Area Forecast Discussion
Issued by The National Weather Service
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FXUS66 KSTO 122225

Area Forecast Discussion
National Weather Service Sacramento CA
225 PM PST Mon Nov 12 2018

Dry weather continues with cool nights and near to above normal high
temperatures through the week. Diminishing winds ease critical fire
weather conditions this week, but widespread smoke from the Camp
Fire will continue to impact the area.


Ridge axis along the coast shifts inland tonight as a weakening trof
moves into the mean ridge position. High cloudiness forecast to
drift inland over Norcal on Tue, exiting the area on Wed. The cloud
cover will likely not impact min temps significantly as the dry air
mass will result in strong radiational cooling. Also does not appear
the smoke layer is having too much of an impact especially as it
shifts gradually overnight with the downslope/drainage winds. RHs
recovered very well from MYV-MOD and with similar conditions
expected this coming night from last night, expect some dew/frost
may form in this area again by Tue morning. Otherwise the dry air
mass will preclude widespread heavy dew/frost, although there is
some moisture in the ground from local watering.

Persistent upper ridging over Norcal will result in light/lighter
winds over Norcal and limited mixing heights (1 kft - 1.5 kft), due
to the time of the year, will tend to keep persistent smoke over a
large portion of the CWA for the next couple of days. Satellite
indicates some improvement on the east side of the CWA with the help
of downslope flow overnight. But during the day, with light winds,
upslope flow may carry some smoke back to the east again through
evening. Smoke may also spread towards RDD per the HRRR smoke loop
through this evening.

With no major changes in the wx pattern during the short term,
little change expected in the forecast. Smoke might help to keep
temperatures cooler the next couple of days, otherwise they will
continue to run above normal, especially in the far Nrn portion of
the CWA where they are less impacted by smoke. High temps will be in
the 60s to mid 70s for the Central Valley, with mostly 50s to 60s
for the foothills and mountains. Cold overnight temperatures are
expected mainly over the Central Sacramento Valley southward, with
lows in the 30s to low 40s. Lows will be in the teens to mid 20s
across mountain basin locations.   JHM



Broad upper ridge forecast to continue across the region later in
the week maintaining dry weather with mild days and cool nights,
and no strong wind events are expected. Forecast guidance is
indicating the possibility of a pattern change as an upper trough
approaches the area early next week. Big question is will the
cut-off low approaching the region next week bring any chance of
rain to Norcal. 12/12z GFS weaker and farther south than the
12/00z ECMWF Mon/Tue next week, and the 12/12z ECMWF following
suit, but also showing a Nrn stream trof bringing precip to Norcal
next Tue. These differences yield low confidence in model solutions
at this time.   JHM



Widespread MVFR likely the next 24 hours across the entire
Sacramento Valley with local IFR for the southern terminals due to
smoke from the Butte County wildfire. Northerly winds under 10




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