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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Quoting jeffs713:

Thats not what I meant. Stronger systems tend to come from the S or SE, since they are usually longer-track systems. Generally, the longer the track, the more likely it is to strike perpendicular to the coast.
Interesting point.
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A Big Open sloppy wave.

LOL

But the Surface chart Guys are REALLY reaching today
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.
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Quoting Patrap:
The 96L is a Open wave..

Click FRONTS and MSLP

Gulf Of Mexico - Rainbow Loop


Nope

Member Since: October 28, 2006 Posts: 57 Comments: 29919
983. Daveg
So far, models are sticking with a spot somewhere in between Brownsville and Corpus Christi for 96L.

Been in that spot with ever so slight of a northerly trend for the past 24 hours almost.

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Wamp wahhhhhhhhhhhhh
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The 96L is a Open wave..

Click FRONTS and MSLP

Gulf Of Mexico - Rainbow Loop
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Quoting kelley9:


.

Got you all beat. I actually have a period. :P OK. Maybe that's taking it too far.


Quoting Squid28:


Speaking of birds, I have a bird feeder full of them at the house. I use them like a bettle in a matchbox box type deal. Lots of birds: no problem; a few birds: something minor coming; no birds: head for the hills


I have heard sometimes larger birds that get swept up in powerful updrafts can become exhausted out over open seas and end up lucky to land on the larger floaties out there to rest. The gulf has had it's share of up drafts for the past week. Of course no instrument lasts forever either. Remarkable that both sensors are exhibiting unusual behavior.
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Quoting KarenRei:


Yep -- she's going to be a rain machine. Not Alex's caliber, but more than I think most people are expecting.


Yeah it does not take much in these tropical feeder bands to drop an inch or two quick. And with last weeks 5-15 inch spots of rain it will not take much to flood The Houston and surrounding areas again!
Member Since: July 5, 2010 Posts: 0 Comments: 170
Quoting CoopNTexas:
dont think the rain in setx is 96L....


They are due to the Trof and the old LLC which broke away from 96L 2 days ago...
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Quoting Drakoen:
TCFA about time.

Great job tracking this one, Sir Dude. :)
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Quoting weatherblog:
It's weird how it's hitting in the same exact spot as Alex. Hope it isn't a trend this season. I'd rather a storm hit the United States (where there isn't oil anyways) than for it to hit Mexico where it can kill thousands of people.


Don't think it will be the same exact spot, but close enough never the less....
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973. HadesGodWyvern (Mod)
LOL. ya
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Quoting jeffs713:

Thats not what I meant. Stronger systems tend to come from the S or SE, since they are usually longer-track systems. Generally, the longer the track, the more likely it is to strike perpendicular to the coast.


Got ya, read it wrong.
Member Since: August 11, 2008 Posts: 0 Comments: 2315
953. Guess you've been bored with the lack of CPAC and WPAC storms.
Member Since: September 6, 2009 Posts: 2 Comments: 3710
It's weird how it's hitting in the same exact spot as Alex. Hope it isn't a trend this season. I'd rather a storm hit the United States (where there isn't oil anyways) than for it to hit Mexico where it can kill thousands of people.
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Quoting CoopNTexas:
dont think the rain in setx is 96L....

Its part of the moisture plume from 96L.
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Quoting CoopNTexas:
dont think the rain in setx is 96L....


not yet anyways....
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Quoting StormW:
18Z
STATISTICAL MODELS


DYNAMIC MODELS
Storm those are the 18z dynamic models from yesterday.
Member Since: September 2, 2009 Posts: 130 Comments: 21091
Quoting Drakoen:
TCFA about time.


No kidding! Shheeeesh!
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dont think the rain in setx is 96L....
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TCFA about time.
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962. Daveg
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Quoting DellOperator:


Ever hear of birds resting on the instruments out at sea? Hard to believe redundancy has failed.


Speaking of birds, I have a bird feeder full of them at the house. I use them like a bettle in a matchbox box type deal. Lots of birds: no problem; a few birds: something minor coming; no birds: head for the hills
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Quoting StormW:
18Z
STATISTICAL MODELS


DYNAMIC MODELS


Storm, Why is there so much difference with initialization if they are both 18Z runs? Stat has the COC out over water and the dyn does not.
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Quoting StormChaser81:


Texas has a huge amount of land on the coast, I'm sure the angle and landmass have more to do with it than the tropical system.

Thats not what I meant. Stronger systems tend to come from the S or SE, since they are usually longer-track systems. Generally, the longer the track, the more likely it is to strike perpendicular to the coast.
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957. HadesGodWyvern (Mod)
There we go.

good oh imageshack.

=P
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Quoting MiamiHurricanes09:
They should definitely watch 96L but probably won't get the "brunt" of it. Up there you'll probably get some rain and gusts nothing big though.

18z (statistical) and 12z (dynamic) model runs.





K thx!
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Quoting jeffs713:

Exactly right. It is hard to find examples of storms hitting more than 30 degrees from perpendicular to the coast. Especially strong storms.


Texas has a huge amount of land on the coast, I'm sure the angle and landmass have more to do with it than the tropical system.
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954. HadesGodWyvern (Mod)
oh forgot FMNOC is a no direct linking site..
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953. HadesGodWyvern (Mod)
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Quoting angiest:


Storms striking Texas seem to hit at close to perpendicular to the coast. You can look through the database and see some that hit at odd angles, but they appear to be the exception.

Exactly right. It is hard to find examples of storms hitting more than 30 degrees from perpendicular to the coast. Especially strong storms.
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Quoting atmoaggie:
But, without a wind direction reading, I have trouble trusting the wind speeds. What if the anemometer isn't swinging the face the winds correctly?

And how come we don't have wind direction? I know for a fact that this one is supposed to have 2 anemometers. Are they both not functioning correctly?


Ever hear of birds resting on the instruments out at sea? Hard to believe redundancy has failed.
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Quoting AustinTXWeather:


What's the thinking on Central Texas watching? Welcome the info -
They should definitely watch 96L but probably won't get the "brunt" of it. Up there you'll probably get some rain and gusts nothing big though.

18z (statistical) and 12z (dynamic) model runs.



Member Since: September 2, 2009 Posts: 130 Comments: 21091
Quoting atmoaggie:
But, without a wind direction reading, I have trouble trusting the wind speeds. What if the anemometer isn't swinging the face the winds correctly?

And how come we don't have wind direction? I know for a fact that this one is supposed to have 2 anemometers. Are they both not functioning correctly?



Great questions, Atmo. I certainly dunno. Checked the maintenance chart, didn't see a date scheduled for repair yet either. May be kind of tough to dart out there in between TDs. Oh, wait, this one's not a TD yet either. ;P
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Quoting atmoaggie:
? east side is normally the worst for a south to north mover.

That said, west side *can* sometimes have higher individual gust instances due to the turbulence of winds flowing over the land than on-shore winds on the east side. And the west side commonly has drier air, which can raise wind gusts in the presence of downbursts higher than if in moist air.


DOOOH, You are right, I flubbed that pretty good. I was thinking angle of approach when typing the original entry and somehow combined the two into one tangled mess.
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Quoting MiamiHurricanes09:
Interests along northern Mexico, southern Texas, and central Texas should all watch 96L with southern Texas having the highest chance of landfall.


What's the thinking on Central Texas watching? Welcome the info -
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Quoting USSINS:
Reading "intermittently", but looks like it's spitting out some data at least. And, considering the location and the recent high traffic volume, this bouy would be a good tool to have up and working.
But, without a wind direction reading, I have trouble trusting the wind speeds. What if the anemometer isn't swinging the face the winds correctly?

And how come we don't have wind direction? I know for a fact that this one is supposed to have 2 anemometers. Are they both not functioning correctly?
Member Since: August 16, 2007 Posts: 6 Comments: 12461
If this becomes classified as I expect, then it will be done before recon I'm sure. Hopefully we get the chance to put recon in it before landfall though.
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Thank you - MiamiHurricanes09

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Quoting extreme236:


Convection becoming more concentrated. Looks like it's developing into a tropical cyclone.


Yup
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Quoting extreme236:


If the NHC does say a tropical depression is forming...the chances would be 90%-nearly 100%. But that's only if they use that wording.
Probably. Honestly I would give 96L a 90% chance in the next 48 hours, but considering how the NHC might want to tone it down a bit since recon has not investigated, 70% would be a good bet.
Member Since: September 2, 2009 Posts: 130 Comments: 21091
Reading "intermittently", but looks like it's spitting out some data at least. And, considering the location and the recent high traffic volume, this bouy would be a good tool to have up and working.




Station 42002 (LLNR 1405) - W GULF 207 NM East of Brownsville, TX

10-meter discus buoy
ARES payload
25.790 N 93.666 W


Site elevation: sea level
Air temp height: 10 m above site elevation
Anemometer height: 10 m above site elevation
Barometer elevation: sea level
Sea temp depth: 1 m below site elevation
Water depth: 3566.16 m
Watch circle radius: 3523 yards

42002 is transmitting intermittently.

This buoy will be serviced when it can be worked into the schedule. When the service date is known, it will be posted in the maintenance report.



Wind Speed (WSPD): 19.4 kts
Wind Gust (GST): 21.4 kts
Atmospheric Pressure (PRES): 29.78 in
Pressure Tendency (PTDY): +0.02 in ( Rising )
Air Temperature (ATMP): 80.6 °F
Water Temperature (WTMP): 84.4 °F
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Quoting atmoaggie:
All in.


I fold. :) Looks like a Monte Carlo distribution pattern. Nice one ATMO.
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Quoting DellOperator:


I was always instructed to use RFQ (right front quadrant) instead of using east and west terminology. It all depends on the relative motion of the circulation. And depending on where you are on this oblique spheroid we live on, that can make a difference.
Correct!

Procrastination time exhausted, back at it. L8R.
Member Since: August 16, 2007 Posts: 6 Comments: 12461

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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.