Hot, But Not Too Humid

Since it is now summer, it is easy to characterize all summer days as hot and humid.  That would probably be the correct assumption if you lived in Houston or Miami, but Oklahoma’s humidity can vary greatly over a short distance.

Take today for example, eastern Oklahoma is sweltering with dewpoint temperatures in the low 70s, while central and eastern Oklahoma’s air is drier with dewpoints in the 60s.  Combine those dewpoints with temperatures in the 90s, and you get a wide variation in heat index values.

As you can see from our friends at the Oklahoma Mesonet, the mid afternoon heat index is highest in the east where dewpoint temperatures are in the 70s.  It feels like 100 to 104 in much of eastern Oklahoma, while heat index values in the 90s are the rule in central and western Oklahoma where dewpoint temps are lower.  Here’s a mid afternoon dewpoint map:

It looks like drier air has moved into western and central Oklahoma since yesterday.  This next map shows the 24 hour dewpoint change in Oklahoma:

Notice how the dews have dropped more than 10 degrees in parts of western Oklahoma.  Of course lower dewpoint temperatures lead to lower heat index values, but drier air is also easier to heat and cool than moist air.  What that means is that even though western Oklahoma will have a lower heat index, their actual temperature will likely be higher.

Given the fact that little change is expected in our weather the next few days, soil moisture will continue to slowly decrease, leading the sun to use less energy on evaporation, and more energy on heating our atmosphere.  The result could be afternoon temps slowly climbing into the upper 90s as opposed to the low 90s that we’ve had in central Oklahoma the last few days.

Make sure you respect the heat, whether it is high air temperatures, or a high heat index.  Drink plenty of water, take breaks, wear light-colored clothing, and listen to your body.  We don’t want you to succumb to the heat.

Rick

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