Area Forecast Discussion
Issued by NWS Sacramento, CA

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000
FXUS66 KSTO 221102
AFDSTO

Area Forecast Discussion
National Weather Service Sacramento CA
402 AM PDT THU SEP 22 2016

.SYNOPSIS...
A slight chance of showers or thunderstorms across the northern
mountains and Sierra today then dry through the middle of next
week. Breezy north winds through the weekend. Cooler than normal
temperatures through Friday then warmer than normal over the
weekend and into next week.

&&

.Discussion...
Cool upper low pressure system currently centered near the
California/Oregon border and continuing eastward. Upward motion
east of the low center is generating some light showers over the
southern Cascades at this time. Models dig the low center to the
southeast and into the Great Basin today. Disturbances dropping
down the back side of the low and wrap around moisture may allow
for some scattered showers over the Sierra Cascade range today.
Instability is limited so have kept mention of thunderstorms to
just the highest elevations. For the rest of the forecast
area...expecting still cooler temperatures with highs remaining in
the 70s throughout the valley. Northerly flow behind the
retreating low will bring breezy north winds across the forecast
area over the next few days. High pressure building over the west
coast will bring the beginning of a warming trend on Friday with
highs warming several degrees. Still more warming on Saturday as
the upper ridge amplifies along the west coast. Substance and
northerly breezes will bring daytime highs up to a few degrees
above normal for late September. Upper ridge axis shifts inland on
Sunday for a bit more warming. Daytime maximum temps will reach
about 10 degrees above normal reaching into the 90s most valley
locations. The autumnal equinox occurs today at 7:21 AM local
time.


.EXTENDED DISCUSSION (Monday THROUGH Thursday)

Strong high pressure over the eastern Pacific Ocean will continue
to impact interior NorCal with daytime highs 5-12 degrees above
normal on Monday. The high gradually weakens through midweek as a
trough over the Pacific Ocean approaches the west coast. Temperatures
undergo a subtle cooling trend: on Monday, valley highs will be
mid to upper 90s cooling to the upper 80s to low 90s by Thursday.
Dry weather persists in the extended forecast.  JBB

&&

.AVIATION...

Northerly flow developing today at TAF sites as VFR conditions
dominate much of interior NorCal. Periods of MVFR possible along
western Sierra slopes and in portions of Shasta County where
showers/thunderstorms may develop today. Winds at TAF sites will
range 5-15 kts...occasional gusts up to 20 kts possible. JBB
&&

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

$$



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