Area Forecast Discussion
Issued by NWS Sacramento, CA
FXUS66 KSTO 231020
Area Forecast Discussion
National Weather Service Sacramento CA
320 AM PDT Sun Oct 23 2016
Cooling trend with a chance of precipitation spreading over the
forecast area Monday through next week as an upper level disturbance
approaches northern California.
A few high level clouds were moving across the interior overnight
as moisture streams ahead of the incoming upper level disturbance
currently located over the eastern Pacific. Model height analysis
and water vapor imagery continued to show the eastward progression
of the system, which will impact northern California starting
Patchy fog is possible once again this morning in low lying areas
especially near rivers and creek basins in the valley. Any
developing patchy fog this morning should dissipate by mid
morning. Cloud cover will gradually increase later today as the
upper low approaches from the west with high temperatures
remaining near normal to slightly below normal.
The main forecast concern continues to be the approaching storm
system in the eastern Pacific. Latest model guidance continues to
be on track with bringing the precipitation arrival late tonight
and early Monday morning and spreading in coverage from west to
east over northern California throughout the day. High
precipitable water values increase changes that moderate to heavy
rain is likely at times for many locations and could impact travel
from Monday through Tuesday night. Breezy winds are expected with
the associated stronger jet stream moving into northern
California, especially for higher elevations. Widespread rain will
continue through Tuesday night and will decrease in coverage and
intensity on Wednesday.
Snow levels with this storm should remain mostly above 8000 feet
for locations along and south of Red Bluff, but northern mountains
could see snow levels drop to 7000 feet. Mountain passes will
receive little snow accumulations, but the main area of concern
for significant snowfall are the mountains near Lassen Park for
Monday night into Tuesday. Winds gusts in combination with heavy
snowfall at higher elevations near the park could create
dangerous whiteout conditions at times.
.EXTENDED DISCUSSION (Thursday THROUGH Sunday)
Unsettled weather forecast to continue later next week as NorCal
will remain between the trough over the eastern Pacific and
ridging over the Rockies. Snow levels expected to remain rather
high the potential for entrainment of deeper moisture up from the
south in this pattern.
VFR conds prevail next 24 hrs with SCT-BKN250. Generally light
winds under 10 kts at TAF sites.