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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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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how many points dos 90L have for ATCF is i spelled that right
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1853. DDR
Good morning all,expecting one or 2 showers today again in Trinidad.The gfs is showing 3-5 inches by months end which would put us just below or on average in terms on rainfall.
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all so one thing i like tooo point out is 90L is a small compact storm this storm can spin up vary fast and i think we are starting too see that
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Well this should wake up the blog for today!
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1849. hydrus
I do believe 90L is feeling the weakness shown here..
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1848. GetReal


90L is in a good position for further development today... No doubt that it is becoming better organized. IMO a would give it a 40% chance of TC development.
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1847. hydrus
Quoting DoubleAction:
90L is going to take off today. The steering is WNW but if it ontinues to slow down it will be NW after today. Conditions will be favorable throughout it's life so no reason not to see a Cane from this one. Texas just might get some rain after all. Question will be how strong it gets and whether it tracks more north after 48 hours.
24 hour 300mb forecast chart. It would seem possible for a decent jog to the north before heading west.
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Quoting DestinJeff:
Told you so.

Good morning, everyone. Another day, another blogger.


Good morning Senior Chief!!




sorry, i miss that.

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Quoting MrstormX:


6z DGEX now showing a TS hitting Texas as well.


cool
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Quoting Tazmanian:



90L is getig strong fast


6z DGEX now showing a TS hitting Texas as well.
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CMC shows the moisture from 90L in the GOM, not organized though. 12z might initialize different.

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Quoting stormpetrol:
Station 42056
NDBC
Location: 19.802N 84.857W
Conditions as of:
Tue, 26 Jul 2011 10:50:00 UTC
Winds: at 0.0 kt gusting to 1.9 kt
Significant Wave Height: 2.3 ft
Dominant Wave Period: 6 sec
Mean Wave Direction: E (82�)
Atmospheric Pressure: 29.83 in and falling
Air Temperature: 83.3 F
Dew Point: 75.4 F
Water Temperature: 85.8 F1827. neutralenso 11:59 AM GMT on July 26, 2011 Hide this comment.
Does anyone have pressure reading currently where 90L is

This probably the closest , ithink that around 1010mb, i suspect 90L is 1008/1009mb



90L is getig strong fast
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1834. hydrus
Quoting stormwatcherCI:
That looks to me like one system in the central Caribbean and one NE of the northern Antilles. Please correct me if I am wrong.
Maybe...Could be part of the Caribbean wave too...
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things can get out of hand quickly nhc 80% of not developing? do they set the odds in las vegas good bet
Member Since: September 11, 2010 Posts: 1 Comments: 4602
90L is going to take off today. The steering is WNW but if it ontinues to slow down it will be NW after today. Conditions will be favorable throughout it's life so no reason not to see a Cane from this one. Texas just might get some rain after all. Question will be how strong it gets and whether it tracks more north after 48 hours.
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Station 42056
NDBC
Location: 19.802N 84.857W
Conditions as of:
Tue, 26 Jul 2011 10:50:00 UTC
Winds: at 0.0 kt gusting to 1.9 kt
Significant Wave Height: 2.3 ft
Dominant Wave Period: 6 sec
Mean Wave Direction: E (82)
Atmospheric Pressure: 29.83 in and falling
Air Temperature: 83.3 F
Dew Point: 75.4 F
Water Temperature: 85.8 F1827. neutralenso 11:59 AM GMT on July 26, 2011 Hide this comment.
Does anyone have pressure reading currently where 90L is

This probably the closest , ithink that around 1010mb, i suspect 90L is 1008/1009mb
Member Since: April 29, 2007 Posts: 0 Comments: 7862
I think they should put Recon in 90L this PM.jmo
Member Since: April 29, 2007 Posts: 0 Comments: 7862
Quoting hydrus:
The NAM has another strong system behind 90L. Here is the 84 hour loop...Link
That looks to me like one system in the central Caribbean and one NE of the northern Antilles. Please correct me if I am wrong.
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nhc said 80% chance 90l does not develop for 48hrs seems high
Member Since: September 11, 2010 Posts: 1 Comments: 4602
Link
Member Since: April 29, 2007 Posts: 0 Comments: 7862
am happy for 90L 90L today cat 5 next week
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I think 20N/82.5 is probably where the COC is forming or formed
Member Since: April 29, 2007 Posts: 0 Comments: 7862
90L rocks
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Quoting MrstormX:


2 comments to go btw



yup
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Quoting Tazmanian:



i help it heel up a little now its doing better


2 comments to go btw
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Quoting Saltydogbwi1:
stormwatcherci is it raining in east end yet?
All night and still :D
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Quoting stormpetrol:
Link

Look like most of the weather stations here in Grand Cayman is not working, this one in East End has winds out of the S/SSW. tells me a low level circulation is probably off to our WNW.
LOL. Airport is showing pressure is at 1059.9MB.
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Mostly exposed pho center becoming apparent on the high def vis loop,looks to be about 100 or so miles ssw of isle of youth,rendevous w/Yucatan likely,just north of Cancun area imo
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1815. hydrus
Quoting stormpetrol:
Link

Look like most of the weather stations here in Grand Cayman is not working, this one in East End has winds out of the S/SSW. tells me a low level circulation is probably off to our WNW.
The NAM has another strong system behind 90L. Here is the 84 hour loop...Link
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Quoting MrstormX:
Uhoh Taz, your RIP might have been premature after all. :)



i help it heel up a little now its doing better
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Uhoh Taz, your RIP might have been premature after all. :)
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this is the best 90L has evere look
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stormwatcherci is it raining in east end yet?
Member Since: October 21, 2009 Posts: 0 Comments: 362
90L sould be moveing overe the loop eddy
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Link

Look like most of the weather stations here in Grand Cayman is not working, this one in East End has winds out of the S/SSW. tells me a low level circulation is probably off to our WNW.
Member Since: April 29, 2007 Posts: 0 Comments: 7862
all so 90L has slow way down
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Quoting islander101010:
nhc is still not all that impressed
layoffs shuttle program bet the last ones to go are the garbage and f.b.i people watching them.
Member Since: September 11, 2010 Posts: 1 Comments: 4602

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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.