The Northeast Heatwave

By: Dr. Jeff Masters , 9:08 AM GMT on July 07, 2010

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Hi, Dr. Rob Carver, filling in for Jeff while he's on vacation.

The most significant weather event in the US on July 6, 2010 didn't show up on any radar. The geostationary satellites didn't see it in their constant watch over the Earth's atmosphere. Instead, the tale of this event was told by the thermometers, because the heatwave in the Northeast was the most significant event for July 6, and it will likely be the most important weather story for July 7.

The heat wave covers Pennsylvania to Maine, but Tuesday's worst was centered over New York City. All six of the stations used by the New York NWS office for climate reports (Central Park, La Guardia, JFK, Islip, Bridgeport, and Newark) set or tied the daily high temperature record. Newark and Central Park both reached 103 degrees F.

How unusual is this heat wave?
Figures 1 and 2 show how warm the highs and lows are compared to 30 year averages. Unless you were at the Great Lakes, the Midwest and Northeast have highs well above normal, with 10-15+ degree F differences over the coastal cities of the Northeast. Using my gridded temperature data, the low for New York City was 6 degrees F above normal, which should happen 30% of the time (1.1 standard deviations away from normal). The high was roughly 20 degrees above normal, which should happen only 0.29% of the time (3.04 standard deviations away from normal). This is an unusually strong heat wave.

Why it's hot
Basically, it's because there is "the Bull of a high pressure ridge [over the NE US]" to quote the Mount Holly NWS office forecast discussion. The large ridge of high pressure is forcing air to slowly descend across the Northeast, preventing clouds from forming. Without no clouds and plenty of daylight, the Sun heats the ground which then heats the air.

When will it cool down?
That's an excellent question. A trough of low pressure off the coast will bring onshore winds to the Tri-State area and MA by Thursday, so they should cool down a bit. The southern part of the heat wave, DC and Philadelphia, will have to wait for a cold front to arrive from the Great Lakes sometime Saturday to get relief.

Population affected
As Figure 3 shows, heat advisories covered most of the urban areas of the northeastern US. By my calculations, over 32 million people were under a heat advisory. Different offices have different guidelines for heat advisories. The NWS office responsible for New York issues a heat advisory if the heat index will be above 95 deg. F for two or more days or if the index will be above 100 deg. F for any length of time.


Fig.1 Plot of the difference between maximum temperature (the high for the day) and average maximum temperature in degrees F for July 6.


Fig.2 Plot of the difference between minimum temperature (the low for the day) and average minimum temperature in degrees F for July 6.


Fig.3 Plot of the active heat advisories across the northeastern US for July 6.

Heatwave impacts
The predominant impact from heat waves is increased mortality. CDC estimates that over 8,000 people died during heat waves from 1979 to 2003. That's more than all of the deaths due to lightning, flooding, tornadoes, hurricanes, and earthquakes. The elderly, sick, poor, and very young face the worst of the effects of the heat. Wikipedia has an interesting article describing the Chicago Heat Wave of 1995, a modern heat wave with a large number of fatalities due to the heat.

Heatwave coping strategies
The Centers for Disease Control have some tips for dealing with the heat. In summary, drink plenty of water, spend time in air-conditioned buildings, and wear light-colored clothing.

Is this heat wave due to global warming?
Ah, the $64,000 question. In the absence of detailed analysis, it's hard to specify the exact cause for this heat wave, from a meteorological or climatological view point. However, events like this are consistent with research showing that heat waves are more likely with
global warming
. I like the metaphor of loaded dice, global warming is not specifically responsible for any heat wave, but it will make them happen more often.

Tropics
My thinking on Invest 96L is unchanged from this blog entry. In summary, I believe that 96L has a <50 % chance becoming a tropical cyclone before it makes landfall. If it does so, it will likely be near the coast when that happens. In any event though, the winds and waves it generates will likely disrupt oil spill recovery efforts. Also, I would expect a broad area of showers and 20+ mph winds will affect the Gulf coast somewhere from south Texas to Louisiana.

Next update
I'll have an update this afternoon to talk about the tropics.

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just a trace of rain in Corpus so far.
Houston looked like it got some heavy rain earlier on the radar
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1386. Levi32
Quoting StSimonsIslandGAGuy:
Gustav took 24 hours, not 18. So did Ida. Lorenzo did do it in 18. That's from looking at the wunderground tropical history database.

However, I still believe that 96L becoming a hurricane is very unlikely.


Nearly impossible, I would go so far as to say.
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I'll say with the winds I suspect 96L are packing they might well go straight to TS status.This is much more potent system at this stage than Alex was imo.
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overreacting how?

by saying this has a high chance to be a TD or weak TS before landfall?

Where are the CAT 4 predictions? how is this overreacting? seriously
Member Since: March 10, 2010 Posts: 1 Comments: 7874
1383. IKE
My prediction was 50% and that's being generous.
Member Since: June 9, 2005 Posts: 23 Comments: 37860
Quoting IKE:
If this is 70% I'm either blind or an idiot or both....

You see disorganization, I see progress.
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Quoting CybrTeddy:


Actually ever since 2007 they've happened every season.

1) Humberto of course.
2) Lorenzo 2007 although was a TD for a while, when it got TS status it became a Hurricane a few hours later.
3) Gustav tied Humberto from TD to Hurricane in 18 hours.
4) Ida also did it in under 24 hours in 2009.


Indeed, rapid intensification is certainly possible at times, and these days, concerningly common. But I don't think the conditions support it here. Not to mention that storms this year have been trying to spin up the entire GOM. :P That doesn't happen quickly.
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I give it 60% Mr. 09
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Quoting IKE:
If this is 70% I'm either blind or an idiot or both....



amen... people are reallly overreacting
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1377. IKE
If this is 70% I'm either blind or an idiot or both....



Member Since: June 9, 2005 Posts: 23 Comments: 37860
Quoting NRAamy:
1326. Dakster 4:36 PM PDT on July 07, 2010

Are we getting a red alert for the 8pm??



a red shower curtain-speedo alert...

-wig and dress alert
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Quoting PtownBryan:
I missed the cutoff time but I am going with 70%!
Since it hasn't come in yet I'll add you in.
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1374. Becca36
Quoting TxMarc71:
It's always sureal (neat in a way) that with tropical weather it can be raining as hard as it can possibly rain... with virtually no thunder and lightning..


I've always marveled at that as well.
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1373. bakers
96L HAS POOR BANDING FEATURES AND WILL NOT DEVELOPE. CONVECTION IS ALREADY DECREASING.
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I missed the cutoff time but I am going with 70%!
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Quoting CybrTeddy:


Actually ever since 2007 they've happened every season.

1) Humberto of course.
2) Lorenzo 2007 although was a TD for a while, when it got TS status it became a Hurricane a few hours later.
3) Gustav tied Humberto from TD to Hurricane in 18 hours.
4) Ida also did it in under 24 hours in 2009.


Alex went from a TD to a 65mph storm in about 24 hours as well
Member Since: March 10, 2010 Posts: 1 Comments: 7874
Hi - so at this point in the location of the invest, barring any major surprises, are the statistical odds pretty high we know where a system will make landfall? (ie.. in this case, N MX/S TX)>? I recall someone saying there is a window of time where we become more certain of the path but I don't recall what that window of time is.
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Quoting KoritheMan:


I don't know, but the NHC isn't presently identifying it as a tropical wave.


Ahhh - forgot to look at the surface analysis. Good point.
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1367. NRAamy
you know I love you, Dak...


;)
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What is the worst Corpus Christi might expect from 96? I realize there are several possibilities,just want thoughts on it.
I boarded up for Alex as a precautionary and havent removed them all just yet.
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it will be inland in the morning before it has a chance to form into a TD . NEXT !!
Member Since: January 24, 2010 Posts: 0 Comments: 529
Quoting CanesfanatUT:
I got a quick non 96L questions - on the voricity map, the strong rotation over around 25W and 10N is that ball of convection that left Africa yesterday afternoon???

If so - looks like it's kept it's rotation.

Thanks.


I don't know, but the NHC isn't presently identifying it as a tropical wave.
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Quoting StSimonsIslandGAGuy:
I think 96L will become a tropical depression, and maybe a weak storm before landfall.

I am glad we did not have another strong hurricane like Alex form. I suppose a hurricane is still possible, but Humberto-style intensifications don't happen every season.


Actually ever since 2007 they've happened every season.

1) Humberto of course.
2) Lorenzo 2007 although was a TD for a while, when it got TS status it became a Hurricane a few hours later.
3) Gustav tied Humberto from TD to Hurricane in 18 hours.
4) Ida also did it in under 24 hours in 2009.
Member Since: July 8, 2005 Posts: 259 Comments: 24550
1361. Dakster
Quoting NRAamy:
1326. Dakster 4:36 PM PDT on July 07, 2010

Are we getting a red alert for the 8pm??



a red shower curtain-speedo alert...


Again with the images...
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Quoting Daveg:
That's a NW movement if I've ever seen it. Definitely no W or WNW.


It is moving NW now?
Member Since: July 2, 2009 Posts: 0 Comments: 2811
1359. leo305
Quoting TropicalAnalystwx13:


lol, I try.


wow super saiyan 2 goku =D

if only Iknew how to upload an avatar.. I would do so..

On topic:

Looks like it's organizing at the surface, now all it needs is some heavy convection
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Good evening all. Looking at the movement in satellite loops, I'm going to go out on a limb and say Corpus Christi is not the target, looks more like Port Lavaca (Matagorda Bay). In any event, I'd bet we're going to get a boatload of rain in Houston tonight thru Friday night. Definitely going to get interesting here in Houston real fast.
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1357. calder
Quoting USSINS:



Simon, this one time I'm going to respond and agree with a good portion of what you say. Though colder weather actually kills more people than hot weather, but death, by whichever means, is still death and tragic.

The heatwave blogging is fine, and yes, appropriate, considering; however, imo, should strike an better balance with the severe weather occurring in the topics. 96L has one paragraph since yesterday. I'd say that's weighted. But, Doc C does say he would have an afternoon update, so, I expect one is coming that will enlighten us further.


and i'm actually going to agree with you! This is meant to be primarily a tropical weather blog but with focus on other areas when the tropics are quiet. I agree that 96L should be the focus
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Quoting NRAamy:
1326. Dakster 4:36 PM PDT on July 07, 2010

Are we getting a red alert for the 8pm??



a red shower curtain-speedo alert...


XD
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I got a quick non 96L questions - on the voricity map, the strong rotation over around 25W and 10N is that ball of convection that left Africa yesterday afternoon???

If so - looks like it's kept it's rotation.

Thanks.
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1352. Daveg
That's a NW movement if I've ever seen it. Definitely no W or WNW.
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1351. oakland
Quoting KarenRei:


Sure they could. It could be exactly 0% or exactly 100%, and thus not between them. If at 8PM they call it a TD, for example. ;)


You're right...Ooops
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Whatever 96L becomes or doesn't become it has some punch. today at swim lessons a cell came in -- got black quickly... poured.. winds had chairs flying all around.

There is even wind damage in Houston from the storms.

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1349. USSINS
Quoting StSimonsIslandGAGuy:
And I think the heatwave header is entirely appropriate, since the 1980 heatwave killed over 1,000 people in the USA, and another heatwave killed over 700 in Chicago in 1995. 96L has no chance of a death toll like that.



Simon, this one time I'm going to respond and agree with a good portion of what you say. Though colder weather actually kills more people than hot weather, but death, by whichever means, is still death and tragic.

The heatwave blogging is fine, and yes, appropriate, considering; however, imo, should strike a better balance with the severe weather occurring in the tropics. 96L has one paragraph since yesterday. I'd say that's weighted. But, Doc C does say he would have an afternoon update, so, I expect one is coming quite soon that will enlighten us further.
1348. calder
im sticking at 50% i think
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Quoting KarenRei:


Oh really?





If that doesn't have a center, then neither does the Houston Rockets. ;)




LOL - you are in fine form tonight :-)
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1346. NRAamy
1326. Dakster 4:36 PM PDT on July 07, 2010

Are we getting a red alert for the 8pm??



a red shower curtain-speedo alert...
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Quoting TropicalAnalystwx13:


lol, I try.


Too bad Karen just owned you, though. :/
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Well we know it's not going to be a Depression at 8:00 p.m. But we will get the line that a Depression could form tonight or tomorrow morning.
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Quoting KoritheMan:


Give this man a medal.


lol, I try.
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Looks like a TD forming.
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Quoting oakland:


LOL You can't possibly be wrong.


Sure they could. It could be exactly 0% or exactly 100%, and thus not between them. If at 8PM they call it a TD, for example. ;)
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Quoting TropicalAnalystwx13:
I say that the 8 PM percentage for 96L will be between 0 and 100%


Give this man a medal.
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Quoting earthlydragonfly:


But isnt it also found after the one??? or even between the 1 and the 3??

LOL


Followed immediately by the Pi.
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1337. oakland
Quoting TropicalAnalystwx13:
I say that the 8 PM percentage for 96L will be between 0 and 100%


LOL You can't possibly be wrong.
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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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