The jet stream will soon be in a configuration that isn’t favorable for Great Plains thunderstorms. Offshore winds through traditional Tornado Alley will keep humidity pushed well to the south and east in what is known as a rex block. This atmospheric constipation won’t last, though. A deep dip in the jet stream next week is the first sign that a pattern change is expected in the second half of the busiest month for tornadoes. Early outlooks suggest much of the Plains will be wetter than average and perhaps stormier as we head into the last half of May.