Area Forecast Discussion
Issued by NWS Sacramento, CA

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FXUS66 KSTO 172240

Area Forecast Discussion
National Weather Service Sacramento CA
340 PM PDT Thu Aug 17 2017

Temperatures near to slightly above normal with a threat of
afternoon/evening mountain thunderstorms.


.DISCUSSION (Today through Saturday)...
At 3 pm, temperatures across interior NorCal valley were generally
in the 90s except for upper 80s closer to the Delta region and
a little over 100 around Redding. High pressure is building over
the Eastern Pacific and is causing a warming trend for our for
NorCal. Expect a little more warming this afternoon as daytime
highs should peak between 94 to 104 in the valley...mid 70s to low
90s across higher terrain...80s in the Delta.

As forecast, we`re seeing a few cells of convection over the
Sierra near and just north of Yosemite on radar this afternoon.
These thunderstorms are popping up as small cells and tend to
weaken soon after developing. However, they can still produce
small hail, lightning, and locally gusty winds.

Warming trend peaks tomorrow as much of our forecast area nudges
up the thermometer by a degree or two. The hot spot will again be
the Redding area reaching around 106 degrees. The chance of
afternoon/evening thunderstorms over mountains is expected again
tomorrow and through the rest of the short-term forecast period.
However, daytime highs will gradually trend cooler over the
weekend.  JBB


An upper level low will be setting up off the coast of southern
California to start the extended period on Saturday. This will
push moisture north into NorCal and bring a chance for Mountain
thunderstorms during the afternoon and for both Sunday and Monday.
There could be enough moisture to see some clouds in the valley,
but widespread cloud cover is not expected. Tuesday moisture will
decrease and should limit the thunderstorm chances, but still
could see some activity mainly over the coastal range of Tahama
and Shasta Counties. On Wednesday the upper level low pushes east
as a trough moves south out of the Gulf of Alaska. This will bring
unstable conditions for the end of the period but mountain
thunderstorm chances look limited. Overall temperatures will be
seasonal throughout the period to maybe a few degrees below normal
on Tuesday.


VFR conditions the next 24 hours at the TAF sites. Winds under 10
knots except in the Delta where gusts to 30 knots will be
possible. Afternoon thunderstorms and CB possible over the Sierra
this afternoon and through the early evening.



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