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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i wonder if doc has a username and comments on his own blog or convo and we dont know it yet
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I really like the live daily updates while the good Doc Masters is gone. These are much better than his "canned" blogs that he usually does while he is out.

Keep up the good work Angela... I appreciate it!

---

So what is the latest with 90L, gone, coming back??? Couldn't keep up with following it from last night thru today.
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Quoting P451:


July 25, 1900Z isn't old unless the time stamp is incorrect.

It's 38 minutes old.







Yeah it is old...the timestamps for each pass are at the bottom of the respective passes on the image in purple numbers. That pass you posted is from 02:50 UTC last night.



Current: (15:24UTC)

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I don't really see anything very impressive with 90L. Looks like any near term development would probably come from the eastern Atlantic.
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X-90L will probaly do as so many have done before, develop just before making landfall in Mexico or Texas.
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Quoting Buhdog:
That was very random and disturbing to say the least
things can happen so fast....
Member Since: September 27, 2007 Posts: 1 Comments: 20345
446. red0
Meanwhile in Fort Smith, Arkansas having broken the 1934 Dust Bowl record days ago this will be the 21st straight day over 100 degrees.
Those 90 degree highs for the midwest described in Dr. Masters blog sure sound nice right about now. Maybe I should move there. Oh wait...
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Quoting hcubed:


Was this "heat wave" ever mentioned this year?

"...FAIRBANKS — It’s Memorial Day weekend in Interior Alaska, so it must be time for another record-breaking heat wave.

One year after Fairbanks set a record high temperature of 82 degrees on May 27, 2010, temperatures soared to 85 degrees. The city wasn’t alone — Tanana, Bettles, Kaltag, Nenana, Eagle and Big Delta also saw record highs set last year replaced by new records Friday.

Fairbanks’ 85-degree mark was just five degrees shy of the all-time May record, set this date in 1947, and is the highest May temperature since May 11, 1995.

If you’re wondering what’s causing this warm weather, look up.

With more than 20 hours of daylight, the sun warms all levels of the atmosphere effectively, explained meteorologist Corey Bogel at the National Weather Service office in Fairbanks.

“We have a ridge of strong high pressure that’s across the Interior that’s accompanied by warm air aloft. With the strong solar heating we get this time of year ... we’re able to mix all this warm air around.”

Without a front of cooler air moving in from Outside, the sun has ample time to reheat the Interior each day..."

From the Fairbanks Daily News-Miner

Nothing to see here, it's just the sun...

Yeah, I had seen that. The fact is, Alaska, like most of the Arctic, has seen increasing numbers of heeat waves. For instance, Fairbanks' Northway Airport saw a record July high last year of 94; that record was broken again last week with a high of 97.
Member Since: November 8, 2009 Posts: 4 Comments: 13442
443. 7544
ex90l is popping up stroms all around but the spin u looking south of jamica isnt that a ull and thats why the nhc says not fav for develpment
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That was very random and disturbing to say the least
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Quoting DestinJeff:


Dewey, TampaTom, Super, anyone? Please... please...don't make me do it.
What did I say??? Do it, or not....:)
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Quoting hydrus:
Definitely some convection and rotation...And it does look much improved on satellite.

Better than yesterday.
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Quoting DestinJeff:


Dewey, TampaTom, Super, anyone? Please... please...don't make me do it.
sorry,.....
Member Since: September 27, 2007 Posts: 1 Comments: 20345
Quoting TampaSpin:



Ya you are correct after looking at it again.....it is currently in a very small pocket of lower shear.....but its very small.
Correct, but I'm thinking it kind of created the low pocket itself, through heating the upper troposphere with convection. If it continues to fire convection shear shouldn't be much of a problem in the short term.
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Post 432

I knew you could do it!

:)
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Quoting SouthDadeFish:
Tampa, that's at the fringes of the storm. Over the center shear is very low as you don't see any of the cirrus getting blown off. CIMSS products are pretty accurate...



Ya you are correct after looking at it again.....it is currently in a very small pocket of lower shear.....but its very small.
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Quoting P451:


Oh...my mistake.
It's cool, now you know ;~)
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Quoting TropicalAnalystwx13:


90L isn't being sheared, shear is low.




Sorry to disagree but, look at this and put it in motion..........the tops are being blowed right off from the West...

http://wwwghcc.msfc.nasa.gov/GOES/goeseastconus.h tml
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Quoting WeatherNerdPR:
Ex-90L looks WAY better.
Definitely some convection and rotation...And it does look much improved on satellite.
Member Since: September 27, 2007 Posts: 1 Comments: 20345
Quoting TampaSpin:




Much higher than that more like 30kts. LOOk at the loop!
Tampa, that's at the fringes of the storm. Over the center shear is very low as you don't see any of the cirrus getting blown off. CIMSS products are pretty accurate...
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There is shear to the north, and shear far to the west, but where 90L is and where it is headed, shear is low.
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On the KW radar at least I can see the northern coast of Cuba and what is coming off that island.

Jeff... just do it.
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it would be great if we could keep this system undercontrol and on a path smack dab in the middle of the texan coast that would get my attention
Member Since: September 11, 2010 Posts: 1 Comments: 4268
Quoting TampaSpin:




Much higher than that more like 30kts. LOOk at the loop!


90L isn't being sheared, shear is low.
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418. LBAR
So is the lack of waves related to the severe drought in The Horn of Africa (Sudan)?
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Quoting SouthDadeFish:
Very high shear of 5-10 knots??

Link




Much higher than that more like 30kts. LOOk at the loop!
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I went to the radar and KW is still down. I got to look at Miami radar, just to see if I will be able to swim tonight, and it really isn't the same. On the KW radar at least I can see the northern coast of Cuba and what is coming off that island. Wouldn't you know it, the first sign of sloppy weather, and the radar is off line. Figures:(
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Quoting TampaSpin:


MOre like 24hrs.........Shear is currently very high as you can see the tops being blowed off from the West. Shear is forecast to lower in 24-36 hrs. But, that can change too. Wait and see with a small percentage of development over the next 72hrs.
Very high shear of 5-10 knots??

Link
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Ex-90L looks WAY better.
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Quoting P451:


Yeah...just a little still. Gotta give this thing a look see in another 6 hours or so.

200/500/700/850:





MOre like 24hrs.........Shear is currently very high as you can see the tops being blowed off from the West. Shear is forecast to lower in 24-36 hrs. But, that can change too. Wait and see with a small percentage of development over the next 72hrs.
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Every time I try to click on a link to imagery, or for that matter, even when I go to any of the maps, models or imagery on the main WU site, My FF crashes. I lose every tab. I tried it on IE, and it does the same thing, but on IE it will crash only the tab involved. I'm missing all of these great links folks are posting, and have no idea what has happened. Can one of you computer geniuses out there give me a hand? (This has been going on for months, just haven't attempted to do anything about it.)
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Quoting P451:


July 25, 1900Z isn't old unless the time stamp is incorrect.

It's 38 minutes old.





The time stamp isn't the black at the top, it's the purple at the bottom. It's like 17 hours old.
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Quoting beell:


No worries. That's a southern hemisphere storm.
ahah
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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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