Scientific Forecaster Discussion
fxus66 ksto 181129
Area forecast discussion
National Weather Service Sacramento California
329 am PST Sat Nov 18 2017
dry weather through Sunday. Next system moves through Monday with
another during mid week. Each of these next systems will come
with light to moderate precipitation and high snow levels well above
Discussion (today through tuesday)...
Model analysis and satellite wind fields showed an upper level
ridge of high pressure present over California overnight with dry
air over the interior. Observations were clear with valley
temperatures in the low to mid 40s.
Model forecasts are in agreement to the amplitude increasing on
the upper level ridge over the forecast area today before
transitioning to a zonal flow aloft Sunday. This will result in
dry weather with mostly clear skies across the region with high
temperatures right around normal for mid November.
The next weather disturbance will arrive Monday into Tuesday as
the upper level set up involves a high pressure ridge to the south
and a trough of low pressure to the northwest. As a result of the
upper wind circulation, moisture is anticipated to stream into the
West Coast. The main brunt of moisture should pass to the north
into Oregon, but light precipitation will occur Monday and
Tuesday. The ridge to the south should remain positioned enough to
keep the cooler air to the north, which will keep high snow levels
for the mountains at 10k feet and above.
Extended discussion (wednesday through saturday)
Forecast confidence remains low through the extended period. The
latest runs of the GFS and European model (ecmwf) continue a very strong ridge over
the west which favors limiting precipitation chances to areas
mainly north of Interstate 80. Along with high snow levels,
impacts to travel around Thanksgiving appear fairly minimal at
Mainly VFR conditions with light north winds the next 24 hours.
Local MVFR visibilities in fog may develop south of ksac 14z-18z.