Weekly Tropical Climate Note
Issued on Tuesday 21 May 2013
A taste of dry headed to north Australia
A moderate Madden-Julian Oscillation (MJO) traversed the Maritime Continent last week bringing enhanced convective activity across Indonesia, New Guinea and northern Australia. This pulse, however, has weakened significantly over the past few days and failed to enter the Pacific Ocean region. Although models surveyed by the Bureau currently differ in the MJO pulse trajectory, they all agree the MJO will remain weak over the next week or two with little contribution to tropical weather.
Across northern Australia, a northwest cloudband will enhance the influx of tropical moisture into arid parts of central Australia, bringing unseasonable rainfall until the end of the week. However, over the weekend a strong high pressure system over the Bight will push a cool and dry surge towards the north. This gusty surge will bring northern Australians their first taste of dry season conditions as humidity levels and night-time temperatures finally drop to values more typical for this time of the year.
See the Bureau's MJO Monitoring for more information on location and tracking of the MJO.
ENSO state: neutral
The Pacific Ocean remains ENSO-neutral with the latest sea surface temperature anomalies in the NINO3.4 region slightly cooler than the previous five weeks at -0.1 °C. This is the first time since late January that all weekly NINO indices are negative. The latest 30-day SOI to the 18th of May is +1.6 with contributing pressure anomalies of +0.3 at Tahiti and +0.2 at Darwin.
Looking west, the Indian Ocean Dipole (IOD) outlook remains on track for a weak negative IOD event to develop later in the dry season, as four out of five models surveyed by the Bureau are leaning towards that possibility. A negative IOD during the dry season increases the chances of above average rainfall over central Australia and increased moisture influx from the Indian Ocean towards the north (that is, raised humidity levels).
See the Bureau's ENSO Wrap-Up which includes a compilation of ENSO computer model predictions.
Next update expected by 28 May 2013| Product Code IDCKGEWOOO
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