Hurricane forecasts for 2008

[Gray-Wolf]

http://www.planetark.org/dailynewsstory.cf...47777/story.htm

With thanks to the MetO who have this as todays news story.

It would appear that we are looking at an 'above normal' season this year with the current global setup likely to produce more storms over summer.

Anyone else got access to other Forcasts for the 08 season?

[BrickFielder]

Little bit early yet for many forecasts. Warm waters will help to initiate storms but la nina and the westerly QBO will perhaps create higher levels of wind shear across the region, destroying storms before they get to really develop. Should give us plenty of wet weather though. Kold Weather should know where all the forecasts are as this is a particular interest of his.

[Gray-Wolf]

Cheers Brickfielder!

The Post about an 'upping' of predicted No.'s was down to the presence of a weak La-Nina so maybe it's the El-Nino that increases shear (as we saw 2 years back) knocking the tops off systems and quashing development.

Post Katrina things have stalled and maybe the U.S. has been getting off lightly......I for one am looking forward to seasons start......magnificent beasties as they form/develop. A great pity they can cause so much harm.

[BrickFielder]

La nina is unlikely to weaken enough in the key areas to make much difference and SST charts at this time of year are a little hard to judge anyway with spring being a typical time for la nina to weaken before strengthening again later in the year.

What may be likely is that storms develop further east and we may get more Cape verde developing storms. This perhaps suggests storms which manage to dodge shear will be stronger with a greater risk of recurvature. I think we might see some early storms and perhaps one for the eastern seaboard this year. What do you think 15,7,5 ?

[kold weather]

Well La Ninas tend to promote lower levels of shear in the deep tropics and its El nino that usually causes shear to increase. What is noticeable about La Ninas however is that they do also tend to cause some cooling of the tropics, esp the western Atlantic (as the eastrern Atlantic temps tends to be more dominated by factors like the NAO and the jet stream.

The lower shear is the reason why La Nina seasons rarely if ever get 15 or more tropical storms simply becasue the sea temps aren't there.

They tend to feature a much higher ratio of major hurricanes to tropical storms then normal seasons as well, two such seasons that stand out like that are 1950 and 1999, which had:

1950: 13/12/8

1999: 12/8/5

Should be noted the 1950 season is probably over-estimated and I suspect when its re-looked at the majors and hurricane numbers will decrease but even if it does still will be impressive to look at, 1999 had FIVE cat-4's including hurricane Floyd.

Brick-Yeah I also think there are going to be a lot more long range trackers this year then in recent seasons, indeed the only real long tracker last season was Dean. As for an early start, i'm not sure yet though in nearly every season has had a system develop in June, usually forming near the USA. Also a feature of La Nina seasons is a lot of late season storms (October onwards) such as hurricane Lenny in 1999 in November (category-4 storngest ever hurricane in November!)

My own numbers aren't all that far away from yours Brick, if recall correctly I went for 14/9/5.

[BrickFielder]

Well La Ninas tend to promote lower levels of shear in the deep tropics and its El nino that usually causes shear to increase. What is noticeable about La Ninas however is that they do also tend to cause some cooling of the tropics, esp the western Atlantic (as the eastrern Atlantic temps tends to be more dominated by factors like the NAO and the jet stream.

The lower shear is the reason why La Nina seasons rarely if ever get 15 or more tropical storms simply becasue the sea temps aren't there.

CPC agrees with you on the shear.

CPC

Last years season with la nina and an easterly QBO should have been a bumper season, so la nina is oly part of the equation. Colorado state assessment of their forecast suggest spring to early summer dust from the african deserst played an important role. Equally the wind shear across the atlantic did not reduce as a result of the la nina with the jetstream pattern being particularly non condusive to hurricane formation during October.

2007 forecast assessment

[kold weather]

Yes the problem with the la nina last year is that the la nina didn't get going until about November time, which is a good deal slower then most la ninas and therefore thorughout most of the hurricane season the set-up across the Atlantic was more akin to what it is like when we have neutral set-ups and other factors dominated.

The most obvious one being a upper level trough (In the states they sometimes call these TUTT's, I think it stands for tropical upper tropospheric trough) decided to develop about 40-50W in the Atlantic basin. this meant that any cape verde system that strayed too far north around this longitude got sheared quite heavily by it and there were a few examples of this such as:

Ingrid

Jerry (though other factors also played a part)

Karen (Did get a breif let-off and became a hurricane whilst this occured)

Melissa

TD15

All of these happened right in the meat of the season, September and had the TUTT not been in place I rekcon at least 2, maybe 3 of those would have gone on to become major hurricanes and a real threat to the USA, so in some ways we were lucky it formed when it did. the only systems that avoided this upper feature were the very southerly tracking ones such as Dean and Felix which both had steller conditions and so no surprise they both went on to beocme cat-5 brutes.

EDIT- here is another forecast, i think the Gray+Klotzbach forecast (I believe Gray's last one at the head of the project) comes on Wednesday.

http://tsr.mssl.ucl.ac.uk/

[kold weather]

Well here is the Klotzbach and Gray forecast:

http://typhoon.atmos.colostate.edu/forecas...008/apr2008.pdf

New numbers are: 15/8/4

Anolouge years: 1950, 1989, 1999 and 2000

[Cookie]

it seems like a bit of a guessing game all this!

[summer blizzard]

My official forecast will be released in late May, however my thinking is that La Nina will mean that the ITCZ will be further north than average, with plenty of Tropical Waves leaving Africa, however the westerly QBO should also mean lower than average pressure in the Tropics, meaning that many systems will be sheared or recurve, however La Nina will also encourage a negative PNA, meaning that systems which do make it towards the Carribean will likely not recurve...

12/7/3 are my numbers for the moment...

[kold weather]

I wouldn't have thought lower pressure on its own would reduce the chances of high tropical storm actvity though SB, the 2005 for example had well below normal pressure over the tropics and yet that was a good part of the reason why we got such powerful systems that year, because pressures were lower at the start systems were able to deepen more then normal, hence why we had 3 systems in the top 10 strongest ever, indeed it was far more like a typhoon season which also features lower pressures.

Of course if we get a upper low slap bang in the middle of the basin where the systems are tracking then everything will shear but who knows I suppose it may limit tropical storm numbers, I do think there will be a lot of recurves and maybe a threat to the east coast.

[Calrissian]

it seems like a bit of a guessing game all this!

Lets be clear, none of the 'experts' have any more idea than John Mc'Cain does about fiscal policy.

--

After the insanely active and fun 05' season, almost all experts were predicting doom and destruction for 06. We didn't get it. Despite that totally embaressing failure in prediction, the same experts gunned high for '07. We all know what last year was like.

Now, they preach high again for 08'.

--

All these predictions are meaningless. The science is still too primitive. Pointless to hope anyone has the slightest clue what is ahead this summer.

Calrissian: 100/200/300 (yeah, go figure those numbers out)

[kold weather]

Not sure I'd go that far Calrissian, there is clear ideas behind most agencies forecasts and they aren't just random guesses they pluck out of the air but tend to be averages on from the different features, for example this year the anlouge years averaged out something like 12.5 named storms whilst there statistical factors give 18 storms and they went for something close to the average which was around the 15 mark.

as for the other seasons you mention, well i think the problem is sometimes agencies aren't able to read the small signs. For example with the 06 season it wasn't really at all obvious a el nino would cap storm development towards the end of the season and at the start of the season SAL prevented any long tracked storms so that left a little period in September that gave the majors of that season.

In 05 and 07 there were small features that to be honest aren't at all easily forecasted and they both developed quite strongly compared to the average. In 2005 we had a monsoonal trough stretched into the Caribbean and the gulf which lowered pressures (Hence why we got 3 out of the 10 deepest pressures ever recorded in a tropical cyclone in the Atlantic that year) and is a feature more often found in the active W.Pacific basin. As for 2007 we had a tropical upper trough sit in the north-Atlantic just where most storms develop and so whilst we DID get a pretty high number of named storms (15) only a few were able to develop. note the two that remianed south of this feature however were Dean and felix and both became powerful cat-5s.

[johnholmes]

this is the prediction by UK Met on 18 June for this season, this link

http://www.metoffice.gov.uk/weather/tropic...thatlantic.html

[Cookie]

thanks jhon

[kold weather]

Whilst the UKMO forecast is obviously only gives a broad idea as a freebie I will say they did do very well last summer, indeed they made quite an impressive forecast if my memory is correct. Ever since then I have been keeping an eye on their forecasts, they do appear to be one of the better ones.