2006 Atlantic Hurricane Season Thoughts.

[kold weather]

Actually SB there have been a fair few seasons that have had 16 storms or more, infact 2003 had that amount and obviously 2005 had WAy above that even!

SnowBear, may well be worth watching because last year was year of the hybrid's for sure.

Intresting developments recntly on the SSTA front.

La nina has gotten stronger despite some people thinking it would weaken as we get into Spring quite the opposite is occuring.

in the Atlantic there is a large patch of below average SST's from about 40W towards the African coast which may mean weaker CV systems then normal though these SSTA still have time to change alot yet. The Gulf of mexico is a good 1-1.5c above normal thanks to the very mild winter in the USA and I can't see that going away anytime soon tohugh the waters are quite shallow so changes can occur in a matter of a few weeks.

[summer blizzard]

What i meant that there would be the amount of storms listed, therefore 29 storms would make it to Tropical Storm status.

[Gray-Wolf]

I think the recent revelations of the 'hot spots' that developed in the Caribean last year will be the controlling factor this season as well.

For two months last year I remember remarking on a 'hot spot' located to the South of Cuba Jamaica which aided in the rapid formation of at least 3 of the Cat. 4 and above storms. The most recent papers acknowledge the importance of these 'plumes' in the "rapid intensification" of the major storms which passed over the area. The formation of the 'hot spots/plumes' is put down to global temp increase and not La nina/El nino effects.

As such I'd say we can expect more of the same this season if not even more intense!!!

[BrickFielder]

Well I thought I would have an attempt at forecasting the 2006 Hurricane season this year. I am not an expert in this stuff so please treat the forecast as an interesting discussion point rather than a serious forecast. For those who do not want to wade through all the technical stuff the summary is as follows.

Summary

I think there is a good chance of a very active tropical storm season with probably in excess of 30 named storms ,only 8 of which will reach hurricane status and 3 reaching severe category with the earlier part of the season will be the most active. Chances of US land fall would seem to be less this year with perhaps east coast areas favoured over the gulf. The one factor that reduces severity and number of storms this year is the lower sea temperatures forecast in the development region. If this higher temperatures materialise here then all indicators are that 2006 would be an exceptional hurricane season with US land fall of a severe storm a probability rather than possibility.

Atlantic MultiDecadal Oscillation (AMO)

This is really a slowing down and speeding up of the Gulf Stream and is linked to periods of strong thermohaline circulation and weaker thermohaline circulation (THC). During a positive phase the tropical area of the pacific becomes very warm and this warmth is advected northwards by a strong gulf stream. This heat causes convection causing heavy rain and hurricanes which slowly reduce the salinity of the water in the tropics. A critical point is reached and the Gulf Stream and THC slow mixing surface and deep water in the tropics and causing the Atlantic waters to cool. With a slow gulf stream warm water accumulates in the tropics and is not transported northwards. This build up of warm water sets the Gulf Stream speeding up again.

At the moment we are in a positive phase of the AMO although it is suspected that the THC has started to slow in advance of a negative phase. Positive Phases of the AMO have been linked to an increased number of annual hurricanes by means of Sea Surface Temperatures, strengthening the walker circulation and by affecting the QBO or tropical winds.

El Nino/La Nina

Current Forecasts suggest that la Nina conditions which have recently peaked will trail off to neutral perhaps before returning again slightly later in the year. SOI remaining generally positive confirms that la Nina conditions should continue to prevail. Both neutral and la Nina conditions have been shown to substantially increase the number of hurricanes by adjusting the trade winds such that high level wind sheer is less likely to present and conditions are better for hurricane and tropical depression development. Compared to last year which was El Nino to neutral conditions are more favourable to developments and la Nina years have a greater possibility of higher category hurricanes making landfall.

Sea Surface Temperatures.

Despite being in a positive phase of the AMO sea surface temperatures at the tropics are set to fall off this year according to both NCEP and IRI. This reduces the energy available for serious hurricanes to develop. Further north into the Atlantic and IRI suggests temperatures cool as well while the NCEP suggests it will remain warm. This suggests there might be more mid Atlantic synoptic ridging. This would tend to divert the storm track perhaps further north.

QBO.

It looks as if a westerly regime of winds is in the process of starting as opposed to the easterly regime that existed last year. Atlantic hurricane activity is enhanced during the west phase of the QBO and diminished in the east QBO years. This relationship may be due to alterations in the static stability and dynamics near the tropopause. So we should expect more developments this year.

Africa Intertropical Convergence Zone (ITCZ)

We are expecting a poleward shift of the African ITCZ again this year. This should mean less subsidence and drying, a deeper boundary layer and more moisture in the middle troposphere. It also means that low level cyclonic vorticity will be spawned into the main development area of the coast of Africa. This means there should be an abundance of short waves coming of the coast of Africa for development.

Conclusions and Forecasts.

Bearing all this in mind I think there is a good chance of a very active tropical storm season with probably in excess of 30 named storms ,only 8 of which will reach hurricane status and 3 reaching severe category with the earlier part of the season will be the most active. Chances of US land fall would seem to be less this year with perhaps east coast areas favoured over the gulf. The one factor that reduces severity and number of storms this year is the lower sea temperatures forecast in the development region. If this higher temperatures materialise here then all indicators are that 2006 would be an exceptional hurricane season with US land fall of a severe storm a probability rather than possibility.

[kold weather]

Intresting idea Brickfielder, though i would disagree with you numbers in that:

A:To have just 8 hurricanes from 30 tropical storms would be a tough ask, even 10 hurricanes wouold be on the low side if you were to forecast 30 TS.

B: I don't think things are quite so prime as last year, one thing that made so many cat-5's last year was the almost monsoon type set-up in the Caribbean region in terms of pressure, which were decently below average and almost comparable at times to the NW, hence Wilma's record I suspect.

In terms of cape verde waves, La nina should really promote those long trackes, esp as its quite strong still but there are certainly two things that are going against it this year.

1: SST's are very much below average as mr.B said above.

2: I can see there being more dust and dry air coming out of Africa and drying out any developing system around that system.

It might be the case that any system will need to get west of 40W before they enter much favorable condtions and become more organised.

Here are my revised figures:

22/15/5

I actually think there will be several cat-2's this year and I agree with mr.B in that the east coast could be at threat, esp Florida IF the strong Bermuda high stuck put though thres no certainty it will.

The concerning thing for the folks of the gulf coast must be that for the time of year the SST's there are decently above average, so any storm that gets in there with favorable condtions could do a Katrina/Rita iover the gulf current.

[SNOW-MAN2006]

i think this years hurricane season will be one with few hurricanes as the oceans have let off alot of steam last year and unless we see record temps this year in the usa we can expect a bad hurricane season

[P.K.]

30 named storms would be rather a lot.

By the way there is now a 28th named storm from last year, no dates given by I read somewhere it was in April.

[Paranoid]

I see the storm reports for 2005 have been completed and checked. Emily is now the earliest Category 5 on record. Rita's windspeeds and pressure are now slighlty more intesne. 180mph, 895mbar instead of 175mph 897mbar.

30 tropical storms? That seems a little too many. Keep in mind that the second most active Hurricane season on record had 21 storms. Whilst 2005's season beat that by 6 ( or seven, depending on this "April storm), i don't think we'll reach thirty this year. (now that i've said this, i will probably be proved wrong)

[kold weather]

Thats quite intresting P.K, must look into that!

As for the hurricane reports, well they are all done bar Beta at the moment, Rita is stronger as has been said though slightly weaker at landfall and also Emily has been unsuprisngly upgraded to a category-5!!!

Just to give you a idea of how crazy this season is, there has only been 4 cat-5's since 1992 upto the 2004!!!

so, emily is now a 160mph as was to be expected by recon reports.

Rita is a powerful 180mph hurricane with pressure down to 895mbs and Wilma the strongest of them al lat 882mbs and 185mph winds!

Cindy was also upgraded to hurricane status as well a little while back.

[johnholmes]

i think this years hurricane season will be one with few hurricanes as the oceans have let off alot of steam last year and unless we see record temps this year in the usa we can expect a bad hurricane season

hi

Its not the temps in the USA that are the main cause, its the sea temps in the areas where they develop, and also, crucially, for the USA, the Gulf of Mexico.

Certainly the USA temps have a part to play but they are not the most important.

John

[P.K.]

Turns out it was actually October, the report will hopefully be out soon.

[kold weather]

Yeah its on the first page of the Zeta report:

http://www.nhc.noaa.gov/pdf/TCR-AL302005_Zeta.pdf

Intresting to know that there was Sub-tropical depression 22 in October

"A NEW BURST HAS

FORMED JUST WEST-NORTHWEST OF THE CENTER. SATELLITE INTENSITY

ESTIMATES ARE SUBTROPICAL 35-40 KT FROM SAB"

I wonder whether it'll be that or will it be a new system that we missed???

(pk, got any ideas as to what system this may be??)

I personally think it'll be one we missed during the Wilma episode but who knows!

[P.K.]

Good question. The problem with looking back at old sat images is all the other systems that also formed in October!

It must be a new system as the subtropical depression 22 report is already out.

[kold weather]

Indeed P.K, then again as I said on Storm2k, surely the NHC shouldn't have missed anything, even if the floaters were on Alpha and Wilma, they do have other satilites that keep a broader veiw on things.

Very intresting this!

[P.K.]

I guess it might be the image I posted to S2K. Can't find any others that look good candidates during the Wilma period.

[kold weather]

It does rather look like a weaker Vince at its start and it does look weak, I suppose just by chance they may have come across something on the wind analysis charts when looking at Wilma's best track.

As I said though it does rather look like a hybrid system to me, if rather small and weak.

[kold weather]

Intrestingly just seen the TNA data for Feb and its down to 0.19, the lowest in a fair while, infact since May 2003.

This can be explained by the presance of a rather large cold anomaly over the east of the Atlantic, but this has now died away somewhat and the seas are warming back up now.

[summer blizzard]

This is the latest sea surface temperature anomoly chart.

Here is a sea surface temperature chart from this time last year.

As you can see, the area is around Cape Verdes is still above average but not as warm as last year however the Carribean is a lot warmer than this time last year, if La Nino does favour more Tropical Waves, i would say that while it is harder for them to develop, any that do survive will have a much better chance of development and intensification than last year.

[crimsone]

Does La Nina favour a tendancy towards subsidence by any chance? I wasn't following the preseason all that closely last year, and so don't have it for comparison, but the East Pacific does seem to be throwing a lot of systems over the gulf, almost like their blocking the systems up in the Atlantic. Or maybe I'm just reading something that isn't there again. I do that sometimes.

[BrickFielder]

Does La Nina favour a tendancy towards subsidence by any chance? I wasn't following the preseason all that closely last year, and so don't have it for comparison, but the East Pacific does seem to be throwing a lot of systems over the gulf, almost like their blocking the systems up in the Atlantic. Or maybe I'm just reading something that isn't there again. I do that sometimes.

Yes La Nina does favour subsidence and less shear. The trigger for Hurricanes are small disturbances some of these disturbances come of the coast of Africa and this is related to the movements of the ITCZ

(intertropical convergence zone).Generally we get more disturbances when the trade winds are in a particular direction (westerly) due to generally lower wind speeds in westerly trade flows. For these disturbances to develop they must pass over warm water and generally the amount that they develop is related to the warmth of the water. Warmer seas and we get more powerfull hurricanes. Many hurricanes are destroyed before they really get going by high level winds destroying any structure.So subsidence (high pressure) and lack of upper level winds allow more hurricanes to develop.

The amount of East Pacific systems crossing into the gulf I think is related to the jetstream pattern over the US and the souther hemisphere jetstream. Suggestions are that if/when la nina reestablishes itself this will stop. I fit does continue then this would affect the hurricane season.

[bartlett_hi]

Well one thing's for sure- after last hurricane season it would take something unbelievable for this one to top it- even an above normal year will probably seem very quiet in comparison! Having said that, how memorable a hurricane season is often doesn't have much to do with the number of systems - it only takes one Katrina or Andrew to make landfall at cat 3 or above in a fairly well known area and most people forget about whether it was an active or quiet season! I guess it's like the whole 'cold winter' debate- we could have had the coldest winter since the early 60s this year with ice days galore and plenty of people would have moaned that it had been rubbish because they haven't got snowed in! For most people it's all about the 'big' one off events and often these can occur in otherwise uneventful years!

I have a gut feeling that this may actually be an average to below average year for number of storms- as we are surely due one- not very scientific thinking I know but wouldn't it be boring if we really could predict the weather that accurately in advance? Will be interesting to watch how the year develops though- wonder if we will get any more really early tropical storms/hurricanes like last year?

cheers,

Steve

http://www.cyclone-tours.com - see some real weather - storm chasing holidays in tornado alley 2006 and 2007! check out the pics!

[kold weather]

Intrestingly some studies indicate that La nina, at least at the strength its at now doesn't have that large of an impact on the amount of storms compared to a normal SSTA arrangment in the Pacific.

[wolves78]

i dunno if it has already been said in here but in feb 26th 2006 90L.INVEST was named

90LINVEST.25kts-NAmb-290S-360W

southern hem storms so far this year are

99S.INVEST

98S.INVEST

20S.GLENDA

19S.FLOYD

18P.WATI

17P.LARRY

16S.DIWA

15S.EMMA

14S.CARINA

13P.KATE

12S.NONAME

11P.VAIANU

10P.JIM

09S.BOLOETSE

08S.DARYL

07P.URMIL

06P.TAM

05S.CLARE

04S.NONAME

03S.BERTIE

02S.NONAME

01S.NONAME

very active season there will the atlantic hold even more a shock this year compared to last year?

Edited March 27, 2006 by wolves78

[kold weather]

Well Dr.Gray's latest forecast is out (well really its also mr.Klotzbach forecast as well)

Here it is, the numbers are trhe same as they were in his last update:

http://hurricane.atmos.colostate.edu/forec...2006/april2006/

[crimsone]

Wow. Did they ever get it wrong last year! lol.

Interesting never the less.