Well above normal temperatures continue through this week, peaking on Tuesday and Wednesday, with widespread triple digit highs in the Delta and Valley. North to East winds continue into Tuesday bringing drying conditions, with low humidity in the Valley and foothills in the teens and locally into single digits. Winds will peak this morning through midday with gusts up to 20 to 30 mph over the northern and western Sacramento Valley and for northeast oriented drainages in the mountains and foothills. Elevated to critical fire weather conditions are expected due to the winds and low humidity, so be sure to practice fire safety. Temperatures gradually trend cooler late in the week, but are expected to remain above normal.
Discussion
Upper level troughing that brought some cooling over the weekend shifts eastward our of the area today. Strong eastern Pacific ridging is building into the region and will extend eastward, connecting with ridging over the 4-Corners area. This will bring well above normal temperatures (+8 to 12 degrees)today and areas of Moderate HeatRisk across.
Even hotter temperatures arrive Tuesday and Wednesday, with widespread Moderate HeatRisk across the area, and areas of Major HeatRisk in the foothills and adjacent Valley. Temperatures in the Valley are likely to reach triple digits on these days, with the NBM continuing to predict a 30 to 80% probability of temperatures of 100 degrees or greater.
Daily record temperatures are possible. Thursday continues hot, with ridging flattening a bit ahead of an approaching Pacific Northwest trough. High temperatures will be just a few degrees lower than on Wednesday. Valley and Delta highs in the upper 90s to around 100 are expected.
Drying north to east winds have developed overnight with elevated fire weather conditions for the northern Sacramento Valley and the adjacent foothills and mountains. Redding and Red Bluff are seeing gusts to 23-26 mph early this morning, with very poor recovery. These winds will peak in the morning hours through mid- day.
There is a 65 to 85% probability that winds could gust to 30 mph. Jarbo Gap in the Feather River Canyon at 2 am was seeing northeast gusts to 33 mph. The gusty winds are expected to gradually decrease in the afternoon.
Humidity levels for that area are forecast to drop into the single digits this afternoon. Humidity recovery Monday night into early Tuesday will be poor, with elevated fire weather concerns continuing through Tuesday, and to a lesser extent into Wednesday. Avoid any activities that could spark a wildfire!
Extended Discussion (Friday through Monday)
Dry weather expected through the extended forecast period as upper level ridging remains main synoptic feature. Several short wave troughs interact with upper ridge as they progress through the PacNW. Model differ with timing and strength of waves leading to some uncertainty with temperature forecast. NBM showing highs in the 90s in the Central Valley with 60s to 80s for the mountains and foothills Friday through Monday.