Now, the heat dome languishes over the Tennessee Valley and brings 95- to 100-degree highs from the Corn Belt to the Carolinas, with exceptional humidity in the Midwest heightening just how sultry the feeling. High humidity levels contribute to heat index values pushing 115 degrees in places.
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Due to the harrowing combination of heat and humidity, more than 95 million Americans are subject to excessive heat warnings or heat advisories from the Florida Panhandle in northern Michigan.
Excessive heat warnings and heat advisories remain in effect today from Michigan to northern Florida. High temperatures are expected to reach the upper 90s to near 100, with heat indexes well into the triple digits. Be sure to take extra precautions if you spend time outdoors. pic.twitter.com/r4FNAJPWQa
– NWS Weather Prediction Center (@NWSWPC) June 15, 2022
Record highs are expected Wednesday in Detroit, Chicago, Indianapolis, Columbus, Knoxville and Atlanta.
A new heat pulse, meanwhile, is looming on the horizon and appears to be settling in early next week. There are signs the abnormally hot temperatures could linger for seven to 10 days or more, wreaking havoc on heat-stressed residents.
Here’s yesterday’s min/max in the Midwest. Records include St. Louis min/max 81°/99°, Kansas City min/max 81°, Nashville min/max 79°/97°, Madison max 96°, Indianapolis min 78°, Des Moines min 78°, Springfield (MO ) min 75°, Springfield (IL) min 79° and Evansville monthly min 81°. pic.twitter.com/e1P9yDrbUE
—Maxar | WeatherDesk (@Maxar_Weather) June 15, 2022
Since the weekend, the heat has spread north and east while retreating from California and the southwest, resulting in a series of record high temperatures from the plains to the southeast. The current episode is impressive not only for its outstanding daytime highs, but also for its nightly high lows and sauna-like humidity.
Here are some of the more notable recordings collected over the past two days:
- Saint Louis experienced its hottest overnight low on record for the month of June from Monday evening to Tuesday morning. Temperatures did not drop below 83 degrees. A record daily warm minimum was also set Wednesday morning with a low of 81 degrees. St. Louis also reached 100 degrees on Monday, breaking the record of 98 set in 1952. Another record was set Tuesday with a high of 98 degrees.
- Kansas City had an early morning low of 81 degrees on Monday, which was the hottest in nearly 16 years there. At 4 a.m. Monday morning, the heat index was still 92 degrees.
- Chicago (Midway Airport) hit a high of 100 degrees on Tuesday, the earliest this year it hit triple digits since 2012. The average high in mid-June is 80 degrees.
- Milwaukee experienced its highest heat index in June since 1948. It reached 109 degrees at 3:52 p.m. Tuesday, tweeted the Maxar weather officethe product of a temperature of 98 degrees and a dew point of 73 degrees.
- Columbus, Oh. recorded an all-time high dew point, which is a measure of humidity, of 84 degrees at 6:45 p.m. Tuesday. Any dew point above 80 degrees is exceptionally sweltering. According to the National Weather Service in Wilmington, Oh., this dew point broke the previous record by 3 degrees. Columbus also posted a heat index of 115 degrees on Tuesday – among the highest ever recorded.
- Dodge City, Kansas. posted a low temperature of just 83 degrees on Monday, its hottest minimum ever in any month of the year.
- North Platte, Neb. climbed to 108 on Monday, its highest June temperature on record.
- Additional Records: Columbia, SC hit 103 degrees on Monday. Madison, Wisconsin set a record 96 on Tuesday. Nashville hit a high of 97 degrees on Monday and Tuesday, tying one record and breaking another. The Music City also recorded a Tuesday morning record low of 81 degrees.
Record low temperatures overnight, of which there have been many, are potentially even more dangerous than daytime high temperatures. While heat-vulnerable groups may be able to escape to an air-conditioned public environment such as a mall, shopping complex, library, or public cooling system during the day, they may not have access to cooling the night. This is especially true for people in difficult financial circumstances.
When nighttime temperatures remain warm, the human body is deprived of its natural cooling window and does not have the opportunity to reset before daytime heat returns. This accumulated heat stress can be fatal for vulnerable people.
Before the heat spread through the central and eastern states, a litany of records occurred over the past week and over the weekend from Texas to California’s Central Valley. Death Valley, Calif., soared to 123 degrees on Friday while, over the weekend, Phoenix hit 114 and Las Vegas soared to 109. Weekend highs peaked at 105 degrees in Austin and San Antonio .
Dozens more records are in jeopardy on Wednesday, with triple-digit heat expected in Atlanta and Columbia, SC while Chicago is expected to soar into the mid-to-high 90s. Nashville could flirt with 100 degrees, and the mid to upper 90s are probably pretty much everywhere in the South.
The heat is expected to continue Thursday, with Nashville around 100, upper 90s in northern Florida, lower 100s in southwest Kansas and a high around 98 in Houston.
A cold front will bring some relief to the Upper Midwest, Great Lakes and Ohio Valley on Thursday, along with the risk of severe thunderstorms, but by Friday the next heat wave will move north -west with 90s extending into Montana.
The heat dome is expected to intensify again over the weekend in the central states, leading to a spike in record high temperatures across the central and northern plains. Early to mid next week, excessive heat will move into the Upper Midwest and Ohio Valley, and possibly the East Coast.