Forecasters say this July will likely go down as one of the coolest in the Arkansas record books. Several rounds of cold fronts have move through the state, leaving the average temperature around 76.4 degrees Fahrenheit through July 30th, placing it tentatively as the second coolest on record.
For Little Rock, an average near 77.7 degrees Fahrenheit (as it was by Wednesday, July 30th) would place the month as the fourth coolest on record. John Robinson, a Warning Coordination Meteorologist with the National Weather Service says a steady succession of July rain showers have kept temperatures low.
“When you get the ground being very moist, it’s very difficult to heat up too much in the daytime. That’s because the sun’s energy goes into evaporating the moisture rather than heating the air. So as long as we have fairly soggy ground, it’s very difficult to get into the upper 90’s or higher,” he says.
The state’s coolest July was in 1967 at 76.3 degrees Fahrenheit, according to a Weather Service report. Robinson says the Little Rock area’s coolest July was in 1891, when the average was 76.8 degrees Fahrenheit.
The constant flow of cool air and moisture may be related to a recently southward expanding Polar Vortex, Robinson says.
“[The Polar Vortex] gets kind of a bulge, like taking something sticking out of a circle and the part that sticks out extends farther to the south. That pushes cool air farther to the south. So you can also say ‘well, the Jet Stream moves farther south.’ Well, that’s right. When the cooler air aloft starts coming down, the Jet Stream drops farther south, the cold fronts come through more. So, you can name a number of reasons of why it’s cooler than normal, but they’re all somewhat interrelated,” he says.
Robinson notes that many eastern counties in the state received record rainfall and flooding at the end of June, with other periods of flash flooding in western Arkansas. Although he is reluctant to predict a mild August as well, Robinson says the first few days of the month should remain wet and relatively cool.