Area Forecast Discussion
Issued by NWS Sacramento, CA
Issued by NWS Sacramento, CA
439 FXUS66 KSTO 110845 AFDSTO Area Forecast Discussion National Weather Service Sacramento CA 145 AM PDT Thu Jul 11 2024 .SYNOPSIS... Hot and dry weather will continue this week with Moderate to Extreme HeatRisk persisting across much of the region. Elevated fire weather concerns will also continue. Cooler this weekend into early next week. && Key Points - Long-duration, dangerous heat event persists this week. - Very hot thru Friday, followed by some cooling over the weekend into next week -Chances of showers/isolated T-storms along the Sierra Crest this weekend .Discussion... Major to Extreme HeatRisk continues today and tomorrow with Extreme HeatRisk in the foothills and portions of the Northern Sacramento Valley. There will be widespread 100s across the Valley and foothills with upper 80s, 90s across the mountains with localized areas of up to 106. Limited overnight relief is expected with lows mainly in the upper 60s to lower 80s. NBM probabilities show a 70-95% chance of highs greater than 105 deg F in the Valley and foothills with higher chances today than Friday. As an result, an Excessive Heat Warning remains in effect for the Valley and foothills until 8 PM Friday. Additionally, a Heat Advisory remains in effect for the Delta, Sierra, southern Cascades, and Burney Basin until 8 PM Friday. Please continue to practice heat safety and reconsider plans during the hottest parts of the day. Ensembles continue to show an area of low pressure move northward up the CA coast and by this weekend allow for some relief as moisture and cooler air moves into the region. Portions of the Central and Northern Sacramento Valley retain Major and Extreme HeatRisk values on Saturday but near the Delta and the Greater Sacramento area will cool to Moderate HeatRisk. Saturday`s highs will be 5-8 deg F cooler (Outside of the Northern Sacramento Valley) than Friday but still see widespread 100s throughout the Valley. The cooling trend continues on Sunday as onshore flow strengthens with 90s forecasted in the Valley, up to low 100s across areas of the foothills and the Northern Sac. Valley. With the onshore flow developing this weekend, this will allow for moisture to increase, primarily along the Sierra crest and eastward. This bring chances for afternoon and evening showers/isolated thunderstorms over the Sierra with highest chances occurring on Saturday. NBM depicts a 15-30% chance of thunderstorm development Saturday, 10-20% on Sunday. Any thunderstorms that develop could be capable of gusty winds, and possible fire starts due to lightning. Latest HeatRisk: wpc.ncep.noaa.gov/heatrisk/ Heat Safety Tips: weather.gov/safety/heat && .EXTENDED DISCUSSION (Monday THROUGH Thursday)... Ensembles continue to show relief from our anomalously hot weather as the high pressure system moves further from the area and onshore flow along the CA coast. Clusters show ridging over the Four Corners region with troughing over the coast into the Pacific NW. This will help temper afternoon highs keeping much of the area under Minor to Moderate HeatRisk, forecasting 90s throughout much of the Valley and low 100s along portions of the foothills and Northern Sacramento Valley. && .AVIATION... VFR conditions next 24 hrs. Surface wind gusts mainly below 12 kts except vicinity west Delta southwest 15-20 kts after 00Z Friday. && .STO WATCHES/WARNINGS/ADVISORIES... Excessive Heat Warning until 8 PM PDT Friday for Central Sacramento Valley-Motherlode-Mountains Southwestern Shasta County to Western Colusa County-Northeast Foothills/Sacramento Valley-Northern Sacramento Valley-Northern San Joaquin Valley- Shasta Lake Area / Northern Shasta County-Southern Sacramento Valley. Heat Advisory until 8 PM PDT Friday for Burney Basin / Eastern Shasta County-Carquinez Strait and Delta-West Slope Northern Sierra Nevada-Western Plumas County/Lassen Park. && $$