A “particularly dangerous situation” (PDS) is unfolding across the Midwest, the Storm Prediction Center (SPC) said Monday afternoon.A very dangerous derecho is moving out of Iowa into northern Illinois, toward Chicago, prompting the SPC to issue a PDS thunderstorm watch through 7 p.m. central time Monday.”PDS severe thunderstorm watches are rare, and reserved for only the strongest thunderstorm events,” CNN meteorologist Brandon Miller said. “Wind