A heat wave recap; generally quiet tropics
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
Reader Comments
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It just comes screaming out of the gate.
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.
We can have TD today
Mornin Frank!!
This is not a wave signature. This is a TD signature.
The NWS office in New Orleans said they are considering flash flood watches for all of the forecast area. Can you say goodbye to the drought?
Hope Texas can get some precip out of this and glad to hear you guys have gotten some rain. It is interesting to watch as it appears to finally be getting some legs under it....where is it 10% or have they dropped it already??
Hey Kori!
Good morning! I've about had it with 90L -- it had better make up its mind this time!
Seems most of the landfalls of 90L energy are from mex/tx border to tx/la border,from a blob of rain to possible tropical storm
Feeder Band.....................LOL
I've been reading your recent blogs on 90L and you have never been too bullish. Are you surprised at its resilience? I am. I pronounced it not worthy of further discussion yesterday.
Sir....Step away from the map.....slowly....keep your hands where we can see them....
The Don says he refuses to sleep with da fish's!
Well, one thing you learn in this field is to become conservative. Else, you will lose credibility amongst your peers.
But to answer your question, kind of. On one hand, I called several days ago for it to generate transient bursts of convection thanks to diffluent upper lows, convection that would allow it to thrive until it reached the western Caribbean. That has happened. So in that sense, I am not surprised, but the way the vorticity survived the Greater Antilles DID baffle me.
lmao
maybe time for an intervention...lol....he is suffering from acute onset wishcastaphelia..lol
If there are two things in this world I have a seething hatred for, it's teases (ala 90L) and systems that do the loop-de-loop. Grinds my gears. :P
LMFAO breathe man.....breathe....you watch...this thing is going to ramp up and be a fire breathing bohemeth in a couple days...
....or it might just sputter out too...lol
GN Frank....U got mail!!
Crowd goes wild!!
Interesting....on this browser I cannot see the fine print....is that the 0600??
Station 42056
NDBC
Location: 19.802N 84.857W
Conditions as of:
Tue, 26 Jul 2011 07:50:00 UTC
Winds: NE (40°) at 7.8 kt gusting to 7.8 kt
Significant Wave Height: 2.6 ft
Dominant Wave Period: 6 sec
Mean Wave Direction: E (91°)
Atmospheric Pressure: 29.88 in
Air Temperature: 83.8 F
Dew Point: 75.0 F
Water Temperature: 85.8 F
Viewing: 1701 - 1751
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