100° Coming?
It's the end of July and no 100° days so far this year. 41% of Arkansas summers since 1880 do NOT hit 100°. That statistic surprised me a little when I saw it.
Look at the graph further down the page. There's a lot going on here so let me explain.
This is a chart displaying yearly average temperatures and rainfall for Little Rock. The green bars show average precipitation by month. Notice the 2 peaks: one in April and the other in November. Did you know we have more rain in the fall and early winter compared to spring? Look at the rainfall minimum in the summer.
The red line is the average daily high temperature, the blue line is the average daily low temperature, and the brown line is the average temperature. Those peak right now! The end of July into the middle of August is typically the hottest time of year. Then we slowly get cooler sliding into the fall months.
The latest 1st 100° day is September 6th, 1922. That date might be important to watch this year.
Why haven't we hit 100° this summer? For 100 degree heat, you need 3 things in Arkansas: strong ridge of high pressure, mostly sunny skies, and a dry ground. For most of this summer, the strong ridge has not been centered over Arkansas and when it is, it usually moves away within days. The key to summer 2019 is the soil moisture. As long as that stays elevated, the suns energy will go into evaporation before efficiently heating the surface temperatures. The map below calculates the soil moisture anomalies as of July 28th. We are WAY ABOVE! Look at the max over southwest Arkansas! That's because of the record rainfall from the remnants of Barry. As long as that soil moisture level is high, forget about hitting 100°. It might feel like it with the humidity, but not the actual temperature.
The forecast over the 8-14 day time period (August 6th through the 12th) favors below average temperatures with a persistent weather pattern.
Will we hit 100° this summer? If we do, it will be the last half of August or the very beginning of September. If I had to put a percentage on it, I would say there's a 80% chance we will NOT and the summer of 2019 will go down as a very cool one for Arkansas. I know, the humidity has been high, but it's Arkansas!