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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Quoting Saltydogbwi1:


just a light sprinkle here in savannah winds calm had a good shower earlier but it didnt last very long
We had a severe downpour up here. Loss of power and internet was knocked out at the post office.
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Quoting CybrTeddy:
IMO 90L will be at 0% at 8pm, 'maybe' 10% at 2am if it sustains convection and has a sudden burst of convection but right now it looks likely that 90L will not develop into a tropical cyclone.


You really don't like this system, do you? Ever since the beginning, you've said it won't develop. Maybe you'll be right.
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Wrote a blog on our Tropical Waves!

Please feel free to check it out
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Dont know what the hell is going on, but pressures are dropping everywhere, may have a big giant on our hands in coming days...to be continued, back on tomm AM
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the funny thing about IE vs firefox etc...i have no problem opening anything from anyone that posts using IE...only the other ones...something not compatable with all the other systems...IE is the only one i can use as it is what we have to use for business...
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Quoting TropicalAnalystwx13:


Pressure is expected to fall at this time in the evening. Doesn't say much about the organization of ex-90L.


I'm aware of that, but instead of falling anymore it should be steady or rising, pressures are alot lower in the western caribbean than they were a day or 2 ago.
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Quoting cloudburst2011:
in the big easy athome..


Ah. Ok. Y'all have the opposite problem than us. Hope y'all dry out some soon.
Member Since: August 24, 2010 Posts: 0 Comments: 459
IMO it should never have been below 10%. For the 8pm TWO I'll go with 10%, but wouldn't be surprised to see 20% if it keeps on track the next hour.
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IMO 90L will be at 0% at 8pm, 'maybe' 10% at 2am if it sustains convection and has a sudden burst of convection but right now it looks likely that 90L will not develop into a tropical cyclone.
Member Since: July 8, 2005 Posts: 259 Comments: 23009
Quoting JRRP:
12z... TW near 30w

18z.... no TW near 30w

not surprised.
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90L will be held at Near 0% at 8PM. However, if 90L gains more organization between TWO times, I believe it will be upped to 10% at 2AM.

That's my prediction.
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692. JRRP
12z... TW near 30w

18z.... no TW near 30w

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Quoting TropicalAnalystwx13:




Or...Instead of ignoring a perfectly good blogger, you could get Google Chrome or Firefox.
Will eventually go to FF, I guess, but trying not to do that with this elderly laptop. I'd really like to see the correction made at Wunderground, though.

Quoting Saltydogbwi1:


windows 7 64bit and 64bitIE9 have no issues at all that i have noticed I dont know what version your using though
So you are suggesting it might be a Windows problem rather than an IE problem? That actually could be the case; the IE has been updated fairly regularly, but the Windows is an older version....

Quoting druseljic:


There's no problem with folks that have Firefox or Chrome.

Only IE users are reporting the problem as you mentioned.

Try some of the new browsers and there should be no problem.
Lots of pple have been saying new browser, but I'm wondering now if it's an "underlying" problem.

BTW, thanks for all the advice. FWIW, ignoring PRwxcentre for a few days while I make some adjustments is IMO a reasonable solution. U guys know it's not a method of choice for me; my ignore list was virginal until a few minutes ago.....

I still think something should be done by WUnderAdmin to address the problem, since it seems to be code-related. Frankly, I'd prefer just a big X in those posts instead of the kind of disruption which means that I have to take such drastic measures....
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Quoting TropicalAnalystwx13:


Pressure is expected to fall at this time in the evening. Doesn't say much about the organization of ex-90L.
true, but it is falling more than the typical pressure cycles as indicated on the pressure graph



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I'm thinking 90L will be reactivated.
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686. JRRP
Quoting Abacosurf:
Near 0%. Then 20% at 2 AM if the convection holds or deepens....

+1
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Quoting j2008:
Quick poll
The Carrebean wave will be ________ @ 8Pm.
A. < 30%
B. 30% Reactivated 90L
C. 50% Reactivated 90L
D. > 50% Reactivated 90L possible TD #4


Don't normally do polls but this one seems to have gained some following.

I answer A...
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Hey guys, it's my birthday! Shocked to see 2 TDs in Pacific.
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Just a reminder where we were with 90 four days ago:
img src=
http://i508.photobucket.com/albums/s330/HCW2008/a 9ddc63e.jpg">

I can't find any pictures of (dare I say it? Don's! birthday).
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Quoting stormpetrol:
Station 42057
NDBC
Location: 17.003N 81.501W
Conditions as of:
Mon, 25 Jul 2011 20:50:00 UTC
Winds: E (90°) at 9.7 kt gusting to 11.7 kt
Significant Wave Height: 3.6 ft
Dominant Wave Period: 8 sec
Mean Wave Direction: E (91°)
Atmospheric Pressure: 29.83 in and falling
Air Temperature: 82.4 F
Dew Point: 77.0 F
Water Temperature: 84.6 F

Pressure is 1010mb at this buoy


Pressure is expected to fall at this time in the evening. Doesn't say much about the organization of ex-90L.
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680. JRRP
Quoting RitaEvac:
90L looks better now than at any previous moment

nop
was better when was east of antilles
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Quoting Tropicsweatherpr:


None of the above.

10%


but 10% would be <30% right? snicker snicker
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Quoting Tropicsweatherpr:


None of the above.

10%


That's A...
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Quoting Abacosurf:
Near 0%. Then 20% at 2 AM if the convection holds or deepens....


+1
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I believe in ya 90 (hehe). Deactivated but not quite dead. Give us something to talk about, keep the blog going.
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Station 42057
NDBC
Location: 17.003N 81.501W
Conditions as of:
Mon, 25 Jul 2011 20:50:00 UTC
Winds: E (90°) at 9.7 kt gusting to 11.7 kt
Significant Wave Height: 3.6 ft
Dominant Wave Period: 8 sec
Mean Wave Direction: E (91°)
Atmospheric Pressure: 29.83 in and falling
Air Temperature: 82.4 F
Dew Point: 77.0 F
Water Temperature: 84.6 F

Pressure is 1010mb at this buoy
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Quoting NICycloneChaser:


A.


None of the above.

10%
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Quoting j2008:
Quick poll
The Carrebean wave will be ________ @ 8Pm.
A. < 30%
B. 30% Reactivated 90L
C. 50% Reactivated 90L
D. > 50% Reactivated 90L possible TD #4
A
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Quoting stormpetrol:


About an hour ago , but for now its stopped


some good convection firing between us and little cayman/Brac

Link
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Quoting j2008:
Quick poll
The Carrebean wave will be ________ @ 8Pm.
A. < 30%
B. 30% Reactivated 90L
C. 50% Reactivated 90L
D. > 50% Reactivated 90L possible TD #4


A

I get my poll time at 7PM just so you know! (:
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Quoting j2008:
Quick poll
The Carrebean wave will be ________ @ 8Pm.
A. < 30%
B. 30% Reactivated 90L
C. 50% Reactivated 90L
D. > 50% Reactivated 90L possible TD #4
Near 0%. Then 20% at 2 AM if the convection holds or deepens....
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You're right she did. No wonder I'm still teaching Special Ed Kindergarten. As my kids say, "They won't promote her yet." *G* Sorry Angela!
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Quoting NICycloneChaser:


Regardless, you can't claim that land passage is going to help ex-90L.


It can, especially if it crosses the Yucatan Peninsula. The friction created when a system comes ashore here causes a system to grow in size, and can also help to develop a circulation. That is, if the system doesn't spend a lot of time. For example, when Alex made landfall last year on the Yucatan peninsula, a eye popped out shortly after. It is likely that Alex strengthened at first, but then, after spending nearly a day over the Peninsula, it weakened down to a TD.
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Quoting j2008:
Quick poll
The Carrebean wave will be ________ @ 8Pm.
A. < 30%
B. 30% Reactivated 90L
C. 50% Reactivated 90L
D. > 50% Reactivated 90L possible TD #4



40% at 2am
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Quoting j2008:
Quick poll
The Carrebean wave will be ________ @ 8Pm.
A. < 30%
B. 30% Reactivated 90L
C. 50% Reactivated 90L
D. > 50% Reactivated 90L possible TD #4


A.
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Quoting cloudburst2011:
at home they may have to issue a flash flood watch for tues and wed....we have had enough rain as i speak its storming with lightning and thunder here...


Ah. That's no fun. :( Where are you located? I got about 5 minutes of rain.
Member Since: August 24, 2010 Posts: 0 Comments: 459
i felt 6 raindrops on my arm while i waited with my niece at the tire shop for her to get a tire...
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662. j2008
Quick poll
The Carrebean wave will be ________ @ 8Pm.
A. < 30%
B. 30% Reactivated 90L
C. 50% Reactivated 90L
D. > 50% Reactivated 90L possible TD #4
Member Since: Posts: Comments:
Quoting superpete:
Stormpetrol-Are you seeing much rain/ wind down on south sound?


just a light sprinkle here in savannah winds calm had a good shower earlier but it didnt last very long
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Quoting superpete:
Stormpetrol-Are you seeing much rain/ wind down on south sound?


About an hour ago , but for now its stopped
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WAIT! I GOT SOME! LOL! :)
Member Since: August 24, 2010 Posts: 0 Comments: 459
Quoting TropicalAnalystwx13:


That's not true. As the case with 90L, if it were to go over land at this present time, how would land disrupt it more so than a hurricane with a well-defined circulation? As was the case with Bonnie, while not as developed as hurricanes, its circulation was well-defined, and land disrupted it severely.


Regardless, you can't claim that land passage is going to help ex-90L.
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Stormpetrol-Are you seeing much rain/ wind down on south sound?
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About JeffMasters

Jeff co-founded the Weather Underground in 1995 while working on his Ph.D. He flew with the NOAA Hurricane Hunters from 1986-1990.