I've seen something similar happen and think I figured out the reason. Weather forecasts in my area were very accurate for decades, then they got much worse.

I've seen something similar happen and think I figured out the reason. Weather forecasts in my area were very accurate for decades, then they got much worse. They were off in timing for events, and incorrect about whether rain was going to fall or not. Then I realized that the change happened around the time the local nuclear power plant was shut down. The plant had been funding a local weather station and weather radio station as part of government requirements to provide early warning of problems to citizens. When the plant shut down the weather station went with it. So NOAA was no longer getting accurate data from this area and the forecasts were off because of that. I've been thinking of setting up my own station and linking it into the public data to see if that makes forecasts get more accurate.