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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poll time

what will 90L be at 2pm


A 30%

B 40%

C 50%

D higher

E the chart
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1905. hydrus
Quoting Tazmanian:



under the t-storms i think
Should strengthen then..
Member Since: September 27, 2007 Posts: 1 Comments: 20332
in reality the nhc is not giving 90L much of a chance to do anything but stay at blob status are maybe blob1
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1900. hydrus
The western edge of the Bermuda High will weaken in a week according to the GFS..Link
Member Since: September 27, 2007 Posts: 1 Comments: 20332
Quoting Neapolitan:
Pressure dropping:

AL, 90, 2011072612, , BEST, 0, 200N, 830W, 25, 1010, DB, 34, NEQ, 0, 0, 0, 0, 1011, 110, 75, 0, 0, L, 0, , 0, 0, INVEST, M,


i see at lest 30 to 50% comeing at the next two
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After looking at this mornings convection and satellite appearance, I would say Don is on the way. All interests along the western and NW gulf coast should keep an eye on this system as conditions are becoming more favorable.
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Quoting hydrus:
Can anyone find a center of circulation in there?



under the t-storms i think
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Quoting FLdewey:

For some reason the opening of Super Troopers just popped into my head...

Mother of God...
90L tastes like snozzberries? Morning peeps!
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Pressure dropping:

AL, 90, 2011072612, , BEST, 0, 200N, 830W, 25, 1010, DB, 34, NEQ, 0, 0, 0, 0, 1011, 110, 75, 0, 0, L, 0, , 0, 0, INVEST, M,
Member Since: November 8, 2009 Posts: 4 Comments: 13442
Quoting Tazmanian:
90L sorry best i can do



No problem Thanks
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451 dot loop please i remember seeing a few dots near the texan coast but am not sure about the nw carib.
Member Since: September 11, 2010 Posts: 1 Comments: 4266
Aint that nice.

Link

Link
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1885. hydrus
Can anyone find a center of circulation in there?
Member Since: September 27, 2007 Posts: 1 Comments: 20332
Man reading this blog first I thought thier was a camille headed for the coast lol.Well Im glad i read the Nhc centers forecast what a relief lol.Well correct me if I'am wrong; but does 20 percent mean 1 in 5 chance?From what i read you would have thought it was 80 percent chance.Oh well you folks that think 20 percent is a sure thing I will play the 80 percent odds with you at the poker table at Harrahs lol.Well seriously this could develop but its probably NE mexico bound.Im sorry but to me the pattern remains the same.and if it develops where they think, and it indeed hits the yuc it will be a struggeler at best.But watch Cloud Top come on later and say a major headed for Lousina lol.Now thats 100% probability.
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90L sorry best i can do

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NHC should put up a Floater on 90L, it deserves one now!
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1874. Jax82
Given the warm SST's and the TCHP (currently over a high amount) it should help 90L get more organized, and add in lower forecasted wind shear it will be interesting to watch. Anyone have an MJO map? I thought we were in the downward phase right now in this part of the world.


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Quoting Tazmanian:



90L is looking better and better and better


Through me a picture or something Taz I just got on this morning Thanks
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Quoting BobinTampa:



"90L looks a lot better than (name of storm) back in (year of storm). I can't believe the NHC hasn't upgraded this yet!!"



they will this give them time
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i think 90L is going under a RI
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Quoting CaicosRetiredSailor:





90L is looking better and better and better
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Quoting FLdewey:
Is this beast up to cat 4 yet or is it still just a thunderstorm with wings?



"90L looks a lot better than (name of storm) back in (year of storm). I can't believe the NHC hasn't upgraded this yet!!"
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Quoting CaicosRetiredSailor:




Has that look!!
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1865. Matt74
Quoting DestinJeff:
1858 ..

That is for a system with greater than 1000mb central pressure, which is 90L for now I think around 1010 or something (haven't looked).

Anyway, yes, it is for a weak system.
Ok Thanks
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such a small system. we need to guide 90 right smack dab in the middle of this texan drought.
Member Since: September 11, 2010 Posts: 1 Comments: 4266
1861. hydrus
Wave train looks similar to 1980 like Levi32 mentioned in his update..
Member Since: September 27, 2007 Posts: 1 Comments: 20332
Good morning, everyone. I see 90L appears to have organized itself a bit last night.
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1858. Matt74
Quoting DestinJeff:
Here is current steering layer, but whenever I try and predict what will happen I am wrong.

Jeff, would that be for a weaker system?
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1857. hydrus
48 hour favorable conditions forecast chart..
Member Since: September 27, 2007 Posts: 1 Comments: 20332
1856. Stats56
Quoting DestinJeff:
850 vort does appear to have decreased a bit on CIMMS product from 0600 to 0900.

I will spare you the map.


Are you a member of the "90L cult" now? ;)
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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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