Area Forecast Discussion
Issued by NWS Sacramento, CA
FXUS66 KSTO 291013
Area Forecast Discussion
National Weather Service Sacramento CA
313 AM PDT THU SEP 29 2016
Near normal temperatures today then a cooling trend through the
weekend with daytime highs 15 to 25 degrees below normal by
Sunday. Chance of showers and isolated thunderstorms Sunday into
Tuesday. Drier the middle of next week. A warming trend next week.
The cooling trend continues today as a low pressure system in the
Gulf of Alaska drops southeast towards the coast. Highs today
should come in right around normal for this time of year. A
moderate delta breeze has brought coastal stratus into the delta
this morning. As the upper trough drops into the eastern Pacific
still more cooling is expected Friday. A continued delta breeze on
Friday will bring the most cooling in the delta influenced areas.
Still more cooling is expected on Saturday with daytime highs
dropping to around 10 degrees below normal. The upper low centers
around the northwest corner of the state by Sunday afternoon.
Enough moisture and instability associated with this low for a
threat of precipitation over nearly the entire forecast area. GFS
UVV and most unstable cape show the best chance of any
thunderstorm activity will be Sunday afternoon and evening over
the Sierra cascade crest, northern mountains and northern
Sacramento valley and coast range. Still more cooling will make
Sunday the coolest day of the forecast period with daytime highs
forecast to drop to between 15 and 20 degrees below normal.
.EXTENDED DISCUSSION (Monday THROUGH Thursday)
The upper level low quickly moves through the region, shifting
east into the Great Basin by Monday. Cool northerly flow aloft takes
hold across the region on Monday, and there may be enough residual
moisture for a few showers as well. Overnight temperatures will
likely be on the cool side for a few nights, with 40s across the
Central Valley and 20s possible over higher terrain.
Drier weather is expected by the middle of next week as the
eastern Pacific ridge rebuilds into California. High temperatures
are expected to warm back to near normal levels, though overnight
lows may remain on the cooler side.
VFR conditions across Valley terminals the next 24 hours. South to
west winds 10-15 kt will continue across the Valley today, with
local gusts up to 25 kt during the afternoon. Near the Delta and
over higher terrain...higher gusts are possible.