A heat wave recap; generally quiet tropics

By: Dr. Jeff Masters , 4:45 PM GMT on July 25, 2011

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Last week's U.S. heat wave has finally subsided, and most of the Northeast will see some cool highs in the 70s today. Unfortunately, the Midwest, and mid-Atlantic will continue to see high temperatures in the 90s for the rest of this week, and the southern Plains will be forced to continue to endure triple-digits.

According to the National Climatic Data Center (NCDC), 2,100 daily high maximum temperature records have been set so far in July 2011, and 51% of those were set last week. 4,734 daily high minimum temperature records have been set so far this month, and 55% of those were set last week. Here's a breakdown of last week's records for the period July 18 through July 24:

High Maximum:

• 1,076 warmest maximum temperature for the date
• 90 warmest maximum temperature for the month of July
• 56 warmest maximum temperature of all time

High Minimum:

• 2,595 warmest minimum temperature for the date
• 207 warmest minimum temperature for the month of July
• 123 warmest minimum temperature of all time

The number of warm minimum temperatures is especially disturbing, as these tend to have more of an impact on health than the high maximums. When the temperature remains high at night, it prevents the body from being able to recover from the day's heat. According to NOAA, from July 1 through July 19, there were 22 heat-related deaths in the United States. Reuters is reporting that 34 deaths resulted from this heat wave. In an average year, heat remains the number one weather-related killer in this country. In some ways, the overnight low temperatures are the best way to quantify a heat wave, possibly even better than the heat index.


Figure 1. Map of daily high maximum temperature records for the period July 1 through July 25 from NCDC. Red circles without an X denote a broken record; red circles with an X denote a tied record.

Tropical Overview

The wave formerly known as Invest 90L

The wave formerly known as Invest 90L is moving slowly west through the Caribbean near Jamaica. A new burst of convection started this morning, which will undoubtedly produce some heavy rain over southern Cuba and Jamaica. While low-level circulation has remained about the same since late last week, the wave has become top-heavy with increased circulation at higher levels (700-500mb). None of the models (GFS, ECMWF, CMC, NGPS, UKMET) are developing this wave as tracks into the Gulf of Mexico, and they're all in agreement that the path will be toward far southern Texas or northern Mexico, except for the ECMWF deterministic run, which hints that it will take a turn toward the northern Gulf. However, this model hasn't shown actual development from the wave since Tuesday or Wednesday of last week.

NHC has dropped this invest as of Saturday afternoon, but it remains on their radar. They're giving the wave a 0% chance to form over the next 48 hours. Given the recent uptick in mid-level circulation, I'd imagine they're still a little concerned about the potential for this wave to fire-up again once it's in the Gulf, and it will surely be of concern for Cuba as it tracks westward. However, given the lack of model support for almost 7 days in a row now, I'd say this wave has seen its glory come and go.


Figure 2. Visible tropical Atlantic satellite captured at 11:14am EDT on Monday.

Other North Atlantic waves

There are a couple other waves to speak of that have left the coast of Africa in the past few days, one located near 40W and the other closer to Africa, around 30W, which is tangled up in the monsoon trough. The former is expected to take a southerly track, skirting northern South America, and possibly into the Bay of Campeche. Given this track, none of the models are suggesting it will develop. However, tropical cyclones that spin up in the Bay of Campeche generally have a short forecast lead time, so it's something to watch. The latter wave could take a slightly more northern track through the Caribbean islands, and a couple of the models seem to favor this wave for development at the end of their runs.

Tropical wave activity has been lacking so far this season, but climatologically we should see an increase in African easterly waves in August and September.

Angela

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Quoting Tazmanian:



you mean 2007 lol
Ok. You are correct.
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personally taking an old school/old timer approach to this season...watching critters and bugs and the leaves on the trees
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Quoting stormwatcherCI:
So did Dean and Felix in 2008.



you mean 2007 lol
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Quoting stormpetrol:
90L has slowed almost to crawl compared to even yesterday, more time to fester!
Steering currents are weakening.
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Quoting Tazmanian:
do you re call Iavn in 2004 well it fromed at low latitude
So did Dean and Felix in 2008.
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Quoting AtHomeInTX:


The end of that run takes it strait west into Mexico. But at least it tried to swing some precip toward the Texas coast.
I believe the wave made a northward jog the past few hours...
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90L has slowed almost to crawl compared to even yesterday, more time to fester!
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49. JRRP


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Quoting DestinJeff:


Is that the 2TWO?

Don't be mad. Not worth the energy.


I won't get mad, in reality I'll keep an eye on it either way, but I don't want possible effected areas to be taken off guard by a "deactivated" invest that still seems to have potential to be destructive.
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Quoting angelafritz:


Bold predictions, both from the model and the forecaster, are how we advance the forecast lead-time for TC development! It's the "wave" of the future. ;)


Thanks for the update, "Wave" of the future, bold models with bold forecasters nice; going old school with new technoligy.
Member Since: August 23, 2008 Posts: 0 Comments: 1918
10-20% at 2pm imo.
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It's getting sooo hot down here in swfl wouldent mind a 90L type system to invigorate the garden.. What's with the Nam model? anyone think Texas could get some much needed rain? TIA
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do you re call Iavn in 2004 well it fromed at low latitude
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hey ya petrol...former 90L still looks like it has a bit of embers left from that fire it had a few days ago by the pic u posted
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Quoting prcane4you:

Too low latitude.


Oh ok. Thanks. :)
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Link

Rain coming down on the South Side of Grand Cayman
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IMO, 0% at 2.
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Quoting AtHomeInTX:


Do you think this will be an invest soon? Looks good.
Too low latitude.
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10% on the 2pm TWO or I'll be mad. Wouldn't be surprised if it was 20-30%.
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Quoting hydrus:
NAM at 60 hours..


The end of that run takes it strait west into Mexico. But at least it tried to swing some precip toward the Texas coast.
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Quoting Neapolitan:
"Generally quiet tropics" are good. Right?
Amen..
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"Generally quiet tropics" are good. Right?
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Quoting TropicalAnalystwx13:
Thanks for the update. However, I don't think it would be wise to make such a bold prediction such as saying a wave will skirt South American and enter the BOC when it is still in the Eastern Atlantic.


It's better than just the usual "No reliable models predict TC formation the next 7 days." It's nice to see a real met to go out on a limb and give their long range forecast.
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Quoting hydrus:
NAM at 60 hours..


Love that!!
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Quoting JLPR2:
We have a Floater on the 33W Wave courtesy of Ramsdis.



Thank you for the update Angela!
Here we go again.A good looking one.
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Oh ye of little faith!
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Quoting JLPR2:
We have a Floater on the 33W Wave courtesy of Ramsdis.



Thank you for the update Angela!


Do you think this will be an invest soon? Looks good.
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Quoting TropicalAnalystwx13:
Thanks for the update. However, I don't think it would be wise to make such a bold prediction such as saying a wave will skirt South American and enter the BOC when it is still in the Eastern Atlantic.


Expected and possibly are certainly not"bold" predictions. Just my interpretation.

The former is expected to take a southerly track, skirting northern South America, and possibly into the Bay of Campeche.

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Quoting angelafritz:


Bold predictions, both from the model and the forecaster, are how we advance the forecast lead-time for TC development! It's the "wave" of the future. ;)


You've got a point there.
Member Since: July 6, 2010 Posts: 113 Comments: 32267
Quoting DestinJeff:


Levi is in AK ... nowhere near East Aftrica.


LOL.
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Quoting lordhuracan01:
who is angela?


She's filling in for Dr. Masters while he is on vacation.

Link
Member Since: July 6, 2010 Posts: 113 Comments: 32267
12. JLPR2 9:52 AM PDT on July 25, 2011 Hide this comment.
We have a Floater on the 33W Wave courtesy of Ramsdis


91L may not be far behid then
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20. angelafritz (Admin)
Quoting TropicalAnalystwx13:
Thanks for the update. However, I don't think it would be wise to make such a bold prediction such as saying a wave will skirt South American and enter the BOC when it is still in the Eastern Atlantic.


Bold predictions, both from the model and the forecaster, are how we advance the forecast lead-time for TC development! It's the "wave" of the future. ;)
Thank you Angela. Not sure I like this steering pattern setting up. It may come to a point when Texas can't avoid being hit. Of course we have a long time to go and things change. Timing's everything!
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Quoting CybrTeddy:
Tropical wave activity has been lacking so far this season, but climatologically we should see an increase in African easterly waves in August and September.

Really? If anything it seemed above normal to me. Maybe Levi could give some clarification if he's out there.
Lacking? Completely wrong.
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who is angela?
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NAM at 60 hours..
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getting that comma look
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We have a Floater on the 33W Wave courtesy of Ramsdis.



Thank you for the update Angela!
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Thanks for the update Angela. A very complete and concise overview of the tropics, something this blog has been missing lately!
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There's a hint of rotation on the east side of 90L, but it could be an illusion created by the burst of convection.

Even so, I don't see how the NHC can keep it at 'near 0%'. I'd say 20% at 2pm. But, if it starts to develop, it could do so very quickly and be a hurricane by the time it gets into the GOM, given the heat in the water there. Land interaction will be a problem for it, though.
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Member Since: July 3, 2005 Posts: 426 Comments: 128645
Thanks for the update. However, I don't think it would be wise to make such a bold prediction such as saying a wave will skirt South American and enter the BOC when it is still in the Eastern Atlantic.
Member Since: July 6, 2010 Posts: 113 Comments: 32267
Tropical wave activity has been lacking so far this season, but climatologically we should see an increase in African easterly waves in August and September.

Really? If anything it seemed above normal to me. Maybe Levi could give some clarification if he's out there.
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Jeff co-founded the Weather Underground in 1995 while working on his Ph.D. He flew with the NOAA Hurricane Hunters from 1986-1990.