Seasonal Climate forecast, issued 23rd September 2012.

Seasonal Climate Outlook;  October 2012 – January 2013.

Issued by Anthony Violi, on 22rd September 2012

Current Overview :

Currently, we turn our attention again to the Pacific ocean, and over to the Indian Ocean. As i have pointed out previously, the forecast El nino has failed to gain any semblance in the Pacific. The forecast of cool neutral appears well on track. All other indicators are well de-coupled from the oceans, in fact the oceans are starting to couple with the atmosphere at present.

Here is the current drivers for the Pacific Ocean region that i am seeing as influencing the climatic pattern.

Trades are still Easterly, consistent with a La Nada.

Southern Oscillation Index is 4.60 for the 30 day reading, and -3.29 for the 90 day reading. By the end of October it should be at zero for the 90 day average as we lose the negative figures from June which was a -10 month.

Here is the graph: The positives are La Nina tendencies, and the negatives are El Nino tendencies. The SOI is calculated as the difference in Sea Level Air Pressure between Darwin and Tahiti.

CFS still forecasting an El Nino, though has markedly decreased the strength of an El Nino. As it stands it will be a warm neutral or bare minimum El Nino briefly. Here is the Nino 3.4 area, the centre of the Equatorial Pacific

Here is Nino 1 and 2, close to the South American coast. This is where the cooling of the oceans start as a result of upwelling of cold water.

Notice the huge plunge as evidenced by the blue lines, which are the latest model runs! The models are now seeing what i what seeing 3 months ago. I think it will plunge further as there are no Kelvin Waves to be seen anywhere.

Here is the Kelvin Wave plot. Kelvin Waves are pools of warm water in the subsurface and indicate imminent surface warming, as they travel westwards, usually carried by a Westerly Wind Burst.  As you can see,at the moment there are none that are warm of any nature in the pipeline for the next two months.

Sea Surface temperatures continue to lose heat, here is the anomaly chart.

At this stage, im still forecasting a cool neutral, (and also note a weak La nina cannot be ruled out by January at this stage, by next update we can defintively call it), as my belief is the warm anomalies in Nino 3.4 have peaked.

The other area is the Indian Ocean, you can see the area near Indonesia is rapidly warming, as i forecasted the last month. The pattern has started to shift early as i also mentioned, which is allowing the seasonal cooling of this area to now warm from below. I expect the whole basin of the Nw coast to be above average within 4-6 weeks, which also ties in with the call for above average rainfall in the next 3 months.

As noted in previous forecasts, notice the warmth in the Central Indian Ocean, providing fuel for fronts and low pressure systems over the next few months with a great moisture source. Once both areas are warm in tandem i think it lines us up for an enormous summer rainfall problem again for most of the country.

Another side note is the air in the interior is hot, due to the dry air from the winter cold snaps from the South. This will filter South into the Southern states, and we will see hot weather and humidity increasing in the next 4 weeks. Its my forecast that hot and humid will be a key player to start with until November, then we may see enough moisture to keep the extreme temperatures at bay for another season. I will update this in the next months forecast.

Forecast for Spring: October 2012 to January 2013.

Northern Territory : Temperatures will be slightly above average through Spring, tending less so in November.  Rainfall will be above average through the Northern areas for all of Spring, and average to slightly below average for the remainder of the inland areas.

Queensland: Temperatures will now be slightly warmer than average through the forecast period for all of Queensland except the far north. Rainfall in October will be average through all of Queensland, except the inland which will be below average. However during November through January rainfall will increase substantially for all areas of Queensland.

New South Wales : Temperatures will be slightly above average for Spring in NSW. Rainfall will be below average in the NW initially in October, then average for the remainder. The remainder of NSW will have average to above average rainfall this forecast period.

Victoria : Temperatures in Victoria will also be average for all of the forecast period, particularly through Southern areas. Rainfall will also remain above average for all southern areas, and below average for the Northern areas in early October, however rainfall will increase through late October through Northern areas and be slightly above average for the forecast period.

Tasmania : A continuation of the trend for Tasmania with below average temperatures for the entire period and state. Rainfall will be variable, average in western areas and below average slightly in Eastern areas.

South Australia : Southern areas will be slightly above average for temperatures for the entire forecast period. Northern areas will see early above average temperatures through October, averaging out by November. Rainfall will also be highly variable, southern areas will average rainfall tending wetter through the latter part of Spring, Northern areas of SA will see below average rainfall until late October when rain will increase markedly.

Western Australia : Temperatures will be slightly above average in October, particularly through the Southern and inland areas. Early season records are likely in the coming weeks through the Northern parts of the state, then November will see temperatures average out to normal. Rainfall will be slightly below average for the entire state through October. However i expect rainfall to increase markedly through November through January

Notes: We are now seeing early Spring warmth for most of the inland areas, moving South, as previously forecast. Humidity will increase from early October onwards, deep Easterly trades should ensure lots of moisture will be advected over the country. Also, the Indian Ocean has rapidly warm as previously suggested, this warming trend will stick around for the next 6 to 9 months and should ensure above average rainfall across much of the Northern half of Australia, and the SE states. I am also forecasting a much earlier build up season, and then earlier monsoon arrival than last summer. probably mid December. 

Also the risk now of serious flooding is greater than the last forecast that i put up. We have a set up the likes not seen that often, warm water off both coasts will develop in the next few weeks and increase as time goes on. So as a general rule, rainfall will do the same. The position of the Long Wave Trough also puts us at significant risk this summer yet again for another deluge, this is another ace in the pack that didnt quite line up in the last 2 years despite record rainfall. This is something to be watched as the pattern should retreat slightly through October, if it does not then all bets are off.

Next Update by October 20th 2012.

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