Climate in-brief

• Australia has found itself hostage to anomalous high-pressure (chart adjacent), with very little moisture transport from the tropics to inland areas, with the exception of isolated pockets along the coastline

• The Southern Annular Mode has tanked negative, which will not assist moisture inflow to central-eastern areas during the remainder of November, but the SAM is expected to move more positive (wet) in December

• With a benign MJO, very little tropical activity and subsequent cyclonic activity, however, the air pressure at Darwin has fallen to well below average this week

• Multi-week models showing consensus for a more general rain event ~4-14 December where guidance suggests the current stronger than normal air pressure anomaly will abate - enabling easterly moisture penetration into NSW and Qld

• Temperatures to remain around normal for the remainder of November, and

• Seasonal models for summer season not showing consensus for a typical La Niña rainfall signature, as some caution is recommended for N NSW and SE Qld areas, with the eastern half of Qld and SE NSW showing the most potential for higher-than normal rainfall.

The chart above shows higher-than-normal air pressure across eastern/northern Australia. The low pressure associated with the MJO has not propagated eastward, with cyclonic activity centred in the Bay of Bengal and western Indian Ocean.

Australian weekly rainfall and relative landscape water balance

Some handy falls in the big rivers area of NT and the gulf over the past week and smaller scattered totals elsewhere along the coast and ranges. http://www.bom.gov.au/jsp/awap/rain/

Water balance anomaly still shows a dry area in SW Qld, with areas along the NSW ranges still above average after reasonable october totals

Australian relative landscape water balance ‘upper soil’ courtesy BOM

Multi-week model analysis (8-28 days)

A signal coming through from the multi-week models for a general event around 4-14 December. With the MJO currently inactive, models seem to suggest the current high-pressure acting as an umbrella across eastern Australia will abate and moisture from the NW and NE can penetrate inland areas during the first half of December. Despite many areas will register low rainfall totals for November, big-picture drivers remain reasonably bullish (particularly for Southern NSW and NE QLD).

Model commentary: a surprise this morning to see the typically doomsday IRI model showing general moisture for the first half of December! The interesting feature of the JMA wet forecast was the easterly systems developing along the coast and ranges of NSW, which we’ve not seen since the Autumn. The 16-day NCEP is more of a ‘weather’ model and it was not too excited about anything much except rain in the Ord and Katherine areas. The BOMs ACCESS model has been off with the pixies since May, but now in-line with the other two multi-week models showing a wet first half of December, the next fortnight or so will be interesting to see how this pans out. Keep an eye on the Meteologix 10 day Forecast XL for a full summary of all ‘weather models’ as events draw closer for your area: https://meteologix.com/au

Monitoring the SAM

The SAM has retreated into negative territory this week, although it is forecast to recover to neutral phase for the remainder of the month. Climatologists expect the SAM to become entrenched in positive phase through summer, in line with the La Nina signal. Until this occurs with some consistency, it is difficult for farmers in NSW and S Qld to get too optimistic with hopes for a fairytale wet La Niña summer.

Antarctic Oscillation or SAM values (20 Nov)

https://www.cpc.ncep.noaa.gov/products/precip/CWlink/daily_ao_index/aao/aao_index.html

Recent research by Hendon et al, (2014) at the Centre for Australian Weather and Climate Research found the Southern Annular Mode to be the leading mode of circulation variability through parts of inland eastern Australia where cotton is grown; particularly in the spring planting period.
 
A positive SAM has been proven to increase moisture supply into fronts and troughs forming in eastern Australia. The chart provided by Climate Prediction Center (US) shows the most recent observations of the SAM or (AAO). 

A negative SAM traditionally leads to a dry westerly circulation pattern through eastern Australian cropping areas.
 
BOM researchers Lim and Hendon (2013) found the SAM has the strongest connection with El-Niño Southern Oscillation in October and November – whereby the SAM is influenced most by El Niño or La Niña conditions.

Growers and advisors are encouraged to monitor the phases of the SAM together with seasonal forecasting, multi-week and short term weather models during planting. A short cartoon explaining the SAM can be found HERE. 

Global tropical hazards

(from U.S Climate Prediction Center)

The noticeable features in the chart below show the green colours in the Indian Ocean where the MJO currently resides, not really progressing eastwards towards Australia. When the tropical moisture in the Pacific begins to move Easterly (towards Australia), this will increase the probability of our cyclonic activity and rainfall.

Seasonal forecast: December 2020 - February 2021

Here are four of the major seasonal rainfall models showing for December, January, February.

The general circulation models (GCMs) are not exactly showing a conventional La Niña signature through central inland areas, instead favouring coastal Queensland, Cape York and SE corner of NSW. The cooler waters to Australia’s north and ever-persistent high-pressure systems in the Tasman Sea are perceived as having a negative influence on rainfall through central NSW through to the Darling Downs/Southern Qld.

Despite forecast rain for the first week in December, some caution is needed for northern NSW and southern Qld areas looking to plant summer crops or purchase livestock. The Southern Annular Mode has not progressed into a positive phase (in keeping with La Niña), which is likely flowing through into these model outputs and requires careful monitoring during the next few weeks.

What to know more about climate drivers and how they are measured? Click here

IRI MME (US)

BOM (AU)

ECMWF (EU)

CMCC (ITA)

Farmer climate focus - Nigel Burnett

Nigel and Beth Burnett run a mixed broadacre cropping farm near Emerald, QLD. With a mixture of both irrigated and rain grown cropping enterprises, the climate is a key management consideration. Nigel shares with us how he is preparing for an altered summer cropping program based on the favourable 2020-21 outlook.

Nigel Burnett

Emerald, Qld

Location snapshot

Catchment:   Fitzroy Catchment (Comet River sub basin and Nogoa River sub basin)

Altitude:        156m

Enterprise:    Broadacre cropping (irrigated & dryland).
Winter cereals and legumes, Summer (Cotton and sorghum)

Rainfall:        Wet season (Oct-Mar): 76% rainfall
Cool season (Apr-Sep): 24% rainfall

Seasonal rainfall climate drivers: Niño 4 ocean indicator seems to be the one to watch for Emerald

El Nino-Southern Oscillation (ENSO) is the key climate driver, however, ENSO impacts are very weak post-January to May.

Very little impact from the Indian Ocean dipole in this location - strongly ENSO related climate influences

What are your ‘go-to’ sources of climate/weather information?

OCF and OzForecast for weekly weather forecast. Jon Welsh’s seasonal climate analysis, WXMAPS (GFS) for a broad picture of what's going on and the BOM to round it all out.

How do you consider climate in your farm management? Consideration of climate plays a big part in our farm management strategy. It is a key driver in our decision making and is integral to our risk management strategy. We use it mainly to get a feel for where things are heading in terms of our seasonal outlook for our region and the rest of the Eastern cropping zone. The weather conditions we receive during fallow and in-crop are out of our control, but we can manipulate our production system to maximise the opportunity provided by a favourable seasonal outlook or manage our exposure to risk from a poor seasonal outlook. Some of the management decisions which we make to respond to the climate outlook are planting decision, planting timing, rotation, variety and maturity, fertiliser program and stubble management.

Can you share a climate success (or failure) story with us?

I was on the Cotton Industry Awards judging trip in April of 2016 and and was fortunate to spend some time discussing the seasonal outlook with Jon Welsh on our visit to Narrabri. Jon was very bullish on the rainfall outlook for winter for the whole eastern cropping zone and after analyzing other climate forecasts and considering other important management drivers, I came back to Emerald and planted wall to wall chickpeas including all of our irrigated fields. Luckily this turned out to be a very good decision as that winter was very favourable in terms of rain and temperature. It was easily our most profitable winter crop that I can remember growing ever. Now I am sure Welshy will be the first to advocate not to plant your whole farm to one particular crop on his advice of an improvement in the seasonal condition. But it was a very important consideration among other drivers such as soil moisture, commodity price, water availability for irrigation and cash flow.

There was early talk of a wetter winter, however you haven’t received much rain after your wetter than average Feb/Mar. How did your winter crop pan out?

Our area certainly missed the wetter winter memo and it has been a tough winter cropping season for Central Queensland. We planted 3000Ha of wheat and chickpeas on predominantly rain grown country and a small amount of semi irrigated wheat. Our team had to chase moisture deep for planting the wheat and the chickpeas using a moisture profile from the last significant rainfall from late February/ early March. The profile wasn't consistent and plant stand wasn't ideal, further contributing to the effect of the tough season on the very average yields. However, even with the benefit hind sight, I would still plant those crops for the new crop stubble benefit. 

What are you thoughts for this summer crop?

We have received 50-60mm in the last week of October across our entire area and with the improved seasonal forecast we are feeling more and more optimistic by the day. If the rain continues and we fill our soil profile during November, we will plant a significant portion of our area to irrigated and rain grown cotton. Although August has become the preferred option to plant irrigated cotton in our region, I think there is still enough time to grow a good crop of cotton in CQ that is planted in November and harvested in May.

Have a farming climate story to share? Please contact us.

9-day ECMWF rainfall outlook

Fresh this morning, this European model shows rainfall for the next week mainly confined to Katherine, Kununurra and the parched NSW northern ranges. Some handy falls possible along the Great Dividing Range further south. Date range: 26th November - 6 December.

The remainder of December looks interesting. Air pressure at Darwin is now at 1005 hPa, which is well below average - exhibiting monsoon-like characteristics. The bug-bear at the moment is cooling sea temperatures around the Arafura and Coral Seas, not consistent with a La Niña like conditions. In turn, the MJO is losing steam when it comes from west-east and arrives in the Australian region. The latest multi-week models are still bullish for a general change and rain week 2-3 (coinciding with a weak MJO) of December and a return to average temps.

Access courtesy https://meteologix.com/au

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