STORM2K

Why is there no TC activity in the south-central Pacific and south-eastern Pacific basins? I'm going to guess the reason is lack of a ITCZ and strong wind shear like the South Atlantic. If that's true, then why? Why does the south-western Pacific have TC's and not the other southern parts of the Pacific?

Has there ever been a recorded south-eastern or south-central Pacific tropical cyclone?

The water in the Southeastern Pacific is cooler due to the Humboldt Currents. Not a good environment for hurricanes. That is one reason why Atacama Desert is the driest place in the world because cooler water puts an inversion cap on that area preventing rain from forming. If I am correct, there have been TC in south central Pacific, but that is during El Nino. No TC has ever been recorded to form in the southeastern Pacific. The South Pacific is vast and large. One would think, a TC could form and get really large and strong, even more so than the WPAC. Also, the Southern Ocean surrounding Antartica plays a role. That area is the stormiest in the world with powerful extratropical lows, that often affect the Southern Cone of South America. They often create windsheers, which puts a lid on TC formation.

Ptarmigan wrote:The water in the Southeastern Pacific is cooler due to the Humboldt Currents. Not a good environment for hurricanes. That is one reason why Atacama Desert is the driest place in the world because cooler water puts an inversion cap on that area preventing rain from forming. If I am correct, there have been TC in south central Pacific, but that is during El Nino. No TC has ever been recorded to form in the southeastern Pacific. The South Pacific is vast and large. One would think, a TC could form and get really large and strong, even more so than the WPAC. Also, the Southern Ocean surrounding Antartica plays a role. That area is the stormiest in the world with powerful extratropical lows, that often affect the Southern Cone of South America. They often create windsheers, which puts a lid on TC formation.

Some interesting information presented here. I think I can recall a south-central Pacific tropical cyclone as well but I wasn't sure on it. So Antarctic Extratropical low pressure systems (that are large and powerful) affect the formation of tropical cyclones (wind shear) mostly in the southern-Pacific?

Cyclenall wrote: Some interesting information presented here. I think I can recall a south-central Pacific tropical cyclone as well but I wasn't sure on it. So Antarctic Extratropical low pressure systems (that are large and powerful) affect the formation of tropical cyclones (wind shear) mostly in the southern-Pacific?

Yes. If you ever see satellite images of Antartica, it is always surrounded by those extratropical lows. You see it on TV a lot with those Antartica exploration teams who go by ship. These storms are MUCH larger than hurricanes. They can produce a lot of rain, wind, hail, and snow. That would also explain why South Atlantic is devoid of TC as well. South Indian Ocean is interestingly very active, I believe second to WPAC. In fact they see 21/10/4, which is 21 TS, 10 TC or Hurricanes and 4 Category 3+ TC or Major Hurricanes.

There IS a TRUE ITCZ (Convergence between the Trades of opposing Hemispheres) in the South Central and South Pacific, but true ITCZ's are not favorable areas of formation since the convergence is linear thus a Coriolis input is needed and since the southern ITCZ doesn't wander far from the Equator that input is lacking. The presence of a strong Polar Cold Sink plus the lack of any major mid and high latitude land masses elsewhere means that the Southern Hemisphere westerlies do not shift as far poleward as they do in the Northern Hemisphere and you have only limited Hot spots to develop and drive a monsoon and none exist in the areas in question. The SIO monsoon exists because of the Cold Northenr Hemisphere during the Boreal Winter sending cross equatorial flow into the Southern plus the heat of Australia and South Africa.

Steve

Cyclenall wrote:Why is there no TC activity in the south-central Pacific and south-eastern Pacific basins? I'm going to guess the reason is lack of a ITCZ and strong wind shear like the South Atlantic. If that's true, then why? Why does the south-western Pacific have TC's and not the other southern parts of the Pacific?

Has there ever been a recorded south-eastern or south-central Pacific tropical cyclone?

If you take "South-central" to mean the same boundaries as Central North (i.e. 180 to 140W) yes, there have been, although they're rare and usually barely get to named storm status. Fiji's area of responsibility extends eastward to 120W, east of which there haven't been any recorded TCs.

Thanks for all the great information everyone. Is there a track from anywhere of the south-central Pacific TC?

If you take "South-central" to mean the same boundaries as Central North (i.e. 180 to 140W) yes, there have been, although they're rare and usually barely get to named storm status.

Yes that's what I mean.

Cyclenall wrote:Thanks for all the great information everyone. Is there a track from anywhere of the south-central Pacific TC?

This past season, there has been two named storms in the central South Pacific (Zita, January 18-25, peak of 60 kts, moved SSE; Arthur, January 21-27, peak of 60 kts, moved ESE to SE). One formed in the Southwest Pacific (west of IDL) before moving into SC Pacific: Cliff. Most though are weak depressions (this season: 02F, 03F, 06F, 09F).


Zita track.


Arthur track.

Generally, this area is still considered to be within the "Southwest Pacific". Most cyclones in this area end up affecting the French Polynesia, Tonga and the Samoas. It's not as uncommon as I thought earlier apparently, I apologise for that error.