Dry weather and breezy northerly winds continue today. Warming trend through mid-week, then cooler with a chance of rain over the weekend. Red Flag Warning in effect until 8 PM PDT this evening.
Discussion
Other than a few remaining clouds over the northern Sierra, skies are clear across interior NorCal early this morning. Northerly surface pressure gradient remains in place (MFR-SAC still around 9 mbs) with gusts around 15-25 mph persisting over the northern Sacramento Valley and along the western edge where RH remains around 20-35%.
Northeasterly winds have developed in the foothills and Sierra with local gusts of 20-30 mph. A light Delta Breeze has returned to the southern Sacramento Valley bringing locally higher RH inland to about the Sacramento region. Surface gradient will tighten again early this morning and we’ll see northerly gusts pick up again in the valley after sunrise. Gusty northerly winds will continue into the afternoon before gradually tapering late in the day as surface gradient finally relaxes.
In the Sierra, easterly breezes will likely peak this morning. The wind combined with low RH will continue critical fire weather conditions for the valley until this evening.
Temperatures will be around 5-10 degrees warmer today compared to Memorial Day as short-wave ridging builds in. Highs will be around 90 this afternoon across most of the Central Valley.
Warming trend is still forecast to peak on Wednesday as the ridge moves overhead. By Thursday and Friday, the ridge is forecast to shift east as the large Gulf of Alaska low edges closer to the West Coast. This will allow minor cooling Thursday as onshore flow returns.
A few late- day showers or thunderstorms will be possible over Shasta County Thursday as the initial short-wave lifts out. A little better cooling develops Friday with stronger onshore flow and minor synoptic cooling.
Extended Discussion (Saturday through Tuesday)
Ensembles still pointing toward a late-season wet weather event for much of interior NorCal this weekend as moisture moving eastward beneath the Gulf of Alaska low moves into the region. QPF is expected to be generally light, and mainly to the north of Interstate 80.
Local amounts around an inch will be possible over the mountains of Shasta County. Snow levels will be too high for any travel impacts (above 9-10k ft). Light precipitation and extensive cloud cover will help to keep temperatures around 5-10 degrees below average. Ridging forecast to return early next week as the low retrogrades resulting in warming and drying.