Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Sacramento California
1039 am PST Mon Mar 2 2015
another wave drops down from the north today bringing scattered
showers, mainly for the northern Sierra Nevada, and a slight
chance of thunderstorms. The mountains may see some light snowfall
accumulation. Drier and milder weather returns Tuesday and
continues through the remainder of the week.
scattered showers continue this morning with the best coverage
over the Sierra. Main forecast challenge today will be snow amounts
with convective bands over the Sierra. Snow levels are currently
around 5000 feet and expect snow amounts 2-4 inches above this
level with locally higher amounts with stronger convection.
Strengthening March sun will help melt snow off roadways between
bands. Updated forecast to raise Sierra precip amounts/chances
more in line with hrrr which will likely handle this convective
scenario better. Will maintain isolated thunderstorm threat over
the valley given 250 j/g of cape forecast by NAM buf sounding.
satellite imagery shows the next wave dropping quickly southward
off the coast of Oregon and northwest California. Lots of
cloudiness has overspread norcal overnight and even a few showers
are beginning to develop across the far southern portion of the
forecast area from far eastern Stanislaus County into Tuolumne
County. Temperatures are a little milder early this morning across
much of the region, though Redding and Red Bluff are running 10
degrees cooler compared to 24 hours ago due to the lack of north
winds compared to yesterday.
Most of the energy with this next wave is expected to remain
offshore or right along the coast, but there will be enough for
scattered showers inland across norcal today along with enough
instability forecast this afternoon for a slight chance for a few
thunderstorms over the southern portion of the forecast area
(generally Sacramento area southward in the valley).
While available moisture for this system will be quite meager,
satellite imagery is showing tpw of around 1/2 inch being drawn
back north ahead of this next wave, so there will be potential for
a tenth or two of quantitative precipitation forecast in the northern Sierra along with an inch or
two of snowfall accumulation over the higher elevations.
Snow levels expected to start out around 3500-4500 feet this
morning then rise slightly by this afternoon.
High pressure begins to rebuild over the area later tonight and
Tuesday with a return of generally light north to east winds
bringing a drying and moderating airmass. Another even weaker
wave is forecast to drop southward Wednesday slowing the warming
trend, but even milder weather is expected behind this feature for
the second half of the week.
Extended discussion (friday through monday)
No significant weather impacts through next Monday as high pressure
ridge builds and remains in control over the West Coast. A mostly
clear sky resulting in more dry weather will rule with above
normal temperatures and light winds. Daytime highs are expected
in the 60s to 70s within the valley and 50s to 60s over the
mountains through Monday. Patchy morning fog may form in northern
San Joaquin Valley and southern SAC valley. Models show a minimal
threat of precipitation next Tuesday, then increasing the
potential mid to late next week. Jclapp
Mainly VFR conditions across the valley the next 24 hours, with
scattered -shra possible during the day. For the mountains,
widespread IFR/LIFR conditions will continue through this evening.
Snow levels will be around 4000 ft. Across the valley...south
winds 5-15 kt will become light tonight.