Area Forecast Discussion
Issued by NWS Sacramento, CA

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FXUS66 KSTO 281615
AFDSTO

Area Forecast Discussion
National Weather Service Sacramento CA
915 AM PDT WED SEP 28 2016


.SYNOPSIS...
Cooling trend to below normal by Friday and continuing through the
weekend with a chance of precipitation Sunday. Drier with a
warming trend next week.

&&

.DISCUSSION...
Cooling trend in store for Interior NorCal through the remainder
of the week and into the weekend as deep low pressure currently
in the GOA tracks into the area. Cooling begins today as heights
and thicknesses begin to decrease with approaching system. Upper
low over SoCal remains far enough to the south today to not impact
our area and is forecast to weaken tonight and shift east. Delta
breeze is weak at this time but expected to increase this
afternoon into evening as marine layer deepens. High temperatures
are forecast to be 5 to 10 degrees lower today with low to mid
90s for the Central Valley and mostly 70s to 80s for the mountains
and foothills.

Upper low progged to dig near 130 W Thursday into Friday with
increasing onshore flow. Weak dry front pushes inland Friday.
Moderate to strong Delta breeze will provide cooling into the
Central Valley as NorCal impacted by overall by larger scale
cooling. Highs expected near normal on Thursday with mainly mid
80s in the Central Valley. Below normal temperatures Friday as
some upper 70s are introduced into the Southern Sacramento Valley.
Mostly 60s to lower 70s forecast for the mountains and foothills
Friday.

Upper low weakens to trough and forecast to move through Interior
NorCal Saturday bringing some breezy wind and additional cooling.
Deeper secondary low is forecast by both GFS and ECMWF to follow
inland Sunday. Models showing some QPF with this feature with GFS
from about I-80 northward while ECMWF, in its normal fashion, is
showing more widespread precip over the entire CWA Sunday.
Significant cooling expected over the area Sunday with highs in
the upper 60s to lower 70s for the Central Valley. Although
overall QPF looks light, some snow possible over the higher
terrain as snow levels lower to 6000 to 7000 feet Sunday. GFS
also showing some CAPE over Interior NorCal Sunday afternoon to
suggest potential for some isolated thunderstorms.

Main low shifts into the Great Basin Monday as channeled vort max
tracks through in the morning, keeping a threat of showers...
mainly over the mountains. Increasing subsidence builds inland
from the west Monday. Northwesterly flow aloft develops with drier
and warmer weather expected early next week, except for a slight
chance of showers over the Northern mountains Tuesday.

PCH

&&

.AVIATION...

VFR conds ovr Intr NorCal nxt 24 hrs. SWly sfc wnd 15 to 20 kts
with gusts to 30 kts thru Delta this eve and ovrngt.

&&

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

$$



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