Scientific Forecaster Discussion
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Area forecast discussion
National Weather Service Sacramento California
405 PM PST Fri Dec 9 2016
wet weather tonight through Saturday. Periods of wet weather
likely to continue mid-to-late next week.
moist westerly flow continues over the western US. Radar imagery
shows a few light showers across interior northern California,
mainly up along the mountains. Otherwise, low clouds and patchy
fog are blanketing a good chunk of the region.
The next plume of moisture is rapidly approaching the area, and
should bring precipitation later today and into Saturday. Valley
precipitation should remain light for the most part, and moderate
to heavy precipitation is expected for the Sierra. Precipitation
rates suggest that hydrologic impacts will be limited. Snow
levels are forecast to be very high for the bulk of the event
(potentially 8500 ft or above along the sierra). However, snow
levels will lower below major passes Saturday evening as
precipitation starts to wind down, and could bring light
accumulations along Interstate 80 and Highway 50.
Mainly dry weather is expected Sunday into Monday as a Flat Ridge
of high pressure moves across California.
extended discussion (tuesday through friday)
Large-scale pattern will continue through the end of the forecast
period with an abundant moisture tap. Guidance shows a Pacific
moisture plume aimed at interior norcal, but the ec is wetter and
has a more northerly track when compared to the GFS. Meanwhile,
the GFS keeps our County Warning Area dry on Thursday. Have blended model output
for this forecast package.
Forecast confidence is low by the end of the forecast period as
long range models highlight opposite scenarios. An upper-level
system could drop into the Pacific northwest with a series of
shortwaves rotating through the main feature sometime late next
week. However, forecast models show differences regarding track
and evolution of this system. Therefore, timing and precipitation
amounts remain uncertain, and it is difficult to determine any
Widespread MVFR ceilings/visible with areas IFR will continue next 24
hours. Precipitation should reach the northern Sacramento Valley
after 01z Saturday, and spread southward overnight. Locally
strong southwesterly winds across the higher elevations of the
northern Sierra Nevada. Gusty southerly winds will develop over
the Sacramento Valley mainly after 12z Saturday.