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080
FXUS66 KSTO 010955
AFDSTO

Area Forecast Discussion
National Weather Service Sacramento CA
255 AM PDT Mon Jul 1 2024

.SYNOPSIS...
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Widespread major to extreme HeatRisk from Tuesday into next
weekend. Critical fire weather conditions are also anticipated in
the Sacramento Valley and adjacent foothills tonight through
Wednesday.
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Key Points
- Long-duration, major heat event expected this week impacting
  holiday outdoor events.
- Excessive Heat Warning remains in effect for the Valley, Delta
  and foothills from Tuesday morning through Saturday evening.
- Red Flag Warning is in effect for much of the Sacramento Valley
  and adjacent elevations below 3000 feet tonight through
  Wednesday evening.

.Discussion...
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Clear skies cover the region as very strong ridging over the
eastern Pacific edges closer. Another short-wave trough will slide
over the ridge later today before shifting east. This will help to
moderate the rise in temperatures across the region today as
warming of only up to 5 degrees is expected compared to Sunday.
Behind the wave, northerly surface gradient is forecast to tighten
overnight tonight resulting in locally breezy north wind across
western portions of the Sacramento Valley. The breezes will last
into Tuesday afternoon before weakening, then another bout of
northerly breezes is expected Tuesday night and Wednesday (though
not quite as strong). Combined with very low humidity, the result
will be areas of critical fire weather conditions and a Red Flag
Warning remains in effect for late tonight into Wednesday.

Long duration heatwave will result in widespread major to extreme
heat risk across much of NorCal beginning Tuesday and lasting into
at least the weekend. Highs of 105 to 115 will be possible through
much of the valley and foothills during the week with overnight
lows only mainly in the 70s. This level of HeatRisk is very
dangerous to anyone without proper hydration or adequate cooling.
Strongly consider canceling outdoor activities. An Excessive Heat
Warning remains in effect for the Valley, Delta and foothills from
Tuesday morning through Saturday evening.
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.EXTENDED DISCUSSION (Friday THROUGH Monday)...
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597 DM upper high progged off the CA coast Friday continues the
heat across interior NorCal. High progged to shift inland
Saturday/Sunday over CA as EC bumps heights up to 600 DM. High
then drifts into the Great Basin Monday. NBM forecasting max temps
from 107 to 117 Friday into Saturday, then a slight trend down
Sunday into Monday but remaining 5 to 15 degrees above normal.
Overnight low temperatures forecast from the upper 60s near the
Delta to mid 80s in the thermal belts of the foothills.
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.AVIATION...
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VFR conditions over interior NorCal next 24 hrs. Sfc wind mainly
at or below 12 kts except SWly up to 17 kts vcnty of Delta aft 00z
Tue.
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&&

.STO WATCHES/WARNINGS/ADVISORIES...
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Red Flag Warning from 11 PM this evening to 8 PM PDT Wednesday
for Carquinez Strait and Delta-Central Sacramento Valley in
Glenn, Colusa, Yuba, Northern Sutter, and Butte County Below
1000 Ft-Eastern Mendocino NF-Eastern Portion of Shasta/Trinity
NF-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 from 11 AM Tuesday to 8 PM PDT Saturday
for Carquinez Strait and Delta-Central Sacramento Valley-
Motherlode-Mountains Southwestern Shasta County to Western
Colusa County-Northeast Foothills/Sacramento Valley-Northern
Sacramento Valley-Northern San Joaquin Valley-Southern
Sacramento Valley.
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&&

$$