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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I get the center being at 93.3/23.3, so what's going on around 21/91.3? It looks like another spin trying to come off the coast. ???
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So USS than it should have been named just because it had an impact on someone?

That is even worse criteria IMO
Member Since: March 10, 2010 Posts: 1 Comments: 7874
Quoting Hardcoreweather2010:
96L is half the man that 95L was... or would that be half the woman :)


yep 96L still has too many vortices
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Quoting StormW:


The following is based not only with my in depth discussions with NHC forecasters during the National Hurricane Conference, but the NHC definition of a Tropical Cyclone, and criteria clarified in an email between James Franklin (NHC) and myself regarding INVEST 90L of earlier in the season:

Tropical Cyclone:
A warm-core non-frontal synoptic-scale cyclone, originating over tropical or subtropical waters, with organized deep convection and a closed surface wind circulation about a well-defined center. Once formed, a tropical cyclone is maintained by the extraction of heat energy from the ocean at high temperature and heat export at the low temperatures of the upper troposphere. In this they differ from extratropical cyclones, which derive their energy from horizontal temperature contrasts in the atmosphere (baroclinic effects).

Now, based on the definition, per the response provided to me in the email from the NHC, the NHC requires the organized deep convection to persist 12-24 hours before classifying a system as a Tropical Cyclone.



StormW, got the most respect for you and your immense weather knowledge, as well as the NHC. But, that definition doesn't mean an iota to the fella unaware that anything serious may be quickly approaching his home or work.
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this is the most oragnized 96L has bee since classified,look at the FACTS and not just sat presentation,Surface observations are much more important to classify TC formation,sat can be misleading espcially when its in the UL(eastcoast AOI.In a coupledays the feature combined w/the wave to its SE could form a warm core surface low off NC and skirt the south NE coastline ...
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Quoting StormW:


The following is based not only with my in depth discussions with NHC forecasters during the National Hurricane Conference, but the NHC definition of a Tropical Cyclone, and criteria clarified in an email between James Franklin (NHC) and myself regarding INVEST 90L of earlier in the season:

Tropical Cyclone:
A warm-core non-frontal synoptic-scale cyclone, originating over tropical or subtropical waters, with organized deep convection and a closed surface wind circulation about a well-defined center. Once formed, a tropical cyclone is maintained by the extraction of heat energy from the ocean at high temperature and heat export at the low temperatures of the upper troposphere. In this they differ from extratropical cyclones, which derive their energy from horizontal temperature contrasts in the atmosphere (baroclinic effects).

Now, based on the definition, per the response provided to me in the email from the NHC, the NHC requires the organized deep convection to persist 12-24 hours before classifying a system as a Tropical Cyclone.


So it would seem the definition has been tightened up somewhat over the years, or else I have misunderstood it.
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interesting but I can't see COC...
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Quoting USSINS:
I'm old school, so imo, it's been a "depression" for three or four days already. It's had sustained organized convection, increasing winds, low and upper level circulation, albeit in general and not stacked necessarily. Not trying to define it as a TS or cane - simply not there yet, but it's clearly tropical with serious potential still.

IMO, we've gone way overboard with the technicalities of classification, resulting in a climate of less awareness to the general public. If there was more awareness that a TD was close by, folks would be paying more attention and cognizant to make plans, etc. As it is now, if this thing blows up close to shore (and it very well could) there will be less reaction time, etc, even in today's fast-paced communicable, technical and busy world.
I agree with you about the public not receiving enough warning in some cases. That's the original reason I found this blog. I wouldn't have looked for other sources of information but just wasn't receiving enough advanced notice. On the other hand if the NHC and other authorities reported every invest and area of interest, in my opinion, the "Boy Cried Wolf" Syndrome would occure or as Governor Jeb Bush stated during the 2004 or 2005 season, "Hurricance-Denial" and "Hurricane-Fatigue."
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96L is half the man that 95L was... or would that be half the woman :)
Member Since: January 24, 2010 Posts: 0 Comments: 529
Quoting reedzone:
NON-TROPICAL low invest area, may get tagged if it continues to organize, very large, a large Ocean Storm for right now, it seems to be absorbing the wave to the southeast.



I also think about it,but we have to wait
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Going out for a late breakfast, bbl
Member Since: July 1, 2008 Posts: 13 Comments: 7423

You can get with THIS...or you can get with THAT...I dunno which one to pick...lol

Link
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Quoting NewYork4Life:


Low end Cat. 3 by Friday..
Waiting for someone to ask you if the heatwave is beginning to take its affect on you! LOL But hey, never say never when it comes to the weather.
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Quoting CybrTeddy:


Yep, 96L has finally acquired a closed LLC. The question is, is it too late? 93L acquired one and a few hours later it became a TD.


Unless the definition has changed, wouldn't a closed LLC with a warm core automatically become a TD?
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Most don't sit and ponder at swirls like the WU. Awareness and preparedness is the name of the game, imo. And, IMO that's what the NHC should keep first and foremost in their mission - not whether or not something is "technically" this or that.
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Quoting reedzone:
This is not organized to me, it's a mess..



More organized than it was this morning. Convection has increased. Plus it has developed a surface circulation.
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Quoting reedzone:
This is not organized to me, it's a mess..



So is the area off the Carolina's. Don't look at the current satellite, look at the trends. I agree its disorganized but some sort of surface circulation is forming.
Member Since: July 8, 2005 Posts: 259 Comments: 24512
466. IKE
Quoting reedzone:
This is not organized to me, it's a mess..



I agree...

Member Since: June 9, 2005 Posts: 23 Comments: 37860
I'm old school, so imo, it's been a "depression" for three or four days already. It's had sustained organized convection, increasing winds, low and upper level circulation, albeit in general and not stacked necessarily. Not trying to define it as a TS or cane - simply not there yet, but it's clearly tropical with serious potential still.

IMO, we've gone way overboard with the technicalities of classification, resulting in a climate of less awareness to the general public. If there was more awareness that a TD was close by, folks would be paying more attention and cognizant to make plans, etc. As it is now, if this thing blows up close to shore (and it very well could) there will be less reaction time, etc, even in today's fast-paced communicable, technical and busy world.
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>
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Quoting StormW:


Taking a quick look, I would say the border to south of Padre Island...should know more later this evening.


Low end Cat. 3 by Friday..
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Quoting rmbjoe1954:
Thank you, Reedzone.


No problem, nobody is mentioning it, but it could very well surprise them if this gets tagged 97L in the next day or so as it drifts SW.
Member Since: July 1, 2008 Posts: 13 Comments: 7423
This is not organized to me, it's a mess..

Member Since: July 1, 2008 Posts: 13 Comments: 7423
Quoting StormW:


Taking a quick look, I would say the border to south of Padre Island...should know more later this evening.


ok, thanks.
Member Since: July 2, 2009 Posts: 0 Comments: 2811
Thank you, Reedzone.
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Quoting Drakoen:
Buoy 42055

Wind Direction (WDIR): W ( 260 deg true )
Wind Speed (WSPD): 5.8 kts
Wind Gust (GST): 7.8 kts
Wave Height (WVHT): 1.6 ft
Dominant Wave Period (DPD): 6 sec
Average Period (APD): 4.9 sec
Mean Wave Direction (MWD): ENE ( 64 deg true )
Atmospheric Pressure (PRES): 29.78 in
Pressure Tendency (PTDY): 0.03 in ( Rising )
Air Temperature (ATMP): 81.9 �F
Water Temperature (WTMP): 82.6 �F
Dew Point (DEWP): 75.9 �F
Heat Index (HEAT): 89.1 �F


Yep, 96L has finally acquired a closed LLC. The question is, is it too late? 93L acquired one and a few hours later it became a TD.
Member Since: July 8, 2005 Posts: 259 Comments: 24512
457. Skyepony (Mod)
Kermit has been out there since 0800Z, just landed back near Tampa. Here's the map with after midnight & then the trip out today. Lowest pressure was once again a small area 991.2 mb (~ 29.27 inHg), 12:08Z 21.567N 90.533W. Not a great wind shift, there is west winds. Seems to be several vorticitys. Not the best picture of the surface flying at 12,500' (650mb).
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There is a mistake by myself in post 371 about station 42055 reporting ENE winds. The station has been reporting winds out of the westerly directions.
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Quoting rmbjoe1954:


That is an interesting storm. If it aborbs that wave to its SE will it go towards the NE?


It's moving Southwest right now, should get picked up by a trough and move out to sea sometime this weekend. So it has a few days to acquire Subtropical Characteristics.
Member Since: July 1, 2008 Posts: 13 Comments: 7423
Quoting reedzone:


Yep, this is the tropical wave that everybody was looking to develop lol. However, it's merging with the giant low, this may help the low acquire Subtropical characteristics since the wave is fully warm cored.
Always like watching a wave next to a non-tropical low; sometimes a surface low will circle around the non-tropical low. It's an interesting phenomena. Haven't had time to run models been busy working, and as you wrote, it's expected to be absorbed.
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Quoting muddertracker:
On ASCAT?
Satellite and buoy obs.
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Quoting extreme236:


It looks better organized than it did this morning.


Convection steadily on the increase.

I'm monitoring the system using these satellite images:
NASA GOES
RAMSDIS
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Quoting stillwaiting:
reed:96L still has a good chance(60%+) of becoming bonnie as it approaches south TX coastline tomorrow IMO...
I agree, although that dry air doesn't look to be backing off anytime soon by looking at wv loops.
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Quoting Drakoen:
96L has acquired a closed surface low.
On ASCAT?
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reed:96L still has a good chance(60%+) of becoming bonnie as it approaches south TX coastline tomorrow IMO...
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Quoting StormW:


Give me a minute to recalculate.


sure, no problem
Member Since: July 2, 2009 Posts: 0 Comments: 2811
Winds at buoy 42055 switched from NNW to NW to WNW to now W
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Quoting Drakoen:
96L still has about 24-36 hours before making landfall


It looks better organized than it did this morning.
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Quoting StormW:


Agreed. If it can keep bringing convection to the center, could be a TD before landfall.


Hi Storm,

If 96L does get its act together where do you think it will go? South TX - around CC or so?
Member Since: July 2, 2009 Posts: 0 Comments: 2811
I definately wouldn't count 96L out. I think it has a decent shot at becoming a depression or tropical storm before making land fall. I mean look at 95L it almost became just that and 96L looks alot more impressive now than 95L ever did.
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Quoting reedzone:
NON-TROPICAL low invest area, may get tagged if it continues to organize, very large, a large Ocean Storm for right now, it seems to be absorbing the wave to the southeast.



That is an interesting storm. If it aborbs that wave to its SE will it go towards the NE?
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439. Daveg
96L trying real hard... convection firing up..
Floater - Visible Loop
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Quoting weatherspawn:


Thanks, I just figured that out. I'm actually a programmer/web developer by trade, I just wasn't sure what markup the blog used. I've got it now though!
'Same line of work here. Welcome to the blog.
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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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