Heat dome to pummel Plains, Southwest
The weather pattern from late May to late June was dominated by a relentless heat dome that brought record temperatures everywhere except the northwest and northeast United States. After a bit of a pause, the heat dome is back. It’s settling over the Midwest and Plains and is forecast to gradually shift westward in the coming days.
The heat dome could linger in the Southwest for well over a week, meaning a prolonged period of above normal midsummer temperatures from Texas, which experienced widespread record heat in June, through Phoenix and Las Vegas.
On Tuesday, heat advisories and excessive heat warnings covered a sprawling zone from northern Louisiana to southern Minnesota and Wisconsin, affecting over 60 million people. Temperatures 10 to 15 degrees above normal are affecting much of this zone, with highs in the 90s and triple digits.
The core of the heat — with high temperatures from 100 to 105 degrees — was affecting the zone from northern Texas and Arkansas through Kansas and Missouri, including Kansas City, St. Louis, Oklahoma City, Dallas and Little Rock.
Temperatures won’t hit records in most of these cities, but the combination of elevated temperatures and tropical humidity in the air poses a danger to vulnerable populations, including older adults, outdoor workers and anyone without access to air conditioning.
“Heat related illnesses increase significantly during extreme heat and high humidity events,” wrote the Weather Service office in St. Louis, where it could feel as hot as 110 degrees factoring in the humidity.
Daytime highs in the St. Louis metro will crest around 100 degrees each day through Thursday, but the nighttime lows are equally problematic. Temperatures weren’t expected to dip below 80 degrees Tuesday night and 79 degrees on Wednesday night. That lack of a real nocturnal cool-down period prevents the human body from “resetting” so-to-speak after a day of hot weather, compounding heat stress.
Lower income households — those that often have other systems of vulnerability at play during heat events — are disproportionately more likely to be without access to adequate cooling.
It will be the same story in Little Rock; a heat advisory is in effect Tuesday, but every day through Friday should see highs within a degree either side of 100. Overnight lows will bottom out around 80.
“If you can, check up on those who may be more vulnerable or are without some form of (air conditioning),” wrote the National Weather Service in Little Rock in an online discussion. “The other hazard of note (will) be overnight low temps, as we (will likely) see a few consecutive nights with temperatures only falling into the upper 70s, or even low 80s, and not allowing for any overnight relief.”
By late in the workweek, dew points — a measure of how much moisture is present in the air — will lurch into the mid-70s, combining with the blistering temperatures to lead to stifling heat indexes of 110 to 115 degrees during the heat of the day.
In Dallas, every day, essentially until further notice, will feature highs in the 100 to 105 range and nights in the 80 to 84 degree range.
“A heat advisory will likely be needed across North and Central Texas Wednesday,” wrote the Weather Service office in Fort Worth.
The toasty temperatures in
Texas come after the hottest May-june period on record in Houston, Austin and San Antonio — not to mention cities outside the Lone Star State, including New Orleans, Shreveport, Atlanta, Tampa and Orlando. That figure largely stems from extreme readings associated with the previous heat dome.
The heat broiling the Central States is just the start, however. Over the coming week, the heat dome will retrograde west, backtracking before putting it in park over the Four Corners region and potentially remaining anchored until at least mid- to late July.
Heat domes are composed of high pressure systems. That translates to sinking, drying air and hot temperatures in the summertime. The high acts as a force field of sorts too, diverting jet stream energy and disturbances to the north and fending off widespread inclement weather.