Area Forecast Discussion
Issued by NWS Sacramento, CA
FXUS66 KSTO 201625
Area Forecast Discussion
National Weather Service Sacramento CA
925 AM PDT Thu Oct 20 2016
Dry through the end of the week with a little above normal
temperatures. A little cooling Saturday with a chance of
precipitation spreading over the forecast area late Sunday
through mid week with below normal temperatures.
High pressure centered over 30N will build across SOCAL, Baja and
into the Desert SW will keep the storm track N of Norcal and into
the Pac NW. Nly flow will be lighter today so less adiabatic warming
although 5H heights and thickness values reach their peak today. So
today should be the warmest day, although max temps may not warm to
the dry adiabatic descent from 850 mbs this time of year. Yesterday
they fell about 8 degrees short, and today that number would be
about 88. Following this trend we look for maxes in the low 80s.
An upper trough digging into the eastern Pacific will turn the flow
onshore on Friday. This will initiate a cooling trend that will
continue on Saturday as the upper trough deepens offshore with
daytime highs dropping to below normal. The higher elevations will
see increasing southwest winds. Sunday starts out dry but forecast
models bring a frontal band into northwest California by afternoon.
Models are in fairly good agreement in bringing precipitation into
the northern Sacramento Valley and lee-side of the Coastal Range by
Increasing southwest winds and cooler temperatures will also
result as this frontal band moves inland with daytime highs Sunday
about 10 degrees below normal. Light precipitation will spread
over the north end of the state Sunday night mainly north of about
interstate 80. Precipitation amounts will be light with heavier
rainfall having to wait until later in the week. /JHM
.EXTENDED DISCUSSION (Monday THROUGH Thursday)
Active weather looks on track for next week as forecast models
continue to be in alignment with an upper level low positioned in
the eastern Pacific. The position of the upper level jet stream
will pool moisture into northern California to bring increased
chances for rain, especially for the northern mountains and
northern Sacramento valley. A general lack of instability will not
allow for thunderstorm development. Snow levels are expected to
remain above 6500 feet, so some mountain passes in the northern
mountains could receive some light snow accumulations next week.
Otherwise, the highest elevations of the mountains could receive
heavier accumulations. High temperatures will generally be about 5
to 10 degrees below normal next week in the 50s and 60s as a
result of the weather system continuing to remain over the west.
VFR conditions next 24 hours. Light northerly winds will prevail
across TAF sites.