave will be weakening
as it does so looks like biggest impact it will bring will be
clouds and cooler than normal temperatures. There should be some
showers but amounts look to be light. Can't rule out a
thunderstorm or two with some instability but not too much to get
too worried about.

Next concern shifts to Friday as this system passes...low level
winds will shift to down valley from the north. Once again...given
strength of the wind...not too much to worry about for fire
weather but it will allow temperatures to warm and humidities to
drop.

Friday night into Saturday will be interesting as far smoke
concerns as winds turn to the east. This could drag smoke from
kingfire westward into valley floor. It likely will but westward
extent will be tricky to tell. NAM also showing fair instability
over night Friday into Friday night but GFS much less. Will
probably result in some mid level clouds but have kept some slight
chances of Sierra south of Highway 50.

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Extended discussion (sunday through wednesday)

Interesting long term forecast towards mid week. Early in the week
no strong synoptic features in place but toward day 7 and 8...both
European model (ecmwf) and GFS are now bringing in a large trough into Pacific
northwest. European model (ecmwf) is wetter and more agressive at this point. Given
the better agreement of the operational models at this point seems
appropriate to insert to have at least a 20 percent chance of
moisture...mostly in northern zones...but still alot of
uncertainity with this system...thus pops closer to climotology
make more sense than dry. Rasch



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Aviation...

Mainly VFR conditions next 24 hours with isolated
showers/thunderstorms possible over western Shasta County and
coastal range beginning this afternoon and spreading southeast over
valley and into Sierra by tonight. Local swerly surface wind gusts
up to 35 to 45 kts possible over higher mountain peaks this
afn/eve and overnight. Swerly gusts up to 20-25 kts through Delta
and SAC valley this afternoon.

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

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