Scientific Forecaster Discussion
fxus66 ksto 251720
Area forecast discussion
National Weather Service Sacramento California
920 am PST Sat Feb 25 2017
flooding concerns continue as runoff from the recent rain
continues to work its way downstream adding stress to waterways. A
couple of weak but cold storms move through Saturday and Monday.
Extended period of dry weather starts by the middle of next week.
low pressure system along the coast will move southward during the
day and may bring a few stray showers to the Interior Valley today.
The mountains will see a few more showers but any snowfall
accumulations will be light and less than an inch.
The system will move south of the area overnight and precipitation
chances will diminish. Skies will become clear and another cold
night on tap. Temperatures will lower into the low to mid 30s by
Sunday morning. The coldest temperatures look to be over the north
end of the valley.
Previous discussion... closed upper low is currently situated
off the California/Oregon coast, with associated frontal system
moving through the region. Scattered showers have persisted across
the northern portions of our County Warning Area for much of the night, with
mainly light precipitation totals reported thus far. Snow levels
have been low enough to bring a bit of light snow to roads above
2000 ft or so.
The upper low will continue its path southward today, paralleling
the coast. While a few showers will continue mainly over the
higher elevations today, dynamics will remain far enough off the
cosat to keep most of the region dry. By tonight, skies should be
clearing again, allowing for another cold night across the region.
Some valley locations (particularly across the north) may reach
below freezing temperatures.
A second trough will move into the Pacific northwest Sunday,
bringing another round of showers to the region. Neither this
system nor the previous one tap into any meaningful moisture, so
precipitation won't be heavy. However, enough snow could fall over
the mountains that Sunday evening travel could be impacted. Snow
levels will remain low...mainly between 2000 and 3000 ft across
A few showers will persist into Monday under cyclonic flow aloft.
By Tuesday, drier northwest flow will take hold over the region.
extended discussion (wednesday through saturday)
Upper ridging over the West Coast will bring dry weather through
the extended period. Upper ridge weakens a bit towards the end of
next week as a Pacific storm system passes through the Pacific
northwest but any precipitation should remain north of the
forecast area. Daytime highs start out around normal on Wednesday
then warm through the end of the week especially in the northern
Sacramento Valley where light north winds and adiabatic warming
will push the Redding area up to around 70 degrees. Overall...daytime
temperatures at the end of next week should be up to between 5
and 10 degrees above normal.
Upper trough drops southward through norcal today. MVFR
occasional IFR ceilings over mountains next 24 hours. Mainly VFR
conditions Central Valley. Wdly sct showers mtns. Snow levels
2000 to 3000 feet. Mainly northwest to northeast winds below 10
Winter Weather Advisory from 10 am to 10 PM PST Sunday for
Shasta Lake area / northern Shasta County-West Slope northern
Sierra Nevada-western Plumas County/Lassen park.
Flash Flood Watch through late Thursday night for carquinez