Thoughts on 2013 Atlantic Hurricane Season

[Frank2]

that's an interesting theory and i did view the slideshow linked below too. I recall a theory advanced on the TWC that was just the opposite. they were showing urban heat islands and theorizing that those heat islands helped INCREASE precip as a result of the relative instability related to a local hotspot... it yielded increased convection over, and just downwind of the urban area. i recall satellite pics of thunderstorm activity to demonstrate the phenomenon. On a broader scale, i don't believe deforestation, to the extent that it exists, is in any way responsible for our reduction in TC activity. i would imagine that evapotranspiration is a nominal additive to overall atmospheric water content. afterall, every gallon of water dumped back into the atmosphere via evapotranspiration must have first evaporated from the sea...unless i'm missing something. the sea surface is the proverbial 800lb gorilla. Clearly something is missing this year. i have no idea what that is but something tells me human activity via urbanization/deforestation is not the answer.

Sure the oceans are the main source of moisture, but the balance is so delicate that too much loss of forested land is bound to cause something serious to happen, if nothing else it might upset the balance of the air we breath, but for certain the noticeable lack of rainfall across the US and World is troubling...

Anyway, back to the topic for me - as some said, 1977 was very quiet except for Anita, but that was fine with my parents - we had just returned to Miami after a break of a few years and a busy season might have chased us away for good (lol) - 1979 was another matter, however...

[ninel conde]

i doubt worldwide rainfall is down. once more this year we are way above normal in rainfall here.

[Hammy]

i doubt worldwide rainfall is down. once more this year we are way above normal in rainfall here.

You cannot estimate global rainfall based on one or two locations, it just does not work that way.

[ninel conde]

i realize that, but i havent heard of any lack of worldwide rainfall.

[Ptarmigan]

As this season is drawing to a close (there is no reason to think things will pick up a great deal in October), I am believing that El Nino/La Nina or sea surface temperatures are not the biggest factor of whether or not a season will be active - it is atmospheric moisture. It impacts not only the development of thunderstorms, but shear and other parameters that inhibit development. I do not think I can trust another seasonal forecast unless this parameter is seriously factored in.

I really wish there was more data to find out what was going on in 1977 when the combined E-Pac and Atlantic ACE was 47. There was an El Nino but it was not that strong...beyond that, I do not know what other information is out there. I don't know if it means anything but the following winter (77-78) was indeed a doozy...

I suspect there are many factors for why 1977 was inactive.

Atlantic
Cool phase of Atlantic Multidecadal Oscillation
Higher Than Normal Sea Level Pressure Throughout Atlantic
Dry Air In Upper Atmosphere Over MDR
Westerly Wind Shear Over MDR
Higher Than Normal Precipitable Water Over Northeast South America
Precipitation Rate Higher Over Northeast South America

East Pacific
Higher Than Normal Sea Level Pressure In Main Area Of Development
Dry Air In Upper Atmosphere Off Coast of Central America

West Pacific
Higher Precipitation Rate In Smaller Area Around Equator

Indian Ocean
Higher Than Normal Precipitable Water Over Arabian Sea

There are so many factors at play. PDO went into warm phase in 1976 to 1977. I think monsoon is a factor as well.

I used Monthly/Seasonal Climate Composites from August to October.
http://www.esrl.noaa.gov/psd/cgi-bin/da ... intpage.pl

I set the map to Tropics.
SLP-Anomaly -3 to 3
Vector Wind-Anomaly 2 to 8
Precipitation Rate-Anomaly -3 to 3
Precipitable Water-Anomaly -5 to 5
Specific Humidity-Anomaly -0.8 to 0.8

[Frank2]

Very quiet out there this morning - if this keeps up Jim Cantore might have to unpack his suitcase for good (lol)...

There was a TWC program this year that explained the influence of the Amazon on the Earth's climate - far more than previously thought, so if that's lost, that's bad news...

The Amazon is (was) an incredible rainforest as large as the Sahara, but if it's cut down for the sake of $, then that's the world's loss, and no amount of money can replace that...

Frank

['CaneFreak]

Very quiet out there this morning - if this keeps up Jim Cantore might have to unpack his suitcase for good (lol)...

Trust me, Cantore is loving this quiet weather so he can go out and play a few rounds of golf...

[CrazyC83]

It looks like 1968 and 1977 are the best analogs right now...1968 had no majors anywhere, while 1977 had only Anita which bombed out in the western Gulf but otherwise were duds...

[HurrMark]

I looked at the ACE values since 1950 and ran a quick statistical analysis...some interesting findings...

- During the 1950-1969 period (active), the average ACE per storrm was 11.66. Between 1970-1994 (inactive), it was 6.73. It recovered somewhat between 1995 and 2012 to 9.08...but not to the levels of the 50s and 60s. So more than likely, assuming we have been in a cyclical pattern and were in a 1950s/60s-portion of the cycle, improved data and satellite imagery has helped "boost" the number of storms.

- During the current phase (1995-2012), we have not been above average in mean ACE since 2004 (not even 2005 was above average).

- Unless we get a decent hurricane or long-tracker, 2013 will by far have the lowest mean ACE of any season since 1950 (currently we are at 2.67; the next lowest is 3.40 in 1970).

So basically, we can probably say that we are naming more storms that would not have been considered as storms perhaps as recently as 10 years ago and therefore it is pretty much quantity over quality.

[Ntxw]

It looks like 1968 and 1977 are the best analogs right now...1968 had no majors anywhere, while 1977 had only Anita which bombed out in the western Gulf but otherwise were duds...

Both were turning on El Nino's in the fall (now) as well as -AMO. All of the top 5 lowest seasons as we are in now had one, the other, or both. 2013 has neither just to show how analogs have flipped and flopped all season from 2005 now to the 70s, crazy.

[Ptarmigan]

I looked at the ACE values since 1950 and ran a quick statistical analysis...some interesting findings...

- During the 1950-1969 period (active), the average ACE per storrm was 11.66. Between 1970-1994 (inactive), it was 6.73. It recovered somewhat between 1995 and 2012 to 9.08...but not to the levels of the 50s and 60s. So more than likely, assuming we have been in a cyclical pattern and were in a 1950s/60s-portion of the cycle, improved data and satellite imagery has helped "boost" the number of storms.

- During the current phase (1995-2012), we have not been above average in mean ACE since 2004 (not even 2005 was above average).

- Unless we get a decent hurricane or long-tracker, 2013 will by far have the lowest mean ACE of any season since 1950 (currently we are at 2.67; the next lowest is 3.40 in 1970).

So basically, we can probably say that we are naming more storms that would not have been considered as storms perhaps as recently as 10 years ago and therefore it is pretty much quantity over quality.

I have seen seasons that had really high ACE/Storm like 1915 (6/5/3 ACE: 130 ACE/Storm: 21.7) and 1926 (11/8/6 ACE: 230 ACE/Storm: 20.9). 1915 occurred in less active phase of hurricane season from 1900 to 1925. Of course this was before satellite, so there were likely more storms in those years.

Usually, active phase (warm) lasts longer than less active phase (cool). This is based on Atlantic Multidecadal Oscillation (AMO)
?-1900 Over 30 Years
1901-1925 24 Years
1926-1969 43 Years
1970-1994 24 Years
1995-? 18 Years (As of 2013)

I think this current warm phase of Atlantic could last 10 to 20 years.

[ConvergenceZone]

I'm sure the government is having a party about how much money they've saved this year due to no hurricanes....
That's so awesome!!!!!! (even though I'm still a selfish tracker that wanted more activity )

[vbhoutex]

i doubt worldwide rainfall is down. once more this year we are way above normal in rainfall here.

Uh, what planet are you talking about?
The Central US plains and Southern US from LA West to AZ have been in a drought for years. Perhaps your area is above normal, but our area, even after 5+" of rain last week is still in severe drought and down by almost a foot of rain for the year. For the last five years since Hurricane Ike we are down 5'-6' from normal in many areas of Texas. Might want to check your facts before making blanket statements.

[CrazyC83]

I looked at the ACE values since 1950 and ran a quick statistical analysis...some interesting findings...

- During the 1950-1969 period (active), the average ACE per storrm was 11.66. Between 1970-1994 (inactive), it was 6.73. It recovered somewhat between 1995 and 2012 to 9.08...but not to the levels of the 50s and 60s. So more than likely, assuming we have been in a cyclical pattern and were in a 1950s/60s-portion of the cycle, improved data and satellite imagery has helped "boost" the number of storms.

- During the current phase (1995-2012), we have not been above average in mean ACE since 2004 (not even 2005 was above average).

- Unless we get a decent hurricane or long-tracker, 2013 will by far have the lowest mean ACE of any season since 1950 (currently we are at 2.67; the next lowest is 3.40 in 1970).

So basically, we can probably say that we are naming more storms that would not have been considered as storms perhaps as recently as 10 years ago and therefore it is pretty much quantity over quality.

I looked at the 2012 season with old technology: before satellites and other analytics, it would have been 12/6/1.

Florence, Joyce, Kirk, Michael, Oscar, Patty and Tony would have slipped through the cracks (no ship or land reports) and Helene could only be analyzed as a tropical depression based on pressure relationships and surface observations. Nadine, interestingly, would likely have been counted twice as two separate tropical storms since there were no clues of it making the wild loops. Chris and Nadine (both times) would have only been counted as storms, not hurricanes.

[HurrMark]

Another thing - I think the ratio of TCs (including depressions) to TS's or Hurricanes has increased as well...so I wonder if the NHC is more apt to pull the trigger. It is rare these days for a TD not to become a TS (TD Eight was the first since TD Ten in 2011 not to be named, and it probably would had been named if it had a few more hours over water). For example, in 1992, Andrew may have been Danielle had it occurred today. There was a subtropical storm in April (which under today's rules would have been a named storm), and two TDs after that, which had there been more data (like ASCAT/QuikScat), could have possibly been upgraded to a borderline TS.

[Hammy]

Another thing - I think the ratio of TCs (including depressions) to TS's or Hurricanes has increased as well...so I wonder if the NHC is more apt to pull the trigger. It is rare these days for a TD not to become a TS (TD Eight was the first since TD Ten in 2011 not to be named, and it probably would had been named if it had a few more hours over water). For example, in 1992, Andrew may have been Danielle had it occurred today. There was a subtropical storm in April (which under today's rules would have been a named storm), and two TDs after that, which had there been more data (like ASCAT/QuikScat), could have possibly been upgraded to a borderline TS.

I do agree that the increase in data has likely led to the increase in the number of storms over the years, but I will point out that one of the pre-Andrew depressions in 1992 was close to land, in the Gulf, and under frequent recon surveillance, so I highly doubt that one would have been a storm.

[HurrMark]

I do agree that the increase in data has likely led to the increase in the number of storms over the years, but I will point out that one of the pre-Andrew depressions in 1992 was close to land, in the Gulf, and under frequent recon surveillance, so I highly doubt that one would have been a storm.

I believe Derek Ortt noted a few years back that there was a storm off Bermuda that was likely tropical in nature and a winter noreaster that had tropical characteristics in that year. So even if the depressions didn't become TCs, one or both of these other systems could have.

[cycloneye]

Interesting tweet by NHC forecaster Blake.

@EricBlake12 23m
Hints in the models that we may be breaking our Atlc TC drought. i don't think I will believe it tho until I see the whites of their eyes:)

[SoupBone]

Can someone tell me when I can stop waiting two more weeks for the lid to come off?

Seriously, this is the quietest I've ever seen this board over the last moth and a half.

[TheStormExpert]

Can someone tell me when I can stop waiting two more weeks for the lid to come off?

Seriously, this is the quietest I've ever seen this board over the last moth and a half.

I just gave up about a week and a half ago!