Weekly Tropical Climate Note

Issued on Tuesday 30 April 2013

Late season tropical cyclone

The Madden-Julian Oscillation (MJO) is currently weak and not contributing to tropical convection. Despite this, a low pressure system within the South Pacific Convergence Zone (SPCZ) has recently developed into tropical cyclone Zane over the northern Coral Sea.  This is the latest tropical cyclone to be formed in a season since tropical cyclone Pierre formed briefly in May 2007.  If as expected, it crosses the coastline as a tropical cyclone, it will be the latest tropical cyclone to do so since tropical cyclone Marcelle crossed the coast on the 8 May 1973. The system is currently expected to track westwards over the Cape York Peninsula before weakening considerably as it moves over the Gulf of Carpentaria and the Arafura Sea.

Although dry conditions are now settling in across northern Australia, heralding the start of the dry season, humidity levels may rise in the far north ahead of the low pressure system with a return to normal dry season-like conditions early next week.

With little guidance from any long-term tropical climate drivers, model consensus suggests that the MJO will strengthen slightly during the next week over the western hemisphere before gradually shifting eastwards towards the Indian Ocean over the next fortnight.  Throughout this period and based on recent observations, the area of suppressed convection currently sitting over the central Indian Ocean will gradually move into the Maritime Continent and the SPCZ will experience a decrease of convective activity.

See the Bureau's MJO Monitoring for more information on location and tracking of the MJO.

State of ENSO: Neutral

The Pacific Ocean has recently shown a marked cooling off the west coast of South America.  However, the Pacific Ocean remains ENSO-neutral with the latest sea surface temperature anomalies in the NINO3.4 region remaining at +0.1 °C, the same value as the previous week. The latest 30 day SOI to the 17th of April is +5.3.

See the Bureau's ENSO Wrap-Up which includes a compilation of ENSO computer model predictions.

Next update expected by 07 May 2013| Product Code IDCKGEWOOO

For more information please contact climate.nt@bom.gov.au