Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Sacramento California
339 am PDT Tuesday Sep 1 2015
temperatures will cool to well below normal by mid-week as another
weather system moves into the region. Most of the showers are
expected to remain across the far northern portion of the state.
Milder conditions will return for the Labor Day weekend.
clear skies across the interior of norcal early this morning.
After a rather hot start to the work week on Monday, temperatures
are running a bit warmer in most areas compared to 24 hours ago.
The trend toward milder temperatures will likely begin today as
high pressure starts to weaken a bit over norcal as the deep
closed upper low off the coast of British Columbia drops further
south. Cooling will pick up steam the second half of the week as
the low digs into northern California by Friday. It will also
become breezy to locally windy across the region. High
temperatures later in the week are forecast to be well below
normal (10-15 degrees).
At this point, it appears the threat of showers will be mostly
across far northern California later in the week. But this may
need to be adjusted further south with later forecasts if the
trough digs further south (a few individual model runs are
spreading showers south to about I-80).
Extended discussion (saturday through tuesday)...
weekend forecast still a bit uncertain as model differences
remain in regards to upper level trough progged to move across the
region. Models have been trending southward with this feature over
past several runs though. The GFS lifts trough east-northeast on Saturday as
it weakens. European model (ecmwf) drops trough a little further south, skirting
norcal Saturday into Sunday. Given southward trend, cannot rule
out a few showers this weekend, mainly across Shasta County, but
low confidence at this point as moisture is limited. Otherwise dry
weather expected elsewhere. More zonal flow moves in for the start
of next week with gradual warming trend. Temperatures will be a
few degrees above normal with 90s in the valley and 70s/80s across
higher elevations for Sunday into the start of the work week. Ceo
VFR conditions through the period. Winds generally near or below
10 kts with exception of the Delta Region which could see gusts
20-25 kts later this evening-tonight.