Area Forecast Discussion
Issued by NWS Sacramento, CA
Issued by NWS Sacramento, CA
372 FXUS66 KSTO 042008 AFDSTO Area Forecast Discussion National Weather Service Sacramento CA 108 PM PDT Tue Jun 4 2024 .SYNOPSIS... Hot weather, well above normal temperatures, and areas of moderate to major HeatRisk continue across interior NorCal today through Thursday, with cooler, but still seasonably warm, weather expected heading into the weekend. && .DISCUSSION... Key Points - An Excessive Heat Warning remains in effect through 8 PM PDT Thursday evening across the Valley and adjacent foothills. - Areas of Major HeatRisk today for the Valley, become widespread Wednesday for the Valley & Foothills with widespread triple digit high temperatures. Expect elevated daytime highs and overnight lows and reconsider outdoor activities during the hottest part of the day (3:00-7:00 PM). - Areas of Major HeatRisk continue on Thursday, with Moderate HeatRisk by Friday; Triple digits in the Northern and Central Sacramento Valley and adjacent Valley foothills with mid to upper 90s in the Delta and Sacramento metro area. Short-Term Discussion (Today THROUGH Friday)... Hot and dry weather has arrived for interior NorCal, as of early this afternoon, with no clouds evident on latest GOES-West visible satellite as of 1 PM PDT. Aloft, heights continue to rise as a ridge builds in over the western CONUS. The ridge axis looks to become centered over interior NorCal on Wednesday, before transitioning toward the Great Basin and Intermountain West through the remainder of the week. As a result, Valley high temperatures will begin to flirt with the triple digits this afternoon and are expected to rise firmly into the triple digits on Wednesday afternoon. Higher elevations will still see high temperatures into the 80s to upper 90s. This is resulting in fairly widespread areas of major HeatRisk across the Valley and foothills through Thursday, with moderate HeatRisk in the mountains as well. As a result, an Excessive Heat Warning remains in effect for much of the Valley and foothills through 8 PM PDT Thursday. The building ridge aloft has also ushered in some gusty north to west winds across the region today. Gusts of 20 to 30 mph will continue through the afternoon and early evening before slackening overnight. These gusty winds, combined with lowering RHs into the upper teens to low 20s, will result in elevated fire weather conditions continuing through the remainder of today. North to west winds look to become breezier throughout the day on Wednesday, but are not expected to be as gusty as today. As the aforementioned ridge moves eastward and broad troughing churns across the eastern Pacific, interior NorCal looks to remain underneath southwesterly flow aloft from Thursday into the weekend. While an overall appreciable change is not anticipated, north to west winds are expected to shift to a south to west direction as onshore flow increases. This will lead to a slight cooling trend from well above normal to simply above normal temperatures by Friday. Additionally, this flow pattern aloft will at least introduce some low end potential (5% to 15% chance) for isolated shower or thunderstorm activity along the Sierra crest south of the Highway 50 corridor. Area waterways continue to run fast and cold from snowmelt, creating dangerous conditions for those seeking relief in rivers and lakes next week. Remember to practice heat and cold water safety this week! To view the latest HeatRisk, please visit www.wpc.ncep.noaa.gov/heatrisk/ To view current water temperatures, please visit www.cnrfc.noaa.gov && .EXTENDED DISCUSSION (Saturday THROUGH Tuesday)... A weakening trough passing over the area this weekend will keep temperatures in the Valley a bit lower than during the preceding week, though the southern Sacramento Valley and northern San Joaquin Valley will see the most relief from the heat over the weekend. In the northern and central portions of the Sacramento Valley, there remains a 40 to 65% probability of reaching 100 degrees or more over the weekend. So while temperatures this weekend will likely be capped from going any higher, relief in these areas may be limited. Following this weekend, a ridge rebuilds over the area, bringing temperatures early next week back up. Currently, there is an 50 to 85% probability of temperatures in the Valley reaching or exceeding 100 degrees on Monday and Tuesday, with Major HeatRisk expected over portions of the northern and central Sacramento Valley. Additionally, the foothills will see highs in the 90s, and the mountains will see highs in the 80s early next week. //SP && .AVIATION... VFR conditions prevail across interior NorCal through the forecast period. North to west winds continue through today, with gusts 20 to 25 kts in the Valley and Delta. Winds begin to taper off, generally below 12 kts, after 03z Wednesday, before becoming breezy again after 14z. && .STO WATCHES/WARNINGS/ADVISORIES... Excessive Heat Warning until 8 PM PDT Thursday 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-Shasta Lake Area / Northern Shasta County- Southern Sacramento Valley. && $$