allison chinchar is in the cnn weather center. how long is this -- this heat dome, as it's called, going to last? >> for many, it's going to last for at least another week. some areas could see it for at least another month before we finally start to see it let up. we talked about the wildfires in california where we do have heat advisories out. but it stretches all the way back towards massachusetts as well. philadelphia, new york, chicago, st. louis, nor cities included in this. to understand white it affects major cities, we take a look at the bigger scope here. we've got the ground. now we set up our city. you've got your high pressure system that's been built over top. you have the son baking those temperatures down onto the ground. all of that heat then settles on the ground. it pushes towards the surface, which is what we feel. then it started to lift. the high pressure prevents it. it causes the hair to sink back down to the ground creating that dome. cities are even more special. the key thing is due to the asphalt, the p

meteorologist allison chinchar in the cnn media center now. long is it going to last based on what you can tell? >> okay. so let's take a look at the area of the country where we have the biggest threat. the big chunk is over the central u.s. but we also have some portions in the northeast and we also have portions in the southwest. you can make the argument the heat dome really covers pretty much the entire united states from east to west coast. we have over 110 million people under some type of heat watch, warning, or advisory and that includes 26 states. here you can see that high pressure that is kind of sitting right over the central region of the country but how does that work exactly? let's take a closer look. here you can kind of see the dome of high pressure that's sitting right next to me. what that does is when you have a dome of high pressure, you have all that heat that the sun brings down to the surface. heats up the ground, heat rises, it naturally goes up. but thanks to the high pressure system, it acts like a bowl. it covers a

let's bring in meteorologist allison chinchar. >> it is another hot day across the south. we're talking 97 for the high in dallas. houston and little rock with the heat index reaching triple digits. 93 in detroit. 97 in charleston. further north, we are feeling the heat. st. louis, average of 89. we are in the mid-90s. minneapolis is going to be above average the next couple days. we will finally get a slight cooldown by the time we get to thursday. we're keeping a close eye in the midwest for severe weather today. main threats are damaging winds, large hail and isolated tornadoes from green bay, chicago, des moines to kansas city. that threat will push farther east for the coming days. you can see as we get to evening commute, it starts to move into indianapolis and nashville as well. >> allison, thank you. >>> it is safe to look at your portfolio. s&p is sitting at an all-time high. >> just like me. >> serious tests for the market. i'll tell you what could stop the rally when we get an early start on your money next. >>> by the close of business wednesday, britain will h

let's get the latest with allison chinchar. >> that's right.atches up and down the east coast. the orange color on the screen is a heat advisory. all of the areas you see in pink, including the city of philadelphia, is under an excessive heat warning. that also takes into account the humidity. that feels-like temperature. look at this. philadelphia with a temperature of 92. it will feel like 101. cities like washington, d.c. and norfolk, the temperature is 94. it will feel like 103. we have the threat for severe weather in many of the same cities in the northeast. new york, burlington and washington, d.c. it stretches all the way back toward denver and the yellow areas you see are under a slightly higher risk for severe weather. the main threat is the afternoon into the evening commute hours. alison and john, that is something we will have to keep a close eye on. >>> thank you. donald trump's rise to the republican nominee has shocked wall street. why aren't investors freaking out? we will have an early start on your money next. >>> britain's n

>> allison chinchar has been following this. how can you tell if it is a meteor or piece of junk?imple to tell this. we'll break it down, the basics. you have the earth, we have all the satellites that operate around it. and all the parts that maybe get taken off from it as they get deployed. so over time all of that kind of builds up. and we have about 22,000 objects at least the size of a softball or greater that are currently kind of traveling around. now, here's the difference. let's say a meteor, for example, that comes in, okay, it's going to move at a much steeper angle. because it's coming from a farther distance. and it's coming down in. so if you're looking at it from the sky, it's going to almost look like it's come straight down at you. whereas these objects, because they are slower, they are going to appear like the red line here, almost like they are just floating along the horizon. and moving almost horizontal. the other thing is the speed at which these things travel. because all these objects are moving in orbit around them, by the time they fall back down to eart