Following on the heels of the hottest June in the history of the lower 48 states, an extended, intense and widespread heat wave is likely to develop next week.
During the height of the heat wave, a majority of the contiguous U.S. is likely to see high temperatures well above 90 degrees Fahrenheit, or 32 degrees Celsius. There will also be areas that will see temperatures climb into the 100s Fahrenheit, or above 38 degrees Celsius.
Another hazard may also be found along the northern fringe of the heat dome, from southern Canada across the northern Great Lakes states and into New England. Atmospheric disturbances tend to ripple across the outer edges of such weather patterns, triggering large complexes of severe thunderstorms.
While this is an extended range forecast with details that are subject to change, the warning signs for a major heat wave are present, and have been for several days, in several of the main computer models used to help predict the weather.
Both the European and GFS models, among others, are depicting the height of the 500 millibar pressure surface, which is normally located around 5,000 meters, or 18,000 feet, to be at or above 6,000 meters, or 19,685 feet.
This is a rare event that is an indication that this event may be unusually severe.
Heat waves such as this one, which will also involve high humidity, due to a flow of air that will pump Gulf of Mexico moisture northward into the Plains, have the potential to cause heat-related injuries and fatalities.
One of the most confident conclusions in climate science is that heat waves are becoming more intense and more common as the world warms in response to increasing amounts of greenhouse gases in the air.
Over longer periods of time, the record highs to lows ratio is becoming more skewed in favor of warm temperature records, reflecting the increase in average temperatures that raises the odds of warm records.
If global average surface temperatures were not going up, the ratio between record highs to lows would be expected to be closer to 1-to-1