Area Forecast Discussion
Issued by NWS Sacramento, CA
FXUS66 KSTO 261200
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SACRAMENTO CA
500 AM PDT Sun Oct 26 2014
Drier weather expected today. The brief break into Monday will be
followed by potentially more wet weather mid next week and again
late week, to include Halloween trick or treating.
.Short Term Discussion (Today through Wednesday)...
Shower activity is all but dissipated right now over the Sierra.
A weak post frontal wave is generating some enhanced open-cell
cumulus and showers near the coast, so we left isolated showers
over the northern portion of the forecast area this morning. At
the moment, we turn our attention to fog this morning. Significant
high pressure hasn`t yet built into Oregon, so the light northerly
winds will only down into the northern Sac Valley this morning.
The southern Sac Valley is clear with light to calm winds, so
expect some areas of fog this morning near sunrise. Low clouds/fog
continue over portions of the Sierra, especially northward of
Highway 50. Northerly winds will increase later today in the
Valley, especially over the southern Sac Valley and the northern
San Joaquin Valley. Monday remains dry as the transitory ridge
progresses through the area.
Tuesday and Wednesday the upper pattern turns from anticyclonic to
neutral/cyclonic flow as the ridge axis progresses into the
western Great Basin. This will allow weak positive vorticity maxes
to skirt extreme northern CA, bringing only a slight chance of
precipitation to the northern mountains...northward of Chester and
northern Lake county. Temperatures will rebound into the mid to
upper 70s in the Valley and 50s to low 70s in the mountain and
.Extended Discussion (Thursday through Sunday)
Amplifying ridge forecast over the western US later this week as
another trough deepens over the eastern Pacific. Forecast
confidence has increased somewhat as better agreement has
developed between the GFS, GEM and EC in handling the progression
of the trough inland next weekend. Though, there are still timing
differences in the onset of precipitation that may affect
Halloween. Regardless, appears much of the region will see a
chance of precipitation Friday into Saturday.
General VFR conditions return today as high pressure begins to
rebuild over the area and northwesterly flow aloft develops.
Isolated to scattered showers continue across the northern Sierra
Nevada mainly to the north of KBLU through about 18Z with
widespread MVFR and local IFR conditions. Local MVFR visibilities
may develop in portions of the Sacramento Valley from 13Z-17Z.