As I was writing here last month, I’ve been following the enormous Painted Lady migration that’s been happening in California and the Southwest since late January to early February. While this migration continues northward, it’s now also time to turn more attention eastward as wind and weather patterns have become favorable for Red Admirals and American Ladies to migrate northward into the upper Midwest, the eastern states, and southern Ontario. Painted Ladies may be arriving in our area somewhat later this spring, perhaps from the west, or perhaps from a smaller population that overwintered in Texas.
Red Admirals have arrived in the upper Midwest, and are already here in Iowa – they seem to have come with the warm southerly wind last Saturday, April 6, resulting in sightings in central Iowa's Story and Boone Counties on that day. They were also spotted in Omaha, Nebraska on April 2, and in Kansas City, Missouri on April 5. Chip Taylor, the director of Monarch Watch, spotted his first two in Lawrence, Kansas on April 6th, while suggesting that Red Admirals could have arrived there a few days earlier. A first-of-the-season Red Admiral was also seen on April 8 in Kingsville, Ontario, near Point Pelee National Park.
Since yesterday, it's likely that any further northward Red Admiral movement will be literally stopped cold (at least temporarily) by an enormous low-pressure system passing through the northern Great Plains, Minnesota, and Wisconsin. This storm has brought us two days of high winds in central Iowa, and heavy snow in states to our north. To our south, temperatures were in the 60s F in southern Iowa and in the low 80s in Kansas. Under these conditions, any additional Red Admirals arriving from farther south might stop migrating and accumulate in these areas, resulting in a sudden increase in the number present.
-- Royce Bitzer, April 11, 2019