Area Forecast Discussion
Issued by NWS Sacramento, CA

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000
FXUS66 KSTO 222242
AFDSTO

Area Forecast Discussion
National Weather Service Sacramento CA
342 PM PDT Thu Jun 22 2017


.SYNOPSIS...
Extended heat wave with widespread highs over 100 degrees and
warm nights through the end of the week. Isolated afternoon
thunderstorms possible over the mountains. Not as hot next week.

&&

.DISCUSSION...
Current temperatures ranging 104 to 108 in the valley at 3 pm and
those numbers will climb higher in the next several hours. Yesterday`s
peak heat occurred near 5 to 6 pm. Will have to monitor record
highs for several locations. For example, Modesto is currently at
105 degrees and their record is 106 (1954). Downtown Sacramento is
at 105 and the record is 107 (1981). Redding is at 106 and the
record is 107 (2006).

Northerly winds have picked up this afternoon with strongest
winds over the north and west side of the valley. The high heat,
low relative humidity and increased winds will continue high fire
danger as the Red Flag Warning continues.

Thunderstorm chances likely to be limited to the Sierra south of
Lake Tahoe over the next few days.

Hot weather continues across the northern half of the Sacramento
Valley and in the mountains late this week while cooler weather
gradually returns to the Delta and southern Sacramento Valley as
the Delta Breeze returns.

&&
.EXTENDED DISCUSSION (Monday THROUGH Thursday)

Temperatures continue to cool Monday and Tuesday as an upper
level shortwave trough pushes the ridge axis east. Upper flow will
be mostly zonal over the area, so high temperatures will still
mostly remain a few degrees above normal through midweek. However,
low temperatures will finally fall to normal by Monday night due
to southerly winds and breezy Delta winds which will finally allow
overnight relief from the heat in most areas. Dry weather
expected for interior NorCal beginning Monday as the airmass
stables.

-HEC


&&

.AVIATION...

VFR conditions expected at the TAF sites the next 24 hours.
Isolated thunderstorms possible over the northern Sierra crest in
the afternoon. Northerly winds 15 to 30 kt northern Sacramento
valley and coast range through 6z Friday. Southwest winds 15 to 25
kt through the delta...otherwise winds generally below 15 kt.

&&

.STO WATCHES/WARNINGS/ADVISORIES...
Heat Advisory until 11 PM PDT Saturday 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 noon PDT Friday for Central Sacramento
Valley in Glenn, Colusa, Yuba, Northern Sutter, and Butte County
Below 1000 Ft-Eastern Mendocino NF-Eastern Portion of
Shasta/Trinity NF-Lake County Portion of Lake-Napa-Sonoma Unit-
Northern Sacramento Valley to Southern Tehama County Line Below
1000 Ft-Northern Sierra Foothills from 1000 to 3000 Ft. Includes
portions of Shasta-Trinity and Butte Units-Southeast Edge Shasta-
Trinity NF and Western Portions of Tehama-Glenn Unit-Southern
Sacramento Valley in Yolo-Sacramento Far Western Placer,
southern Sutter and Solano County Below 1000 Ft.

Excessive Heat Warning until 11 PM PDT Friday for Carquinez
Strait and Delta-Central Sacramento Valley-Northern Sacramento
Valley-Northern San Joaquin Valley-Southern Sacramento Valley.

&&

$$



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