A hazy look at North Hill Park along North 4th Street in downtown Burlington at 12:30pm Friday, June 29, 2018 / Temperature of 91 degrees and heat index of 105 degrees / Photo credit: Landon Mitchell, KGRS-FM
Very hot and humid weekend
This round of heat and humidity will surge through at least Saturday evening. Friday and Saturday each will be sunny and well into the mid to upper 90s during the afternoon and evening. High moisture content in the air, humidity, will drastically reduce any evaporative cooling effect of sweat — the air can only hold so much moisture. It’s air you can wear.
Fans help very little in this environment since they can only circulate the hot, humid air already in place. Air conditioning in good working order — and then spending enough time in the air conditioning — is the way to go. Stay hydrated and check on other family and friends to make sure everyone is taking care of themselves — some folks will still want to mow, weed-eat, and wash the house on Saturday afternoon.
The National Weather Service has gone with the Excessive Heat Warning for us for Friday and Saturday. That’s an upgrade to the Heat Advisory. With humidity factored in, the real feel, heat index will be around 110 degrees on Friday afternoon and 105 to 110 degrees on Saturday afternoon and evening.
Severe weather chances
A “cool” frontal boundary will be sweeping through Western Iowa on Saturday and into Illinois on Sunday. Sunday, we could be back to the upper 80s or so for the high — so the front or a touch of cloudiness could cool us off slightly later in the weekend. The more intriguing thing to watch with this development will be keeping an eye on where some severe weather will decide to lay out.
Severe weather will be well-positioned to take hold in Western and even Central Iowa on Saturday afternoon and evening.
Most or all of the Saturday thunderstorm action should be fizzled out by the time it could reach us. On Sunday afternoon and evening, it remains to be seen exactly how far east the cool front advances — and where the eventual mini cool fronts, the little rain-cooled outflow boundaries from Saturday evening’s thunderstorm activity, lay out the following day Sunday.
Unfortunately, those details are pertinent in trying to accurately assess our odds of thunderstorms and severe weather later Sunday. Sunday could bring some cloudiness and even some early-day showers — that would greatly lower the threat for severe weather later. Or, the cool front could slow, we could get more sun early in the day — or an outflow boundary could become positioned such that severe weather breaks out here Sunday afternoon.
As shown by the computer models above, “The Burlington Bubble” could very well be in effect for this weather event — where we miss the nasty storms Saturday to our immediate west (which I think is likely) and to our immediate east on Sunday (more uncertain). As with Thursday’s bad weather that we saw, instability in the atmosphere will be high enough here Sunday that it’s worth noting some severe weather risk and giving a head-up on.