Area Forecast Discussion
Issued by NWS Sacramento, CA

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FXUS66 KSTO 211055
AFDSTO

Area Forecast Discussion
National Weather Service Sacramento CA
355 AM PDT Fri Jul 21 2017


.SYNOPSIS...

Hot and dry weather today. Widespread triple heat across the
valley this weekend. Slight chance of Sierra thunderstorms early
next week.

&&

.DISCUSSION...

Satellite imagery shows clear skies this morning, with dry
southwest flow across interior NorCal. Temperatures are running 3
to 6 degrees warmer than 24 hours ago this morning. Some warming
is expected on Friday with about 1 to 2 degrees of warming for the
Sacramento region and up to about 5 degrees over the north end of
the valley.

Hotter temperatures are expected this weekend as an ridging over
the Four Corners extends into NorCal. As a result, daytime highs
will be around 10 degrees above normal during this period, with
valley highs ranging from 102-109. Thus, an excessive heat watch
remains in effect Saturday-Sunday given the potential for heat-
related illnesses over the northern Sacramento valley.
Temperatures will cool down early next week as an upper trough
approaches the area and the upper ridge shifts to the east.

Elevated instability and monsoonal moisture could lead to
isolated late-day thunderstorm activity near the Sierra crest
Sunday and Monday. However, most of the favorable conditions
appear to remain outside of the forecast area.

&&

.EXTENDED DISCUSSION (Tuesday THROUGH Friday)

Upper low off the Northwest CA coast will slowly move inland early
next week. The GFS/GEM are a bit faster in this scenario than the
ECMWF. Regardless, a chance of thunderstorms will be possible over
the higher elevations with this system. This system will also
bring a period of modestly cooler weather, though temperatures are
likely to warm back up again by late next week after the system
exits the region.

Dang

&&

.AVIATION...

Mainly VFR conditions the next 24 hours, except reduced visibility
with smoke near the Detwiler Fire. Mainly light surface winds
continue, except SW gusts to 25 kt over higher terrain and near
the Delta.

Dang

&&

.STO WATCHES/WARNINGS/ADVISORIES...
Excessive Heat Watch from late tonight through Sunday evening
for Northeast Foothills/Sacramento Valley-Northern Sacramento
Valley.

&&

$$


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