Atlantic ITCZ

[cycloneye]

THE ITCZ...
ITCZ EXTENDS FROM WEST AFRICA NEAR 8N13W TO 2S33W TO THE NORTH
COAST OF BRAZIL AT EQ50W.

The above is from the 8 AM discussion.If I see that right parts of the ITCZ axis is located at the equator or even south of the equator.It's May and the ITCZ is supposed to start climbing in latitud to then allow cyclogenerisis to start.

If (Aquawind) Paul who always post about this every year has some stats about the ITCZ in past years or anyone else can come and post them it would be good to know.What I want to know if it's normal to have the ITCZ axis in the equator or south of the equator in May.

East Atlantic Water Vapor Image

Also if you look at the above image of water vapor you can see a strong jet stream way down into the deep tropics with upper winds at between 60-80 kts.Of course the ITCZ way south combined with that jet stream assures no development in that part of the world anytime soon but anyway that area is not favorable in the early part of the season.

[Hyperstorm]

Yes, I just noticed this yesterday while taking a quick look at the Atlantic satellite image. Typically, the moisture associated with the ITCZ is located near 5N this time of year, but it was very close to the equator. However, one thing to note is that it is becoming much more active and moisture laden from the E. Atlantic to the interior of Africa. It will only be a matter of time before it jumps north in a hurry. Besides, if it stays at a lower latitude than normal, the worst thing that can happen is that the systems will start developing once they are further west in the Atlantic or in the Caribbean and Gulf of Mexico.

Not all good news...

[Matt-hurricanewatcher]

Because of the high Itcz last year alot of the waves/distrabances moved north enough into the SAL. Which helped kill the Eastern Atlantic season, so it works both ways.

[Aquawind]

The latest from CPC.. Most of the monitoring information is in relation to the African coast and rainfalls so thus does not cover the ITCZ over the ATL waters.

The Africa portion of the ITCZ during the period from April 21-30 2006 was located near 11.68 degrees north latitude when averaged from 15W-35E, compared with the long term 1988-2005 mean of around 11.18 degrees north. The current versus mean situation can be seen in Figure 1, and it may be noted that the current ITCZ shows a slight southward bias compared to the climatological average, however this weeks mean ITCZ line looks more like the overall normal for this time of year. Precipitation in the region follows the discontinuity location fairly well during the current period as well. In the west (from 10W-10E), the current ITCZ was located near 13.2N, compared with the long term mean of 13.3N during the same dekad. Much of this bias is seen east of the Prime Meridian as we have seen over the past few weeks. In the east (from 20E-35E), the current ITCZ position is near 9.9N, compared with the long term mean of 10.8 degrees north. This time last year the mean for the same location was further north around 12.0N.

http://www.cpc.ncep.noaa.gov/products/f ... itcz.shtml

So it is considerably further south than last year, but it's early and the migration northward is really in the early stages. The eastward portion over Africa is the area way further south than the long term mean location. In fact overall it is acually closer now to the mean than the prior Decadal

April 11-20 2006 - The Africa portion of the ITCZ was located near 10.23 degrees north latitude when averaged from 15W-35E, compared with the long term 1988-2005 mean of around 11.24 degrees north. It may be noted that the current ITCZ exhibits a strong southward bias compared to the climatological average. Precipitation in the region follows the discontinuity location fairly well during the current period, with an overall lack of rains in northern Nigeria, CAR, and southern Sudan. Portions of southern Mali saw unusually heavy rainfall during the period. In the west (from 10W-10E), the current ITCZ was located near 11.8N, compared with the long term mean of 12.5 during the same period. Much of this bias is seen east of the Prime Meridian, especially over Nigeria. In the east (from 20E-35E), the current ITCZ position is near 8.0N, compared with the long term mean of 9.9 degrees north.

The Azores High is further south at this point and I would assume is helping push the ITCZ southward once it exits the African coast.

http://www.opc.ncep.noaa.gov/UA.shtml (Big analysis loop available)

http://www.ssd.noaa.gov/PS/TROP/DATA/RT/EATL/WV/20.jpg

Per Discussion:

A 1027 MB HIGH IS OVER THE EAST
ATLANTIC SOUTH OF THE AZORES NEAR 35N25W.

http://www.nhc.noaa.gov/text/refresh/MI ... 1059.shtml?

It's early yet.. But with more true CV systems expected this year versus the last couple of years we shall be watching closely to see how the ITCZ location corresponds to any CV development.

[cycloneye]

Thanks Paul for all that information.Yes the Azores high is further south than normal for this time of the year.As you said Paul,we will be watching how the ITCZ behaves during the season.

[Hyperstorm]

Because of the high Itcz last year alot of the waves/distrabances moved north enough into the SAL. Which helped kill the Eastern Atlantic season, so it works both ways.

Climatologically speaking, the higher the ITCZ position during the summer, the higher the number of storms in the Eastern Atlantic. It was not exactly the reason why storms didn't develop in the Eastern Atlantic last year. In 1995, the ITCZ position was higher than last year and we saw an active Cape Verde season that year.

We need to have studies done as to why last year didn't see an active Cape Verde season, even though SSTs were among the warmest recorded in that area. Some have suggested that the SAL and upper-level winds were stronger than normal, but we need to know why that was the case.

[cycloneye]

Yes, I just noticed this yesterday while taking a quick look at the Atlantic satellite image. Typically, the moisture associated with the ITCZ is located near 5N this time of year, but it was very close to the equator. However, one thing to note is that it is becoming much more active and moisture laden from the E. Atlantic to the interior of Africa. It will only be a matter of time before it jumps north in a hurry. Besides, if it stays at a lower latitude than normal, the worst thing that can happen is that the systems will start developing once they are further west in the Atlantic or in the Caribbean and Gulf of Mexico.

Not all good news...

Agree with your comment about this especially when you talk about the ITCZ remaing more south than normal that puts the Caribbean as a hot spot for systems comming from the east.

[Derek Ortt]

Matt,

there was no SAL last year. The dry air came from the Azores high

[Weatherfreak000]

If the ITCZ remains further south then I can assume we could have more Emily-like track scenarios could that be correct?

[meteorologyman]

yes this is all true but didnt some storm actually form in equator orclose to it, and if I remeber it correctly it was 2004 when it happened, and when all the storms nailed us(Florida)

[Ivan14]

I would take it that would be bad for the Gulf right?

[bvigal]

Matt,

there was no SAL last year. The dry air came from the Azores high

Derek, this is news to me! We saw it, read about it in NWS discussions, etc. I could probably look back in my files and find some of those official reports mentioning African dust.

One pic from last July: http://www.osei.noaa.gov/Events/Dust/Af ... 05_G12.jpg

For sure, what little there has been this year, hasn't made it over this far west! I'd welcome it back, as I believe it had a negative effect on storm development in our 'neighborhood' last year - about the only clear spot in the 2006 track map!

[JonathanBelles]

i remeber the dust in the clouds last year

[CHRISTY]

so guessing there wont be any AFRICAN DUST in 2006?that's not good news.

[cheezyWXguy]

yes this is all true but didnt some storm actually form in equator orclose to it, and if I remeber it correctly it was 2004 when it happened, and when all the storms nailed us(Florida)

Yes, that was Hurricane Ivan, now the 4th costliest hurricane in U.S. history, causing 14 billion dollars in damage (1st Katrina-100 bil; 2nd Andrew-45 bil, 3 Charley-15 bil) Ivan formed at I believe was the strongest storm ever to form at such a low latitude(5 or 6 N)

[senorpepr]

There was little SAL last year. Most of what was blamed on SAL was actually dry air / subsidence.

[senorpepr]

Yes, that was Hurricane Ivan, now the 4th costliest hurricane in U.S. history, causing 14 billion dollars in damage (1st Katrina-100 bil; 2nd Andrew-45 bil, 3 Charley-15 bil) Ivan formed at I believe was the strongest storm ever to form at such a low latitude(5 or 6 N)

FWIW, Katrina's official damage estimate is $75B while Andrew's (adjusted for inflation) is around $43.7B.

[Jim Cantore]

I dont usually worry about the ITCZ until August, maybe July from now on. However I dont give it a second thought in May, give it time, it will strieghten out (I'd hope so because the further south the form the better chance we have for Ivan like tracks)

be patient guys, under one month left until (in my opinion) all hell breaks loose.

[cheezyWXguy]

Yes, that was Hurricane Ivan, now the 4th costliest hurricane in U.S. history, causing 14 billion dollars in damage (1st Katrina-100 bil; 2nd Andrew-45 bil, 3 Charley-15 bil) Ivan formed at I believe was the strongest storm ever to form at such a low latitude(5 or 6 N)

FWIW, Katrina's official damage estimate is $75B while Andrew's (adjusted for inflation) is around $43.7B.

close enough...lol

[Jim Cantore]

Ivan is 5th, Wilma moved up to third