By Jim Steele
Here is an example of myth making by NOAA’s “Ask a Scientist” about extreme rainfall.
Their myth: “We know that warmer air can hold more moisture, and moisture is a key ingredient to heavy rainfall, so it stands to reason that a warmer environment overall is capable of generating more extreme rainfall.”
Indeed, the first 2 scientific factoids are absolutely true but totally mis-applied; warmer air does hold more moisture and moisture is a key ingredient to heavy rainfall. But it “does not stand to reason” that global warming is causing more extreme rainfall.
Still click-bait media like the Washington Post mindlessly write the headlines like, “Study finds climate change is bringing more intense rains to U.S.” explaining that it is due to “warmer air’s ability to hold more water.” Focusing on global warming is the easiest way to implicate CO2, and persist with the click-bait climate crisis hoax.
Just because warmer temperatures increase the theoretical maximum of water vapor that the air can hold, extreme rainfall does not correlate with temperatures as data from the US National Weather Service reveals in the table below.
On July 10th, 2023, during each location’s local 3 PM, Death Valley had a temperature of 98°F, the air held 5.92 kg/m2 of water (TPW) but was only 4% of the theoretical maximum.In Shreveport Louisiana, temperatures were 18°F cooler but held 10 times as much water vapor.
In Montpelier Vermont, temperatures were 21°F cooler but the air held 8 times more water than Death Valley. Clearly the much more important rainfall dynamic is how and where moisture is being transported from the ocean to the land.
The position of high- and low-pressure systems determines where moisture will be transported. The summer high pressure off the coast of California blocks rains from reaching Death Valley, while the high-presssure system in the North Atlantic amplified the heavy rainfall reaching Vermont and causing extensive flooding.
Likewise, how the low-pressure cyclonic system migrated up the coast determined Vermont’s temperature and heavy rainfall. On July 9th, the temperature in Montpelier at 3 PM was 67.1°F, 10 degrees cooler than its July average of 77.1°F. On July 10th during the peak of flooding rainfall, temperatures fell to 63.3°F yet the atmosphere was saturated with water vapor increasing to 42 kg/m2.
As rainfall subsided on July 11th, temperatures rose to 81.1°F, but the amount of water vapor fell dramatically to 29.26 kg/m2, just half of the local atmosphere’s capacity.
Below the upper screen shot from the US National Weather Service, shows how the atmospheric surface circulation converged to amplify the transport of moisture into Vermont where the topography then wrung out the moisture. The lighter blue regions represent the greatest amount of water vapor. But such scientific information was rare from click-bait media, that prefers to perpetuate the climate crisis myth!
The lower sceen-shot, show the how the jet stream’s northward flow at 500 mb further added to moisture reaching Vermont.
So the next time the media and alarmist scientists try to convince you a flood was due to global warming go to https://earth.nullschool.net/ where an interactive weather map from the US National Weather Service will allow you to see the relationship between temperature and TPW and how atmospheric circulation concentrates moisture and how it changes over time despite the same CO2 concentrations.
For more information on rainfall and other claims of extreme weather, check out our Claimed Dangers page on Everything Climate