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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It is unbelievably frustrating and disappointing for Texans to see Tampico get every single storm.. surprised Tampico hasn't been entirely washed away.

We need to print up brochures, with Erin and Hermine etc on the cover touting the tourist opportunities and have the HH drop them into blobs that say land here.. see the whole country in two weeks, maybe even Nova Scotia!
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Quoting Levi32:


Nope. I would love to go sometime and experience the weather (namely thunderstorms). The only thing I dread is the heat.
December or January would be the time for you to visit if you come... I know I find it strange to be colder in July and August when visiting WY, CO, or MT than I have ever been at home in the winter... I'm the only person walking through town in a coat, while everybody else is in short sleeves or bare-backed....
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The National Hurricane Center went conservative with the 8AM TWO. I'd give it 30% because ever since yesterday evening, convection has sustained itself right over 90L's MLC. With all that heat piling up, something will work down to the surface. If 90L clips the Yucatan peninsula, well, that's even better for 90L. The friction created would allow an LLC to get going if it didn't already have one.

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Wrong quote, sorry
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Yesterday:



Today:



And this isn't even a 24 hour difference. Much better organized.
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2151. Patrap
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Is there a reason why I can't open some of the posts in order to read them?
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Ull strengthening of east coast of FL
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Quoting RitaEvac:
LLC could be forming north of 20N


Yeah..I see that..sort of on the north east side of the main ball of convection?

LSU low cloud product:
Link
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Quoting Vincent4989:

North-east and East-northeast

I'm Sure u mean NW to WNW
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Good morning everyone.

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Quoting Vincent4989:

North-east and East-northeast
Umm, examine the directions one more time...
;-)
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Quoting Vincent4989:

North-east and East-northeast


LOL
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Quoting rmbjoe1954:


Say again...NE???

North-east and East-northeast
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Quoting Vincent4989:
WPAC is active, and Nock-Ten will pass DIRECTLY OVER US here.
That looks like, primarily, a flood threat if I ever saw one.
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Quoting rmbjoe1954:


Say again...NE???


The compass is reversed this morning
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WPAC is active, and Nock-Ten will pass DIRECTLY OVER US here.
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Oops.
;-)
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Quoting Vincent4989:
GFS and NAM shows that 90L move moves very very slowly to NE and ENE, make that one itsy bitsy tiny dot. Hmm.....


Say again...NE???
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We should see the NHC bump chances to a MEDIUM 30-40% chance at 2 p.m.
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Quoting farupnorth:


Pressures at closest buoys are rising
Diurnal cycles. Not too impressive nonetheless.
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GFS and NAM shows that 90L move moves very very slowly to NE and ENE, make that one itsy bitsy tiny dot. Hmm.....
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Quoting weatherh98:


when do we know thatits low level circulation on the vorticity
I'm not sure what you're asking exactly, but we know when it has a low-level circulation through a variety of possible methods. Recon is easiest way, or surface obs, and even convincing satellite imagery or an ASCAT pass. Vorticity does not necessarily mean a closed circulation, but generally the stronger it is, the greater the chances.
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Quoting MrstormX:


Methinks Gustav


Crap I meant Ida.
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Quoting farupnorth:


Pressures at closest buoys are rising

They were with bret at first too. Things can change quickly.
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This 90L is a fun system to watch. I would love for this to become a TC in the gulf just to see the models eat crow. If it does not then I will put a little more faith in them.
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LLC could be forming north of 20N
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Quoting EasttexasAggie:


Circulation is getting lower.

stronger sign of development.


Pressures at closest buoys are rising
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Quoting SouthDadeFish:
That's good for 90L. That means it's not mainly a mid level feature, but instead the vorticity is starting to work its way towards the surface. As the surface circulation forms and 90L develops (if it does) vorticity will work its way up to the mid levels as 90L strengthens.


when do we know thatits low level circulation on the vorticity
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Quoting weatherh98:
the strongest vorticity appears to be on the 850 mb... is that good, bad, or ugly development wise

Circulation is getting lower.

stronger sign of development.
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Quoting RukusBoondocks:
what a wimpy season so far.........trivia time... when was the last time a storm formed in the carribean and tracked north into the gulf instead of into mexico like they always do??


Methinks Gustav
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Quoting weatherh98:
the strongest vorticity appears to be on the 850 mb... is that good, bad, or ugly development wise
That's good for 90L. That means it's not mainly a mid level feature, but instead the vorticity is starting to work its way towards the surface. As the surface circulation forms and 90L develops (if it does) vorticity will work its way up to the mid levels as 90L strengthens.
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Quoting weatherh98:
the strongest vorticity appears to be on the 850 mb... is that good, bad, or ugly development wise

850 mb? maybe ugly development?
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Quoting muddertracker:
It's a start...it just has to work it's way down to the surface...what does the 700mb show?


about the same 500 gets more ragid and its hardly there at best on the200
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what a wimpy season so far.........trivia time... when was the last time a storm formed in the carribean and tracked north into the gulf instead of into mexico like they always do??
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.
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the strongest vorticity appears to be on the 850 mb... is that good, bad, or ugly development wise
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Quoting TampaSpin:
I wonder why a Floater is not on 90L yet? Dang!
dixiebreeze use to have the phone number to call
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2117. HarryMc
Quoting MrstormX:
Little ball of something going into South Texas.



Think that would be whatever is left of 90L
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Quoting atmoaggie:
Yeah, you guys are still missing out completely (well, almost completely). I do have a fan outside pointing NW...
(I am north of NOLA).
Thanks, keep it going! LOL If that La Nina comes back, I'm planting rocks!!
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2115. Patrap
Atlantic Big Pic, WV



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Over the 12hours spanning the 3 most recently reported ATCF numbers, 90L averaged a steady travel-speed of 18mph(29k/h). Which is too high a fraction of its max.sus.wind of 25knots(46.3k/h) to allow a quick spin up.
However a significant part of the energy contained within its travel-speed could become translated into spin if 90L's movement were reduced suddenly in a ForcedConvergence.

Straightline projection of its travel-speed&heading averaged over the most recently reported 6hours
would take 90L to a 27July~2:30amGMT landfall between Cancun and Cozumel, then into the Gulf of Mexico before the next DiurnalMaximum.

Copy&paste 17.4n70.1w, 17.8n72.1w, 18.1n73.8w, 18.4n75.5w, 18.6n77.0w-18.9n78.5w, 18.9n78.5w-19.2n79.8w, 19.2n79.8w-19.6n81.4w, 19.6n81.4w-20.0n83.0w, cun, czm, gcm into the GreatCircleMapper for more info

That crossing over the northern tip of the YucatanPeninsula into a DiurnalMaximum over very warm waters sounds suspiciously like a 'ForcedConvergence then RapidIntensification' scenario to me.


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Little ball of something going into South Texas.

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2112. Patrap
Models,,operational ones are only run on "Invest".

So the Global runs may show that but Im focused on 90L atm.

When and if that wave becomes a invest,Ill load the ATCF runs on it then.
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Quoting katzanddogz:
I don't know anything about 10inches of rain here just north of the Woodlands. We are still begging for rain. Got about half an inch yesterday but the area is still in very bad shape. Houston is looking to Lake Conroe for water now.
Yeah, you guys are still missing out completely (well, almost completely). I do have a fan outside pointing NW...
(I am north of NOLA).
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Patrap,
Do you have links to the latest models on that other wave behind 90L? The one that NGPS was picking up on when all the others dropped 90L a day or two ago?
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Quoting muddertracker:
There really isn't much going on at the surface with 90l...will that change soon?
There is more going on than yesterday, that's for sure. There is SW inflow now for the first time, and low level clouds on the west side appear that they are starting to turn and become more northerly. These are indicative of a developing surface circulation. It's not there yet, but it's trying.
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Quoting Levi32:


Nope. I would love to go sometime and experience the weather (namely thunderstorms). The only thing I dread is the heat.
Levi, you should apply for a student travel stipend to attend the AMS annual meeting in January, 2012 in NOLA. (Honestly, really could be done, but might be limited to upperclassmen...that sounds familiar.)

You could come down here for free (hopefully). And we could arrange a cold front to come through (with thunderstorms) and then drop the temperature all the way down to 45 F (for a low).
;-)
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I love rapid scan!
Thanks, Levi, for posting the link.
Link
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2106. Patrap
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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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