Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Sacramento California
239 PM PDT Friday Jul 3 2015
near to above normal temperatures along with daily afternoon
thunderstorms mainly over the mountains will continue for the next
northern California remains under southeasterly flow aloft,
between a ridge of high pressure over the Great Basin and an
upper low well off the Southern California coast. A fair amount of
moisture continues to move through the region, with isolated
showers and thunderstorms moving through interior norcal. Most of
the convection this afternoon has been along a line just east of
the Sierra crest from Interstate 80 northwest toward Lassen park.
Temperatures across the forecast area are generally a few degrees
cooler than yesterday.
The best chance of showers and thunderstorms in our forecast
domain this afternoon and evening will be from Lassen park
northwestward into Shasta County. Upper level steering flow has
veered just enough to favor convection east of the crest.
Temperatures are expected to very gradually cool down over the
next few days as the aforementioned upper low slowly approaches
the coast. Mountain thunderstorms will continue to be possible the
next several days. For the weekend...the best instability will
remain along and east of the Sierra crest, but we could see a few
showers encroach west of the crest.
extended discussion (tuesday through friday)
Both the ec and GFS show the eastern Pacific upper low inside
130w, nearing the norcal coastline Tuesday and Wednesday.
Moisture wrapping around the low will bring slight chance to
chance of showers and thunderstorms, mainly over the mountains.
By Thursday, the GFS and ec move the low eastward across norcal
until it weakens and lifts northeastward on Friday. The ec is a
tad slower than the GFS, but that has flipped over the past few
runs. It's tough to figure out the exact track of these upper
lows this far out. Have kept the mountain thunderstorms through
Thursday and dried the area out for Friday. High temperatures
will remain near to below normal. Jclapp
Predominantly VFR conditions today, except for MVFR with heavy
rain in mountain thunderstorms. Storm motions less than 10 kts.
Delta breeze winds re- strengthen again after 00z this afternoon.