Area Forecast Discussion
Issued by NWS Sacramento, CA

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FXUS66 KSTO 171558
AFDSTO

Area Forecast Discussion
National Weather Service Sacramento CA
858 AM PDT Sat Jun 17 2017

.Synopsis...
An extended heat wave continues this weekend through most of next
week with widespread highs over 100 degrees and warm nights.
Isolated afternoon thunderstorms possible near the Sierra Crest
and mainly south of Lake Tahoe Sunday and Tuesday, spreading into
the northern mountains for Monday.

&&

.Discussion...
Temperatures are trending several degrees warmer at this time than
compared to yesterday and will top out over 100 degrees today in
the central valley. Hot weather continues to be the main weather
story this weekend and next week. Northerly winds will continue
this weekend and start to reverse direction Monday. Some help from
the Delta may occur Monday night and Tuesday night but with the
hot airmass over the west we will likely still be over 100 degrees
for Tuesday and Wednesday in Sacramento and close to 105 for the
daytime highs.

Some record highs are listed below.
Record Highs...........Today......Sunday.....Monday.....Tuesday
Redding Apt............104(2012)..102(1988)..104(1988)..107(2001)
Red Bluff..............109(1982)..109(1959)..110(1970)..110(1970)
Sacramento.............102(1976)..105(1945)..106(1988)..108(1920)
Sacramento Exec........103(1963)..102(1988)..105(1988)..109(1961)
Stockton...............103(1963)..104(1981)..108(1981)..107(1981)
Modesto................103(2012)..104(1981)..105(1981)..106(2008)

.Previous Discussion...
High pressure ridging is bringing hot weather to the area, and
this is expected through the weekend into mid week, with a very
gradual cool down by late next week into next weekend.

A Heat Advisory begins today for the Valley. This was upgraded to
a Excessive Heat Warning for Sunday, which has been extended into
Wednesday, with a Heat Advisory for the foothills. Triple digit
highs are expected today, but even hotter weather is expected as
the ridge strengthens, with highs peaking in the 105-110 range in
the Valley for the Sunday-Tuesday period. Daily record highs are
likely to be set in multiple locations. Some slight cooling with
a weak Delta breeze is possible Tuesday, so portions of the
southern Sacramento and northern San Joaquin Valleys may see
peak temperatures on Monday. Other areas will see little change
in the hot weather for Tuesday.

Northerly to northeasterly downsloping winds will keep
temperatures very warm overnight. This particularly true for the
foothills and northern Sacramento Valley, where lows could
potentially remain in the low 80s. Opening windows at night will
give little or no relief from the heat.

A somewhat moister than usual atmosphere with higher dewpoints
could add to the feeling of the heat, particularly on Monday.

The Valley, Delta, and foothills are expected to remain dry with
limited cloud cover. However, mid level moisture with afternoon
heating will allow some showers and thunderstorms to develop over
the higher Sierra Sunday, mainly south of I80. On Monday, enhanced
elevated instability could spread afternoon and evening
thunderstorms into the northern mountains. Some limited afternoon
convection could linger over the Sierra on Tuesday, but conditions
look much less favorable. EK


.EXTENDED DISCUSSION (Wednesday THROUGH Saturday)

Hot and dry conditions will continue during the middle of next
week, then the upper ridge is forecast to weaken somewhat later in
the week resulting in moderating temperatures back to around
average by the end of the week.
&&

.AVIATION...

VFR conditions expected next 24 hours. Northerly surface winds
10-15 KTS with occasional gusts 20-25 KTS in the Central Valley.
&&

.STO WATCHES/WARNINGS/ADVISORIES...
Heat Advisory from noon Sunday to 8 PM PDT Wednesday for
Carquinez Strait and Delta-Central Sacramento Valley-Clear
Lake/Southern Lake County-Motherlode-Mountains Southwestern
Shasta County to Northern Lake County-Northeast
Foothills/Sacramento Valley-Northern Sacramento Valley-Northern
San Joaquin Valley-Shasta Lake Area / Northern Shasta County-
Southern Sacramento Valley-West Slope Northern Sierra Nevada-
Western Plumas County/Lassen Park.

Excessive Heat Warning from noon Sunday to 8 PM PDT Wednesday
for Carquinez Strait and Delta-Central Sacramento Valley-
Northern Sacramento Valley-Northern San Joaquin Valley-Southern
Sacramento Valley.

&&

$$



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