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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1487. IKE
Quoting Hurricanes101:


and??


And?
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NRA - where are you located? We're just a bit south of Sandy Eggo.
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1484. KEEPEROFTHEGATE (Mod)
5.9
Date-Time Wednesday, July 07, 2010 at 23:53:33 UTC
Wednesday, July 07, 2010 at 04:53:33 PM at epicenter

Location 33.417°N, 116.483°W
Depth 11.7 km (7.3 miles)
Region SOUTHERN CALIFORNIA
Distances 22 km (13 miles) NNW (332°) from Borrego Springs, CA
23 km (14 miles) SE (131°) from Anza, CA
33 km (20 miles) NE (52°) from Lake Henshaw, CA
41 km (25 miles) SW (215°) from Indio, CA
45 km (28 miles) S (174°) from Palm Springs, CA
94 km (58 miles) NE (41°) from San Diego, CA

Location Uncertainty horizontal +/- 0.3 km (0.2 miles); depth +/- 0.6 km (0.4 miles)
Parameters Nph=122, Dmin=10 km, Rmss=0.26 sec, Gp= 29°,
M-type=local magnitude (ML), Version=3
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I'm out.
Got the munchies for some crow.
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Quoting Hardcoreweather2010:


95L looked 100X better than 96L has ever looked and I didn't know that you were a mod and I also didn't know that they allowed personal attacks on this board. 96L will make landfall tomorrow morning so it's time to focus on the next storm.
I don't believe I stated a personal attack. And if 95L looked 100 times better than 96L apparently you aren't too familiar with the term "organization".
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Quoting IKE:


Good catch! The same ones!


Yup! From now on we know that the "FORECASTER STEWART/CANGIALOSI" is the less conservative team IMO.
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1479. beell
Quoting Levi32:
Apparently the NHC is impressed. The only thing keeping this from being classified right now is the lack of deep convection, as cloud tops are rather shallow right now. As they mention, if the current rate of organization continues it should be a TD later tonight or tomorrow morning.


Here's your shallow convection. A morning sounding from Brownsville. Dry air is high enough (above 500mb) to allow modestly deep convection. 00Z soundings are not out yet but forecast soundings paint a much better picture in the hours ahead.

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Quoting IKE:


Good catch! The same ones!


and??
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Quoting txalwaysprepared:
I tried to tell yall... LOL

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.



WIND DAMAGE IN HOUSTON TODAY??? CMON MAN GET REAL!! There hasnt even been a breeze here today... the awning in your pic collapsed because of the wieght of the rain water on top of it. It had nothing to do with the LACK of any wind here today...
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we're all fine - just the whole house was MOVING. Was smart though - after the easter quake, I got that stuff to stick your knick knacks to whatever they're on. They don't shake off. That one even woke up the kids upstairs!
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Quoting AustinTXWeather:
@HouGalv08,are you anticipating ongoing showers there even if it makes landfall in Mexico?
Per the NWS forecast discussion issued at 15:13 this afternoon, I'd imagine so--"HOWEVER IT WAS IN-
TERESTING TO NOTE THAT MODELS ARE NOW KEEPING THESE ELEVATED RAIN
CHANCES IN FOR M0ST OF SE TX ON FRI. IT APPEARS THAT THE MOISTURE
FROM THAT WEAK TROPICAL WAVE WILL BE APPROACHING FROM THE S/SW AS
IT MOVES FURTHER INLAND."
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1474. IKE
Quoting HurricaneSwirl:
WAIT A MINUTE guys.. Look at the TWO where 95L got that ridiculous bump

Link

Look at the team who wrote that outlook, and then look at the team who wrote the most recent outlook. LOL! I still think it should be red regardless though.


Good catch! The same ones!
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1473. KEEPEROFTHEGATE (Mod)
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Quoting IKE:


My grilled is still warm from the NY strip I just ate...got 2 crows out of the freezer thawing out now.


Still love ya! ;)
Member Since: August 18, 2007 Posts: 0 Comments: 1642
Quoting MiamiHurricanes09:
The same could have been said about 95L... Please stop with those type of comments unless you want to be banned.


95L looked 100X better than 96L has ever looked and I didn't know that you were a mod and I also didn't know that they allowed personal attacks on this board. 96L will make landfall tomorrow morning so it's time to focus on the next storm.
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NRArmy - where was the earthquake?
Member Since: September 13, 2008 Posts: 0 Comments: 241
Quoting IKE:
Dying convection NHC...R U kidding me? 80%!
You are only looking at convection. There are a lot of things in favor of that percentage, and if the convection was good than 96L would be a TD.
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1468. Drakoen
Dropsonde information from the NOAA G-IV found a bunch of westerlies south of the system
Member Since: October 28, 2006 Posts: 57 Comments: 29883
DEfinitely TS Bonnie within the next 12 hours imo.Don't be so sure it doesn't make to minimal hurricane status either
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1466. IKE
Everybody OK in Cali?
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Quoting PtownBryan:


Yall ok? Was it bad?


Yeah just fine ... I'm about 50 miles SW of Palm Springs ... had some strong swaying here (grabbed onto my monitor to keep it from drifting off its perch) ... that's about it. Waiting for after shocks, hoping it's not a pre-quake :-)
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WAIT A MINUTE guys.. Look at the TWO where 95L got that ridiculous bump

Link

Look at the team who wrote that outlook, and then look at the team who wrote the most recent outlook. LOL! I still think it should be red regardless though.
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The tone of speech in the 8PM TWO is very suggestive of an upgrade soon.

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.
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I tried to tell yall... LOL

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
We should see a renumber before too long.
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1460. NRAamy
here, Dak! here! SoCal!!!!
Member Since: January 24, 2007 Posts: 317 Comments: 31946
1458. IKE
Quoting CanesfanatUT:
How much crow we grillin tonight?? LOL


My grill is still warm from the NY strip I just ate...got 2 crows out of the freezer thawing out now.
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Levi, does this change your thoughts on the possibility of this thing becomine a cane?
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Quoting WatchingThisOne:
Prelim mag 5.9

* 22 km (13 miles) NNW (332°) from Borrego Springs, CA
* 23 km (14 miles) SE (131°) from Anza, CA
* 33 km (20 miles) NE (52°) from Lake Henshaw, CA
* 45 km (28 miles) S (174°) from Palm Springs, CA
* 94 km (58 miles) NE (41°) from San Diego, CA


Depth 12km
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Quoting melwerle:
Holy friggin earthquake!!! We just had a huge rumbler.
You ok?
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That was definitely HUGE. Wow - that'll wake you up. So much for sitting around the house relaxing.
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1452. leo305
Quoting Levi32:
Apparently the NHC is impressed. The only thing keeping this from being classified right now is the lack of deep convection, as cloud tops are rather shallow right now. As they mention, if the current rate of organization continues it should be a TD later tonight or tomorrow morning.


yea, the surface circulation has improved rather quickly and dramaticly since this morning, when it had spins all over the place.. the convection may likely come later tonight, as the system reaches DMAX
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Its anarchy I swear! Expect advisories at 11 pm imo.
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Quoting WatchingThisOne:
Just experienced an EQ in SoCal. Looking it up ...


Yall ok? Was it bad?
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1449. IKE
Dying convection NHC...R U kidding me? 80%!
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Quoting NRAamy:
EARTHQUAKE!!!!!!!

???????
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WOW was not expecting 80%, I thought my 60% prediction was a shoo-in! No cookie for me :(
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80%=td2 at 11pm???
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1444. Levi32
Quoting IKE:
LMAO!

80%!



Well Ike....the colors on that image are the only thing standing in 96L's way of becoming a TD. Every other criteria it has met. 80% isn't a bad call really, I am just waiting to see if it can overcome Alex's cool wake and actually get those cloud tops up higher. Otherwise, it may stay limited to its current state for a while yet. Watch for some bursting tonight during diurnal max and we'll know for sure whether it's a TD or not.
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1442. JLPR2
Quoting IKE:
LMAO!

80%!



But dont you the the eye forming?
LOL!
XD
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Prelim mag 5.9

* 22 km (13 miles) NNW (332°) from Borrego Springs, CA
* 23 km (14 miles) SE (131°) from Anza, CA
* 33 km (20 miles) NE (52°) from Lake Henshaw, CA
* 45 km (28 miles) S (174°) from Palm Springs, CA
* 94 km (58 miles) NE (41°) from San Diego, CA
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1440. centex
They think TD2 coming
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Holy friggin earthquake!!! We just had a huge rumbler.
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I knew Recon had to be out there.
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1437. Dakster
Nraamy? Where?
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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.