Category: GFS

Updated 07.22.21 @ 7:35a

We’re in the midst of the “dog days,” however Summer ’21 has been anything but hot around these parts. July is running 2° below normal, month-to-date, and stretches of hotter weather have been transitional at best.

While the upcoming 6-10 days, as a whole, will offer up an opportunity for heat to build east, we don’t believe this hotter stretch will have staying power as we get deeper into August. Here’s why:

EPO: Note the rather dramatic reversal forecast over the upcoming couple of weeks. We go from a strong positive (now) to a strongly negative EPO state to close out July and open August. While there’s lag here (hence, the hotter days won’t arrive in earnest until early next week), the negative trend to open August will likely drive significant cooling from the Plains and into the Ohio Valley as we move through the first 10 days, or so, of the month.

MJO: While there are several questions pertaining to what phases the MJO will “camp out” in August, one thing that seems to be becoming clear is that we aren’t going to get stuck in the hot phases. Depending on if we recycle or head into the null phase, it sure seems like the MJO will favor the seasonable to cooler than normal phases through the bulk of the month.

Wet Ground: Long-time viewers of IndyWx.com know that we lean heavily on the precipitation pattern from May through July to at least serve as an ingredient in building our August forecast. Drier stretches of weather during these months can really “feedback” this time of year and serve to lead to hot closes to meteorological summer and open to meteorological fall. While it’s not the be all, end all, the opposite can usually be said for wetter years.

While August, has a whole, has a cooler than normal look to it, the upcoming 6-10 days will feature true summer heat as the ridge temporarily builds east. Several days next week will likely top out in the 90° to 92° range with plenty of humidity.

The feeling here though is that the ridge will pull back and open the window up for cooler (relative to normal), more unsettled weather to return as we get through the first full week of August. In fact, note how the latest longer range guidance is already loading up on the precipitation for the remainder of summer.

Our complete August Outlook will be out next week.