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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1706. scott39
I wonder if that is self sustaining convection with 90L?
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It's now 7:06amGMT.
And we can look forward to the exciting race deciding whether the 6amGMT ATCF report will be posted before 90L's ~11amGMT sunrise and the DiurnalMaximum which follows.
Member Since: August 21, 2007 Posts: 0 Comments: 4860
Hard to go to sleep watching one like this, because it's moving so FAST. It's by far the fastest development we've seen since last year.

It just comes screaming out of the gate.
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Quoting TampaSpin:


WOW! Vorticity has improved a great deal the last 3 hours!




But, still no Convergence! Gotta have the Convergence before 90L is a player!
It's called being behind the curve .... A LOT.

This thing looked like a skater hitting the ice, only it's not ice.
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WOW! Vorticity has improved a great deal the last 3 hours!




But, still no Convergence! Gotta have the Convergence before 90L is a player!
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aspectre "From its last reported center position of 19.2n79.8, 184degrees takes the center between Cancun and Cozumel to a QuintanaRoo landfall on the YucatanPeninsula."
1684 scott39 "You're right. If 90L stays at exactly 184 degrees and doesnt change any... it will go where you pointed out.
Mine is just a guess based on how often a wave can fluctuate in direction, and how crazy 90L has been.
"

Closer to an estimate than a guess. 90L's path over the most recently reported 18hours has shown a slight curvature evermore northward.
Just wanted folks to know where 184degrees was pointing.

Speaking of which, new ATCF numbers are overdue.
Member Since: August 21, 2007 Posts: 0 Comments: 4860
1692. scott39
I think 90L is slowing down even more
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The spin on Cuban radar is in the mid level
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As requested ...
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1689. scott39
Quoting alfabob:

Something even better Link
Thanks Saved
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1687. scott39
NHC Please put a floater on 90L.
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1686. scott39
Looks like 90L maybe starting to take advantage of some Dmax...right at the center.
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1684. scott39
Quoting aspectre:
1622 scott39 "90L is heading WNW at 184 degrees."
1624 muddertracker "Might 'shoot the gap'."
1625 scott39 "Yea, I dont see it touching the Yucatan."
1627 muddertracker "Me either...if anything, I think it might brush Cuba...}
1629 scott39 "I see it going over the very tip of West Cuba before going over the Yucatan. Its already at 19.5N"

From its last reported center position of 19.2n79.8, 184degrees takes the center between Cancun and Cozumel to a QuintanaRoo landfall on the YucatanPeninsula.
Copy&paste 19.2n79.8w-cun, 19.2n79.8-czm, gcm into the GreatCircleMapper for more info
Your right, If 90L stays at exactly 184 degrees and doesnt change any... it will go where you pointed out. Mine is just a guess based on how often a wave can fluctuate in direction, and how crazy 90L has been.
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RGEM (Regional GGEM/CMC) develops 90L.

48 hours down to 999mbs

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Quoting JrWeathermanFL:
Who thinks 90L will form?
Who thinks not?
I have been on the side of development since the beginning of 90L. Always thought it would take a few days for it to get going,but not his long. I still see it topping out as a moderate Tropical Storm, with landfall from S Texas to the LA border.....JMI !
Member Since: September 18, 2010 Posts: 0 Comments: 5243
Quoting alfabob:
And I believe it will shoot the gap, at the very least being on the edge of Cuban coastline; not going to inhibit it much though. Has been traveling W/WNW for a while now.
I just saw the model intensity not too long ago and it showed the SHIPS model having it as a 75 mph storm. Could that be true?
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Quoting scott39:
I think the NHC sees more land interaction with W Cuba instead of moving in the open NW Caribbean and then into wind shear once it reaches the GOM. I still think it has a shot. Its all going to be about forward speed and the timing of wind shear.
exactly!
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1622 scott39 "90L is heading WNW at 184 degrees."
1624 muddertracker "Might 'shoot the gap'."
1625 scott39 "Yea, I dont see it touching the Yucatan."
1627 muddertracker "Me either...if anything, I think it might brush Cuba...}
1629 scott39 "I see it going over the very tip of West Cuba before going over the Yucatan. Its already at 19.5N"

From its last reported center position of 19.2n79.8, a heading of 184degrees takes the center between Cancun and Cozumel to a QuintanaRoo landfall on the YucatanPeninsula.
Copy&paste 19.2n79.8w-cun, 19.2n79.8-czm, gcm into the GreatCircleMapper for more info
Member Since: August 21, 2007 Posts: 0 Comments: 4860
Quoting traumaboyy:
Morning night shift!! Coffee is ready!!


Have a good night trauma. Hate to bail but I guess I oughta try for a couple hours. :)
Member Since: August 24, 2010 Posts: 0 Comments: 253
Quoting Patrap:
Multiplatform Satellite Surface Wind Analysis

Time of Latest Image: 201107260000
what exactly does this chart imply?
Member Since: September 18, 2010 Posts: 0 Comments: 5243
1673. scott39
I think the NHC sees more land interaction with W Cuba instead of moving in the open NW Caribbean and then into wind shear once it reaches the GOM. I still think it has a shot. Its all going to be about forward speed and the timing of wind shear.
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Quoting jasonweatherman2011:
That looks pretty impressive on the close up. I believe the NHC is really smoking on something. It should be 30% by the next advisory. HOPEFULLY!
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Quoting muddertracker:
No love for 90l...I'm off...have a good evening everyone.


The Rodney Dangerfield of the Atlantic basin! LOL. Night everyone. :) Don't be surprised if I show back up later. :)
Member Since: August 24, 2010 Posts: 0 Comments: 253
20%
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10%
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Quoting scott39:
It is... The last 6 hours is the slowest it has moved...14.6mph
Yeah cuz at once it was moving at 20 mph. I saw definetly hardly no shear for thursday maybe 5-10knts the most.
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Quoting KoritheMan:


My point was that, regardless of the wavelength of the respective impulses, yesterday's models pointed toward the ridge being weakest at 500 mb. As a rule, a deeper vortex tends to travel more poleward, as the Bermuda/Azores high is typically weaker at the mid levels than the lower ones, hence why weaker systems tend to travel westward within the lower tropospheric flow despite the mid-level flow being weaker.

Basically, right now, I don't think 90L has a deep enough vortex to go significantly northward, though depending on how long this weakness hangs around, it could assuming the vortex gains some vertical integrity while traversing the Gulf.
Vertical Integrity WooooooooDoggggies I like that!
Member Since: September 18, 2010 Posts: 0 Comments: 5243
FWIW CMC takes the 850 vort into South Texas. Not developed and faint. Looks like maybe some part of Texas will get this whatever it may be.

Member Since: August 24, 2010 Posts: 0 Comments: 253
Quoting muddertracker:

It seems to be moving about 10/12 right now? (guess)?
true u right but the wind shear i saw on the front page of wunderground shows that the shear is decreasing by the day after wednesday. we shall see.
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Morning night shift!! Coffee is ready!!
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No love for 90l...I'm off...have a good evening everyone.
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1656. scott39
NHC doesnt like what they see in the GOM for developement.
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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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