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 DestinJeff:


XTRP also develops it into a straight line.

bbbbaaawwwaaaaaaaahhhh.....now that is funny!
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Quoting AllStar17:
The area of interest is to the NW of Jamaica. Convection is continuing to bubble there, which may aid in further development of ex-90L.
if it keeps firing tonight it might be able
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Quoting belizeit:
Link Check out this link they have just moved the floater but there is lots of turning visible .


Really looks like it trying to spin up. On another note,
HPC still sends the wave into TX/MX Friday. Could get interesting.

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Quoting DestinJeff:


XTRP also develops it into a straight line.



A true Forecaster is born.......your a genius!......ROFLMAO
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Quoting P451:


What we see on satellite must be mid level rotation.

That pass is old we don't have a recent ascat pass right now.
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The area of interest is to the NW of Jamaica. Convection is continuing to bubble there, which may aid in further development of ex-90L.
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I'm pretty sure if it does spin up in or close to the GOMEX the BAMM will take a bee line to New Orleans
Member Since: August 23, 2008 Posts: 0 Comments: 1918
Link Check out this link they have just moved the floater but there is lots of turning visible .
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Quoting beell:


No worries. That's a southern hemisphere storm.


Stoopid mirrored sunglasses! Had em on backards.
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Quoting P451:


What we see on satellite must be mid level rotation.



Well that is true if you look at Vorticity. There is only a small amount at the lower levels......but any amount at all at 850mb in those heated waters can spark a fire.
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Quoting DestinJeff:


XTRP also develops it into a straight line.


fascinating.
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Quoting wayfaringstranger:


or if it gives us the finger shape?


What about a yin-yang?
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Quoting TropicalAnalystwx13:


Very high odds for it just coming off the coast of Africa.


Ya i thought that might get some attention.....LOOKS like the first true Cape Verde storm might be coming.
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Quoting DestinJeff:
or I guess an "at" sign is more worrisome.


or if it gives us the finger shape?
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How say you Barbados, glad to see some one else is in Barbados paying attention to the same TW
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Quoting beell:


No worries. That's a southern hemisphere storm.


LOL!
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Quoting Seflhurricane:
tampa it appears we have something brewing to the NW of jamaica


Seems a surface low is attempting to form......Shear is a little high in the front...but, some shear models show very low shear as old 90L moves West. Have to give it 24hrs to really see what happens.
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Quoting PrivateIdaho:


When's the last time you didn't get rain Pat?


Been a spell now.

New Orleans, LA
Light Rain
77.1 °F
Light Rain Mist
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Quoting HurricaneHunterJoe:
True. But 2 models showing development Nam,Nogaps, and the Euro hinting at it.


NAM is not a tropical model.
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Quoting TxHurricanedude11:
this is no near 0% to me should've left it at 10%...remember bret i think it was 30% at 2 and then classified at 5 pm....consertative nhc



duded plzs give this a rest 90L is gone nhc poof it


invest_DEACTIVATE_al902011.ren
Member Since: May 21, 2006 Posts: 5091 Comments: 114728
376. beell
Quoting PcolaDan:


This is when I get really worried.



No worries. That's a southern hemisphere storm.
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convection is continues to build
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Quoting P451:
Surface obs of no real help right now.



tell me about it nothing near by but something is cranking up there
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Quoting TampaSpin:


Very high odds for it just coming off the coast of Africa.
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Quoting TampaSpin:
tampa it appears we have something brewing to the NW of jamaica
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Quoting FLdewey:
As long as it's not a schwa symbol I think we're okay.


This is when I get really worried.

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Quoting CybrTeddy:
the NOGAPS developing storms aint saying much..
True. But 2 models showing development Nam,Nogaps, and the Euro hinting at it.
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Hey, nice writeup, Ange.... KUTGW!!!!

Afternoon, everybody. Just got back in, and boy is A/C wonderful! It feels even hotter out there today than yesterday; even the breezes in the shade are hot today! So far we've had no showers today from the Twave passing to our south.
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A giant Zero with a pin hole eye
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Quoting Patrap:


When's the last time you didn't get rain Pat?
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Quoting NavarreMark:
The group of clouds formerly known as 90L has gone from a definite comma shape to an obscure question mark shape. If this keeps up, we may get a zero shape.


Could be just (
Member Since: August 23, 2008 Posts: 0 Comments: 1918
358. beell
181 of 200 sites in service.

NWS Level III Radar Site Status as of Mon Jul 25 19:09:59 UTC 2011
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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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