1821 Hurricane would be much worse than Sandy

[Amped]

Here's the article. It suggest Sandy may not have been a 500 year event.   The 1821 storm was close to what Irene would have been if the ECMWF intensity forecasts had verified.

 

 

 http://www.usatoday.com/story/weather/2014/09/18/east-coast-hurricane-disaster/15829585/

 

Losses linked to the hurricane's storm surge and wind damage potentially top $100 billion, roughly twice Sandy's toll.

Such a storm already has hit — in 1821 — and Tropical Storm Irene took a similar track in 2011, according to Swiss Re, a global reinsurance company, which released its study Thursday.

 

 

Linkin said Swiss Re's modeling showed that the 1821 storm was a Category 4 hurricane at landfall in North Carolina and a Category 3 storm when it struck Sept. 3 at Cape May.

Here's the report on it.

http://media.swissre.com/documents/the_big_one_us_hurricane.pdf

 

 

[billgwx]

Irene was moving slowly enough to allow a surface-based inversion to set up, so no way were those 90+ kt flight level winds going to reach ground level. As I recall, the intensity we were seeing in the ECMWF (at least MSLP) was a bogus interpolation artifact of the 1-degree model resolution as we could see it in the free distribution, and not truly what the model was forecasting anyway?

 

What gives me pause about the 1821 hurricane are the high storm tides which occurred at low astronomical tide. Sandy broke the NYC record tide at the Battery thanks to coming in at high astronomical tide, so imagine an 1821-type storm at high tide, at that time of year when astronomical high tides are running at their peak.

[Kory]

Here's the article. It suggest Sandy may not have been a 500 year event.   The 1821 storm was close to what Irene would have been if the ECMWF intensity forecasts had verified.

 

 

 http://www.usatoday.com/story/weather/2014/09/18/east-coast-hurricane-disaster/15829585/

 

Here's the report on it.

http://media.swissre.com/documents/the_big_one_us_hurricane.pdf

Actually, Sandy was a 1 in 700 year event.  Very rare set up.  But just because something is a 1 in 700 year event doesn't mean it'll only happen once every 700 years.  Just means there is a 0.14% chance of it happening in ant given year.  Astronomically small chances, but not impossible.  

 

http://www.livescience.com/38144-hurricane-sandy-700-year-event.html

[icebreaker5221]

Here's the article. It suggest Sandy may not have been a 500 year event.   The 1821 storm was close to what Irene would have been if the ECMWF intensity forecasts had verified.

 

 

 http://www.usatoday.com/story/weather/2014/09/18/east-coast-hurricane-disaster/15829585/

 

Here's the report on it.

http://media.swissre.com/documents/the_big_one_us_hurricane.pdf

 

Actually, Sandy was a 1 in 700 year event.  Very rare set up.  But just because something is a 1 in 700 year event doesn't mean it'll only happen once every 700 years.  Just means there is a 0.14% chance of it happening in ant given year.  Astronomically small chances, but not impossible.  

 

http://www.livescience.com/38144-hurricane-sandy-700-year-event.html

 

Sandy was a 1 in 700 year event due to its angle of approach.  That does not imply at all that a stronger storm, but with a more traditional track, would have a similar return period.  Something along the likes of 1938, 1821, 1869, etc is more likely to occur over the next century than another Sandy. 

[Absolute Humidity]

Sandy was a 1 in 700 year event due to its angle of approach.  That does not imply at all that a stronger storm, but with a more traditional track, would have a similar return period.  Something along the likes of 1938, 1821, 1869, etc is more likely to occur over the next century than another Sandy.

Perhaps equally as freakish was the nor'easter occurring just 1 week after Sandy dumping a foot plus of snow just a few miles inland in central NJ and upto 6" along the devastated NJ coastline.

[Rjay]

Perhaps equally as freakish was the nor'easter occurring just 1 week after Sandy dumping a foot plus of snow just a few miles inland in central NJ and upto 6" along the devastated NJ coastline.

I had just gotten my power back and lost it due to the weight of the snow on the trees. Some really cold nights with no heat in our area. Long Island (especially JM-land/barrier islands and Freeport/Lindenhurst on the bay) was really devastated by Sandy. The snow and more falling trees just added insult to injury.

[Rjay]

Irene was moving slowly enough to allow a surface-based inversion to set up, so no way were those 90+ kt flight level winds going to reach ground level. As I recall, the intensity we were seeing in the ECMWF (at least MSLP) was a bogus interpolation artifact of the 1-degree model resolution as we could see it in the free distribution, and not truly what the model was forecasting anyway?

What gives me pause about the 1821 hurricane are the high storm tides which occurred at low astronomical tide. Sandy broke the NYC record tide at the Battery thanks to coming in at high astronomical tide, so imagine an 1821-type storm at high tide, at that time of year when astronomical high tides are running at their peak.

There was a 92 mph wind gust recorded in Shirley on Long Island during Irene but most max gusts were in the 60-70 mph range.

Sandy's size, angle of approach along with it hitting a few hours before at astronomical high tide was what made the storm surge so bad. I wonder what the size of the 1821 storm was.

[Absolute Humidity]

I had just gotten my power back and lost it due to the weight of the snow on the trees. Some really cold nights with no heat in our area. Long Island (especially JM-land/barrier islands and Freeport/Lindenhurst on the bay) was really devastated by Sandy. The snow and more falling trees just added insult to injury.

Yes, had more tree damage from the snow than Sandy

[Harry]

Back in the late 80s/early 90s when i lived at the DE coast we had this crazy blowout tide and i noticed what looked like a ton of tree trunks where the water usually covered them ( bay and Ocean ) and i asked around about it and was told about this hurricane. Evidently a number of barrier islands were lost and wiped clean by the hurricane.

[AvantHiatus]

I disagree in regards to 1 in 700 year event, mostly because Sandy was not a traditional tropical cyclone. Patterns will change as we shift into uncharted territory in the future.

[Sunny and Warm]

I disagree in regards to 1 in 700 year event, mostly because Sandy was not a traditional tropical cyclone. Patterns will change as we shift into uncharted territory in the future.

By definition, the future is uncharted.  That said, the Earth has been through a snowball Earth and a Hot Earth and everything in between.  As long as the weather doesn't defy the physical laws, we'll be able to chart it.

[JBG]

Perhaps equally as freakish was the nor'easter occurring just 1 week after Sandy dumping a foot plus of snow just a few miles inland in central NJ and upto 6" along the devastated NJ coastline.

Wasn't that storm to some extent a "son of Sandy"? I mean in the sense that the amount of cold air pulled down was astronomical for that time of year and the trough was left in perfect position by Sandy? Imagine how much snow if that could have replicated in February?

[donsutherland1]

Perhaps equally as freakish was the nor'easter occurring just 1 week after Sandy dumping a foot plus of snow just a few miles inland in central NJ and upto 6" along the devastated NJ coastline.

Some photos from that snowfall: http://wintercenter.homestead.com/photonov2012a.html

[Absolute Humidity]

Some photos from that snowfall: http://wintercenter.homestead.com/photonov2012a.html

Great shots Don. The last one with the fallen snow covered Sandy trees is a testament to the extreme weather we had for those two events. Here's a few pics from the Nov nor'easter

[Amped]

You can get 2 very rare events in the same week before the longwave pattern breaks down.  Once the patterns gone it's not coming back though.

 

However with increased October blocking in recent years from AGW, I don't think these events are all that rare anymore. Just for giggles, look at the 00z GFS 384.     September events like 1821 and 1938 maybe a little to early to be effected by the increased fall blocking and could remain rarities.

[Sunny and Warm]

You can get 2 very rare events in the same week before the longwave pattern breaks down.  Once the patterns gone it's not coming back though.

 

However with increased October blocking in recent years from AGW, I don't think these events are all that rare anymore. Just for giggles, look at the 00z GFS 384.     September events like 1821 and 1938 maybe a little to early to be effected by the increased fall blocking and could remain rarities.

You cannot pin 2012 on AGW any more than I can pin the beautiful fall weather I've had for the past week on AGW.  You cannot pick and choose what is caused by AGW and claim causation.  Let's leave AGW to the climate forum where it belongs.

[JBG]

You can get 2 very rare events in the same week before the longwave pattern breaks down.  Once the patterns gone it's not coming back though.

 

However with increased October blocking in recent years from AGW, I don't think these events are all that rare anymore. Just for giggles, look at the 00z GFS 384.     September events like 1821 and 1938 maybe a little to early to be effected by the increased fall blocking and could remain rarities.

I guess everything is caused by AGW. Maybe my hangover after some wine tasting in the Sukkot was really AGW?

You cannot pin 2012 on AGW any more than I can pin the beautiful fall weather I've had for the past week on AGW. You cannot pick and choose what is caused by AGW and claim causation.

I agree. This is beyond stupid.

[vortex95]

I guess everything is caused by AGW. Maybe my hangover after some wine tasting in the Sukkot was really AGW?

I agree. This is beyond stupid.

 

Let me add one more thing here to prove a point...how about *three* extreme events in short period?  You had the Jan 20-21, 1978 blizzard that produced BOS's record 24 hour snowfall up to this time.  Then the "Cleveland Superbomb" 4 days later, and then the Blizzard of '78 Feb 6-7.  Similar pattern breeds similar events, and if it is an extreme pattern, then extreme storms happen.  Nothing much too it.  Sometimes when it rains, it pours.

[chubbs]

Mid-Atlantic coast is becoming more vulnerable to flooding. Sea level has risen 16" in past 100 years at Atlantic City

[Sunny and Warm]

Mid-Atlantic coast is becoming more vulnerable to flooding. Sea level has risen 16" in past 100 years at Atlantic City

has the sea risen by 16", or has the land subsided by 16", or a combination of both?

[StudentOfClimatology]

has the sea risen by 16", or has the land subsided by 16", or a combination of both?

A lot of it is indeed a result of geologic/topographical changes. Looks like it's the same group of nutcases going from forum to forum, derailing threads with CC-forum crap.

[chubbs]

has the sea risen by 16", or has the land subsided by 16", or a combination of both?

 It is roughly 50/50 sea level rise and local subsidence/sediment compaction. Similar pattern is seen at other mid-Atlantic tide gauges

[Typhoon Tip]

Sandy was a 1 in 700 year event due to its angle of approach.  That does not imply at all that a stronger storm, but with a more traditional track, would have a similar return period.  Something along the likes of 1938, 1821, 1869, etc is more likely to occur over the next century than another Sandy. 

 

That's the way I understood of Sandy, too. It didn't have much to do with any other aspect about the storm.  The interest in terms of statistical rarity as it applied to Sandy was entirely storm track related.  

 

For the general read ... Getting a TC to resume a westward motion that high in latitude is rare because typical planetary atmospheric physics rarely supports easterly deep layer steering as high as NJ; with the exception of closed lows, but that's a different aspect.   It took some extraordinary timing and arrangement of large scaled mass fields associated with the NAO domain in tandem with a perturbation in the PNAP circulation over the U.S. to bring all that about.  

 

As far as the "imagine if" , truth is oft stranger than fiction.  "What if" Sandy was a category 2 or 3 cyclone?  What if Sandy came in not at Brigantine NJ but closer to the NY Bite area, itself??  The epicosity of Sandy could very easily be rewritten with higher implications and still not be too absurd relative to 'what can happen' to believe the scenarios could not take place.  It's just a matter of time, be it 1::500 or one in 1::500,000.  Moreover, 1::500 could mean you get horror, three years in a row, and then quiescence for 1,500 ...and so on and so on. 

 

However, Sandy, according to NOAA was not actually a hurricane at landfall.  They release press in February of 2013 stating that it was in fact a "post-tropical-cyclone with hurricane force winds."    I'm like, ....really?    Tongue in cheek:  I always found that to be a little convenient (right or wrong...) considering that there was some heat in the aftermath that hurricane warnings were not officially issued prior to the havoc.  Either way, what's the difference ... really.  J.Q. dock hand, boat-owner, beach front Inn masters to mayors and municipalities and back would be lost in semantics;  imho they should have stuck to something that resonates with public awareness. 

 

Any culpability aside (and philosophically the blame is really demographic swelling in the line of fire anyway) ... the entire megalopolis is in danger as a static base-line risk assessment.  Whether it be for a 1938 redux, or a Canary Island geological bifurcation event sending a 500' tsunamis to the foothills of the Apps ... there's plenty of available chapters in that macabre story about an ill-fate society, with less excuse than a hapless Pompeiin. With everything science and society knows of natural threat, there is a shockingly low regard for heeding to the information at hand. 

 

Of course... what's the point in an Ebola world with a comets in orbit - ha!

[vortex95]

That's the way I understood of Sandy, too. It didn't have much to do with any other aspect about the storm.  The interest in terms of statistical rarity as it applied to Sandy was entirely storm track related.  

 

For the general read ... Getting a TC to resume a westward motion that high in latitude is rare because typical planetary atmospheric physics rarely supports easterly deep layer steering as high as NJ; with the exception of closed lows, but that's a different aspect.   It took some extraordinary timing and arrangement of large scaled mass fields associated with the NAO domain in tandem with a perturbation in the PNAP circulation over the U.S. to bring all that about.  

 

As far as the "imagine if" , truth is oft stranger than fiction.  "What if" Sandy was a category 2 or 3 cyclone?  What if Sandy came in not at Brigantine NJ but closer to the NY Bite area, itself??  The epicosity of Sandy could very easily be rewritten with higher implications and still not be too absurd relative to 'what can happen' to believe the scenarios could not take place.  It's just a matter of time, be it 1::500 or one in 1::500,000.  Moreover, 1::500 could mean you get horror, three years in a row, and then quiescence for 1,500 ...and so on and so on. 

 

However, Sandy, according to NOAA was not actually a hurricane at landfall.  They release press in February of 2013 stating that it was in fact a "post-tropical-cyclone with hurricane force winds."    I'm like, ....really?    Tongue in cheek:  I always found that to be a little convenient (right or wrong...) considering that there was some heat in the aftermath that hurricane warnings were not officially issued prior to the havoc.  Either way, what's the difference ... really.  J.Q. dock hand, boat-owner, beach front Inn masters to mayors and municipalities and back would be lost in semantics;  imho they should have stuck to something that resonates with public awareness. 

 

Any culpability aside (and philosophically the blame is really demographic swelling in the line of fire anyway) ... the entire megalopolis is in danger as a static base-line risk assessment.  Whether it be for a 1938 redux, or a Canary Island geological bifurcation event sending a 500' tsunamis to the foothills of the Apps ... there's plenty of available chapters in that macabre story about an ill-fate society, with less excuse than a hapless Pompeiin. With everything science and society knows of natural threat, there is a shockingly low regard for heeding to the information at hand. 

 

Of course... what's the point in an Ebola world with a comets in orbit - ha!

 

Not to open a can of worms again, but since we are taking about Sandy's nature and impact here,

I'd thought I'd repost something I wrote up not long after the event.  Disclaimer:  I recognize

that exact transition of tropical to ET/PT is not a fine line and even with a plethora of in-situ data

available, that call can still be subjective.  That said, I point out that we have seen a number of

times TCs in the ET/PT transition look a lot less tropical on satellite, and they were still held at

TC status.  Case in point, look at TS Fay at 15z today.  Look at how far removed the convection is

from the center, let alone disorganized.  Sandy looked more tropical and organized overall at

landfall.  Food for thought.  When it is subjective, it can go either way.

 

One thing I will add that I did not mention the first time...yes,I know the NAM is not the greatest

when it comes to handling TCs, but that is for forecasts only.  Initial 00 hr analyses I chose because

of the model's resolution.

 

**********************

 

Looking at the 1000-500 mb thickness pattern from the NAM 00 hour

initial analyses,  I think this shows decent overview of Sandy's core

nature.

 

 

12z 10/28...582 and 576 closed thickness contours around Sandy's

surface center.

http://home.comcast.net/~trwplusa/namsfc12102812z.gif

582 dm is a common with TCs.  Sometimes you will see 588, but I don't

recall ever seeing 594 with a TC, at least on NAM.  It probably does

occur, just it is so small that the NAM's resolution does not pick it

up.

18z 10/29...slightly cooler column with closed 576 and 570 dm contours

around the surface center.  Yes, there is a strong thickness gradient

to the W, but the important thing is that the center appears still

isolated from that, indicating we still have mostly a TC here at the

core.

http://home.comcast.net/~trwplusa/namsfc12102918z.gif

00z 10/30...the thickness pool has continued to cool, but we still

have closed 570 and 564 dm thickness contours around the surface center.  

The 570 center and the surface center are not co-located exactly, but I

would say here the two 6 dm closure is still indicative that from 500

mb and below in the mean, the core is still mostly isolated from the

strong baroclinic zone nearby.

http://home.comcast.net/~trwplusa/namsfc12103000z.gif

06z 10/30...the closed thickness contours around the surface center are

gone and the thickness is now below 558 dm over the surface center.

http://home.comcast.net/~trwplusa/namsfc12103006z.gif

12z 10/30...the thickness has dropped to 546 dm over the surface center.

http://home.comcast.net/~trwplusa/namsfc12103012z.gif

So from 00z to 12z on 10/30, you have a drop from 570 to 546 dm 1000-500

thickness.  That's going from a rather warm thickness to a fairly cool

one.  Going by the NAM 00 hour initial 1000-500 thickness analyses alone,

I would still call Sandy a fairly strong warm core structure at 30/00z,

with rapid extratropical transition by 06z as rapid cooling of the column

occurred and the loss of the closed 6 dm thickness contours indicating

the surface low was no longer isolated from the baroclinic zone.

Sandy type evolutions/events I believe have occurred before on the U.S.

East Coast...Hurricane Hazel in October 1954 and the Long Island Express

in September 1938.  Both were close to Sandy's pressure at landfall with

fronts and strong baroclinic zones very near the center.  Hazel was kept

at hurricane status at a landfall in initial analysis and recent

re-analysis, and the Long Island Express that had been analyzed

extratropical initially prior to landfall was reanalyzed as a hurricane

at landfall.  Both were analyzed extratropical a few hours after

landfall.

 

[Typhoon Tip]

Not to open a can of worms again, but since we are taking about Sandy's nature and impact here,

I'd thought I'd repost something I wrote up not long after the event.  Disclaimer:  I recognize

that exact transition of tropical to ET/PT is not a fine line and even with a plethora of in-situ data

available, that call can still be subjective.  That said, I point out that we have seen a number of

times TCs in the ET/PT transition look a lot less tropical on satellite, and they were still held at

TC status.  Case in point, look at TS Fay at 15z today.  Look at how far removed the convection is

from the center, let alone disorganized.  Sandy looked more tropical and organized overall at

landfall.  Food for thought.  When it is subjective, it can go either way.

 

One thing I will add that I did not mention the first time...yes,I know the NAM is not the greatest

when it comes to handling TCs, but that is for forecasts only.  Initial 00 hr analyses I chose because

of the model's resolution.

 

**********************

 

Looking at the 1000-500 mb thickness pattern from the NAM 00 hour

initial analyses,  I think this shows decent overview of Sandy's core

nature.

 

 

12z 10/28...582 and 576 closed thickness contours around Sandy's

surface center.

http://home.comcast.net/~trwplusa/namsfc12102812z.gif

582 dm is a common with TCs.  Sometimes you will see 588, but I don't

recall ever seeing 594 with a TC, at least on NAM.  It probably does

occur, just it is so small that the NAM's resolution does not pick it

up.

18z 10/29...slightly cooler column with closed 576 and 570 dm contours

around the surface center.  Yes, there is a strong thickness gradient

to the W, but the important thing is that the center appears still

isolated from that, indicating we still have mostly a TC here at the

core.

http://home.comcast.net/~trwplusa/namsfc12102918z.gif

00z 10/30...the thickness pool has continued to cool, but we still

have closed 570 and 564 dm thickness contours around the surface center.  

The 570 center and the surface center are not co-located exactly, but I

would say here the two 6 dm closure is still indicative that from 500

mb and below in the mean, the core is still mostly isolated from the

strong baroclinic zone nearby.

http://home.comcast.net/~trwplusa/namsfc12103000z.gif

06z 10/30...the closed thickness contours around the surface center are

gone and the thickness is now below 558 dm over the surface center.

http://home.comcast.net/~trwplusa/namsfc12103006z.gif

12z 10/30...the thickness has dropped to 546 dm over the surface center.

http://home.comcast.net/~trwplusa/namsfc12103012z.gif

So from 00z to 12z on 10/30, you have a drop from 570 to 546 dm 1000-500

thickness.  That's going from a rather warm thickness to a fairly cool

one.  Going by the NAM 00 hour initial 1000-500 thickness analyses alone,

I would still call Sandy a fairly strong warm core structure at 30/00z,

with rapid extratropical transition by 06z as rapid cooling of the column

occurred and the loss of the closed 6 dm thickness contours indicating

the surface low was no longer isolated from the baroclinic zone.

Sandy type evolutions/events I believe have occurred before on the U.S.

East Coast...Hurricane Hazel in October 1954 and the Long Island Express

in September 1938.  Both were close to Sandy's pressure at landfall with

fronts and strong baroclinic zones very near the center.  Hazel was kept

at hurricane status at a landfall in initial analysis and recent

re-analysis, and the Long Island Express that had been analyzed

extratropical initially prior to landfall was reanalyzed as a hurricane

at landfall.  Both were analyzed extratropical a few hours after

landfall.

 

 

 

Fun read... nice diligence there.  

 

Yeah the impetus for my bring that up was really not to impugn the subjective opinion about what Sandy really was... I really was just lightly criticizing the public awareness and that regardless of an exacting interpretation (that comes off a little heavy like an excuse) the importance here is the public awareness.  Hurricane Warning resonates...  and since the "subjective" boundary between hurricane and what they called it could veraciously be evenly applied, they would have been fine ... more importantly, meeting with the goal of public safety if they just stuck with the former. 

[MGorse]

Fun read... nice diligence there.  

 

Yeah the impetus for my bring that up was really not to impugn the subjective opinion about what Sandy really was... I really was just lightly criticizing the public awareness and that regardless of an exacting interpretation (that comes off a little heavy like an excuse) the importance here is the public awareness.  Hurricane Warning resonates...  and since the "subjective" boundary between hurricane and what they called it could veraciously be evenly applied, they would have been fine ... more importantly, meeting with the goal of public safety if they just stuck with the former. 

 

A change has been made regarding scenario's like this, thus hurricane warnings will be issued instead of non-tropical warnings.

 

Hurricane warning resonates? Yes, however hurricane warnings were up well in advance of Katrina in 2005, and look what happened there.

[Typhoon Tip]

A change has been made regarding scenario's like this, thus hurricane warnings will be issued instead of non-tropical warnings.

 

Hurricane warning resonates? Hurricane warnings were up well in advance of Katrina in 2005, and look what happened there.

 

 Word... 

 

However, that's a different sort of phenomenon altogether.  It's called Darwinism ... 

 

I suppose more precisely, "Hurricane Warning" resonates 'MORE', but not absolutely ... no.   We're always going to have to deal with apathetic jamokes oblivious to threat and/or disrespectful to it, due to all kind of degrees of lacks enlightenment.  There's nothing one can do about that guy on the volcano, that refuses to leave during the earthquake swarming pre-eruption phase that's so obviously impending a doom to anyone with a modicum of self-preservation ... Their personal beliefs, based upon irrationality and ignorance in varying proportions, prevents them from prudence.  It's not even sad to me, because that requires some kind of unavoidable dark irony and tragedy ... It's stupid, and an opportunity to remove them from the gene pool.    

[JBG]

 Word... 

 

However, that's a different sort of phenomenon altogether.  It's called Darwinism ... 

 

I suppose more precisely, "Hurricane Warning" resonates 'MORE', but not absolutely ... no.   We're always going to have to deal with apathetic jamokes oblivious to threat and/or disrespectful to it, due to all kind of degrees of lacks enlightenment.  There's nothing one can do about that guy on the volcano, that refuses to leave during the earthquake swarming pre-eruption phase that's so obviously impending a doom to anyone with a modicum of self-preservation ... Their personal beliefs, based upon irrationality and ignorance in varying proportions, prevents them from prudence.  It's not even sad to me, because that requires some kind of unavoidable dark irony and tragedy ... It's stupid, and an opportunity to remove them from the gene pool.

The problem though is false alarms and over-hyping. Irene, for example, was under-publicized in Vermont and upstate New York. The overhyping in New York City was destructive and expensive. Generals always fight the last war, however, and that one was Sandy. At the time of Sandy it was Irene, and Sandy indeed did not produce much rain, at least in New York City, Long Island and Westchester. It produced untold devastation, however.

Some of the main effects, such as lengthy power outages and gasoline shortages were either the result of mismanagement or unforecast.

[Amped]

Not to open a can of worms again, but since we are taking about Sandy's nature and impact here,

I'd thought I'd repost something I wrote up not long after the event.  Disclaimer:  I recognize

that exact transition of tropical to ET/PT is not a fine line and even with a plethora of in-situ data

available, that call can still be subjective.  That said, I point out that we have seen a number of

times TCs in the ET/PT transition look a lot less tropical on satellite, and they were still held at

TC status.  Case in point, look at TS Fay at 15z today.  Look at how far removed the convection is

from the center, let alone disorganized.  Sandy looked more tropical and organized overall at

landfall.  Food for thought.  When it is subjective, it can go either way.

 

One thing I will add that I did not mention the first time...yes,I know the NAM is not the greatest

when it comes to handling TCs, but that is for forecasts only.  Initial 00 hr analyses I chose because

of the model's resolution.

 

**********************

 

Looking at the 1000-500 mb thickness pattern from the NAM 00 hour

initial analyses,  I think this shows decent overview of Sandy's core

nature.

 

 

12z 10/28...582 and 576 closed thickness contours around Sandy's

surface center.

http://home.comcast.net/~trwplusa/namsfc12102812z.gif

582 dm is a common with TCs.  Sometimes you will see 588, but I don't

recall ever seeing 594 with a TC, at least on NAM.  It probably does

occur, just it is so small that the NAM's resolution does not pick it

up.

18z 10/29...slightly cooler column with closed 576 and 570 dm contours

around the surface center.  Yes, there is a strong thickness gradient

to the W, but the important thing is that the center appears still

isolated from that, indicating we still have mostly a TC here at the

core.

http://home.comcast.net/~trwplusa/namsfc12102918z.gif

00z 10/30...the thickness pool has continued to cool, but we still

have closed 570 and 564 dm thickness contours around the surface center.  

The 570 center and the surface center are not co-located exactly, but I

would say here the two 6 dm closure is still indicative that from 500

mb and below in the mean, the core is still mostly isolated from the

strong baroclinic zone nearby.

http://home.comcast.net/~trwplusa/namsfc12103000z.gif

06z 10/30...the closed thickness contours around the surface center are

gone and the thickness is now below 558 dm over the surface center.

http://home.comcast.net/~trwplusa/namsfc12103006z.gif

12z 10/30...the thickness has dropped to 546 dm over the surface center.

http://home.comcast.net/~trwplusa/namsfc12103012z.gif

So from 00z to 12z on 10/30, you have a drop from 570 to 546 dm 1000-500

thickness.  That's going from a rather warm thickness to a fairly cool

one.  Going by the NAM 00 hour initial 1000-500 thickness analyses alone,

I would still call Sandy a fairly strong warm core structure at 30/00z,

with rapid extratropical transition by 06z as rapid cooling of the column

occurred and the loss of the closed 6 dm thickness contours indicating

the surface low was no longer isolated from the baroclinic zone.

Sandy type evolutions/events I believe have occurred before on the U.S.

East Coast...Hurricane Hazel in October 1954 and the Long Island Express

in September 1938.  Both were close to Sandy's pressure at landfall with

fronts and strong baroclinic zones very near the center.  Hazel was kept

at hurricane status at a landfall in initial analysis and recent

re-analysis, and the Long Island Express that had been analyzed

extratropical initially prior to landfall was reanalyzed as a hurricane

at landfall.  Both were analyzed extratropical a few hours after

landfall.

 

 I thought I was the only one watching Sandy deepen at 500mb.  It seems ET transition usually occurs when it hits the cooler shelf waters.  That cool shelf  has saved NE, NJ and NYC from many storms that could have been a lot worse. Frictional convergence with land can also help the surface CF collapse in on the center of a TC. 850 temp over Sandy's center dropped about 15C during the 24 hrs surrounding landfall.

[jm1220]

 I thought I was the only one watching Sandy deepen at 500mb.  It seems ET transition usually occurs when it hits the cooler shelf waters.  That cool shelf  has saved NE, NJ and NYC from many storms that could have been a lot worse. Frictional convergence with land can also help the surface CF collapse in on the center of a TC. 850 temp over Sandy's center dropped about 15C during the 24 hrs surrounding landfall.

Sandy was very much like a 1991 Perfect Storm but much deeper and dominated by the tropical system rather than the baroclinic one like 1991, which ingested Grace into its circulation. There was tremendous divergence aloft over Sandy caused by the negative tilt and then the phase with the system coming out of the Midwest. The -NAO did the dirty work by forcing a NW track. Pure hurricanes aren't the greatest threat up here (i.e. an Irene)-hurricanes really need an assist from mid latitude systems to really be a danger at this latitude. They prevent the east recurve and provide a barrier against weakening from the dry and cold air intrusions from land and cold waters.

 

Needless to say Sandy was unlike any storm I've ever experienced and is the new benchmark storm for this area (1938 becomes worse once into Suffolk County-the effects from Sandy became less severe once you head not far east from here). Three feet of water flooded my house, we had wind gusts up to 90 mph and no utilities including tap water for weeks. One way in which we lucked out is that it was well forecast for days, and people had time to prepare. If anything, I'm surprised the death toll wasn't higher given how incredibly densely populated the areas hit hardest are.