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.

Categories: Heat

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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

1352. Daveg 11:43 PM GMT on July 07, 2010
That's a NW movement if I've ever seen it. Definitely no W or WNW. Member Since: September 23, 2005 Posts: 0 Comments: 426

1353. CanesfanatUT 11:43 PM GMT on July 07, 2010
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. Member Since: September 3, 2007 Posts: 0 Comments: 459

1354. KoritheMan 11:43 PM GMT on July 07, 2010
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 Member Since: March 7, 2007 Posts: 411 Comments: 15473

1357. calder 11:44 PM GMT on July 07, 2010
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 Member Since: July 26, 2006 Posts: 0 Comments: 412

1358. HouGalv08 11:44 PM GMT on July 07, 2010
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. Member Since: July 21, 2008 Posts: 0 Comments: 313

1359. leo305 11:44 PM GMT on July 07, 2010
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 Member Since: April 17, 2010 Posts: 0 Comments: 1752

1360. TexasHurricane 11:44 PM GMT on July 07, 2010
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

1361. Dakster 11:44 PM GMT on July 07, 2010
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... Member Since: March 10, 2006 Posts: 0 Comments: 4942

1362. CybrTeddy 11:45 PM GMT on July 07, 2010
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: 253 Comments: 20276

1363. KoritheMan 11:45 PM GMT on July 07, 2010
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. Member Since: March 7, 2007 Posts: 411 Comments: 15473

1365. Hardcoreweather2010 11:45 PM GMT on July 07, 2010
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

1366. duajones78413 11:46 PM GMT on July 07, 2010
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. Member Since: August 30, 2008 Posts: 0 Comments: 276

1367. NRAamy 11:46 PM GMT on July 07, 2010
you know I love you, Dak... ;) Member Since: January 24, 2007 Posts: 315 Comments: 31937

1368. CanesfanatUT 11:46 PM GMT on July 07, 2010
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. Member Since: September 3, 2007 Posts: 0 Comments: 459

1369. AustinTXWeather 11:46 PM GMT on July 07, 2010
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. Member Since: September 13, 2008 Posts: 0 Comments: 241

1371. Hurricanes101 11:46 PM GMT on July 07, 2010
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: 6902

1372. PtownBryan 11:47 PM GMT on July 07, 2010
I missed the cutoff time but I am going with 70%! Member Since: July 5, 2010 Posts: 0 Comments: 170

1373. bakers 11:48 PM GMT on July 07, 2010
96L HAS POOR BANDING FEATURES AND WILL NOT DEVELOPE. CONVECTION IS ALREADY DECREASING. Member Since: June 17, 2010 Posts: 0 Comments: 45

1374. Becca36 11:48 PM GMT on July 07, 2010
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. Member Since: June 26, 2009 Posts: 0 Comments: 157

1375. MiamiHurricanes09 11:48 PM GMT on July 07, 2010
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. Member Since: September 2, 2009 Posts: 129 Comments: 19976

1376. ElConando 11:48 PM GMT on July 07, 2010
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 Member Since: September 6, 2009 Posts: 2 Comments: 3703

1377. IKE 11:49 PM GMT on July 07, 2010
If this is 70% I'm either blind or an idiot or both.... Member Since: June 9, 2005 Posts: 23 Comments: 37044

1378. wfyweather 11:49 PM GMT on July 07, 2010
Quoting IKE: If this is 70% I'm either blind or an idiot or both.... amen... people are reallly overreacting Member Since: July 12, 2008 Posts: 11 Comments: 422

1379. ElConando 11:49 PM GMT on July 07, 2010
I give it 60% Mr. 09 Member Since: September 6, 2009 Posts: 2 Comments: 3703

1380. KarenRei 11:50 PM GMT on July 07, 2010
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. Member Since: September 7, 2007 Posts: 1 Comments: 934

1382. MiamiHurricanes09 11:50 PM GMT on July 07, 2010
Quoting IKE: If this is 70% I'm either blind or an idiot or both.... You see disorganization, I see progress. Member Since: September 2, 2009 Posts: 129 Comments: 19976

1383. IKE 11:50 PM GMT on July 07, 2010
My prediction was 50% and that's being generous. Member Since: June 9, 2005 Posts: 23 Comments: 37044

1384. Hurricanes101 11:50 PM GMT on July 07, 2010
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: 6902

1385. stormpetrol 11:50 PM GMT on July 07, 2010
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. Member Since: April 29, 2007 Posts: 0 Comments: 6404

1386. Levi32 11:50 PM GMT on July 07, 2010
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. Member Since: November 24, 2005 Posts: 586 Comments: 25459

1387. duajones78413 11:51 PM GMT on July 07, 2010
just a trace of rain in Corpus so far. Houston looked like it got some heavy rain earlier on the radar Member Since: August 30, 2008 Posts: 0 Comments: 276

1388. reedzone 11:51 PM GMT on July 07, 2010
Quoting IKE: If this is 70% I'm either blind or an idiot or both.... I agree, I"m still not impressed with 96L. I'm looking to see a yellow circle over the NON-TROPICAL (Reed) Low. Member Since: July 1, 2008 Posts: 13 Comments: 7247

1390. IKE 11:51 PM GMT on July 07, 2010
F5...F5.....refresh...refresh...F5....F5.... Member Since: June 9, 2005 Posts: 23 Comments: 37044

1391. duajones78413 11:52 PM GMT on July 07, 2010
Quoting Levi32: Nearly impossible, I would go so far as to say. That is good news Member Since: August 30, 2008 Posts: 0 Comments: 276

1392. IKE 11:52 PM GMT on July 07, 2010
Quoting reedzone: I agree, I"m still not impressed with 96L. I'm looking to see a yellow circle over the NON-TROPICAL (Reed) Low. Convection has waned....yeah, I know about DMIN...plus it looks stretched out still. It looked better earlier this afternoon then it does now. Member Since: June 9, 2005 Posts: 23 Comments: 37044

1393. Hurricanes101 11:52 PM GMT on July 07, 2010
I think a few are over-analyzing the analysis of 96L lol I guess watching 96L means we all think it will be a hurricane lol Member Since: March 10, 2010 Posts: 1 Comments: 6902

1394. leo305 11:52 PM GMT on July 07, 2010
It looks bad convectively sure.. but at the surface it's becoming better organized.. and that matters alot when it comes to development Member Since: April 17, 2010 Posts: 0 Comments: 1752

1395. txwxnut2 11:52 PM GMT on July 07, 2010
Corpus christi - wind and lots of rain. kinda like an april day, but add rain - LOL! recall the 50mph winds we had this past April/May w/ no storm. Also, tides 2-4ft above normal; unless this thing pulls a claudette or humberto... Member Since: August 26, 2006 Posts: 0 Comments: 68

1396. HaboobsRsweet 11:53 PM GMT on July 07, 2010
This system will not be a TD until the HH fly and find a closed low which at the moment doesnt look good. I doubt we see red either. It might go to 50% orange or something along those lines but got to watch for the flight. There is little progress and its only hope is if they find a closed center. Member Since: May 20, 2009 Posts: 0 Comments: 1640

1397. Daveg 11:53 PM GMT on July 07, 2010
Quoting TexasHurricane: It is moving NW now? Definitely not moving West or WNW. Member Since: September 23, 2005 Posts: 0 Comments: 426

1398. Hardcoreweather2010 11:53 PM GMT on July 07, 2010
I love yellow :) Time for a 10% Member Since: January 24, 2010 Posts: 0 Comments: 529

1399. AustinTXWeather 11:53 PM GMT on July 07, 2010
@HouGalv08,are you anticipating ongoing showers there even if it makes landfall in Mexico? Member Since: September 13, 2008 Posts: 0 Comments: 241

1400. wfyweather 11:53 PM GMT on July 07, 2010
LARGE LOW PRESSURE SYSTEM LOCATED ABOUT 290 MILES SOUTHEAST OF THE TEXAS/MEXICO BORDER IS MOVING WEST-NORTHWESTWARD AT 10 TO 15 MPH. THIS SYSTEM HAS BECOME MUCH BETTER ORGANIZED THIS AFTERNOON AND EVENING...AND THUNDERSTORM ACTIVITY HAS BECOME MORE CONCENTRATED NEAR THE CENTER. TWO NOAA RECONNAISSANCE AIRCRAFT ARE CURRENTLY CONDUCTING A RESEARCH MISSION IN AND AROUND THE DISTURBANCE...AND INFORMATION RECEIVED SO FAR SUGGESTS THAT A TROPICAL DEPRESSION MAY BE FORMING. ENVIRONMENTAL CONDITIONS ARE CONDUCIVE FOR FURTHER DEVELOPMENT AND IF ADDITIONAL ORGANIZATION CONTINUES...THEN FORECAST ADVISORIES WILL BE INITIATED LATER TONIGHT OR THURSDAY MORNING...WHICH WOULD REQUIRE THAT TROPICAL STORM WATCHES OR WARNINGS BE ISSUED FOR PORTIONS OF THE COASTAL REGIONS OF CENTRAL AND LOWER TEXAS AND NORTHEASTERN MEXICO. THERE IS A HIGH CHANCE...80 PERCENT...OF THIS SYSTEM BECOMING A TROPICAL CYCLONE. THIS DISTURBANCE IS FORECAST TO BRING LOCALLY HEAVY RAINS AND GUSTY WINDS TO PORTIONS OF EASTERN AND SOUTHERN TEXAS AND NORTHEASTERN MEXICO OVER THE NEXT FEW DAYS. Member Since: July 12, 2008 Posts: 11 Comments: 422

1401. KoritheMan 11:53 PM GMT on July 07, 2010
000 ABNT20 KNHC 072353 TWOAT TROPICAL WEATHER OUTLOOK NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 800 PM EDT WED JUL 7 2010 FOR THE NORTH ATLANTIC...CARIBBEAN SEA AND THE GULF OF MEXICO... A LARGE LOW PRESSURE SYSTEM LOCATED ABOUT 290 MILES SOUTHEAST OF THE TEXAS/MEXICO BORDER IS MOVING WEST-NORTHWESTWARD AT 10 TO 15 MPH. THIS SYSTEM HAS BECOME MUCH BETTER ORGANIZED THIS AFTERNOON AND EVENING...AND THUNDERSTORM ACTIVITY HAS BECOME MORE CONCENTRATED NEAR THE CENTER. TWO NOAA RECONNAISSANCE AIRCRAFT ARE CURRENTLY CONDUCTING A RESEARCH MISSION IN AND AROUND THE DISTURBANCE...AND INFORMATION RECEIVED SO FAR SUGGESTS THAT A TROPICAL DEPRESSION MAY BE FORMING. ENVIRONMENTAL CONDITIONS ARE CONDUCIVE FOR FURTHER DEVELOPMENT AND IF ADDITIONAL ORGANIZATION CONTINUES...THEN FORECAST ADVISORIES WILL BE INITIATED LATER TONIGHT OR THURSDAY MORNING...WHICH WOULD REQUIRE THAT TROPICAL STORM WATCHES OR WARNINGS BE ISSUED FOR PORTIONS OF THE COASTAL REGIONS OF CENTRAL AND LOWER TEXAS AND NORTHEASTERN MEXICO. THERE IS A HIGH CHANCE...80 PERCENT...OF THIS SYSTEM BECOMING A TROPICAL CYCLONE. THIS DISTURBANCE IS FORECAST TO BRING LOCALLY HEAVY RAINS AND GUSTY WINDS TO PORTIONS OF EASTERN AND SOUTHERN TEXAS AND NORTHEASTERN MEXICO OVER THE NEXT FEW DAYS. ELSEWHERE...TROPICAL CYCLONE FORMATION IS NOT EXPECTED DURING THE NEXT 48 HOURS. Member Since: March 7, 2007 Posts: 411 Comments: 15473

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