ITCZ activity

[chadtm80]

When does it "usualy" pull north?

[cycloneye]

Slowly it begins to shift north from may from the equator and then by august and september the peak months of the CV season it is almost at 10n making it more easy to tropical waves to begin spinning lows.

[Rainband]

Thanks for the info Cyc!!

[Steve H.]

I am likin' the way the ITCZ is beginning to show up already. waves are starting to look healthy for June. Nice area of convection where the ITCZ has gotten pulled north. One of these waves should eventually develop in the Caribbean. One thing to remember is that the SSTs are pretty darn warm in the Atlantic west of 40W. Could recessitate waaves that come across the pond. That is why I'm thinkin' an earlier start to the "regular" season. Cheers!!

[Rainband]

That makes sense Steve..Thanks for the info..

[Derecho]

Slowly it begins to shift north from may from the equator and then by august and september the peak months of the CV season it is almost at 10n making it more easy to tropical waves to begin spinning lows.

Basically the CV season is so short and takes so long to get going because the region needs to warm, and the window with low shear is so small.

One thing to remember is that in MANY ways, the Atlantic is the "oddball" tropical basin (and the EPAC meterologically is really sort of an extension of the Atlantic); the West Pac, Indian Ocean, and SW Pac are the "normal" basins.

One of the key anomalies of the Atlantic is how few storms form close to the equator; this is routinely attributed, TOTALLY inaccurately, to "not enough coriolois."

That has nothing to do with it. The Coriolois effect, at the same distance from the equator, is the same all over the world, and outside the Atlantic it is common for tropical systems to form closer than 10 degrees to the equator, and in some rare cases systems, even of hurricane/typhoon strength, have formed within THREE degrees of the equator.

In contrast, hardly any Atlantic storm is ever below 9 N and I think the most southerly advisory position ever was something like 7N.

It's not totally clear to me why this is, I have discussed it with some people, but it seems to be the position of the ITCZ, but it's because the ITCZ is so far north WHEN the water temps AND shear profiles are favorable, that storms don't form south of it....so it's not the ITCZ moving north that allows lows to form, it's that the conditions happen to be favorable when the ITCZ is as far north as it gets.

Also, the location of the low-level Easterly Jet that comes off Africa seems to play a role.

[Anonymous]

This is the best link you will probably find relating to the position of the ITCZ. It shows the current latitude compared to the long term average.

http://www.cpc.noaa.gov/products/fews/ITCZ/itcz.html