Sunrise 5:41 AM   Sunset 8:39 PM Moonrise 12:32 AM   Moonset 2:32 PM

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FXUS66 KSTO 302038 AFDSTO

Area Forecast Discussion National Weather Service Sacramento CA 138 PM PDT Sun Jun 30 2024

SYNOPSIS
A general warming trend begins today, culminating in dangerous heat and widespread major HeatRisk with areas of extreme HeatRisk from Tuesday into next weekend. Critical fire weather conditions are also anticipated in the Sacramento Valley and adjacent foothills from late Monday through Wednesday.

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 the western side of the northern and central Sacramento Valley and adjacent elevations below 3000 feet late Monday through Wednesday evening.

Discussion
Satellite imagery depicts broad troughing aloft clipping the region today. Widespread 90s to around 100 degrees are anticipated in the Valley and foothills this afternoon. Occasional gusts of 15 to 25 mph will remain possible through the early evening while the trough axis is overhead. A brief instance of an isolated shower or thunderstorm cannot be completely ruled out this afternoon and evening across portions of Plumas County, but thunderstorm activity will likely remain outside of the forecast area per HRRR guidance. NBM depicts less than 5 to 10% probability of thunderstorm development this afternoon and evening.

Ensembles and clusters show strong, anomalous ridging building into NorCal from the eastern Pacific this week resulting in a long-duration heat event. By Monday, daytime temperatures will be in the 100 to 105 range across the Valley. Temperatures will continue to warm on Tuesday and Wednesday, with widespread triple digits ranging from 100 to 110 degrees in the Valley and adjacent foothills. NBM probabilities indicate a 60-90% chance of high temperatures greater than 105 degrees Tuesday- Wednesday. Little relief is expected overnight with lows forecast in the upper 60s to around 80. As a result, widespread major HeatRisk and areas of extreme HeatRisk look to arrive on Tuesday and remain in place into at least next weekend. 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.

Areas of gusty northerly winds are expected throughout the Sacramento Valley and adjacent foothills from late Monday night through Wednesday, with gusts up to 30 mph. The strongest winds are expected on Tuesday, especially along western portions of the northern and central Sacramento Valley. Afternoon minimum humidities in the single digits to low teens are anticipated on Tuesday and Wednesday. Overnight humidity recovery looks to remain poor as well, especially across the northern and central Sacramento Valley. The combination of gusty winds and low humidity will lead to critical fire weather conditions. A Red Flag Warning remains in effect from 11 PM Monday through 8 PM Wednesday.

.EXTENDED DISCUSSION (Thursday THROUGH Sunday)...

Ensemble guidance indicates a slight eastward transition of the eastern Pacific ridge through the late week period as the ridge axis looks to become centered over NorCal. Therefore, the long- duration heat event is projected to continue through the extended period. Resultant widespread high temperatures in the triple digits are expected from Thursday through Sunday across the Valley and adjacent foothills, with widespread Major HeatRisk and areas of Extreme HeatRisk. Overnight lows will mainly be in the mid 60s to near 80, warmest in the foothills. Daytime temperatures may trend slightly downward on Sunday, but will remain hot. In addition, the extended period of very hot and dry conditions will bring elevated fire weather concerns through the forecast period.

AVIATION

VFR conditions next 24 hours. Local northwesterly surface wind gusts 15-25 kts northern Sacramento Valley thru 06Z Monday, and aft 15Z Monday. Local southwest gusts 20-30 kts vicinity west Delta after 00Z Monday, otherwise surface wind gusts generally below 12 kts.

STO WATCHES/WARNINGS/ADVISORIES
Red Flag Warning from 11 PM Monday 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.

Sacramento #4
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Sun -- 01:33 AM PDT     Moonrise
Sun -- 02:45 AM PDT     2.92 feet High Tide
Sun -- 05:45 AM PDT     Sunrise
Sun -- 11:12 AM PDT     0.17 feet Low Tide
Sun -- 03:31 PM PDT     Moonset
Sun -- 03:32 PM PDT     1.94 feet High Tide
Sun -- 08:34 PM PDT     Sunset
Sun -- 10:15 PM PDT     0.36 feet Low Tide
Tide / Current data from XTide NOT FOR NAVIGATION

Sacramento #4, Sacramento River, California, Tide feet

Clarksburg #4
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Sun -- 01:34 AM PDT     Moonrise
Sun -- 01:35 AM PDT     2.92 feet High Tide
Sun -- 05:45 AM PDT     Sunrise
Sun -- 09:42 AM PDT     0.17 feet Low Tide
Sun -- 02:23 PM PDT     1.94 feet High Tide
Sun -- 03:30 PM PDT     Moonset
Sun -- 08:33 PM PDT     Sunset
Sun -- 08:45 PM PDT     0.36 feet Low Tide
Tide / Current data from XTide NOT FOR NAVIGATION

Clarksburg #4, Sacramento River, California, Tide feet

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