March 2, 2020 – Windy today across portions of interior Northern California. Otherwise dry this week with well above normal daytime temperatures. Some record highs likely in the Central Valley Tuesday and Wednesday. Chance of precipitation late Friday into the weekend.
544 DM closed upper low off the SoCal coast this morning as strong upper ridging begins building into NorCal from the north. Breezy to windy conditions this morning across western portions of the Sacramento Valley extending into the Delta. KRDD-KSAC surface pressure gradient has trended up overnight and is now over 6 mb. KDAX wind profiler showing 40 kt northerly wind above the surface. Wind expected to increase during the morning as stronger wind aloft begins to mix down. Guidance suggest wind advisory speeds across northern and western portions of the Sacramento Valley, extending into the Coastal Range of Lake county, and in the Delta area today. Have issued a wind advisory to cover this. Strongest wind expected this afternoon. AMS warms today under increasing subsidence and downslope flow. Highs today forecast in the upper 60s to lower 70s for the Central Valley, with 40s to lower 60s for the mountains and foothills.
Surface wind decreases in the Central Valley this evening, as boundary layer decouples. However 925 mb winds progged to trend up tonight over Lake county which will need to be monitored. Locally gusty northeast to east will also be possible through favorably oriented canyons in the eastern foothills overnight.
Warming continues Tuesday with some breezy wind again in the Central Valley, but lighter than today. Highs expected around the 80 degree mark in the Northern Sacramento Valley Tuesday which could break records at KRDD and KRBL. 70s elsewhere forecast in the Central Valley. Foothills and mountains will see 50s to low 70s tomorrow.
Additional warming expected in the southern half of the Sacramento Valley and Northern San Joaquin Valley Wednesday. Likely to see additional high temperatures records broken in those areas.
Cooling trend begins Thursday as upper ridge begins to flatten and progress in response to Pacific frontal system approaching the West Coast. High temps remain about 10 degrees above normal Thursday but below record values.
Extended Discussion (Friday through Monday)
Wet weather is slated to return to interior Northern California next weekend. Ensemble models continue to indicate an upper level trough approaching California Friday. Details are uncertain at this time as models remain inconsistent in timing and precipitation amounts. Current forecast suggests the trough will produce precipitation beginning in the northern mountains Friday before slowly spreading across the area Friday night into early Saturday. Showers are forecast to be widespread across interior NorCal Saturday before becoming limited to mainly the mountains and foothills Saturday night through Sunday. Snow levels forecast around 5500-6500 feet Friday before falling after the trough passage by Saturday. Although it is still too early to be confident in precipitation totals, this is not currently looking to be a particularly wet system. Gusty southerly winds will accompany the trough passage Friday night through Saturday. Temperatures will cool to normal on Friday and a few degrees below normal for the weekend.