May 9, 2018 – Warm and dry weather continues. Slight cooling returns early next week along with a chance of showers and thunderstorms over the mountains.
Some cloudiness lingers across the far northern portion of the forecast area in the wake of yesterday evening’s short-wave that brought a few showers and thunderstorms to Shasta County. The remainder of the area is under clear skies. Current temps range from the upper 30s to mid 40s in the mountain valleys to the upper 50s and 60s across the Central Valley.
Warm and dry weather will continue across the region through the end of the week under broad cyclonic flow aloft. Temperatures won’t be as warm as earlier in the week as the upper ridge has been displaced to the east allowing better onshore flow through the Delta and some synoptic cooling.
The models continue to trend further to the west with the track of the next closed low dropping down from the north later in the week. They now have it moving into the Great Basin vs earlier over the northern Rockies. While it’s still expected to be breezy/windy through the Sacramento Valley on Friday, the winds don’t look like they’ll be quite as strong as it was looking a day or so ago. Also,a chance of showers may develop as early as Saturday across the northern Sierra Nevada.
Extended discussion (Sunday through Wednesday)
A retrograding trough over the Great Basin continues to trend further west for the weekend through the middle of next week, bringing cooler temperatures across the area and increasing chances of precipitation over the Sierra-Cascade range. Instability could be enough for some mountain thunderstorms. Temperatures are now looking much closer to average levels than previously, and could potentially end up below normal, if the low tracks further westward.
There are also hints of an upper level low from the Pacific moving in mid to late the week, which could bring more unsettled weather and near to below normal temperatures.