How are the Invests numbered?

[micktooth]

Why are the invests numbered the way they are such as 90L, 91L etc.?
Just something I've always wondered. Wouldn't it be easier to number them in order such as 2005#1 or something like that? Thanks for your help in advance.

[cycloneye]

Atlantic(L): North of the equator between N. America and Africa
East Pacific(E): North of the equator between 140W and N. America
Central Pacific(C): North of the equator between 180W and 140W longitude
West Pacific(W): North of the equator between 100E and 180E longitude
Indian Ocean:
(A) North of the equator between Africa and 77E longitude
(B) North of the equator between 77E and 100E longitude
Southern Hemisphere:
(P) South of the equator between 135E and S. America
(S) South of the equator between Africa and 135E longitude
Letter identifiers are assigned to the storm's basin of origin. If a storm passes over a basin boundary, the storm will maintain it's basin of origin letter identifier even though it has entered a new region. For example, storm "Alpha" originates in the Eastern Pacific and is assigned 01E. If it makes its way into the Central Pacific it will still maintain its number and name designation even though it is seen under the Central Pacific header.

The storm number can be an eighty series (80-89), ninety series (90-99), or a number between 1 and 50. Storms seen with a number between 80 and 89 are usually used for testing purposes only. Storms with numbers between 90 and 99 are areas that forecasters use to monitor suspect regions typically with disorganized large-scale convection that has a chance to develop into a more organized system such as a tropical depression. Storms with numbers between 1 and 50 are/were storms that reached tropical storm strength or higher.

The naming convention after the number/basin pair can be called INVEST, NONAME, or assigned name. All storms will start with an INVEST name. When the system becomes a tropical storm this name will change to either NONAME or assigned name. NONAME is assigned to storms which do not have an official assigned name yet. Assigned names are given to tropical storms according to the World Meteorological Organization (WMO). Typically, storms that form in the Indian Ocean north of the equator will have NONAME. There are a few occasions where a tropical storm name will have an INVEST or a ONE, TWO,... following the number/basin pair. This name is only temporary and typically lasts for only a couple of hours. This is caused by the timing of the position updates generated by the Automated Tropical Cyclone Forecasting (ATCF) system and when forecasters determine that the system has become a tropical storm.

I think that the above answers bigtime your question.

[micktooth]

Wow, what an answer! I still think using 1,2,3,etc would be a little easier!

[jlauderdal]

Wow, what an answer! I still think using 1,2,3,etc would be a little easier!

i hope that was a copy n paste he did..lol

[WeatherEmperor]

cyclone is one of the best.

<RICKY>

[senorpepr]

Wow, what an answer! I still think using 1,2,3,etc would be a little easier!

Well, one of the main reasons they use a 90-series number rather than a 1, 2, 3, etc, is because a majority of these invests never become a numbered depression. The switch from Invest 17 to Depression 05 would be more confusing than the current system. Additionally, the invests that don't develop usually have no significance to the meteorological community after it dissipates, unlike a tropical cyclone. The main reason they do number invests now is simply to allow the models to perform on the given invest. Furthermore, if they forecasters used a 1, 2, 3, etc numbering system on invests, that would confuse their programs between the invests and the bone fide tropical cyclones.

[P.K.]

Just to add T is used for the South Atlantic, although not that often.

[senorpepr]

Just to add T is used for the South Atlantic, although not that often.

Right, I didn't mention the rare suffixes.

T = South Atlantic
M = Mediterranean Sea

I'm not sure what was used for the Black Sea storm, if anything. My guess would be K since B, L, A, and C are already suffixes.

[P.K.]

You missed these ones Mike.

There are a few other suffixes that are used by regional met offices such as R=Meteo-France La Reunion (SWIO), U=Australia, F=Fiji (SWPAC)

Which is something you posted just last night.

[senorpepr]

You missed these ones Mike.

There are a few other suffixes that are used by regional met offices such as R=Meteo-France La Reunion (SWIO), U=Australia, F=Fiji (SWPAC)

Which is something you posted just last night.

Well, technically those aren't rare like T and M. Those are normal suffixes that aren't seen by those who frequent the NRL page.

But... you're right.

[P.K.]

I know those aren't rare, well I didn't mean to make it sound like they were.

Hopefully nothing forms around La Reunion at the moment as the website is down. In fact the whole Meteo France website is down.