Area Forecast Discussion
Issued by NWS Sacramento, CA

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FXUS66 KSTO 132119

219 PM PDT TUE OCT 13 2015

Warm and dry weather continues Wednesday with a cooldown and
chance of mainly Sierra Nevada showers Thursday into Friday. A
stronger frontal system brings more widespread shower chances
over the weekend.


.Short Term Discussion (Tonight through Friday)...
The ridge is beginning to erode tonight into Wednesday. Although
Wednesday afternoon temperatures will be down compared to today,
readings will still be 8-14F above normal. A weakening upper low
about 350 miles west-southwest of San Diego will become a player
in our weather Thursday and Friday as it tracks northeast over
central California in response to the eastward progression of an
eastern Pacific frontal system. As the low opens into a trough
over California, it may generate some Sierra Nevada shower
activity south of Highway 50 on Wednesday and potentially expand
to near Lassen Park on Thursday and Friday. Cloudiness will
increase and temperatures decrease to near and below normal with
this low on Thursday along with continued cloud coverage on
Friday due to the approaching frontal system.          JClapp

.Extended Discussion (Saturday THROUGH Tuesday)
Medium range models similar in showing short wave trough moving
through Interior NorCal Saturday into Sunday. 12z ECMWF has come
more in line with the GFS/GEM in showing open wave moving through.
Dynamics look limited as system progged to weaken as it moves
onshore. PWs however are progged upwards of 1.25 inches and models
are generating some light QPF over most of the forecast area
between 12z Sat and 12z Sun. On average, about 10 degrees of
cooling expected Saturday with highs in the Central Valley mainly
in the upper 70s.

Precipitation threat looks to wind down Sunday morning as
increasing subsidence moves onshore and air mass begins to warm.
Dry weather with above normal temperatures expected through the
first half of next week as strong upper ridging rebuilds over


Lgt and vrbl wnds alf with upr rdg ovhd bcmg SEly alf Wed as upr
low, W of Baja, movs N. VFR conds ovr Intr NorCal nxt 24 hrs genly
lgt sfc wnds.



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