Area Forecast Discussion
Issued by NWS Sacramento, CA
Issued by NWS Sacramento, CA
269 FXUS66 KSTO 230817 AFDSTO Area Forecast Discussion National Weather Service Sacramento CA 117 AM PDT Sun Jun 23 2024 .SYNOPSIS... Slight cooling trend begins today and through the week, with mostly dry weather expected. Temperatures are expected to reach near normal by the end of the week, though there is a potential for a new warming trend next weekend. && Key Points - Widespread Moderate HeatRisk is expected today. - Decreasing areas of Moderate HeatRisk remain in the Valley Monday through Wednesday. - Temperatures cool to near normal by the end of the week, with a new warming trend possible late in the weekend. Short-Term Discussion (Today THROUGH Wednesday)... The Heat Advisory that was in place today has expired as of 8PM this evening. Overnight temperatures remain quite warm tonight, with the midnight measurements around the Valley and foothills ranging from the high 70s to mid 80s. Conditions will continue to cool a bit, but will remain in the mid 60s to mid 70s in most of these Valley and foothill locations. On Sunday, a slight cooling trend begins as the ridge bringing the hot temperatures today moves further east. Daytime highs will be cooler by a few degrees, though widespread Moderate HeatRisk remains throughout interior NorCal on Sunday. As a trough moves in over the CONUS from the Pacific, the cooling trend continues in our area, and HeatRisk begins to recede to mostly Minor risk, with diminishing areas of Moderate expected until Wednesday. High temperatures will range in the Valley between the 90s and very low 100s, and in the foothills and mountains in the 80s and 70s respectively. Accompanying and assisting this gradual decline in temperatures will be onshore flow, with occasionally gusty south to west winds late in the day. Conditions will generally remain dry throughout this period, though on Tuesday ensemble members have some agreement that there is a slight chance (10-15% probabilities) for isolated thunderstorms in the mountains, primarily south of I-80. Any storms that develop will quickly move east off the Sierra crest, but will be capable of producing brief heavy rain, gusty winds, and lightning while in our area. && .EXTENDED DISCUSSION (Thursday THROUGH Sunday)... Thursday and Friday see only widespread Minor HeatRisk, as the troughing pattern begins to move across CONUS in earnest. High temperatures will continue to trend down and end up reaching near normal levels for the time of year. Highs will be in the 90s in the Valley, 80s in the foothills, and 70s in the mountains. There is still some uncertainty over what the upper levels will do over the weekend, though confidence is growing that westerly flow will develop at some point, and most ensembles and clusters are showing growing heights on Sunday. If this holds, it generally means that Saturday`s high temperatures will remain closer to normal before a warming trend begins again on Sunday. Otherwise, dry and calm weather continues throughout the extended period. && .AVIATION... VFR conditions next 24 hours. Surface wind gusts generally below 12 kts except local south to west gusts 15-20 kts 20Z thru about 02Z Monday. Local southwest gusts 15-25 kts vicinity west Delta. && .STO WATCHES/WARNINGS/ADVISORIES... None. && $$