Area Forecast Discussion
Issued by NWS Sacramento, CA

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FXUS66 KSTO 182103

Area Forecast Discussion
National Weather Service Sacramento CA
203 PM PDT Sun Jun 18 2017

An extended heat wave continues through most of this week with
widespread highs over 100 degrees and warm nights. Isolated
afternoon thunderstorms possible near the Sierra Crest from around
Lake Tahoe and southward through this evening, spreading into the
northern mountains for Monday and Tuesday.


Hot weather continues to be the main weather story this week with
record and near record heat. Northerly winds will continue into
the evening before reversing direction for places near the Delta.
This will allow temperatures to cool a few degrees more than last
night. The north end of the valley will only cool off near 80 and
thermal belt areas in the foothill will only cool off into the
mid 70s to lower 80s.

Some help from the Delta may occur Monday night and Tuesday night
to help cool overnight lows a little for the Sacramento region 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. Further north in the valley
temperatures will be remain closer to 110 degrees.

Some record highs are listed below.
Record Highs...........Today.......Monday.....Tuesday...Wednesday
Redding Apt............102(1988)..104(1988)..107(2001)..110(1992)
Red Bluff..............109(1959)..110(1970)..110(1970)..110(1962)
Sacramento Exec........102(1988)..105(1988)..109(1961)..111(1961)

Later this afternoon some thunderstorms may develop along the
crest south of Lake Tahoe. The flow pattern is east to southeast
in that area this evening so if activity does get going there
would be a chance that some showers and isolated thunderstorms may
make it into the higher elevations of the southern Motherlode
this evening.

There is a weak shortwave that will approach the region on Monday
then move through the region Tuesday and Wednesday.
Models are hinting at some thunderstorm potential over the
northern mountains and along the crest...mainly crest and to the
east for Monday. GFS continues to be more bullish with the amount
of convection the next couple of days but have opted to follow
the NAM due to lack of moisture present.


The strong ridge will remain in place for the extended period
keeping the hot dry weather around. The Excessive Heat Warning
will remain in effect on Thursday as highs once again will be
105-110 for the valley and into the 70`s to lower 90`s for the
higher elevations. A trough to our east will be digging south and
that will help to bring slightly lower heights for us and a small
cool down. Highs will be just above the 100 mark for Friday but
possibly falling below the 100 mark by Sunday. Closer to average
overnight lows will also return by Friday night. A delta breeze
dose look to develop on Friday and continue into the weekend and
that should bring some relief from the heat for the Delta regions.
We do start to see some weak instability build into the higher
elevations over the weekend but not expecting any showers or
t-storms at this time.




VFR conditions the next 24 hours at the TAF sites. Breezy northern
winds 10-15 knots gusting 20-25 knots this afternoon will diminish
to 5-10 knots by 00z Mon.


Heat Advisory until 8 PM PDT Thursday for Clear Lake/Southern
Lake County-Motherlode-Mountains Southwestern Shasta County to
Northern Lake County-Northeast Foothills/Sacramento Valley-
Shasta Lake Area / Northern Shasta County-West Slope Northern
Sierra Nevada-Western Plumas County/Lassen Park.

Red Flag Warning until 9 PM PDT this evening for Central
Sacramento Valley in Glenn, Colusa, Yuba, Northern Sutter, and
Butte County Below 1000 Ft-Lake County Portion of Lake-Napa-
Sonoma Unit-Northern Sacramento Valley to Southern Tehama County
Line Below 1000 Ft.

Excessive Heat Warning until 8 PM PDT Thursday for Carquinez
Strait and Delta-Central Sacramento Valley-Northern Sacramento
Valley-Northern San Joaquin Valley-Southern Sacramento Valley.


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