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000 
FXUS66 KSTO 090028
AFDSTO

Area Forecast Discussion
National Weather Service Sacramento CA
428 PM PST Thu Dec 8 2016



.SYNOPSIS...
Wet pattern through the weekend as a series of weather systems
move through northern California. Moderate snow levels expected.
Periods of rain and mountain snow possible for first half of next
week. 

&&

.DISCUSSION...
Current radar showing only light, isolated showers across NorCal
this afternoon. An active wet pattern will continue into this
weekend with the bulk of precipitation occurring early Friday
through early Sunday.

Considering the increased precipitation forecast from CA-NV River
Forecast Center earlier today, we recalculated snow levels and
snow amounts to see how impactful this next round of wet weather
will be to the mountains. Although we could see some decent snow
amounts above 7000 ft elevation over the Sierra, the forecast only
shows a few inches near pass levels. Snow levels should remain
above 7000 ft until Saturday when some mountain areas, especially
north of I-80, could lower to around 6000 ft. That slight lowering
of snow levels could bring 1-4 inches of snow for Donner and Echo
Passes in a 48 hour period which doesn't warrant a Winter Storm
Watch at this point.

For lower elevations, this wet wave from Friday into Sunday will 
likely bring around 0.5-1 inch of rain in the valley with up to 2 
inches or more in the foothills.

The main concern during this period is driving safety. Slick roads
from rain and snow always create the potential for spinouts and
traffic accidents. Please drive with caution.

By Sunday afternoon into Monday, we should get a break in the wet
weather, but additional waves of moisture will move inland later
in the forecast period.  JBB

&&
.EXTENDED DISCUSSION (Monday THROUGH Thursday)

Long range models keep the forecast area mainly dry on Monday
under zonal flow. The exception could be a few lingering showers
across higher elevations. The pattern becomes more active Tuesday
through the extended forecast as significant moisture transport 
impacts interior NorCal. As for now, have increased precipitation 
chances across our CWA given model consistency. However, models
have been inconsistent over the past few days so changes in storm
track might occur. Regardless, better chances of precipitation 
will be across higher elevations.

A trough will deepen along the West Coast late next week resulting 
in lower snow levels. Gusty winds could develop over higher 
terrain as the system moves through. Temperatures could be 
slightly warmer by the end of the forecast period. 

&&

.AVIATION...

Widespread MVFR CIGS/VIS with areas IFR will continue next 24 
hours under warm-advection regime. Freezing level 9-11,000 MSL 
over Norcal. Southeasterly winds 10-15 kts with gusts 20-25 kts 
in the Central Valley south of KSAC into this evening. Locally 
strong southwesterly winds across the higher elevations of the 
northern Sierra Nevada.
&&

.STO WATCHES/WARNINGS/ADVISORIES...

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