The hottest weather of the summer so far is likely for many major cities, including Chicago, Minneapolis, and Des Moines, Iowa. Tropical moisture could keep extreme heat at bay for one part of the nation’s mid-section that has been roasting this summer.
A major change in the weather pattern is coming as a massive heat dome develops over the Heartland of the United States later this week, and it may persist through much of the second half of August, AccuWeather meteorologists warn.
Along with triggering a string of days where temperatures push the upper 90s to 100 F in many areas of the nation's midsection, some relief from heat and dryness is anticipated in parts of the South and West as the setup shifts, forecasters say. Rounds of thunderstorms are likely to continue in the Northeast.
Revived heat dome to shift northward
Texas has been the focal point of unrelenting heat this summer with the temperature in Dallas, Austin, San Antonio and Houston running 3 to 5 degrees above the historical average since meteorological summer began on June 1.
Houston (Hobby Airport) has experienced 100-degree temperatures every day this month, except for Aug. 3, when the high was 99. The historical average high is 94 for the Texas city situated near the northwest Gulf Coast. Additionally, the mercury has only dipped below 80 on two nights during the month, compared to a historical average low temperature in the mid-70s.
Extreme heat has not only been commonplace in Texas, but it has also reached as far to the east as Florida and as far to the west as interior Southern California this summer.
"The same type of weather system that has been responsible for relentless heat in Texas and the South-Central states, as well as the interior Southwest much of this summer, will regroup and set up shop farther north starting late this week," AccuWeather Senior Meteorologist Adam Douty said.
The heat dome represents a zone of high pressure from near the surface of the Earth to the level where jets fly. Once established, it can create a cycle of building heat and dryness that is difficult to break.
"The heat dome and associated heat wave may have the staying power to last for five to seven days in some areas," AccuWeather Long-Range Meteorologist Brandon Buckingham said.
Cities in the central and northern Plains to parts of the Midwest could experience the highest temperature readings so far in 2023 as heat surges in this weekend into next week.
For example, the highest temperature that Des Moines, Iowa, recorded all summer was 98 degrees on July 28. AccuWeather meteorologists are projecting that temperatures may reach or exceed the season-high mark there around the middle of next week.
A vast area where AccuWeather RealFeel® Temperatures will reach or exceed 105 F will extend from Oklahoma to eastern South Dakota as early as Saturday.
Other major cities on the list that may experience season-high marks with temperatures reaching the 90s next week include Minneapolis and Chicago. Temperatures in some locations will fall short of the hottest weather of the summer so far, but these same places will experience extreme heat nonetheless. Highs near or just above the 100-degree mark are likely in Omaha, Nebraska; Kansas City, Missouri; and Topeka, Kansas.
A factor contributing to the quick buildup of heat has been a stubborn drought over the middle of the nation. Portions of Kansas, Nebraska, Missouri, Iowa, Minnesota and Wisconsin are experiencing severe to exceptional drought, according to the United States Drought Monitor.
Dry ground tends to heat up more quickly than moist ground as less of the sun's energy is used up in the process of evaporating moisture.
Some of the locations from the Midwest to the Tennessee Valley that have been frequent recipients of flooding downpours and severe weather are likely to get a break from the stormy conditions.
Not every location will bake and broil across the U.S. Some areas will even trend cooler and wetter compared to much of the summer.
Tropics may help cool, douse Texas and Florida
"On the rim of the massive heat dome, moisture and cooler air will be found," Douty said. "These fringe areas will include the Gulf Coast, the western third of the nation and the Northeast."
"The influx of moisture should bring some relief from heat along the Gulf Coast and from heat and drought in parts of Texas by early next week," AccuWeather Senior Meteorologist Heather Zehr said.
Easterly breezes alone should help take the edge off the extreme heat on coastal areas of Texas, including Houston, as well as other locations farther inland.
Embedded in the easterly breezes and moisture from the Gulf will be weak disturbances.
"Not only may these [disturbances] grab moisture from the Gulf, but there is also the chance that one or more could also develop tropically," Douty added. "It would not be out of the question for a tropical depression or storm to brew over the western and northern part of the Gulf and towards Texas or northern Mexico with heavy rain next week."
Prior to affecting Texas, a tropical disturbance, known in the weather community as a tropical wave, will bring drenching downpours and gusty thunderstorms to a large part of the Florida Peninsula this weekend. So much rain may fall to not only help ease drought in the western part of the peninsula but also trigger localized flooding.
AccuWeather's long-range and tropical teams have outlined a low-risk tropical development zone for early next week near the northwestern Gulf Coast. At least two other disturbances in the Atlantic are being monitored for development from later this week to this weekend.
Tropical Storm Hilary to trim back heat in western US, raise flood risk in Southwest
Another zone where moisture will come into play and help to ease heat, drought and the wildfire risk will be along the Pacific coast and perhaps as far inland as New Mexico, Utah, Idaho, and Alberta, Canada.
A dip in the jet stream will help to direct moisture in from the tropical Pacific starting late this week.
"The influx of moisture will help bring opportunities for cloud cover and much-needed rain, as well as lower temperatures in the western parts of the U.S. and Canada from late this week to next week," Buckingham said.
There is a significant risk that moisture from Tropical Storm Hilary will blast the region with the potential for historic rainfall and major flooding in parts of the Southwest from this weekend to early next week.
Rounds of thunderstorms to continue in the Northeast
"Meanwhile, on the northeastern periphery of the massive high pressure area, fast-moving complexes of severe thunderstorms may dive southeastern from central Canada to parts of New England, the central Appalachians and the mid-Atlantic zone this weekend to next week," Douty said.
Similar patterns in the past have triggered powerful thunderstorm wind gusts over a broad area. The upcoming pattern could yield some of the strongest storms of the summer as thunderstorms erupt along the clash of hot air to the south and cooler air to the north. The bulk of the severe weather may set up over upstate New York and New England.
It is possible that complexes of thunderstorms will begin to break down the heat dome and cause it to shrink southward later next week, but this will not be before many locations in the middle of the nation have several days to perhaps a week of extreme heat, Buckingham said.
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