August 26, 2019 – Above normal temperatures early this week, peaking Tuesday, then slight cooling by the weekend. Slight chance of thunderstorms Tuesday night and Wednesday.
Clear skies cover interior NorCal early this morning. Current temperatures are pretty similar to 24 hours ago across most of the area and range from the mid 40s to lower 50s in the colder mountain valleys to the upper 70s to lower 80s across milder portions of the Central Valley and foothills.
Hot weather pattern will continue across the region early this week as the broad strong upper ridge extending from the Desert Southwest to off the coast of the PacNW remains in place.
Highs of 105-110 will be possible, especially Tuesday, across the northern Sacramento Valley (heat advisory has been posted for that area) while a trickle of a Delta Breeze will help to moderate temperatures slightly for areas to the south.
Non-zero potential for some elevated convection across the area Tuesday night and Wednesday as inverted trough/weakening remnants of Ivo push northward ahead of the weak closed low that`s been stalled vicinity 30N/140W. Forecast soundings indicate a healthy amount of elevated CAPE (>500 J/kg in some areas) which if lifted will result in high-based thunderstorms.
Gradual moderation of temperature is expected Wednesday (from an increase in cloud cover) and Thursday (slight synoptic cooling behind the wave and the Delta Breeze).
Extended Discussion (Friday through Monday)
Main synoptic feature of the extended period will be the prominent upper ridge located over the southwestern US. Dry weather is forecast Friday through early next week as monsoon moisture is confined to areas south and east of the interior of NorCal.
A trough approaches the west coast late Friday night with the main impacts being enhanced onshore flow and near to slightly above average temperatures. Valley temperatures values will continue to be in the 90s each afternoon, with mountain highs in the upper 70s to low 80s.