Area Forecast Discussion
Issued by NWS Sacramento, CA
FXUS66 KSTO 221132
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SACRAMENTO CA
432 AM PDT Wed Oct 22 2014
Dry today under weak high pressure with a weak weather system
bringing precipitation chances north of interstate 80 Thursday. A
few lingering showers possible Friday with another system bringing
precip chances to most of the forecast area Saturday. More chances
of precipitation for NORCAL during the middle of next week.
Daytime temperatures below normal through the coming week.
Northern California currently under flat high pressure ridge for
dry conditions across the north state. A weak Pacific frontal band
now moving inside 130 west is currently spreading high cloudiness
across most of the forecast area. It should warm up a bit over
yesterday under the ridge of high pressure but overall airmass
remains on the cool side so daytime highs today likely to come in
a little below normal. The weak frontal band is forecast to push
onto the coast tonight and drop southeast through NORCAL during
the day on Thursday. Dynamics with this system weaken as it moves
inland into the high pressure ridge and QPF values are expected to
remain fairly light. The heaviest amounts of rainfall will be
along the coast range and over the Shasta county mountains with
lighter amounts farther east as the system weakens. Friday looks
fairly dry at this time with models placing a rebuilding ridge
over the western U.S. ECMWF a little more progressive with the
next Pacfic storm system so left some precip over the coast range
Friday. May need to remove precip chances for Friday if subsequent
model runs keep precip offshore. Daytime highs will push upward on
Friday but still are likely to coming in below normal for the
season. Models in fairly good agreement in bringing a stronger
more consolidated frontal system into NORCAL on Saturday.
Precipitation amounts do not appear to be especially high but most
areas of NORCAL should get some rainfall and successive runs have
come in with a higher precip amount trend. Much cooler conditions
and breezy winds will accompany this system.
.Extended Discussion (Sunday through Wednesday)
Showers will remain possible on Sunday as an upper trough moves
through the Pacific northwest and NORCAL. Most of the shower
activity should remain north of interstate 80 during the day.
Daytime highs will remain well below normal under cool airmass and
cloudy skies. Extended models remain in good agreement on Monday
showing a high pressure ridge rebuilding over the west coast.
Daytime highs warm Monday but still remain below normal for this
time of year. Next in series of Pacific frontal systems is
currently forecast to push into the northwest corner of the state
on Tuesday but models begin to diverge on timing. GFS the
fastest...ECMWF the slowest and looks like GEM is somewhere in
between. ECMWF model also weaker and farther north with this
system while GFS would bring precip to most of the forecast area.
For now...have gone middle of the road keeping majority of precip
north of interstate 80 Tuesday and Wednesday.
VFR conditions today with increasing high and mid clouds ahead of
an approaching cold front. Generally light winds for the Valley,
around 10kt or less. Rain will gradually begin to spread into the
northern Sacramento Valley after 00z this evening. EK