Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Sacramento California
945 PM PST sun Nov 29 2015
another cold morning Monday. A few showers are possible across
northern portions of the area Monday and Wednesday. The next
storm system arrives Thursday with wet and windy weather.
Short term discussion...
Another cold nite over norcal as sub-freezing temperatures again
expected in the Central Valley later tonite and into Mon morning.
Widespread freeze this morning precludes issuance of freeze warnings
until trees begin to Bud late Jan/Feb...or there is a massive Arctic
outbreak before that time. Jhm
Offshore cold front will weaken as it encounters the blocking ridge
currently over the West Coast. A few showers will be possible on
Monday, mainly across northern portions of the area but only light
accumulations expected. Air mass is very dry and precip will be
subjected to evaporation. 12z European model (ecmwf) hints at some showers further
south across the Delta and southern valley but appears to be the
outlier among latest hi-res solutions, GFS, and NAM. For now, have
kept any chance of precip north of Clearlake to Quincy line. Rest
of the area will remain dry.
Dry weather will rule on Tuesday as ridging briefly rebuilds over the
region. Temperatures will warm a few degrees from Monday to Tuesday.
Another shortwave will move across the area Wednesday in advance of
next major system that will move across the area in the extended.
Wave is fairly moisture-starved so only expecting a few showers with
little to no accumulations across far northern portions of the area.
Extended discussion (thursday through sunday)
a wet and windy weather system will move through the region on
Thursday, with perhaps some lingering precipitation on Friday. The
GFS remains to be a bit faster with this system than the ECMWF,
but otherwise the models are in good agreement. This system
appears to be a bit warmer than last week's, and wetter especially
for lower elevations. Accumulating snow is expected above 5000 ft,
with up to a foot above 6000 ft. The most significant difference
with this storm is that it will pack some wind, with gusts around
40 mph possible across the valley. This combined with moderate
rain could bring down tree branches, causing local power outages.
Additionally, fallen leaves could clog gutters and drains and
cause slippery conditions on roads.
Drier weather is expected by Friday (depending on how quickly the
system moves through). Another weaker system will approach the
region next Sunday, but confidence is low on the handling of that
VFR conditions with generally light winds the next 24 hours.