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The Latest NWS Regional Area Forecast Discussions
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NWS Area Weather Forecast Discussion
County Warning Area [CWA]: STO Regional NWS Weather Office: Sacramento, CA 283 FXUS66 KSTO 031902 AFDSTO Area Forecast Discussion National Weather Service Sacramento CA 1202 PM PDT Sun May 3 2026 For additional details on weather and expected impacts over the next 7 days, please visit weather.gov/sto/briefing. .KEY MESSAGES... - Showers and thunderstorms this afternoon and evening for the mountains, foothills, and northern Sacramento Valley. A few isolated strong to severe storms are possible. - Continued chances for showers and thunderstorms Monday afternoon/evening and again on Tuesday for the mountains, Valley, and foothills. - Hot and dry conditions are expected to develop end of the week and into next weekend, with Minor and Moderate HeatRisk. && .DISCUSSION... ...Sunday through Tuesday... Upper level system is tracking across the Southwestern United States bringing moisture, instability, and sufficient shear to the region. Breaks in the cloud coverage at times has helped increase instability across the area. Current satellite and radar have a few cells developing in the mountains around Hwy 50 and tracking NW. HIRES guidance has picked up on this and started to initialize further development around 20-21z and continuing through the evening hours. Shear profiles show sufficient speed and directional shear to support thunderstorm growth. A few of the thunderstorms could be strong to severe, with hail up to 1 inch, gusty winds, frequent lightning, and brief heavy rain rates. Make sure you have a way to receive alerts this afternoon and evening. Precipitation chances shift down into the Valley overnight and into tomorrow morning with scattered rain showers Monday morning. Chances for thunderstorms arise once again during the afternoon and evening, with a few stronger storms possible. We will continue to see rain and thunderstorm potential into Tuesday, but chances are on the lower end as the main upper level system shifts further away from the area. At the highest peaks south of Highway 50 there will be chances for snow tonight through Tuesday, with minor accumulations possible. Temperatures through Tuesday will be on the cooler side across the area, with highs in the 60s to lower 70s Monday and the 70s on Tuesday. ...Wednesday and beyond... Conditions dry out as we move into Wednesday and continue into next weekend. An upper level ridge builds and amplifies over the western United States end of the week into next weekend. This increases our temperatures and drys out conditions across the area. Minor HeatRisk is expected across the Valley Wednesday, but becomes more widespread into the foothills and mountains by the end of the week. Minimum RH values start to drop into the 20s across the area, with a few isolated values in the teens. By next weekend, we are seeing increasing confidence temperatures will reach into the 90s, with the probabilities of seeing over 95 degrees 50-60 percent Saturday and Sunday. Potential for Moderate HeatRisk Saturday. && .AVIATION... BKN to OVC skies through the TAF period, with thunderstorm chances near RDD and RBL this afternoon and evening. Winds will begin to increase out of the southwest at 10-15kts for the Sacramento sites this afternoon and go light and variable overnight. Near 08z-13z chances for rain develop through the Valley affecting each site through the end of the TAF period. Ceilings go MVFR during this time. && .STO WATCHES/WARNINGS/ADVISORIES... None. && $$
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