By the first week of July in 2016 our temperatures were consistently in the mid to upper 90s. This year however we only warmed above 90 once: July 1st saw a high of 92. The slightly cooler air is in part because it’s been a significantly wetter summer so far in 2017. Huntsville has already picked up 1.52 inches of rain this month.
As we head into the second full week of July, we’re looking at more dry weather and more heat. Temperatures start rising after a ridge of high pressure shifts over the Tennessee Valley by mid week. We’re still not expecting ‘extreme’ heat, but a rise in humidity will certainly still make it feel oppressive at times.
Expect highs by Monday in the low 90s and ‘feels like’ temperatures near 100 by Tuesday and Wednesday. Along with the heat, mainly dry weather will continue. As more moisture builds into Alabama we’ll begin to include small storm chances in the forecast, starting Tuesday.
We’ll have to wait for the ridge to break down and move back towards the west for storm chance to really amp up. Right now, it does’t look like that happens until next weekend.
Why does a ridge bring heat? A large ridge or upper level high pressure is often accompanied by a prolonged period of heat. This happens often in the summertime as ridges spread eastward from the western half of the US.
High pressure in the upper levels of the atmosphere causes the air to sink. As air sinks it’s forced to compress, which causes it to heat up. Sinking air also leads to mainly dry weather. That means there won’t be a lot of cloud cover or rain to keep temperatures in check.