Area Forecast Discussion
Issued by NWS Sacramento, CA

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000
FXUS66 KSTO 291655
AFDSTO

Area Forecast Discussion
National Weather Service Sacramento CA
955 AM PDT THU SEP 29 2016

.SYNOPSIS...
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
Monday. Drier Tuesday into Thursday with a warming trend.

&&

.DISCUSSION...
Strong Delta breeze overnight has resulted in some low level CAA
into the Central Valley with morning temps running up to 10 degrees
cooler. Cooling trend continues today as large upper low off the
B.C. Coast slowly digs and progress towards the West Coast. High
temperatures today expected to be near normal with 80s in the
Central Valley.

Moderate to Strong Delta breeze continues tonight into Friday as
marine layer deepens. NAM Bufkit showing a blob of low level
moisture in the Southern Sac Valley Friday morning, so will have
to look at the potential for some patchy morning stratus around
the Sacramento area.

Moisture starved surface front pushes into northwest CA tonight
into Friday with main impact being some breezy to windy conditions
ahead of boundary over Interior NorCal. Additional cooling will
result, with max temps Friday forecast mostly in the upper 70s to
around 80 with upper 50s to mid 70s for the mountains and
foothills.

Frontolysis occurs along baroclinic zone as it slides south Friday
night, while associated upper low weakens to trough and swings
inland Saturday. Cooling trend continues Saturday with some breezy
conditions. Secondary colder, more dynamic, low is progged to drop
down the base of long wave and track into NorCal Sunday. Models
continue to show widespread precip with this feature over Interior
NorCal. GFS maintains some increased afternoon CAPE over the CWA
to support deep moist convection. Best instability currently
depicted over the Northern and Central Sacramento Valley and along
the eastern foothills and Motherlode. 700 MB temps cool to around
-5 to -6 Deg C Sunday afternoon with 1000-500 MB thicknesses from
around 541-544 DM over the Shasta and Coastal mountains to 545-550
DM over the Sierra Nevada. This suggest snow levels could lower to
around 5500 feet in the north to 6500 feet over the Sierra later
Sunday. Although precipitation is expected to be scattered and highly
variable amounts given the showery pattern, potential exists for
several inches of accumulation at pass levels. Sunday`s high
temperatures forecast to be 15 to 25 degrees below normal with mid
60s to lower 70s for the Central Valley. Potential exists for some
new record lowest maximum temperatures to be set Sunday.

PCH

&&

.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.

Dang

&&

.AVIATION...
Incrsg SWly flow alf as ofshr upr low apchs. VFR conds ovr Intr
NorCal nxt 24 hrs exc lcl MVFR/IFR poss in ST vcnty of Delta and
isold in Srn Sac Vly btwn 10z-18z Fri. SWly sfc wnd gsts up to 30
kts poss thru Delta and ovr hyr mtn trrn.

&&

.STO Watches/Warnings/Advisories...
None.
&&

$$


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