Dr. Jeff Masters' WunderBlog

The Northeast Heatwave

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

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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1301. KarenRei 11:26 PM GMT on July 07, 2010
Stron Quoting bakers: 96L will not develope. it is nothing more than a big ball of convection. Yep. Nothing more than a big ball of warm-core convection with a surface circulation over tropical waters in low to moderate shear with increasingly sustained convection over its center and an anticyclone overhead. Who ever heard of something like that developing? ;) Member Since: September 7, 2007 Posts: 1 Comments: 934

1302. wxvoyeur 11:26 PM GMT on July 07, 2010
Quoting MiamiHurricanes09: Last call! What percentage will the NHC give 96L of tropical cyclone formation in the next 48 hours on the 8PM TWO? The person that guesses correctly gets a cookie. Lol. By the way I went with a 70% chance. I'll play, I'll say 80% just to be different. Member Since: June 26, 2010 Posts: 0 Comments: 100

1303. Levi32 11:27 PM GMT on July 07, 2010
I say 60% from the NHC...it should be a "high" chance in any case. Member Since: November 24, 2005 Posts: 586 Comments: 25441

1306. hunkerdown 11:29 PM GMT on July 07, 2010
Quoting KarenRei: Stron Yep. Nothing more than a big ball of warm-core convection with a surface circulation over tropical waters in low to moderate shear with increasingly sustained convection over its center and an anticyclone overhead. Who ever heard of something like that developing? ;) C-L-A-S-S-I-C Member Since: August 15, 2008 Posts: 0 Comments: 2514

1307. earthlydragonfly 11:29 PM GMT on July 07, 2010
Evening everyone... ok it is driving me crazy now.... What is the "TWO" everyone is talking about? I assume short for something... Member Since: July 1, 2005 Posts: 10 Comments: 1649

1309. USSINS 11:30 PM GMT on July 07, 2010
Imminently landfalling tropical system/depression (maybe more) and we've a heatwave header still. Yup, lots of heatwave posts today. ;) Seems to more accurately reflect AGW politics rather than the nature of severe weather itself. Yup, it's hot alright, but there's at least substantial, serious dangerous, life-threatening flooding coming to a large portion of the western GoM. Thanks out to the tropical posters here, staying abreast of the current conditions and possibilities. Let's hope 96L doesn't it get its act together.

1310. MiamiHurricanes09 11:30 PM GMT on July 07, 2010
Polls are now closed and no more predictions will be received. Member Since: September 2, 2009 Posts: 129 Comments: 19976

1311. Levi32 11:30 PM GMT on July 07, 2010
Quoting earthlydragonfly: Evening everyone... ok it is driving me crazy now.... What is the "TWO" everyone is talking about? I assume short for something... Tropical Weather Outlook....from the NHC. Member Since: November 24, 2005 Posts: 586 Comments: 25441

1312. bakers 11:31 PM GMT on July 07, 2010
Quoting KarenRei: if it had a center it would be classified and it is not going to be. Member Since: June 17, 2010 Posts: 0 Comments: 45

1313. hunkerdown 11:31 PM GMT on July 07, 2010
Quoting MiamiHurricanes09: Polls are now closed and no more predictions will be received. does that mean I miss out on the chance for a cookie ? Probably was stale and out of date anyway :) Member Since: August 15, 2008 Posts: 0 Comments: 2514

1314. weathermancer 11:31 PM GMT on July 07, 2010
Quoting KarenRei: Stron Yep. Nothing more than a big ball of warm-core convection with a surface circulation over tropical waters in low to moderate shear with increasingly sustained convection over its center and an anticyclone overhead. Who ever heard of something like that developing? ;) Yep. Never heard of it. Member Since: August 29, 2009 Posts: 10 Comments: 481

1315. KarenRei 11:31 PM GMT on July 07, 2010
Quoting earthlydragonfly: Evening everyone... ok it is driving me crazy now.... What is the "TWO" everyone is talking about? I assume short for something... It comes right before the THREE. ;) (j/k -- Tropical Weather Outlook) Member Since: September 7, 2007 Posts: 1 Comments: 934

1316. earthlydragonfly 11:31 PM GMT on July 07, 2010
Quoting Levi32: Tropical Weather Outlook....from the NHC. AAAAAaaaahhhhhhh.... Thanks Levi Member Since: July 1, 2005 Posts: 10 Comments: 1649

1317. KoritheMan 11:31 PM GMT on July 07, 2010
Quoting earthlydragonfly: Evening everyone... ok it is driving me crazy now.... What is the "TWO" everyone is talking about? I assume short for something... Tropical Weather Outlook. The product the NHC releases four times per day, once every six hours. It can be found here (just look below the image of the Atlantic, and it will say "Tropical Weather Outlook"). Member Since: March 7, 2007 Posts: 408 Comments: 15418

1318. Patrap 11:32 PM GMT on July 07, 2010
96L has now and to the Coast to make a run on Lowering the Central Pressure and becoming all she can be. That H to the NE is gonna scoot things along. W to WnW. Member Since: July 3, 2005 Posts: 370 Comments: 111244

1319. MiamiHurricanes09 11:32 PM GMT on July 07, 2010
Quoting bakers: All systems have a center. Member Since: September 2, 2009 Posts: 129 Comments: 19976

1320. sailingallover 11:33 PM GMT on July 07, 2010
A TD a 8:00 Member Since: September 1, 2009 Posts: 23 Comments: 982

1321. MiamiHurricanes09 11:33 PM GMT on July 07, 2010
Quoting hunkerdown: does that mean I miss out on the chance for a cookie ? Probably was stale and out of date anyway :) LOL! Ok I'll take your prediction. But that's it. Member Since: September 2, 2009 Posts: 129 Comments: 19976

1322. earthlydragonfly 11:33 PM GMT on July 07, 2010
Quoting KarenRei: It comes right before the THREE. ;) (j/k -- Tropical Weather Outlook) But isnt it also found after the one??? or even between the 1 and the 3?? LOL Member Since: July 1, 2005 Posts: 10 Comments: 1649

1324. wfyweather 11:35 PM GMT on July 07, 2010
I think a 60 percent.... or maybe 50 but all these people saying 70 and 80..... i think is an overstatement Member Since: July 12, 2008 Posts: 11 Comments: 422

1325. hunkerdown 11:35 PM GMT on July 07, 2010
Quoting MiamiHurricanes09: LOL! Ok I'll take your prediction. But that's it. 60.1% Member Since: August 15, 2008 Posts: 0 Comments: 2514

1326. Dakster 11:36 PM GMT on July 07, 2010
Are we getting a red alert for the 8pm?? Member Since: March 10, 2006 Posts: 0 Comments: 4931

1327. Levi32 11:36 PM GMT on July 07, 2010
Quoting MiamiHurricanes09: All systems have a center. Depends on how you define "center". All invests are given coordinates but they do not necessarily represent a low pressure center of any kind or the center of any kind of circulation. In disorganized disturbances the "center" is given as just the approximate center-point of the area of disturbed weather. Member Since: November 24, 2005 Posts: 586 Comments: 25441

1328. KarenRei 11:36 PM GMT on July 07, 2010
Quoting bakers: Oh really? If that doesn't have a center, then neither does the Houston Rockets. ;) Member Since: September 7, 2007 Posts: 1 Comments: 934

1329. MiamiHurricanes09 11:37 PM GMT on July 07, 2010
Quoting hunkerdown: 60.1% LOL. Ok, that's it. Member Since: September 2, 2009 Posts: 129 Comments: 19976

1330. TexasHurricane 11:37 PM GMT on July 07, 2010
Quoting Levi32: Depends on how you define "center". All invests are given coordinates but they do not necessarily represent a low pressure center of any kind or the center of any kind of circulation. In disorganized disturbances the "center" is given as just the approximate center-point of the area of disturbed weather. Hi Levi, any changes in your thinking on 96L? Member Since: July 2, 2009 Posts: 0 Comments: 2811

1331. GeoffreyWPB 11:37 PM GMT on July 07, 2010
I would say yes to code red. Member Since: September 10, 2007 Posts: 0 Comments: 9112

1333. MiamiHurricanes09 11:38 PM GMT on July 07, 2010
Quoting Levi32: Depends on how you define "center". All invests are given coordinates but they do not necessarily represent a low pressure center of any kind or the center of any kind of circulation. In disorganized disturbances the "center" is given as just the approximate center-point of the area of disturbed weather. It was sorta meant in a sarcastic way, like the center point of a system, not necessarily the circulation. Member Since: September 2, 2009 Posts: 129 Comments: 19976

1334. Levi32 11:38 PM GMT on July 07, 2010
Quoting TexasHurricane: Hi Levi, any changes in your thinking on 96L? Nope, no changes from my blog entry earlier this afternoon. Member Since: November 24, 2005 Posts: 586 Comments: 25441

1335. TxMarc71 11:38 PM GMT on July 07, 2010
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. Heat wave?? ... its hotter than that everyday here in SE Texas from May - Sept and it never makes national news.. Its summer time so it does happen to get hot!! You'll never see the triple digits here reported on the E coast ever... makes zero sense...

1336. TropicalAnalystwx13 11:39 PM GMT on July 07, 2010
I say that the 8 PM percentage for 96L will be between 0 and 100% Member Since: July 6, 2010 Posts: 89 Comments: 25250

1337. oakland 11:40 PM GMT on July 07, 2010
Quoting TropicalAnalystwx13: I say that the 8 PM percentage for 96L will be between 0 and 100% LOL You can't possibly be wrong. Member Since: September 4, 2005 Posts: 41 Comments: 7520

1338. weathermancer 11:40 PM GMT on July 07, 2010
Quoting earthlydragonfly: But isnt it also found after the one??? or even between the 1 and the 3?? LOL Followed immediately by the Pi. Member Since: August 29, 2009 Posts: 10 Comments: 481

1339. KoritheMan 11:40 PM GMT on July 07, 2010
Quoting TropicalAnalystwx13: I say that the 8 PM percentage for 96L will be between 0 and 100% Give this man a medal. Member Since: March 7, 2007 Posts: 408 Comments: 15418

1340. MiamiHurricanes09 11:41 PM GMT on July 07, 2010
Member Since: September 2, 2009 Posts: 129 Comments: 19976

1341. KarenRei 11:41 PM GMT on July 07, 2010
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. ;) Member Since: September 7, 2007 Posts: 1 Comments: 934

1342. tropicaltank 11:41 PM GMT on July 07, 2010
Looks like a TD forming. Member Since: June 27, 2009 Posts: 0 Comments: 242

1343. TropicalAnalystwx13 11:42 PM GMT on July 07, 2010
Quoting KoritheMan: Give this man a medal. lol, I try. Member Since: July 6, 2010 Posts: 89 Comments: 25250

1344. GeoffreyWPB 11:42 PM GMT on July 07, 2010
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. Member Since: September 10, 2007 Posts: 0 Comments: 9112

1345. KoritheMan 11:42 PM GMT on July 07, 2010
Quoting TropicalAnalystwx13: lol, I try. Too bad Karen just owned you, though. :/ Member Since: March 7, 2007 Posts: 408 Comments: 15418

1346. NRAamy 11:42 PM GMT on July 07, 2010
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... Member Since: January 24, 2007 Posts: 315 Comments: 31937

1347. WatchingThisOne 11:42 PM GMT on July 07, 2010
Quoting KarenRei: Oh really? If that doesn't have a center, then neither does the Houston Rockets. ;) LOL - you are in fine form tonight :-) Member Since: July 15, 2005 Posts: 3 Comments: 1249

1348. calder 11:42 PM GMT on July 07, 2010
im sticking at 50% i think Member Since: July 26, 2006 Posts: 0 Comments: 411

1349. USSINS 11:42 PM GMT on July 07, 2010
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.

1350. txalwaysprepared 11:42 PM GMT on July 07, 2010
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. Member Since: August 18, 2007 Posts: 0 Comments: 1642

1351. oakland 11:43 PM GMT on July 07, 2010
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 Member Since: September 4, 2005 Posts: 41 Comments: 7520

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