Here’s a quick overview of weather craziness so far this month:
The weather extremes of July set 10,000 heat and rainfall records worldwide.
In the United States, a record-breaking heat wave saw 80 million people under an extreme heat warning advisory this week.
As of July 25, Phoenix for the first time recorded 24 straight days above 110 degrees Fahrenheit, according to World Weather Attribution.
Miami just set a record 43 straight days of heat indices of 100-plus degrees Fahrenheit.
Wildfires in Canada ejected tons of particulate matter into the central and eastern U.S. in June and July, shrouding city skylines and triggering air-quality warnings, including in East Tennessee and Western North Carolina.
In Canada’s Atlantic province of Nova Scotia, record-breaking amounts of rain fell July 22-23, causing extensive and fatal flash flooding, road washouts and power outages. The deluge was triggered by unusually warm water temperatures off the eastern coast of the continent, contributing to a massive northward surge of near-tropical moisture into the province.
In South Florida, ocean temperatures exceeded 100 degrees, a new record. Abnormally high water temperatures were recorded elsewhere along the East and Gulf coasts.
Marine heat waves are usually defined as any time the ocean temperature is above the 90th percentile for a specific length of time. This means the temperatures are warmer than 90 percent of the previous observations for a given time of year. Marine heat waves, which are disastrous for coral and other marine life, may last for weeks, months or years and influence weather far beyond the coast. Marine heat wave conditions are monitored by NOAA’s Physical Sciences Laboratory (PSL).
Record-breaking heat is also baking Europe and Asia. Disastrous wildfires have hit Greece and Italy. China, along with the U.S. a top emitter of carbon dioxide linked to global warming, posted record high temperatures this month.
These heat waves share a common classification of anti-cyclone heat domes, opposite of cyclones, when they bring high atmospheric pressure and low wind gradients, creating a stable atmosphere keeping super-heated air in place for extended periods of time.
Closer to home, temperatures rose into the 90s on Thursday, and were forecast to hit 96 degrees on Friday. Brandon Wasilewski, general forecaster and meteorologist for the National Weather Service at Morristown, said local above-average temperatures will build into early August. There is a chance that high temperatures will break 100 degrees, especially when including heat indices paired with humidity levels. Earlier this month, air quality was moderately hazardous from Knoxville to Greeneville due to the unprecedented wildfires in Canada.
People working outside should be aware of the extreme heat and take common-sense precautions.
Chances of rain in the forecast are limited, so in the Knoxville region the heat may impact agriculture and home gardens heading into August without adequate rainfall. The area baked during an early heat wave last summer.
Although it’s difficult to pin weather events on climate change, the sheer number of increasingly unusual weather events leads atmospheric scientists to say there’s a strong, and undeniable, cause-and-effect explanation.
These recent heat-wave domes have been three to five degrees warmer than historic averages for heat waves for a given area, as heat-trapping greenhouse gases amplify the frequency and longevity of these events.
It’s worth noting we’re also in an El Niño year.
This means the higher than normal water temperatures in the Pacific Ocean, coupled with warmer air aloft, create a sponge-like effect as warmer water evaporates at a much higher rate, and the warmer air holds more moisture. This heavy, moisture-laden air flows into atmospheric rivers along the westerly jet stream across North America, occasionally wreaking weather havoc.
The consequences of human pollution seem to be increasingly manifesting themselves.