Area Forecast Discussion
Issued by NWS Sacramento, CA
FXUS66 KSTO 182231
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SACRAMENTO CA
331 PM PDT Thu Sep 18 2014
Temperatures cooling to below normal today with a chance of
showers and thunderstorms. Warmer and drier weather returns for
An upper trough will shift further onshore this afternoon and bring
light showers to portions of interior northern California. The
base of the 571mb upper trough is directly along the northern
coast of California extending from the North Bay to Eureka. The
upper low is forecast to dig southeast towards Southern California
and transition into a closed low before ejecting into the Great
Basin via the westerlies late in the weekend.
Overnight precipitation brought light accumulations to portions
of the coastal range, extreme northern Sierra, and Shasta county.
Minor additional accumulations occured earlier today over the
coastal range as showers pushed further inland. Latest composite
radar imagery continues to show light returns over the Coastal
range this afternoon, however the event appears to be winding
down. A report of a funnel cloud near Chico came in late this
morning when shear profiles supported such an event, so most
likely a valid sighting.
The King Fire experienced aggressive growth on the
northern perimeter yesterday and expanded by over 50000 acres due
to low humidities and moderate winds. Conditions today will be
slightly better with higher humidities and lower winds, however
only minimal amounts of precipitation, if any, are expected to
fall over the fire for the rest of the day. Smoke from this fire
will continue to impact nearby communities and could sink into the
valley (mostly along the extreme eastern edge of the Southern
Sacramento and San Joaquin valleys) after Friday when the winds
shift following the trough. Additional resources are in the
process of being added to fight the fire.
Temperatures rebound closer to normal values for tomorrow and into
the weekend after todays dip.
.Extended Discussion (Monday through Thursday)
Dry weather continues Monday into Tuesday as high pressure remains
over the Western US. This will bring a few days of above normal
The pattern changes again during the middle of next week as
another upper trough approaches again. Current progs suggest that
next week`s system may be a bit deeper and could tap into a decent
moisture plume. Feeling confident about the pattern change, but
less so with possible showery coverage and precipitation amounts.
With this forecast package, we`ve bumped up precipitation wording,
keeping the best chances generally north of Interstate 80. At the
very least, this pattern change will bring about some considerable
cooling for the middle of next week.
Mainly VFR conditions the next 24 hours with isolated SHRA along
the Coastal Ranges. These showers will be dissipating this
evening. South to southwest winds 10-15 kt across the Valley will
become light this evening, then become northerly late tonight into
Friday. Local SW wind gusts to 40 kts will continue over Sierra
ridges through this afternoon.