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Midwest heat wave generates a heat index of 131° in Iowa; Bret no threat

By: Dr. Jeff Masters, 1:18 PM GMT on July 19, 2011

A unusually intense, long-lasting, and widespread heat wave with high humidities continues to plague the Central U.S. The heat index--how hot the air feels when factoring in both the temperature and the humidity--exceeded 100°F in twelve states on Monday and thirteen on Sunday, with the dangerous heat extending from Texas northwards to North Dakota, Minnesota, and Wisconsin. At least thirteen deaths are being blamed on the heat in the Midwest. The heat index hit a remarkable 131°F at Knoxville, Iowa on Monday, and a heat index in excess of 120° was recorded at numerous locations in Iowa, Minnesota, and Illinois.


Figure 1. Predicted maximum heat index for Thursday, July 21, 2011. Portions of 33 states are predicted to have a heat index in excess of 100°F. Image credit: NOAA.

A 1-in-7-year heat wave coming for the Eastern U.S.
The extreme heat will shift slowly eastwards this week, peaking in Chicago on Wednesday, Detroit and Pittsburgh on Thursday, and New York City and the mid-Atlantic states on Friday. Temperatures near 100°F are expected in Detroit on Thursday and New York City on Friday. Detroit has hit 100°F 18 different years in its 137-year record, and New York City 22 years out of the past 140 years, so this heat wave is expected to be about a 1 in 7 year event. While that makes it a notable heat wave, the most remarkable feature of this July 2011 U.S. heat wave is the humidity that has accompanied the heat. A heat index over 130°F, such as was observed yesterday in Iowa, is very rare in the U.S., and extremely dangerous. According to Christopher C. Burt, wunderground's weather historian, the only place in the world where a heat index over 130°F is common is along the shores of the Red Sea in the Middle East. A major reason for the remarkably high humidities accompanying the July 2011 Midwest heat wave is the record flooding the region experienced over the past three months. As pointed out by wunderground's climate change blogger Dr. Ricky Rood in his latest post, with hundreds of thousands of acres of farmland still inundated by flood waters, and soils saturated over much of the Upper Midwest, there has been plenty of water available to evaporate into the air and cause remarkably high humdities. This makes for a very dangerous situation, as the human body is not able to cool itself as efficiently when the humidity is high. The extreme heat will last through Sunday in the mid-Atlantic, but should end on Monday, when a cold front is expected to sweep across the region. However, the latest models suggest the heat will re-amplify over the Midwest next week.


Figure 2. Tropical Storm Bret at peak intensity, at 5:15 pm EDT on Monday, July 18, 2011. At the time, Bret was building an eyewall and had begun to clear out an eye. Image credit: NASA/GSFC.

Tropical Storm Bret weakens
Tropical Storm Bret enjoyed a brief burst of intensification yesterday afternoon that brought the storm's winds up to 65 mph. However, Bret has sucked in a lot of dry air today, and is now a much weaker storm with winds of just 50 mph. Satellite imagery shows that Bret has not improved in organization this morning, thanks to dry air to the northwest that has been blown into the storm's core by upper-level northwesterly winds. Wind shear is a high 20 - 25 knots, and is expected to remain in the high range for the next three days. The combination of high wind shear and dry air nearby should act to keep Bret from strengthening, and the storm should slowly decay as it heads out to sea over the next few days. Bret is not a threat to any land areas.

None of the reliable models predict tropical cyclone development over the remainder of the Atlantic through July 26.

Weakened Typhoon Ma-on nearing Japan
Typhoon Ma-on has weakened to minimal Category 1 typhoon with 75 mph winds, and is battering a large swath of the south coast of Japan with tropical storm-force winds, as the storm slides northeast along the coast. Ma-on is expected to turn eastwards out to sea by Wednesday, and is not likely to bring tropical storm-force winds to the troubled Fukushima Nuclear Plant.

Jeff Masters

The views of the author are his/her own and do not necessarily represent the position of The Weather Company or its parent, IBM.

Reader Comments

141 million Americans across almost a million square miles are under heat advisories or excessive heat warnings today:

Click for large image
Uh-oh
1502. Levi32
Quoting CybrTeddy:


Doesn't look too exposed to me, maybe about 50% covered. IMO its nearing classification.


This was Nana in the middle of the Atlantic when it was declared. Completely exposed.


An exposed circulation is not something that should be held against classification.


I agree. Why? Because that kind of a well-defined low-level center can't be formed unless convection was over or at least partially over the center for a portion of its life before getting sheared, which implies it had the "organized convection over the center" checkbox ticked before. Those kinds of systems, if not classified by the time they look like that, generally could have been classified before they looked like that.
Quoting beell:


I agree with you, nrt. That's the way it should work! Should be absorbed into the westerlies/trough before that could happen.


Now the NHC could at any time decide it is no longer attached to the front......
1504. Patrap
99L never was a player in the Season,,so debating it is like debating Matchlite vs Lighter Fluid in my view.
1505. lucreto
Quoting AussieStorm:

It's over water that is 26C, sure is can support a TD but nothing more. Might become TD03L but nothing more. Plus (as what has been pointed out already) it's attached to a front.


I agree with what you're getting at Aussie although the difference between a tropical depression and a minimal storm is very small considerably smaller than the difference between an invest/ open wave an a depression. So it would not shock me if this got named although it really does not look that organized at the moment.
Quoting Neapolitan:

The "Space Race" isn't between countries anymore, and hasn't been for a long time. The shuttle, magnificent as it was, was ill-conceived; no one thought to say anything beyond, "Hey, let's build a truck to carry things into orbit!" The U.S. Government isn't in the truck-building business, and shouldn't be. NASA needs to stick to science--that is, exploration of deep space--and leave the grunt work to competitive companies from around the globe.

The next American into space should be wearing a SpaceX patch, not a NASA one. And the sooner, the better...


I agree, taxpayers don't need to be footing the bill for NASA anymore
1507. Patrap
Quoting Neapolitan:
141 million Americans across almost a million square miles are under heat advisories or excessive heat warnings today:

Click for large imageUh-oh


That CANT be right,, as Im hearing the Globe is cooling rapidly.
1508. hcubed
Quoting cloudburst2011:
hcubed right now all i can say for sure it will be cindy thursday it continues to show organization on all sides.....i can also tell you this it will affect the islands in 72-96 hours...after that we will just have to wait but my guess right now this has the yucatan written all over it and mexico down the line...things could change though i will let you know...


So you don't see it making a track like Dean did in '07?
1509. Levi32
Quoting nrtiwlnvragn:


Now the NHC could at any time decide it is no longer attached to the front......


They did that with Bret. At some point they decided that the boundary it was attached to was no longer a front. That point was when they classified it as a tropical depression.
1510. emcf30
Quoting Levi32:
Good morning.

Blog update:

Tropical Tidbit for Wednessday, July 20th, with Video


Once again nice job Levi. Interesting potential setup with the high over CONUS with Hurricane Allen time frame analog being the best matched as depicted by the model.
hcubed no i dont not at this time..
Come on Rita you know that is Storm top and I want even bother to send it to you by mail lol I think Ray Charles could see that lol.I know pat knows.On a serious note Rita whats your take on this season?The setup is very similar to last year.Will it stay that way?Well if you look at history, if we do not have a hit by the first week in oct the nothern gulf coast from ala to la rarely gets hit by a hurricane.Juan would be the only fly in the oinment i can remember in the last 40 years.looks like we got 9 weeks to go in our area.
ECMWF Develops the wave East of the Caribean and places it crossing FL. Needless to say, this is the one wee need to watch.

Link
1514. scott39
Quoting Levi32:
Good morning.

Blog update:

Tropical Tidbit for Wednessday, July 20th, with Video
Why isnt the NHC giving the AOI in the central Atlantic at least a near 0%? Im confused on thier forecasting of this one!
Noticing some of the models (CMC, NOGAPS, ECMWF) are picking up on something forming near the southern Bahamas in about 6-7 days time. With a trough pushing off the East coast during that time though, whatever forms (if anything) might just end up being a fish storm. Just my preliminary thinking at this time.
1516. 68aggie
How and to whom do I communicate about my subscription?
Quoting Levi32:


I agree. Why? Because that kind of a well-defined low-level center can't be formed unless convection was over or at least partially over the center for a portion of its life before getting sheared, which implies it had the "organized convection over the center" checkbox ticked before. Those kinds of systems, if not classified by the time they look like that, generally could have been classified before they looked like that.

Do you think 99L should of been designate as an invest earlier, as it was developing and not how it is now?
Quoting RitaEvac:


I agree, taxpayers don't need to be footing the bill for NASA anymore

I didn't say that at all. There is a lot of future business in near-space, and private companies need to deal with that. But neither SpaceX nor Boeing nor Rockwell nor ULA have any profit-based imperative to, say, explore Neptune or the Oort Cloud or interstellar space; that is, and should remain, the purview of NASA and other equivalent governmental entities elsewhere.
1519. Levi32
Quoting AussieStorm:

Do you think 99L should of been designate as an invest earlier, as it was developing and not how it is now?


Invests have no criteria. They are subjective taggings for systems that the NHC would like special model data and microwave passes for.
Quoting SAINTHURRIFAN:
Come on Rita you know that is Storm top and I want even bother to send it to you by mail lol I think Ray Charles could see that lol.I know pat knows.On a serious note Rita whats your take on this season?The setup is very similar to last year.Will it stay that way?Well if you look at history, if we do not have a hit by the first week in oct the nothern gulf coast from ala to la rarely gets hit by a hurricane.Juan would be the only fly in the oinment i can remember in the last 40 years.looks like we got 9 weeks to go in our area.


No clue on the season. August and September are the main months so up until now this is expected by not having much going on. Things change on a dime very quickly in the weather world especially in the tropics.
1521. Levi32
Quoting scott39:
Why isnt the NHC giving the AOI in the central Atlantic at least a near 0%? Im confused on thier forecasting of this one!


Because at this point is is very unlikely to develop anytime soon. It is far too broad and is interacting with dry air. Once it gets near the Caribbean, west of 60W, it could become more likely to develop under more favorable/moist conditions. At that point, it may get a circle, but we'll have to see. We have a while to watch it evolve before it gets all the way across.
Quoting Neapolitan:

The "Space Race" isn't between countries anymore, and hasn't been for a long time. The shuttle, magnificent as it was, was ill-conceived; no one thought to say anything beyond, "Hey, let's build a truck to carry things into orbit!" The U.S. Government isn't in the truck-building business, and shouldn't be. NASA needs to stick to science--that is, exploration of deep space--and leave the grunt work to competitive companies from around the globe.

The next American into space should be wearing a SpaceX patch, not a NASA one. And the sooner, the better...


Yes and no. Yes, I'm looking forward to private companies doing all the work for the ISS now that NASA has shown everyone how to do it. Yes, I'm looking forward to NASA's new innovations for working on Deep Space exploration. (The new plasma engines are really going to revolutionize travel - instead of 6 months to Mars it could be done in 3 weeks.....)

My no's - They thought about building a better outpost than what the Russians did.....hence why you needed a "truck" to bring it up. We were the only ones with enough money, resources, and tech to make it happen. When you are the only trucking company around, you have to get things done. Just think of the amount of tech we had to create just to make a returnable vehicle and the science that has been done on the ISS....wouldn't have happened without the "truck"!

No, I don't like the idea of missing out on the Moon. Yeah, we've been there before and I get that you want to put your sights on farther out, but there are plenty of things we could learn about living on the Moon that would be applicable to deeper space.

Both presidents were correct in changing NASA's mission. Innovation and exploration are part of the agency, not "trucking".
Quoting Levi32:


Invests have no criteria. They are subjective taggings for systems that the NHC would like special model data and microwave passes for.

So did the NHC miss the mark on this one, should of tagged it earlier?
1524. Levi32
Quoting AussieStorm:

So did the NHC miss the mark on this one, should of tagged it earlier?


No that's my point. There is no "should have tagged." There are no criteria, and thus we can't say that the NHC was wrong in not tagging it an invest. There is no such thing.
1525. 7544
Quoting Levi32:


Because at this point is is very unlikely to develop anytime soon. It is far too broad and is interacting with dry air. Once it gets near the Caribbean, west of 60W, it could become more likely to develop under more favorable/moist conditions. At that point, it may get a circle, but we'll have to see. We have a while to watch it evolve before it gets all the way across.


agree soon it reaches that area then it willl form also if the euro and cmc pans out right fl could see a coulple of more going the same way . wait watch and see mode for this could be a fl season for tc imo the way things will be setting up
Quoting Levi32:


No that's my point. There is no "should have tagged." There are no criteria, and thus we can't say that the NHC was wrong in not tagging it an invest. There is no such thing.

ok, Chillax mate!
1527. SLU
Quoting AussieStorm:

Bret had it's COC fully under it's convection, not half covered like 99L.
Quoting AussieStorm:

Bret had it's COC fully under it's convection, not half covered like 99L.


A system doesn't need to have a "clothed" COC for it to be designated
My Tropical Update For July 20th, 2011:
Tropical Storm Bret ; Invest 99L ; Hurricane Dora
Comment, and if you have any questions, ask, and i will make an attempt to reply.
Good morning all.

So, Tropical Storm Bret is still hanging on? He's really persistent, and it will be interesting to see what happens with shear beginning to weaken tomorrow. Maybe he'll surprise us, he's impresses us so far. Satellite shows it may be on its decline now.



Invest 99L is unofficially a tropical depression, and has been one since yesterday afternoon. Whether or not it is declared is up to the National Hurricane Center, although they do at least show some interest to it.



Lastly, I'm a bit concerned about this wave in the central Atlantic. It is large and broad right now, but models have been on and off with development, and as Levi said in his video, unless timing is perfect, this could be a threat to the USA, specifically, Florida. Of course, development is no guarantee.

Lol, Levi, I just watched your tropical tidbit, after i had just finished my blog, and i made the same arguement about 99L, how its not a major priority for the NHC due to it going out to sea, and was somewhat sub tropical a while back(though its tropical now).
Quoting TropicalAnalystwx13:
Good morning all.

So, Tropical Storm Bret is still hanging on? He's really persistent, and it will be interesting to see what happens with shear beginning to weaken tomorrow. Maybe he'll surprise us, he's impresses us so far. Satellite shows it may be on its decline now.



Invest 99L is unofficially a tropical depression, and has been one since yesterday afternoon. Whether or not it is declared is up to the National Hurricane Center, although they do at least show some interest to it.



Lastly, I'm a bit concerned about this wave in the central Atlantic. It is large and broad right now, but models have been on and off with development, and as Levi said in his video, unless timing is perfect, this could be a threat to the USA, specifically, Florida. Of course, development is no guarantee.



Great post. The catl wave seems to be supplying most of its energy from the ITCZ,when do you think it will be leaving it? When it does and if it is able to sustain itself i think we will having something to watch.
My new forecast for Bret's ACE:
2.5 to 2.82
Where'd Everyone go? lol
*echo* *Echo* *echo*
1535. 19N81W
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