(Image source: GOES/NOAA)

Today, a very muscular blocking high pressure system located over the Western US flexed. After having set off record fires and heat waves it reached deep into the Arctic and drew moisture and more unstable air down from over Hudson Bay across the Rockies and over top of Arizona and New Mexico, igniting powerful thunderstorms which blanketed large areas in hail, heavy rainfall and lightning. A second moisture stream drawn into the high’s circulation from the Pacific also fed these storms.

You can see the bright, high, cold cloud tops now firing over Arizona and New Mexico.

To the east, an upper level low pressure system is just now starting to draw this concentrated moisture into two other feeding, damp air flows. The largest draws straight up from the Caribbean over Florida and then rushes up the US East Coast. The second, pulls moisture from tropical…