Tonight is going to be one of those nights where if you don’t have air conditioning, you’re going to be uncomfortable. Temperatures for many won’t drop out of the 70s tonight. With humidity remaining very high, the air will be warm and sticky. This will offer a head start to a Saturday that should become our hottest day of the year.

Partly cloudy skies Saturday will help temperatures climb into the upper 80s to near 90 degrees by mid afternoon. Our chief focus Saturday is less the heat and more the prospect for strong to severe thunderstorms. A cold front & lake breeze will serve as a focus for thunderstorm development late afternoon into the evening. Our near 90 degree heat and high dew points will combine to generate quite high instability levels. This is an important ingredient in the production of severe weather, but thankfully not the only one. Wind shear values tomorrow are not impressive, taking the edge off of what storms will be capable of. Typical situations like this (high instability, lower shear) tend to produce storms with plenty of lightning, heavy rain and gusty winds. A few could be healthy enough to prompt severe thunderstorm warnings for 60+ mph gusts and hail.

The main window for this action begins after 3pm and could linger until 10pm before storms start to weakening in the lessening instability after dark. It is important to note, severe weather is only part of the equation we need to be paying attention to. High instability environments typically produce a lot of lightning, which is unrelated to whether a storm is “severe” or not. Wind, hail & tornadoes factor into the severe criteria. Lightning does not. We don’t want those of you outdoors or on the lake to rely on warnings as your queue to get indoors. Have our WROC app on your phone to track the situation and where lightning is firing.

The cold front moves through early Sunday and will keep scattered rain and storms around into the early afternoon. The main risk for severe weather Sunday appears to exist well east of Rochester, but we’ll still be watching just in case. Rain tapers into the afternoon behind the front as much cooler and less humid air spills in by the start of the new week.

~ News 8 Weather Team