Area Forecast Discussion
Issued by NWS Sacramento, CA
Issued by NWS Sacramento, CA
023 FXUS66 KSTO 252008 AFDSTO Area Forecast Discussion National Weather Service Sacramento CA 108 PM PDT Tue Jun 25 2024 .SYNOPSIS... Isolated showers and thunderstorms will remain possible across interior NorCal through early this evening. Seasonable, dry, and periodically breezy weather then persists through the remainder of the week into the weekend. && Key Points - Areas of Moderate HeatRisk today, becoming primarily Minor HeatRisk mid-week into the weekend. - Slight chance of isolated thunderstorms through this evening, best chances over the Sierra Crest south of Highway 50. - Potential for another warming trend by early next week. Short-Term Discussion (Today THROUGH Friday)... As of early this afternoon, GOES-West satellite imagery continues to depict a few plumes of mid level moisture ejecting across interior NorCal. Resultant radar imagery is showing some scattered convection across the region as well, but given the height of the moisture aloft, little, if any, precipitation is reaching the ground. A few updrafts have been strong enough to produce a few isolated lightning strikes across the Valley and foothills though. As a result, there remains a 10 to 15% chance of isolated thunderstorm activity in the Valley and foothills through the early evening hours. At this time, the strongest instability on the order of a few hundred J/kg remains confined along the Sierra, generally south of the I-80 corridor. This will be the primary corridor for additional thunderstorm development this afternoon and evening, with a 15 to 30% probability of thunderstorm development. These mountain thunderstorms will have a better chance at some light rainfall accumulation and small hail production, but the primary hazards will be gusty and erratic winds as well as potential for new fire starts from lightning. Otherwise, high temperatures today are expected to settle in the upper 80s to 90s throughout the Valley and foothills, with 70s to 80s at higher elevations. An upper level trough is then expected to eject through the Pacific Northwest toward the Intermountain West from Wednesday into the end of the week. This will bring lowering heights aloft and generally cooler, near normal temperatures through the end of the week and into the weekend. Cooler is still relative, however, as afternoon high temperatures are still expected to reach the 80s to mid 90s in the Valley and foothills, with 70s to 80s persisting at higher elevations. Given the relative stability in the flow pattern aloft, breezy to occasionally gusty, late day south to west winds are expected to persist as well. && .EXTENDED DISCUSSION (Saturday THROUGH Tuesday)... Latest cluster analysis continues to show rather uniform agreement on another trough ejecting through the Pacific Northwest over the weekend. This will work to keep temperatures steady and seasonable, while onshore flow and breezy late day winds persist through the weekend at this time. The aforementioned trough does look to take a slightly further southward track compared to its predecessor. Additionally, ensemble guidance is indicating that ridging aloft will begin to build in across the eastern Pacific, inducing a period of northwesterly flow and height rises aloft moving into early next week. A resultant warming trend is anticipated during this time frame, with some signals at a period of breezy to gusty north- northwesterly winds on Monday as well. && .AVIATION... VFR conditions expected to prevail across interior NorCal next 24 hours. Isolated showers and thunderstorms possible through 03z, with highest chances along the Sierra. Otherwise, breezy south to west surface winds, with occasional gusts to 20 kts in the Valley through 03z and gusts to 25 kts in the Delta and vicinity persisting overnight. && .STO WATCHES/WARNINGS/ADVISORIES... None. && $$