The Spring and early Summer brought rain and flood’s…
Now it’s the heat coming at us….
A stifling heat wave has begun to take shape across large portions of the United States, with millions likely to see temperatures creep toward the century mark, along with even higher heat indexes by this weekend.
The heat wave is already generating excessive heat watches in the central United States, and by Wednesday the national weather map is likely to feature a blanket of heat advisories from the National Weather Service. The combination of sultry dew points and scorching air temperatures approaching will help make this event a dangerous one from a public health perspective.
Cities including Chicago, St. Louis, Washington, Philadelphia, New York, Nashville and Kansas City, Mo., are likely to see at least three days with temperatures between 95 degrees and 100 degrees, along with dew points — a measure of the amount of moisture in the air — above 70 degrees.
This is likely to create ideal conditions for setting hot overnight low-temperature records, with the possibility that some records for such temperatures might be broken.
For example, the GFS model, which is generally bullish on hot weather, is projecting a low temperature in Washington of 86 degrees Sunday morning. The all-time warmest low temperature for the District is 84 degrees.
Faster warming of overnight lows compared with the warming rate of daytime highs are consistent with model projections and observations of how global warming is reshaping our weather. In cities, “urban heat island” effects also help keep overnight temperatures higher than surrounding areas.
When overnight lows fail to drop below a particular threshold, it’s harder for the human body to cool down and rest, elevating the health threat….
image…Visualization of heat and humidity Friday. (Earth.nullschool.net)