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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937. btwntx08
8:29 PM GMT on July 07, 2010
Quoting hydrus:
Link.....96L is moving fast. Wont have much time.

still gots 18-24 hrs though it have time
Member Since: July 13, 2008 Posts: 6 Comments: 10796
936. MiamiHurricanes09
8:28 PM GMT on July 07, 2010
Quoting ccSparky:
Where are you all thinking this 96L is going to hit. Have not seen anything recent.
Interests along northern Mexico, southern Texas, and central Texas should all watch 96L with southern Texas having the highest chance of landfall.
Member Since: September 2, 2009 Posts: 130 Comments: 21194
935. DellOperator
8:28 PM GMT on July 07, 2010
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 wins 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.


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.
Member Since: May 31, 2007 Posts: 0 Comments: 210
934. extreme236
8:28 PM GMT on July 07, 2010
Quoting MiamiHurricanes09:
After checking out latest satellite imagery, surface observations, CIMSS 18:00 UTC products, and ASCAT, the NHC should raise the chance of development in the next 48 hours to 70%.


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.
Member Since: August 2, 2007 Posts: 19 Comments: 19234
933. ccSparky
8:27 PM GMT on July 07, 2010
Where are you all thinking this 96L is going to hit. Have not seen anything recent.
932. atmoaggie
8:27 PM GMT on July 07, 2010
Quoting DellOperator:


..

I see your period and raise you one.
All in.
Member Since: August 16, 2007 Posts: 6 Comments: 12463
931. hydrus
8:26 PM GMT on July 07, 2010
Link.....96L is moving fast. Wont have much time.
Member Since: September 27, 2007 Posts: 1 Comments: 22261
930. MiamiHurricanes09
8:26 PM GMT on July 07, 2010
After checking out latest satellite imagery, surface observations, CIMSS 18:00 UTC products, and ASCAT, the NHC should raise the chance of development in the next 48 hours to 70%.
Member Since: September 2, 2009 Posts: 130 Comments: 21194
929. extreme236
8:26 PM GMT on July 07, 2010
Quoting Drakoen:


Convection becoming more concentrated. Looks like it's developing into a tropical cyclone.
Member Since: August 2, 2007 Posts: 19 Comments: 19234
928. Levi32
8:26 PM GMT on July 07, 2010
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.


Great point.
Member Since: November 24, 2005 Posts: 635 Comments: 26698
927. Drakoen
8:25 PM GMT on July 07, 2010
Member Since: October 28, 2006 Posts: 57 Comments: 30694
926. SavannahStorm
8:25 PM GMT on July 07, 2010


The East Coast ULL is considerably moist, and is in the vicinity of some low and dropping surface pressures. It may have a shot at working itself to the surface.
Member Since: September 22, 2005 Posts: 18 Comments: 2343
924. AllBoardedUp
8:24 PM GMT on July 07, 2010
Temporary slack in the rain! Need to run errands.
Member Since: July 25, 2008 Posts: 0 Comments: 626
923. DellOperator
8:24 PM GMT on July 07, 2010
Quoting atmoaggie:
.
(since it seems that everyone else is having a lot of fun posting a period)


..

I see your period and raise you one.
Member Since: May 31, 2007 Posts: 0 Comments: 210
922. hydrus
8:23 PM GMT on July 07, 2010
Member Since: September 27, 2007 Posts: 1 Comments: 22261
921. atmoaggie
8:22 PM GMT on July 07, 2010
Quoting Squid28:


One thing that a lot of people do not realize also is that while being on the western side of the eyewall is worse, the angle of the storms approach/landfall also has some effect on the severity of the surge as well.
? 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.
Member Since: August 16, 2007 Posts: 6 Comments: 12463
918. angiest
8:21 PM GMT on July 07, 2010
Quoting Squid28:


One thing that a lot of people do not realize also is that while being on the western side of the eyewall is worse, the angle of the storms approach/landfall also has some effect on the severity of the surge as well.


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.
Member Since: August 26, 2006 Posts: 16 Comments: 4766
917. AllBoardedUp
8:20 PM GMT on July 07, 2010
Quoting extreme236:


GOTTA LOVE THAT CAPS LOCK BUTTON, HUH?
I see it both ways on here! Some people don't ever use the caps and type in all lower case letters. What ever happened to beginning a sentence with a upper case letter. In both instances, I believe it is laziness. Anyway, congratulations on your opportunity.
Member Since: July 25, 2008 Posts: 0 Comments: 626
916. jasoniscoolman2010x
8:19 PM GMT on July 07, 2010
look at the new big t.storm getting next to the low..wow..
Member Since: July 4, 2010 Posts: 4 Comments: 965
915. atmoaggie
8:19 PM GMT on July 07, 2010
.
(since it seems that everyone else is having a lot of fun posting a period)
Member Since: August 16, 2007 Posts: 6 Comments: 12463
914. SavannahStorm
8:18 PM GMT on July 07, 2010


Pretty good pressure drop in the Bahamas wave/ ULL area.
Member Since: September 22, 2005 Posts: 18 Comments: 2343
913. itrackstorms
8:18 PM GMT on July 07, 2010
Sure looks like she is getting close....

Member Since: July 20, 2008 Posts: 0 Comments: 152
912. Squid28
8:18 PM GMT on July 07, 2010
Quoting AllBoardedUp:
I can't imagine a Katrina type of storm surge hitting south of Galveston/Houston area! I know Katrina was probably the exception and not the rule, but it still possible. It's a matter of when, not it it'll happen. But of course, the "when" might not happen in our life times.


One thing that a lot of people do not realize also is that while being on the western side of the eyewall is worse, the angle of the storms approach/landfall also has some effect on the severity of the surge as well.
Member Since: May 23, 2006 Posts: 0 Comments: 343
911. angiest
8:17 PM GMT on July 07, 2010
Area forecast discussion
National Weather Service Houston/Galveston Texas
1227 PM CDT Wednesday Jul 7 2010


Aviation...
deja vu all over again. Deep tropical airmass and associated waves
of rainfall moving through the region expect this to continue for the
next 36 hours. Tough to impossible to pin down timing as to
specifics regarding timing/intensity at each individual taf site.
Overall...expect the heaviest rainfall to occur overnight and
Thursday as increased moisture and better surface convergence/
boundary in the area. Generally advertised MVFR/IFR ceilings and light
rain as prevailing along with vcts's. There's no doubt there will
be several amendments necessary (most likely for the worse) once
timing/confidence is somewhat better but didn't want to go with
24-36 hours Worth of tempos. 47


&&


Discussion...
went ahead and started the Flash Flood Watch to begin now instead
of this evening considering coverage/intensity of precipitation. Still think
flood issues will be more isolated in nature during the day with
an increasing threat overnight and Thursday.
Member Since: August 26, 2006 Posts: 16 Comments: 4766
910. CoopsWife
8:17 PM GMT on July 07, 2010
Quoting watchingnva:F

my ac is too old for this...lol...


Mine was too, but the install of the new one is complete and we're now below 80 in the house - WOO HOO!
Member Since: June 19, 2006 Posts: 63 Comments: 4175
909. watchingnva
8:17 PM GMT on July 07, 2010
Quoting FLdewey:
wunderkidcayman... caps lock key is usually below the tab key, above the shift key. Hit it.


...there was excitement involved...cut some slack...
Member Since: September 7, 2005 Posts: 7 Comments: 1525
908. MiamiHurricanes09
8:17 PM GMT on July 07, 2010
Quoting ElConando:


Hopefully it won't re intensify over land.
I'm sure it won't. But hey, ya' never know with these systems.
Member Since: September 2, 2009 Posts: 130 Comments: 21194
907. sebastianflorida
8:17 PM GMT on July 07, 2010
So, my luck is bahama feature develops, does a loop, lands in my yard
Member Since: August 5, 2007 Posts: 0 Comments: 719
906. whipster
8:16 PM GMT on July 07, 2010
Quoting wunderkidcayman:
HEY GUYS GUESS WHAT JUST HAPPEN TO ME I WAS GIVING A FRIEND OF MINE A WEATHER REPORT SHE IS A HAIR DRESSER AND SHE HAD THE PHONE ON SPEAKER SO EVERYONE COULD HEAR AND THIS GUY THAT HEARD IT CAME UP AND SPOKE TO ME ON THE PHONE HE IS THE DIRECTOR OF CITN/WESTSTAR OUR TV/NEWS NETWORK HERE IN CAYMAN AND HE ASKED ME TO MEET WITH HIM SO THIS IS JUST GREAT


Sounds like a nice job...most days are "sunny and warm, light breeze"
Member Since: August 14, 2007 Posts: 0 Comments: 439
905. KarenRei
8:16 PM GMT on July 07, 2010
Quoting MiamiHurricanes09:
That graph is from July 2nd.


I caught my ECMWF bookmark's mistake right after I submitted the post... but apparently I couldn't edit it fast enough for all of you ;)
Member Since: September 7, 2007 Posts: 1 Comments: 940
904. ElConando
8:16 PM GMT on July 07, 2010
Quoting StormW:


No...if the upper level low organizes to the surface, it may cross FL., or it may stall and head out to sea. If the area of convection to the south of that becomes the feature to watch, it should head out to sea.


my bad got crossed up between the two. Thank you for the clarification though.
Member Since: September 6, 2009 Posts: 2 Comments: 3784
903. IKE
8:16 PM GMT on July 07, 2010
87.6 at my location....humid and sunny.
Member Since: June 9, 2005 Posts: 23 Comments: 37860
902. Hurricanes101
8:15 PM GMT on July 07, 2010
............
Member Since: March 10, 2010 Posts: 1 Comments: 7874
901. angiest
8:15 PM GMT on July 07, 2010
Quoting KarenRei:
Oh great... thanks, ECMWF:



2010's goal is apparently to wash Laredo and Brownsville off the map.


That forecast is most of a week old now. It looks wrong on the intensity but the location is fairly good, it would appear.
Member Since: August 26, 2006 Posts: 16 Comments: 4766
.
Member Since: September 2, 2009 Posts: 130 Comments: 21194
Looks like the tropics could be active next week...and I'm gonna miss most of it being on vacation next week.
Member Since: August 2, 2007 Posts: 19 Comments: 19234
Quoting KarenRei:
Oh great... thanks, ECMWF:



2010's goal is apparently to wash Laredo and Brownsville off the map.
This is from last Friday.
Member Since: Posts: Comments:
Quoting MiamiHurricanes09:
That's a really good example as far as intensity and track goes.


Hopefully it won't re intensify over land.
Member Since: September 6, 2009 Posts: 2 Comments: 3784
wunderkidcayman... caps lock key is usually below the tab key, above the shift key. Hit it.
Member Since: Posts: Comments:
(snip)
Member Since: September 7, 2007 Posts: 1 Comments: 940
Quoting wunderkidcayman:
HEY GUYS GUESS WHAT JUST HAPPEN TO ME I WAS GIVING A FRIEND OF MINE A WEATHER REPORT SHE IS A HAIR DRESSER AND SHE HAD THE PHONE ON SPEAKER SO EVERYONE COULD HEAR AND THIS GUY THAT HEARD IT CAME UP AND SPOKE TO ME ON THE PHONE HE IS THE DIRECTOR OF CITN/WESTSTAR OUR TV/NEWS NETWORK HERE IN CAYMAN AND HE ASKED ME TO MEET WITH HIM SO THIS IS JUST GREAT


GOTTA LOVE THAT CAPS LOCK BUTTON, HUH?
Member Since: August 2, 2007 Posts: 19 Comments: 19234
JAMES RIVER (MADIS)
Updated: 8 sec ago
Scattered Clouds
105.4 F
Scattered Clouds
Humidity: 37%
Dew Point: 69 F
Wind: 0.0 mph
Wind Gust: 1.1 mph
Pressure: 29.93 in (Falling)
Heat Index: 112 F

my ac is too old for this...lol...
Member Since: September 7, 2005 Posts: 7 Comments: 1525
As saturated as the ground is here all along the Texas coast it won't take a whole lot of wind to do some tree damage. I'm not talking limbs, but trees falling over.
Member Since: July 25, 2008 Posts: 0 Comments: 626
2007's Tropical Storm Erin nearing landfall:

Member Since: August 2, 2007 Posts: 19 Comments: 19234
HEY GUYS GUESS WHAT JUST HAPPEN TO ME I WAS GIVING A FRIEND OF MINE A WEATHER REPORT SHE IS A HAIR DRESSER AND SHE HAD THE PHONE ON SPEAKER SO EVERYONE COULD HEAR AND THIS GUY THAT HEARD IT CAME UP AND SPOKE TO ME ON THE PHONE HE IS THE DIRECTOR OF CITN/WESTSTAR OUR TV/NEWS NETWORK HERE IN CAYMAN AND HE ASKED ME TO MEET WITH HIM SO THIS IS JUST GREAT
Member Since: Posts: Comments:
(CNN) -- The International Bridge between Nuevo Laredo, Mexico, and Laredo, Texas, was closed Wednesday because of rising water on the Rio Grande, Laredo officials said. FULL STORY

Member Since: Posts: Comments:
Quoting StormW:


Well, right now, until I get updated steering for tonight, there are 2 possible scenarios...it continues SSW, and crosses into FL., or it continues SSW, stalls, does a semi-cyclonic loop, and heads back out to sea.
Hopefully not a loop thing like Jeanne in 04. Thanks
Member Since: August 5, 2007 Posts: 0 Comments: 719

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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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