2 Alert Days are out...
For the 4th and 5th of July.
Humidity levels pushing us into the danger zone (cue Maverick) Wednesday and Thursday.
We actually won't be far from it even today, but increase cumulus clouds and t-storms should help cut that off just in time. It took a while for the Louisville Metro to see that "cutoff time" and the airport got to 94° with a heat index of 105°. Which I can't rule out today, but I am already seeing signs of developing t-storms on the recent data trends for the afternoon.
When will they pop? Basically any moment now through sunset. 89/90° looks to be the magic temperature threshold to get them going...and that isn't far away.
They will at least move a *big* faster today to the N/NW at roughly 10 mph. This is better than Monday, but still slow enough for a flash flooding concern and isolated downburst winds over 50 mph. In other words, keep that WAVE 3 Weather App handy!
FOURTH OF JULY
This is where the heating builds at the ground level and aloft. This means tall clouds and thunderstorms will have much more of a challenge to develop. In turn, the temperatures can go higher and when you combine that with the humidity...you see the problem. The dewpoint is still forecast to reach to about 73-77° across WAVE Country. That will be the big factor on just how high the heat index goes. I think 105-108° is the main target of concern, but if the dewpoint is on the higher end---110° can be reached. Dangerous stuff if you are not prepared for it. Thunderstorm potential doesn't drop to 0, but lowers to a small 10%.
FIFTH OF JULY
Another day of excessive heat. The difference is the ridge of heat starts to break down form the north. So the more north you are, the better the chance at some clouds and a few t-storms. The more south, well...you will be stuck in the excessive heat. Additional Heat Advisories may come out for those along/south of the Ohio River for Thursday.
Thunderstorms increase with a cold front. Just how widespread they become is unclear at this point as the models have been varying. Flash flooding the main concern here.
If trends hold, we can keep the rain chance out of the forecast with the drier punch of air. It will still "feel" hot during the daytime periods. Just slightly less humid and temperatures at night can actually drop below 70°. Fingers crossed :)