ABC News(NEW YORK) — Thursday was the fourth straight day of severe weather throughout much of the U.S., a period during which 38 tornadoes were reported across six states — 18 in Kansas; five each in Oklahoma, Nebraska and Iowa; four in Missouri; and one in Arkansas.The severe weather is calming down from earlier in the week, and the system is sliding off to the east where it may bring harsh conditions on Friday. Strong to isolated storms are moving toward Dallas, Waco and Austin Friday morning, with strong winds and hail threats. Heavy rain is moving out of Wisconsin, although some of the storms could bring flash flooding to the Milwaukee area.As the system moves off into southern Canada, cooler air behind it will clash with the record-breaking heat in the Northeast, which poses a slight risk of severe weather in areas such as Pittsburgh, Scranton and Syracuse. Damaging hail is possible. The regions most likely to see severe weather are northern Pennsylvania and New York state.By early afternoon, the cold front begins to tap into the summer-like heat, with discrete cells moving through the western Great Lakes. Storms will move across the Appalachians during the early evening, reaching cities from Washington, D.C., up through Boston after sunset.Record highs from Thursday:New York City, 92Newark, 94Hartford, 94Atlantic City, 93Philadelphia, 91Trenton, 91Friday will be another hot day in the Northeast, with high temperatures from Virginia to New Jersey again passing 90 degrees. New York City and Hartford, however, are unlikely to top 90 again, decreasing the chance of an official heat wave.Behind the cold front, temperatures will slowly cool off, with much of the Northeast seeing conditions 20 to 30 degrees cooler on Sunday than Friday. Meanwhile, a push of warm air in the Southwest means an excessive heat watch has been issued for Phoenix, which will near triple digits — as will Las Vegas by Sunday.Copyright © 2018, ABC Radio. All rights reserved.