Atlantic hurricane season

[Dawlish]

I know this is sorely tempting fate, as hurricanes have evolved into January, but this was forecast to be an active hurricane season. It's not an area of any real expertise, for me, but it does seem to highlight the difficulties of forecasting anything seasonal.

What's actually happened to this year's hurricanes? Did they all just curve away from the Caribbean, fizzle out over the Atlantic and wander over to the UK? It just seems very strange!

Paul

[Iceberg]

Individual Storm Summary

Winds in knots, pressure in millibars, category is based on Saffir-Simpson scale.

# Name Date Wind Pres Cat

1 Tropical Storm ALBERTO 10-14 JUN 60 995

2 Tropical Storm BERYL 18-21 JUL 50 1001

3 Tropical Storm CHRIS 01-05 AUG 55

4 Tropical Storm DEBBY 21-27 AUG 45 1000

5 Hurricane ERNESTO 24 AUG-01 SEP 65 1

6 Hurricane FLORENCE 03-12 SEP 80 972 1

7 Hurricane GORDON 11-20 SEP 105 955 3

8 Hurricane HELENE 12-24 SEP 110 954 3

9 Hurricane ISAAC 27 SEP-02 OCT 75 985 1

If this continues then we will be looking at the quietest cane season since 96 or 98.

It was forecasted to be well above average.

Not a single hurricane has hit the US this season, Can't remember how often this happens.

The big players got the forecasts wrong pure and simple, I think it's basically down to the season last year. Nothing major changed so the natural conclusion was to go for an above average season. However things had changed.....

[smich]

There was a helluva lot of Saharan dust over the E atlantic for long periods this season, which would have inhibited H/cane formation.

Not sure why this was though!

smich

[frozen_north]

Well it did look like after a quite start to the season that it would pick up in September. Well we got 5 hurricanes in September none of them particulary powerful and then it just died. We've had nothing since the start of October things are starting to wind down now. Although there is another month left of the hurricane season so we could get something but its looking doubtful now.

Last year it seemed that everyday had something to do with GW and how active the hurricane season was. This year when we have hardly any the GW people have all gone quiet.

[johnholmes]

it will be very interesting to read the NOAA hindcast later this year. They may postulate what they think happened.

John

[kold weather]

I'm not going to make an epic post about why this season was below because i don't have time, but a breif enough reason is that alot of the faovrable condtions ended up being in the E.Pacific rather then in the Atlantic. The main reason does appear to be the onset of El nino type pattern which got going as early as March this year.

This sent the jet further south then normal and shifted everything further south and caused shear to be present in the Atlantic which disrupted most systems.

I think the major problem was the NHc didn't really pay much attention to the developing El nino and if i recall nearly 50% of thier entire forecast was base don the idea that we ar ein an active phase of hurricane formations. so in the end what happened is we got EL Nino when the season was presumed to be neutral, this cuased more shear then they expected (though really it was only a little above average) and thier was quite a lot of dry injested by quite a few of the developing waves which combined with the less favorable upper air profile simply meant that most early waves hjust didn't have the chance to get stronger.

Edited October 29, 2006 by kold weather

[parmenides3]

9 named systems, 2 landfalls, 2 Cat 3+s, ACE 81.1

That makes this an 'average' season by NOAA's measure. They forecast above average, mainly because it fit the patterns of recent years, and the indicators were there in April.

E Pac. has been above average: ACE 157, (150= above ave)

NW Pac should come in around average by the end of the season.

Most Atlantic systems turn before reaching the US coast; nothing unusual in that, either.

We've been 'spoiled', so we expect fireworks; what we get is just ordinary, so we're disappointed, but it han't been a below average season.

:)P

[Gray-Wolf]

I thought that this season was worrying myself. You could see what was starting to occur in July fron watching the SAL layers flowing off Africa yet the folk with all the gadgets and gizmos still revised far to high a figure for the season. It's not okay to believe that an organisation as big as NOAA would temper their forcasts with a "oh it was very busy last year so we'll put up for another busy one". I believe that maybe overreliance on the current models and then not tempering the forcast with good observation/measurement .

It would seem to me that their models failed to predict the onset of El-Nino conditions and then,presumably on the advice of their modeling, refused to allow the 'Anomaly' in late July/early August to become an El-Nino and not just a blip that would subside by september (an so the high revision). Was the current ENSO event so unique in its broader development that the models failed to spot it and trigger alerts?

If the current models did have trouble spotting and then initialy modeling the current El-Nino how can we trust the current models to perform well in modeling it's behaviour over the next 6 months or so?

[parmenides3]

Here's the link to the CPC's August expert discussion:

http://www.cpc.ncep.noaa.gov/products/outl...hurricane.shtml

Just to help jog our memories. They saw the El Nino coming, but offset its effect against the other conditions.

:)P

[Iceberg]

An ACE of 81.1 would give it slightly less than the 100% average, although it would still fall into the near average NHC category.

It would also be below the 9.4 Average for TS's, below the 5.6 average for Hurricanes and well below the 1,7 average of hurricane hits on the US also the quietest season for 8 to 10 years.

MR P if it's not out of the ordinary when was the last time the US was not struck by a Hurricane ? I don't think it's been in the last 10 years.

I think an assumption was made that basically there are no major changes to the main hurricane drivers compared to last year, hence the deliverance of an above average season (Although not a record breaking season like last year).

The NOAA/CPC forecast in August was calling for a neutral ENSO.

"One factor known to significantly impact Atlantic hurricane seasons is ENSO (Gray, 1984). El Niño favors fewer hurricanes and La Niña favors more hurricanes. Based on the most recent ENSO outlook issued by NOAA’s Climate Prediction Center, ENSO-neutral conditions are expected in the tropical Pacific through much of the Atlantic hurricane season. Therefore, ENSO is not expected to impact this hurricane season."

Personally I don't think a weak and very late El NINO is really going to effect the cane season that much, the main driver as Darren menioned was the increase shear, ALL TS and hurricanes really suffered from it and interestingly even in normal low shear environments such as the GOM, TS development was almost none existant.

Also playing a part was the dust factor see this months good article below on the latest theories, an increase in dust will also by it's nature lead to a lack of moisture basically meaning the Atlantic looks more like a Graveyard, The ITCZ was also very patchy at best due to the above reason.

http://www.noaanews.noaa.gov/stories2006/s2719.htm Dust

Matt

[Gray-Wolf]

Thanks Iceberg, I was going to point out the call for a neutral ?ENSO with the blame for the reduction going to the multi-decadal patterns being poorly aligned (if it was a multi-decadal signal that caught them out then why was it missed???)

I think that 'new' global interactions are causing patterns to evolve that the models are not progged to pick up on (Somalian snow etc) and a small shift early on leads to a big shift further down the line. Again, the fact that the revision only scraped in a result (on its lower figure) makes you realise that this was not an 'average' event.

Maybe we should watch the Southern oceans this winter and see how they fare (Argentinian Hurricanes anyone?)

[kold weather]

The problem is with any models Graywolf , sometimes they simply miss things.

You see the problem this summer was that there was really conflicting signals, esp in the Spring. The SOI and sub-surface temps sggested El Nino but SST's did not and suggested neutral.

It just so happened that most models kept us in neutral for mos tof the summer and that was indeed actually correct but the teleconnections behaved LIKE it was el nino and that was something long range models failed to pick up on, easy to miss several months from the event...

[Calrissian]

Lets be clear once again on this...

The models are still at a kinda garden level. They are in general, worthless at predictors of any given season.

The NHC - it could be argued, was just following the hysteria from last year, and played it safe with predicting another highly active season. The fact it has actually been a quiet one makes little difference to them.

---

It remains largely impossible to predict a season, as almost EVERYONE this year has got it wrong. I can't remember reading anyone on this board, or other sites who touted a 'relatively quiet' season.

It really has been a case of mass hysteria.

[Dawlish]

Lets be clear once again on this...

The models are still at a kinda garden level. They are in general, worthless at predictors of any given season.

Clear, incisive and completely correct. Sir, you win the Dawlish prize for assessing the present state of seasonal forecast models. How is Cloud City, by the way?

Paul

[Mondy]

wtf? ^^ <_<

Edited November 2, 2006 by Mondy the clumsy

[summer blizzard]

Personally, i am quite pleased, my September 1st update called for 9 storms from my original estimate of 14 and we have 9.

[summer blizzard]

I just wanted to post some anologue based information for this hurricane season.

Looking at the data since 1948, it appears that assuming no more hurricanes form this year, that this Hurricane season was most similar in frequancy to the hurricane seasons of 1960, in terms of the June-August period, but for the September-November period, 1966 was the best anologue.