314
FXUS66 KSTO 170901
AFDSTO

Area Forecast Discussion
National Weather Service Sacramento CA
201 AM PDT Sat Aug 17 2024

.SYNOPSIS...
Near to slightly below normal temperatures are expected to persist
into next week. A quick moving system on Saturday will introduce a
period of gusty winds to the region and a chance for isolated to
scattered showers and thunderstorms to portions of the northern and
central Sacramento Valley Saturday afternoon and evening as well.

&&

.Discussion...
We`re finally going to see some sub-90 degree temperatures today
in the Valley as a fairly impressive closed low deepens off of the
coast. NBM currently has probabilities of temperatures at or
below 85 degrees in much of the Valley at 25 to 50% today. With
those lower temperatures though, come several other impacts as
well. Winds will be periodically gusty, generally between 20 to 30
mph in the afternoon and evening. The NBM has probabilities of
gusts greater than 30 mph at 45 to 75%, primarily in the northern
and central Sacramento Valley. While winds will be gusty at times,
the onshore flow will also cause higher daytime humidities,
generally between 30 and 55% in the Valley this afternoon.
Finally, moisture with this system, along with the upper level
support presented by a subtle shortwave moving through the flow
pattern, bring chances for isolated showers and thunderstorms to
eastern Shasta and Tehama counties. NBM has probabilities between
20-40% west of the I-5 corridor, with highest chances along the
edge of the Coastal Range.

Sunday through Tuesday see a slightly warmer period as the low backs
off to the northwest, though temperatures are still expected to be
below normal. Daytime relative humidities will also return to the
upper teens to 20s by Monday.

&&

.EXTENDED DISCUSSION (Wednesday THROUGH Saturday)...
Cluster analysis continues to show very strong agreement on the
closed low remaining blocked in the vicinity of the Pacific
Northwest by robust ridging over the central CONUS through much of
the week ahead. Temperatures will likely fluctuate somewhat day
to day, remaining dependent on the strength and orientation of the
closed low as it remains mostly stationary. As a result, there is
a signal for a slight midweek warming trend to near normal high
temperatures, with a gradual downturn toward slightly below normal
temperatures through the end of the week. Late in the week and
early next weekend, there is some signal in some of the ensemble
members that the low could take on an "inside slider" pattern,
where the low moves in from off the coast and then "slides" down
the middle of the inland portion of the PNW and NorCal. This will
need to be monitored as the week progresses as it could have
implications next weekend for fire weather in interior NorCal.
Otherwise, dry conditions are anticipated throughout the long term
alongside periodically breezy winds in the afternoon and evening.

&&

.AVIATION...
VFR conditions next 24 hours except local MVFR vicinity scattered
showers and isolated thunderstorms Coast Range and mountains of
Shasta County 21Z thru about 06Z Sunday. Widespread south to west
surface wind gusts 20-30 kts 18Z thru 03Z Sunday.

&&

.STO WATCHES/WARNINGS/ADVISORIES...
None.

&&

$$