Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Sacramento California
346 am PDT Sat may 30 2015
above normal daytime temperatures tomorrow as high pressure slides
across the West Coast. Cooler early next week with a slight chance
of showers and thunderstorms over the northern Sacramento Valley
and surrounding mountains as the tail end of a Pacific trough
brushes through. Warmer temperatures may return mid to late in the
quiet weather this morning, with a Delta breeze gusting around 30
mph, and generally light winds elsewhere. The marine layer along
the coast is shallower this morning, so just seeing some low
clouds into the Vallejo/western Delta area. High clouds are spread
across northern California this morning.
High pressure will bring another warm, dry day today with
afternoon highs similar to those on Friday. This means upper 80s
and lower 90s for the valley. The upper level ridge which has been
bringing the above normal temperatures is shifting eastward, though. An
upper level will approach on Sunday. This will cool afternoon high temperatures
down about 5 degrees, which will still be a little above normal
levels. Onshore flow will bring breezier southwest winds, and
potentially some morning low clouds through the Delta into the
southern Sacramento Valley. Some afternoon showers and
thunderstorms are possible into the coastal mountains, though
there is a better potential by early evening. Could see a few
showers into the northern Sacramento Valley overnight Sunday.
Monday there is the potential for showers and afternoon
thunderstorms across the northern mountains/foothills with
marginal instability. A slight chance of showers extends through
the northern Sacramento Valley Monday morning through Tuesday
morning as another shortwave passes through. By Tuesday afternoon,
just a slight chance some lingering showers over the Shasta County
mountains are forecast.
Temperatures on Monday cool down to below normal levels.
Temperatures on Tuesday will rise slightly but still remain below
Extended discussion (wednesday through saturday)
Weak upper trough moves into the Pacific northwest on Wednesday
but any precipitation associated with it likely to remain north of
the County Warning Area. Airmass even warms a bit on Wednesday so daytime highs
are likely to nudge up a few degrees to a little above normal.
Models diverge after Wednesday with GFS and Gem slowly pushing in
a ridge off the eastern Pacific Thursday and Friday while the
European model (ecmwf) digs a trough southward down the coast eventually forming a
low centered over the central part of the state leaving the north
state under somewhat unstable conditions. Will keep with the
GFS/Gem solution for now as the European model (ecmwf) still having run to run
inconsistencies. By Friday...daytime highs push up to several
degrees above normal under the ridge. Next weak trough approaches
the coast next Saturday allowing daytime highs to level off.
Current forecast shows no significant precip chances through the
extended period. Smith
VFR conditions all taf sites under upper level high pressure
ridge. Scattered coastal stratus through the Delta through 18z with
variable high clouds at times all areas. Local SW wind gusts to
25 knots through Carquinez Strait/Delta.