September 25, 2020 – Fairly quiet weather today, before we transition to a warmer, drier, and windier pattern this weekend.
North winds start to increase across the western Sacramento Valley by early Saturday afternoon, then spread into the Cascades and Sierra Nevada mountains Saturday evening and overnight. This timeframe is when the strongest winds and falling humidities are expected, which may result in the biggest fire weather impacts. Winds will remain breezy Sunday through Monday morning, decreasing by Monday night.
As a result, the Fire Weather Watch has been upgraded to a Red Flag Warning. Timing has adjusted a bit, with the Warning starting Saturday evening and continuing through Monday morning.
The ridge will dominate the weather for next week, resulting in above average temperatures. Moderate heat risk is expected, so take appropriate precautions if working outdoors.
An upper level ridge offshore will build and shift east toward the Golden State for the weekend and into early next week. This will consequently result in a pronounced warming and drying trend for the region. The wind will reverse from the present moist onshore flow to a dry offshore north to east wind setup. While there has been some model run-to-run inconsistencies over the past few days; the most recent ensemble trends have bumped up, particularly in the European ensembles.
As mentioned, this ridge will promote warming throughout the region. Widespread 90s will return to the Sacramento and northern San Joaquin Valleys for Sunday and Monday, at a minimum. Can`t rule out the chance of some communities hitting 100 deg F. Corresponding heat risks will be in the low to moderate categories with general impacts to those sensitive to the heat. Models keep the ridge in place into the middle of the week. More details are provided in the extended portion of this discussion.
Extended Discussion (Tuesday through Friday)
A highly amplified ridge will bring warmer than normal temperatures and dry weather to interior NorCal next week. High temperatures will be anywhere from 8 to 15 degrees above average next week with temperatures around 100 degrees possible in the northern Sacramento Valley. Areas of moderate heat risk will be seen throughout the week in portions of the Valley and foothills which may impact any sensitive groups including outdoor workers. Extremely dry conditions are expected each day, although winds will be lighter through the week helping to mitigate fire weather concerns. Dry weather is likely to continue through the weekend.