NATIONAL WEATHER SERVICE FORECAST DISCUSSION
Area Forecast Discussion
Issued by The National Weather Service
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000
FXUS66 KSTO 132319
AFDSTO

Area Forecast Discussion
National Weather Service Sacramento CA
319 PM PST Tue Nov 13 2018

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

&&

.DISCUSSION...
Pacific short wave trof encountering the highly amplified ridge axis
over Wrn NOAM won`t bring any rain, but it is spreading a plethora
of high cloudiness over our CWA, masking the smoke layer from the
Camp WF in Butte Co. HRRR smoke loop suggests the smoke layer will
shift Ewd across the coastal range later today and overnite.
Otherwise, light/lighter winds and limited mixing height (generally
1 to 1.5 kft) will tend to keep persistent smoke over a large
portion of the region for the next couple of days.

Still looks as if this initial batch of high cloudiness will exit
our region Wed morning while additional high cloudiness will spill
over the persistent ridge Wed afternoon and Thu. This timing
suggests radiational cooling around sunrise could drop temps into
the low to mid 30s from MYV-MOD where some light frost could form in
outlying areas as humidities are forecast to recover now that the
Nly winds have subsided.

Without any major changes in the weather pattern through the end of
the week there is little daily change expected in the weather over
our region. Smoke is expected to keep temperatures locally cooler
the next couple of days, otherwise they will continue to run near or
above normal while mins run a few to several degrees below normal.
   JHM

&&

.EXTENDED DISCUSSION (Saturday THROUGH Tuesday)

Ridging re-amplifies along the W coast this weekend as a GOA/Wrn
Canadian trof slides across the Canadian and Nrn Rockies. Most of
the max temps in the Valley will be in the 60s, with some low 70s in
the Nrn Sac Vly and surrounding foothills. These temps are about 10
degrees above normal N end of the Vly and many mtn locations to
about 5 degrees above south end of the Vly.

The wx pattern is forecast to change by Mon as low pressure forms
off the SOCAL coast with the lower heights allowing for a deeper,
longer wave trof to develop over the Ern Pac. There are now rumors
of rain over Norcal for the middle of next week, but model
differences continue to cause low confidence in timing and amounts.
13/00z ECMWF suggests as early as Tue nite into Wed and Thu, while
the GFS suggests some rain spreading into our area Wed and
continuing into Thu. However, the 13/12z ECMWF moves this system
through our region on Thu. Although the common theme for rain is
"mid week," the timing differences are problematic. The GFS
5-wave chart forecasts a displacement of the mean 5H ridge into
the mid section of NOAM with a mean trof over the Ern Pac near
130W which would support a pattern change. Have introduced some
PoPs Tue nite, the last grid block.   JHM

&&

.AVIATION...

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

&&

.STO WATCHES/WARNINGS/ADVISORIES...
None.
&&

$$
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