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  #1  
Old 06-30-2012, 09:09 PM
dalej42 dalej42 is online now
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Why is it so hot in the Midwest? Explain it like I'm a 2 year old.

I'm not very knowledgeable about weather, I'm trying to remember back to my high school science classes.

Here is my understanding of why it is so hot in the Midwest. A warm front enters from the south of the United States. Weather, except for hurricanes, travels from west to east. A very warm front traveled from the American west, heating up Denver to 108 degrees. It crossed the Rocky Mountains and since there is more water east of the Rockies, it picks up moisture. So, now there is a warm front sitting over the Midwest, waiting to be replaced by a cold front. There is no cold front coming, so it just sits over the Midwest, circulating hot steamy air for days on end.

Is this right?
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  #2  
Old 06-30-2012, 09:54 PM
Broomstick Broomstick is offline
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Allowing for how simplified your explanation is... basically yes.

I will also note that both hurricanes and tropical storms (Florida just experienced TS Debbie) tend to make Midwestern weather patterns "stall". Whatever we had when the TS or hurricane rolled ashore, that's what we tend to have for a week (or more) and it's frequently hot, humid, hazy weather when that occurs.
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  #3  
Old 06-30-2012, 10:02 PM
Rick Rick is offline
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The exhaust vent from hell is located there.
Either that or what you said.
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  #4  
Old 06-30-2012, 10:10 PM
Michael63129 Michael63129 is offline
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The reason has to do with the upper-air pattern, which currently has a ridge of high pressure situated over the U.S. (left shows actual values and right is anomaly, which shows that heights are abnormally high over the U.S.), which is associated with warmer temperatures. You are right about the air stagnating and just getting hotter and hotter from day to day; developing drought conditions which cover much of the country are also helping to make things even hotter (heat leads to drought, which leads to more heat, which leads to more drought and so on; what starts this in the first place, well, pretty much random weather variations).

Such a pattern can persist for a long time, sometimes not until the seasons change at the end of the summer, as was the case last summer when it was centered over Texas and Oklahoma (shifted further north this year). Note also that it isn't so much because a warm front moves in from the south, since there isn't any large source of hot air south of the U.S. (i.e. warm fronts bring warmer air north, but don't bring in hotter temperatures that where they originated from, although the air can heat up as it moves north).

Also, the current pattern is more or less what we have seen for at least the past year (last summer was also very hot, followed by a warm fall, winter and spring, although at least where I live it was wetter than normal until the past couple months).
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  #5  
Old 06-30-2012, 10:11 PM
Chimera Chimera is offline
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We do get enough sun that it does warm up quite rapidly during the day all on it's own. Like for example, today we went from mid 60's in the early morning to upper 80's in the late afternoon (Minneapolis). From there it's only going to cool off to the upper 60's to about 70 at night, and then tomorrow we get low 90's.

We are at roughly 45 degrees north latitude here in Minneapolis. Halfway between the equator and the north pole. But remember, the axial tilt of the Earth is roughly 23.5 degrees, so at summer solstice, we're the equivalent of 21.5 degrees north latitude when you're looking at the angle of the sun. That is the equivalent of being in central Mexico, or Saudi Arabia, or India on the equinoxes, except that we get 15 hours and 36 minutes of daylight to help warm us up!

That also means we get the other extreme, being at equivalent of 68.5 degrees north latitude at the time of the Winter solstice. We only get an 8 hour, 46 minutes of sun on that day, which isn't a lot of daylight hours to warm things up besides the low angle of the sun.

Last edited by Chimera; 06-30-2012 at 10:13 PM..
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  #6  
Old 06-30-2012, 10:14 PM
Duckster Duckster is offline
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The tropics and much of the Northern Hemisphere are likely to experience an irreversible rise in summer temperatures within the next 20 to 60 years if atmospheric greenhouse gas concentrations continue to increase…. “According to our projections, large areas of the globe are likely to warm up so quickly that, by the middle of this century, even the coolest summers will be hotter than the hottest summers of the past 50 years,” said the study’s lead author, Noah Diffenbaugh, The study, based on observations and models, finds that most major countries, including the United States, are “likely to face unprecedented climate stresses even with the relatively moderate warming expected over the next half-century.”
http://www.eurekalert.org/pub_releas...u-sc060611.php

Quote:
How hot is it? It is so hot that NBC Washington’s Chief Meteorologist, Doug Kammerer, explained on air “If we did not have global warming, we wouldn’t see this.”
http://thinkprogress.org/climate/201...ldnt-see-this/

https://www.youtube.com/embed/i0wNbsy5h4A

Quote:
The U.S. surface temperature map from Unisys at 4 pm, June 29,2012, shows 100° temperatures stretching almost continuously from California eastward to the Carolinas.
http://capitalclimate.blogspot.com/2...aches-mid.html

Bottom line: Expect this to be the "new normal" for summers from now on.
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  #7  
Old 07-01-2012, 12:21 AM
appleciders appleciders is offline
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There's another factor here: the presence of a large body of water, especially the ocean, is a moderating factor in temperature because it acts as a heatsink in heat waves and releases heat in cold waves. That's why coastal cities are somewhat milder in temperature, on average, compared to inland cities of similar latitudes. The Midwest, as you may have noticed, does not have a nearby ocean.
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  #8  
Old 07-01-2012, 12:47 AM
RetroVertigo RetroVertigo is offline
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I can't tell you why it is happening, just make it stop. St. Louis had its highest recorded temperature for the month of June yesterday at 108F.
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  #9  
Old 07-01-2012, 01:26 AM
Bullitt Bullitt is offline
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Explain it like you're a 2 year old?

It's hot because I said so, and I'm the Daddy. That's why.

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  #10  
Old 07-01-2012, 02:17 AM
RetroVertigo RetroVertigo is offline
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Originally Posted by RetroVertigo View Post
I can't tell you why it is happening, just make it stop. St. Louis had its highest recorded temperature for the month of June yesterday at 108F.
My bad I meant Thursday. Yesterday was only a balmy 106.
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  #11  
Old 07-01-2012, 05:53 AM
Bosda Di'Chi of Tricor Bosda Di'Chi of Tricor is offline
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All the hot air from the election year candidates...you fill in the rest.
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  #12  
Old 07-01-2012, 07:48 AM
ftg ftg is offline
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Note that due to the bigger "kinks" in the upper flows, you are also getting record "cold" temperatures in other parts of the country. When I checked the Weather Underground's extremes page a couple days ago, record lows were being set in the upper Columbia basin, parts of Arizona and Jacksonsville, FL.

Checking for June 29th, record lows in MT, NV and FL.

This was also the situation during the spring heat wave in the upper Midwest. Cold weather behind and ahead of the dip.

The extra energy in the atmosphere makes the jet streams and such more energetic, like a river moving fast on a gentle grade, you get more meandering and cutoffs (oxbows).

Jeff Master's regularly posts about weather extremes in his blog. Here's one of his entries from the April heat wave. More discussion about the "why" in posts made around that time.

Remember, extra energy just doesn't mean warmer, it means more aberrations from normal.
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  #13  
Old 07-01-2012, 11:48 AM
Fubaya Fubaya is offline
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It started with a warm and dry spring which caused less moisture in the ground, which makes the air warm faster when the sun hits it. This warms the lower troposphere and increases "thickness", which means the lower atmosphere actually extends higher than normal, so once it heats up, it's harder to cool off since it's so thick.

Then comes the subtropical ridge, an upper high pressure air mass that migrates from the tropics into the US during the summer. It helped heat everything up, then other areas of high pressure, "ridges", came in and basically stacked on to it, adding warm dry air to the air mass that was already warm, dry and very thick and strong. Whatever air masses might have helped break it up weren't strong enough to do it, and there haven't been many of them.

The atmosphere became "blocked," meaning a stationary high pressure area keeps everything stable and forces weather to go around it. The eastern part of the country is locked into what is called an "omega block" where air circulation resembles the greek letter Omega. So we're stuck in a cycle where the air is warm, hard to cool, and nothing can break it for the forseeable future.
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  #14  
Old 07-01-2012, 02:27 PM
Zsofia Zsofia is offline
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Originally Posted by Rick View Post
The exhaust vent from hell is located there.
Either that or what you said.
No, sweetie, that's Columbia motherfucking South Carolina. Friday we had the highest temperature ever recorded. Not for June. For ever.
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  #15  
Old 07-01-2012, 04:12 PM
Fubaya Fubaya is offline
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Originally Posted by Zsofia View Post
No, sweetie, that's Columbia motherfucking South Carolina. Friday we had the highest temperature ever recorded. Not for June. For ever.
Hell must have a lot of vents because that happened in 10 different cities Friday.
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  #16  
Old 07-01-2012, 05:15 PM
Zsofia Zsofia is offline
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Well, that's not the only way you can tell.
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  #17  
Old 07-03-2012, 10:22 AM
septimus septimus is offline
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PBS interviewed a scientist who called attention to lack of rain and snow:

Quote:
... in the Boulder-Denver area, there's about a third of the normal annual precipitation up until now that has occurred.

But in the mountains, there's no snow left. Normally, you don't see any snow left until late August, if then. And by early June, there was no snow left. Snow is a reflector. When it melts, it provides water. It cools the atmosphere. And water is the great air conditioner.

So the absence of all of the water and the snow in the Southwest has meant all of the heat from the sun is going into raising temperatures. This is the building of the heat wave.

...

And the heat then begins to -- begins to move eastward. It picks up moisture out of the Gulf. The humidity goes up to enormous amounts because the oceans have a strong memory of the climate change being warmer and moister over the oceans. And that empowers all of the weather systems, such as the ones that came through, the thunderstorm clusters that came through and did all of the damage yesterday.
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  #18  
Old 07-03-2012, 12:02 PM
Fubaya Fubaya is offline
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Is he talking about a different heat wave? The heat wave didn't come from the west, it came from a high pressure ridge from the south. Warm air from the west may have also moved east and warmed some areas of the midwest, and may have driven the storms that have been in the news, I don't know at the moment, but the big record breaker didn't come from Denver.

The storms that the country has been having are not all that unusual. Derechos, big swaths of strong winds, form from storms that occur in hot summer air and often happen along the northern boundaries of a stationary front. The stationary front that was setting temp records.
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  #19  
Old 07-03-2012, 05:39 PM
barbitu8 barbitu8 is offline
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Quote:
Originally Posted by dalej42 View Post
Weather, except for hurricanes, travels from west to east. A very warm front traveled from the American west, heating up Denver to 108 degrees. It crossed the Rocky Mountains and since there is more water east of the Rockies, it picks up moisture. So, now there is a warm front sitting over the Midwest, waiting to be replaced by a cold front. There is no cold front coming, so it just sits over the Midwest, circulating hot steamy air for days on end.

Is this right?
As already posted, your hot weather came from the Gulf of Mexico, not from "the American west." We here are in the prevailing westerlies, and air masses generally move from west to east. Air masses can originate in Alaska, Canada, or the Pacific. Warmer air masses with low pressures can originate in the warm waters of the Gulf or the Atlantic. If they are associated with a frontal system, they are called barometric or frontal lows; however, tropical low pressure areas are not associated with frontal systems. They will move according to steering systems, which can be westerly or northerly. If they get picked up with a front (leading edge of an air mass, which generally here moves west to east), they will move with the front and lose their tropical characteristics.
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  #20  
Old 07-03-2012, 05:59 PM
carnivorousplant carnivorousplant is offline
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What the hell happened to the Jet Stream, that brings down freezing air from Canada in the Winter?

"Weather Prediction is not a Science, it is a Black Art."

-My Quantum Mechanics Graduate School Professor.

Last edited by carnivorousplant; 07-03-2012 at 05:59 PM..
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  #21  
Old 07-03-2012, 06:03 PM
barbitu8 barbitu8 is offline
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Quote:
Originally Posted by carnivorousplant View Post
What the hell happened to the Jet Stream, that brings down freezing air from Canada in the Winter?

"Weather Prediction is not a Science, it is a Black Art."

-My Quantum Mechanics Graduate School Professor.
The jet stream is not a fixed stream. In the winter, it will go north into Canada, or Alaska, and then loop back down to the USA, creating Canadian air masses or Polar air masses. This time of the year, it bends into the Gulf of Mexico and then ascends either to the midwest or east, providing warm, moist Gulf air to those areas.
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  #22  
Old 07-03-2012, 06:12 PM
carnivorousplant carnivorousplant is offline
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Quote:
Originally Posted by barbitu8 View Post
The jet stream is not a fixed stream. In the winter, it will go north into Canada, or Alaska, and then loop back down to the USA, creating Canadian air masses or Polar air masses. This time of the year, it bends into the Gulf of Mexico and then ascends either to the midwest or east, providing warm, moist Gulf air to those areas.
Warm, my ass!


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  #23  
Old 07-03-2012, 06:29 PM
YogSosoth YogSosoth is offline
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Originally Posted by Zsofia View Post
No, sweetie, that's Columbia motherfucking South Carolina. Friday we had the highest temperature ever recorded. Not for June. For ever.
Well don't leave us hanging, what was the temp?
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  #24  
Old 07-04-2012, 02:44 AM
Fubaya Fubaya is offline
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Ok, I've looked at what happened a little more and my earlier explanation a few days ago missed one thing, one of those ridges (an area of high pressure) was insanely intense. It wasn't so much a compounding of normal high pressure and crappy dry conditions, those were making it hot in general, but more blame should be given to one nasty upper ridge for really pushing us over the edge.

It still didn't come from Denver or the western US though. It actually came from the Pacific, crossed the Baja peninsula and drove northeast to center itself over Kansas for a few days, then slid to the southeast. It was already in the southern US by the time I looked at details and I could have sworn it came up from Mexico or the Gulf. It still came from the south, it just entered Mexico on the Pacific side and headed north to the states.
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  #25  
Old 07-04-2012, 09:08 AM
ftg ftg is offline
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Air coming from either the west or south isn't on its own going to be hot enough to cause what happened. Usually there is another factor that really ramps things up. Often this is sinking air. Sinking air dries out, warms up, clears out, all of which allows for things to get really, really hot.

I don't know if this was going on in this case. Maybe Fubaya knows.
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  #26  
Old 07-04-2012, 01:46 PM
Fubaya Fubaya is offline
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Originally Posted by ftg View Post
Maybe Fubaya knows.
There's something no one ever says! I'm certainly no expert but I was looking for graphics to show and ran across this two part explanation complete with nice graphics: part one and two.
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  #27  
Old 07-05-2012, 10:04 PM
Zebra Zebra is offline
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The Midwest is the bible belt. Now, do you ever see pictures of God wearing a belt? No. No you do not. God is mad at them for stealing his belt.
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  #28  
Old 07-05-2012, 11:18 PM
carnivorousplant carnivorousplant is offline
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Quote:
Originally Posted by Zebra View Post
The Midwest is the bible belt. Now, do you ever see pictures of God wearing a belt? No. No you do not. God is mad at them for stealing his belt.
By G-d, that's...oops.

NM
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  #29  
Old 07-06-2012, 01:05 AM
nikonikosuru nikonikosuru is offline
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Originally Posted by Zebra View Post
The Midwest is the bible belt. Now, do you ever see pictures of God wearing a belt? No. No you do not. God is mad at them for stealing his belt.
The midwest.

The bible belt.
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