April 16, 2020 - The National Weather Service Hanford Office reports isolated thunderstorms are possible near the Sierra crest this afternoon, mainly from Fresno County northward.
The threat of afternoon thunderstorms will extend westward into the Sierra foothills Friday and also include the West Side Hills.
In addition to dangerous lightning, thunderstorms can bring briefly heavy rain and locally strong, gusty winds.
When thunder roars, seek shelter indoors!
Area Forecast Discussion National Weather Service Hanford CA 415 AM PDT Thu Apr 16 2020 .SYNOPSIS... Dry weather and above normal temperatures can be expected over the central California interior through Thursday. A storm system will bring precipitation into the mountains Thursday afternoon then across much of the district Friday into Friday evening along with much cooler temperatures. Showers could linger over the Sierra Saturday. Dry weather will return Sunday before another storm brings showers back into the district early next week. && .DISCUSSION... Satellite images show increasing mid and upper level moisture moving into central California due to a west flow aloft. In addition a closed upper trough off the north California coast will move southward reaching the central coast late this afternoon. Higher resolution models show increasing instability over the high sierra late this afternoon. Convective storms could develop late in the afternoon driven mainly by day time heating as the trough may be too far offshore to provide any synoptic forcing. Storms should be isolated but the southern sierra will be in a col area. This will result in light steering wind so storms may remain near stationary providing locally heavy rain. The trough will push towards Cape Conception tonight and onshore through southern CA Friday. Showers could develop in the San Joaquin Valley tonight as the SJ valley will be in a favorable area of upper level divergence in the NE quadrant of the low. The central CA interior will be in between weather systems as another disturbance moves off the north CA coast on Friday. Models show the potential for convective showers to be more widespread over the sierra. Mid level steering winds will be light again with slow moving storms will increase the potential for locally heavy downpours with any storm. Average precipitation totals from this system should be rather light, ranging from less than a tenth of an inch in the San Joaquin Valley and the Kern county desert to a quarter to a third of an inch in the mountains. Up to four inches of new snow could fall in the Sierra above 8000 feet by Friday evening as the storm exits towards Arizona. The upper level trough in NCa will move SE into central California early this weekend and could rejuvenate additional showers over the foothills and higher elevations of the Sierra Saturday afternoon. Otherwise, high temperatures will be much cooler and closer to normal Friday and Saturday. Dry weather should return to the district Saturday night and continue through Sunday due to short wave ridging aloft. A colder storm system could bring more widespread precipitation across the district early next week. However medium range models remain in poor agreement with the timing of this system. The GFS is more progressive and brings it across CA Monday while the EC closes the low off NCa coast and onshore over CA on Tuesday. Thus confidence in the extended for early next week is low. A prolonged stretch of dry weather may follow this weather system starting next Wednesday as a high amplitude ridge of high pressure builds in from the eastern Pacific.Source: NWS
