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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Check this out lates Vorticity has improved a lot watch out Cancun
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Atmospheric pressure is taking a dive near the Caymans with some higher Carribbean Sea surface waves building up almost perfectly in line with the center of convection.
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Quoting j2008:

NC, FL, and NY year. Especially if the high stays this way all season long.
Really not liking this high setup at all. Really REALLY makes it possible for just about anybody from FL to Maine, with emphasis on the part sticking out in the middle. Not to mention Greater Antilles, NE Lesser Antilles, Bahamas, Turks/Caicos, hey even East Coast Central America can get in the game in November... though less likely. Too many landfall possibilities with this high the way it is...
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802. j2008
Quoting washingtonian115:
That's becuase it sticks out into the Atlantic.So when storms recurve their outer bands will affect them.Cringes teeth.I was hoping for another peaceful year.if that pattern holds true that won't be happening.

Its gotta happen sometime I guess. We (the US) have been fairly safe these past few years, I guess our luck has run out if the high stays this strong.
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Quoting jasonweatherman2011:
WOW!!! WOW!!!! WOW!!
That's why I was watching africa.Conditions will also be favorable.
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Quoting TxHurricanedude11:
I love how some bloggers ask so many questions and I mean so many lol no offense.
questions are a good thing, that's how we learn
Member Since: August 24, 2010 Posts: 19 Comments: 4358
Quoting mcluvincane:


I agree, heck NC gets threatened every year it seems. Earl came real close last year. Why does so many go to NC

That's becuase it sticks out into the Atlantic.So when storms recurve their outer bands will affect them.
Quoting alfabob:

Everyone from Caribbean, Mexico, GOM, to the east coast is in the cross-hairs this year.
Quoting neutralenso:

Well the bad news for the US is the Bermuda high is supposed to be strong meaning more westerly tracks and also the Gulf ridge that shoved arlene into mexico is currently moving northeast and by the end of july and early august it should be up by new england. this will be a very dangerous pattern for the US
Cringes teeth.I was hoping for another peaceful year.if that pattern holds true that won't be happening.
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Quoting washingtonian115:
Looks like I'll be talk'in to myself.It makes me fell more comfterable.


I agree, heck NC gets threatened every year it seems. Earl came real close last year. Why does so many go to NC

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They say seeing is believing, and I'll believe 90L still has a chance if it keeps firing storms overnight...
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Quoting j2008:

NC, FL, and NY year. Especially if the high stays this way all season long.
Those waves from Africa need to be watched.This year reminds me of years like 08,07,04 where CV storms came all the way from Africa to the U.S.1998 is also a good exsample.
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790. beell
I suppose land interaction/higher terrain of Cuba has limited the disturbance's ability to work to the surface, The mid levels can maintain the wave circulation much easier at 8-10,000 ft.
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Quoting washingtonian115:
Looks like this year the high in the Atlantic is to strong to allow storms to recurve like they did last year.Damn....Could it be a North Carolina year?.We'll see.Most of the Analogs suggest it.
Looks like I'll be talk'in to myself.It makes me fell more comfterable.
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787. j2008
Quoting washingtonian115:
Looks like this year the high in the Atlantic is to strong to allow storms to recurve like they did last year.Damn....Could it be a North Carolina year?.We'll see.Most of the Analogs suggest it.

NC, FL, and NY year. Especially if the high stays this way all season long.
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786. xcool
lmaoo
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Quoting washingtonian115:
Hopefully our high pressure in the mid-section of the U.s stays strong enough to push most storms away from the U.S coast(no offense Mexico).
Looks like this year the high in the Atlantic is to strong to allow storms to recurve like they did last year.Damn....Could it be a North Carolina year?.We'll see.Most of the Analogs suggest it.
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Alright, time for the last leg of Monday. Back after work.
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Quoting Levi32:


I dislike giving out percents. I expect the wave to look better as it transverses the NW Caribbean, which I guess means that I expect more convection tomorrow.
Do you expect the convection to wane tonight?
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Quoting TomTaylor:
weeelll that's just the thing, I'm not so sure how much rain you will get.

I hate to sound like a pessimist but just because a vort max is heading your way, doesn't mean precipitation will be lol. On that same 18z run from the GFS it does show some rain for E Texas, but still not too much

Here's the 5 day precip accumulation




Bummer. Lol. No I appreciate the input. :)
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Station LCIY2
Integrated Coral Observing Network (ICON)
Location: 19.699N 80.061W
Conditions as of:
Mon, 25 Jul 2011 22:00:00 UTC
Winds: SE (130°) at 13.0 kt gusting to 20.0 kt
Atmospheric Pressure: 29.85 in and falling
Air Temperature: 82.9 F
Dew Point: 73.9 F
Water Temperature: 86.4 F
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Quoting TxHurricanedude11:
there is a chance it'll miss the yucatan
An excellent chance since we actually have no "it" to start with. This has never been more than a wave. I do think like Levi and others that if anything's gonna' become some sort of "it" IT needs to happen in the next 24 hours, 48 max. And on the other hand I'm staring at that goose egg from the NHC.
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Quoting scott39:
What % would you give on convection building after the sun goes down?


I dislike giving out percents. I expect the wave to look better as it transverses the NW Caribbean, which I guess means that I expect more convection tomorrow.
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Quoting TxHurricanedude11:
Its forecast to chance ouch!


Try to say things which can be understood.
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Air pressure does continue to plummet in the NW Caribbean, fast enough to muffle the diurnal cycles, which means things could still happen. It's not like pressures are 1014mb and staying there with no hope in sight.

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Quoting jasonweatherman2011:
hot water IN the GOM
Hopefully our high pressure in the mid-section of the U.s stays strong enough to push most storms away from the U.S coast(no offense Mexico).
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Quoting Levi32:
Our wave is also becoming intimately involved with the elongated upper trough across the NW Caribbean and SE Gulf of Mexico, which is why the cirrus clouds are streaming eastward on the southern side of the system. The cooler air aloft may be aiding shower activity. Afternoon convection firing nicely over the Yucatan and Cuba indicates a conditionally unstable atmosphere which could allow convection to continue to increase over the water with the tropical wave once the sun goes down. Realistically, upper-level conditions around the wave are not great, as subsidence aloft is impinging upon the southern Gulf of Mexico due to the great southern U.S. high pressure area. If our wave is to have a shot in the gulf, it needs to look very good in the NW Caribbean tomorrow. In other words, I think this will need to develop before leaving the Caribbean or it really is dead.
What % would you give on convection building after the sun goes down?
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Quoting islander101010:
if it dies out tonight crow taste alot like this ahi i had a few months ago almost gagged


I ate so much crow the last few seasons, they are starting to taste like good plate of lobster now, BTW I seen on Discovery a few weeks ago that the crows are the smartest bird on the wing , they are even more intelligent than monkeys according to the report!
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Quoting Levi32:
Our wave is also becoming intimately involved with the elongated upper trough across the NW Caribbean and SE Gulf of Mexico, which is why the cirrus clouds are streaming eastward on the southern side of the system. The cooler air aloft may be aiding shower activity. Afternoon convection firing nicely over the Yucatan and Cuba indicates a conditionally unstable atmosphere which could allow convection to continue to increase over the water with the tropical wave once the sun goes down. Realistically, upper-level conditions around the wave are not great, as subsidence aloft is impinging upon the southern Gulf of Mexico due to the great southern U.S. high pressure area. If our wave is to have a shot in the gulf, it needs to look very good in the NW Caribbean tomorrow. In other words, I think this will need to develop before leaving the Caribbean or it really is dead.
Yes, I'd have to agree. not much of a chance, realistically, but you never know.
Member Since: August 24, 2010 Posts: 19 Comments: 4358
Quoting Levi32:
Our wave is also becoming intimately involved with the elongated upper trough across the NW Caribbean and SE Gulf of Mexico, which is why the cirrus clouds are streaming ENE on the southern side of the system. The cooler air aloft may be aiding shower activity. Afternoon convection firing nicely over the Yucatan and Cuba indicates a conditionally unstable atmosphere which could allow convection to continue to increase over the water with the tropical wave once the sun goes down. Realistically, upper-level conditions around the wave are not great, as subsidence aloft is impinging upon the southern Gulf of Mexico due to the great southern U.S. high pressure area. If our wave is to have a shot in the gulf, it needs to look very good in the NW Caribbean tomorrow. In other words, I think this will need to develop before leaving the Caribbean or it really is dead.
I think land interaction has disruppted it enough to where it will take a while to get it's act together.I looking twards africa for the latest action.
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When does the first hurricane normaly form?
What about the average day over the past 5 years?
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Quoting AtHomeInTX:


Thanks Tom! Will gladly take the rain. :)
weeelll that's just the thing, I'm not so sure how much rain you will get.

I hate to sound like a pessimist but just because a vort max is heading your way, doesn't mean precipitation will be lol. On that same 18z run from the GFS it does show some rain for E Texas, but still not too much

Here's the 5 day precip accumulation


Member Since: August 24, 2010 Posts: 19 Comments: 4358
Our wave is also becoming intimately involved with the elongated upper trough across the NW Caribbean and SE Gulf of Mexico, which is why the cirrus clouds are streaming eastward on the southern side of the system. The cooler air aloft may be aiding shower activity. Afternoon convection firing nicely over the Yucatan and Cuba indicates a conditionally unstable atmosphere which could allow convection to continue to increase over the water with the tropical wave once the sun goes down. Realistically, upper-level conditions around the wave are not great, as subsidence aloft is impinging upon the southern Gulf of Mexico due to the great southern U.S. high pressure area. If our wave is to have a shot in the gulf, it needs to look very good in the NW Caribbean tomorrow. In other words, I think this will need to develop before leaving the Caribbean or it really is dead.
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Quoting aquak9:


We'll call it "Donster the Monster"


LOL! Love it. (Now to keep Donster the Monster going in circles in the Gulf)
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758. xcool
Soon, we'll find out at 8pm
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Quoting islander101010:
if it dies out tonight crow taste alot like this ahi i had a few months ago almost gagged
I think convection will die out tonight.
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Quoting washingtonian115:
The models also show favorable conditions previling in the way of the wave.Am I saing belive the models?.No.It's just something to monitor and track.
Even though 90L is showing some signs of trying to get it's act together I don't think It will be a Erin or Dolly situation as some Bloggers are suggesting.It's circulation will once again be dirupted when It hits the Yucatan.
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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.

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