Scientific Forecaster Discussion
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Area forecast discussion
National Weather Service Sacramento California
147 PM PDT Mon Oct 14 2019
dry and mild weather early this week with temperatures close to
average, then cooler for the second half of the week. A weather
system will bring a chance of showers mid-week.
Visible satellite imagery is showing clear skies over northern
California today, except for localized wildfire smoke from the
Caples fire in the Sierra. Downsloping easterly winds this
morning did allow wildfire smoke to begin to spread west into the
foothills. However, winds have begun to turn westerly which will
keep the smoke over the Sierra into the evening. Daytime temperatures
will be near the same as yesterday and will range from upper 70s
to low 80s in the valley to 50s to 60s in the mountains.
Upper level ridging is building over norcal today, providing more
dry and mild weather the next few days. Mostly sunny skies with highs
near average for mid- October and chilly overnight lows are
expected through Wednesday. Depending on fire activity, there
will continue to be some areas of light smoke in the Central
Valley in the mornings.
A stronger low pressure system approaches the West Coast mid-week
that brings a chance of rain to norcal Wednesday night through
early Thursday. Ensembles are in better agreement with the latest
GFS and European model (ecmwf) operational runs lending confidence to forecast of
light precipitation to the mountains and northern valley, mainly
north of I-80.
A cooling trend begins Wednesday as the associated surface front
passes through, continuing Thursday as the upper trough axis moves
east of California.
Extended discussion (friday through monday)...
Ensemble models suggest the upper level trough will broaden over
the western US Friday into Saturday. A weak shortwave embedded
within the trough will push over the northern part of the state on
Friday. This will bring just a slight chance for showers for the
northern coastal range. A more robust short wave trough will dig
south into the region on Saturday. This will bring a better chance
for showers, but activity is expected to remain over the higher
elevations with the best chances in the north. Chilly overnight
temperatures and below normal daytime temperatures continue with
valley highs in the upper 60s to low 70s and mountain highs in the
40s to 50s.
On Sunday, ensembles then show the upper trough deepening into
the Great Basin and northern plains, east of California. This
pattern could bring somewhat breezy north winds as precipitation
chances end. Currently winds are not expected to be very strong,
generally 10 to 15 mph with gusts up to 20 to 25 mph over higher
elevations. A warming trend begins as daytime temperatures warm to
High pressure is then expected to build over norcal early next
week allowing temperatures to increase to near or slightly above
VFR conditions the next 24 hours at the taf sites. Winds remain
under 12 knots.