Includes Eastern Madera and Mariposa Counties and Yosemite National Park
June 24, 2021 - The National Weather Service Hanford Office reports isolated thunderstorms are possible in the Sierra Nevada, mainly over the higher elevations, during this afternoon and evening.
Gusty erratic winds, brief heavy rainfall, and dangerous lightning are expected with any thunderstorms although it is possible some thunderstorms may produce little or no precipitation at the surface.
Area Forecast Discussion National Weather Service Hanford CA 323 AM PDT Thu Jun 24 2021 .SYNOPSIS...Temperatures will average close to normal over the area through Friday. There is a slight chance of afternoon and evening thunderstorms over the Sierra Nevada today and Friday. Above normal temperatures will return this weekend and continue through next week with a return of isolated thunderstorms to the region. && .DISCUSSION... Closed upper level low off the CENCAL coast is remaining nearly stationary. Onshore flow continues through the Delta and into the San Joaquin Valley with near normal temperatures expected today and tomorrow. Valley temps will once again get back into the triple digits and stay there through the upcoming week. We are expecting a few showers and a possible thunderstorm this afternoon and evening across the Sierra north of Kings Canyon. Models are in decent agreement with the track of the upper level low center moving inland and dissipating over CENCAL as an upper level high pressure center rapidly develops across the PAC NW on Friday. The ridge will take over the pattern across our area. A secondary low center will move to about the same location as the current low center by Sunday night. This is where we will see the Delta breezes kick in across Merced, Mariposa and by Monday... Madera counties. This will lower temperatures north of Fresno county in the valley and provide some relief as temps may drop below the century mark on Monday. The cooler air will be confined to the mainly the eastern side of the SJV through Thursday as the low remains nearly stationary through Monday before lifting northeast towards the NORCAL coast. This will also play a role in possible diurnal convection across the SJV and the Sierra on Tuesday and continue through Thursday as easterly flow will bring sub-tropical moisture into CENCAL. We will continue to monitor the thunderstorm potential for next week as the mid and upper level flow will become favorable to bring in mid level moisture to the region. && .AVIATION...Areas of MVFR ceiling with local mountain obscuring IFR in showers and thunderstorms over the Sierra Nevada from Fresno County northward 18Z Thu through 03Z Friday. Otherwise, VFR conditions will prevail throughout the central CA interior for at least the next 24 hours.
Source: NWS
