Area Forecast Discussion
Issued by NWS Sacramento, CA
FXUS66 KSTO 250614 AAA
Area Forecast Discussion
National Weather Service Sacramento CA
1010 PM PST Fri Feb 24 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 around Saturday and Monday. An
extended period of dry weather starts the middle of next week.
.Discussion (Today through Monday)...
A few showers have developed over the Nrn tier zones in our CWA this
evening as moisture has worked inland from the upper low off the
ORE/Nrn CA coast. This system is forecast to parallel the coast
through Sat with the bulk of the precip remaining W of our CWA. Some
of the higher resolution QPF progs suggest little, if any, precip in
the Valley, while the W Slope Sierra sees light snow showers. The
2nd system currently over AK is forecast to drop Swd along the Coast
and affect Norcal Sun into Mon as it transitions to a broad Wrn
States trof. Precip will be of longer duration and heavier than the
initial system, and hence a WSW (advisory) is in effect for the mtns
given low snow levels. Earlier model runs (from a few days ago)
showed at least one of these systems was supposed to be tapping into
the subtropical moisture associated with the low near 35N/145W for a
more substantial Sierra snow storm. That no longer seems to be the
case. The initial system may tap some subtropical moisture as it
affects Socal Sat nite/Sun, but not our CWA. JHM
Satellite and Radar imagery showed some development of cumulus over
the Sierra, but otherwise conditions were fair across northern
California during the early afternoon hours. Latest short term
models show showers developing and spreading over the forecast area
this evening as an upper level shortwave trough slides over the
area. Models are trending with the upper level shortwave trough
staying off the coast and not influencing northern California too
much. As a result, some light precip can be expected for the valley
with light snow through Saturday morning for foothill and Sierra
locations. Some snow could even fall as low as between 1500 and 2500
feet with this colder system.
Another shortwave trough will clip northern California Sunday,
which will bring another round of rain and snow chances. Between
4 and 6 inches can be expected for the mountain passes Sunday
through Sunday night. A ridge will begin to build into the region
on Monday once the shortwave trough passes, although a few
lingering showers will still be present for the Sierra.
Temperatures through the period will remain between 5 and 10
degrees below normal.
.EXTENDED DISCUSSION (Tuesday THROUGH Friday)
A few showers may linger over far northern Sierra Tuesday but
won`t amount to much additional accumulation. Otherwise, dry
weather returns through at least the end of the week, as ridging
builds in. This will lead to a warming trend in temperatures and
mostly clear skies. A few flooding issues may linger as reservoir
releases continue. CEO
VFR conditions expected through the next 24 hours. Light rain for
the Valley and snow for the Sierra possible beginning this evening
with mainly variable winds below 10 kts. Clouds becoming
broken/overcast through the end of the forecast period.
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
Strait and Delta.