Trend towards La Niña continues.
Issued on Wednesday 7 July 2010 | Product Code IDCKGEWWOO
Sea surface temperatures in the central equatorial Pacific have continued to cool over the past fortnight, and hence the tropical Pacific is now generally cooler than average east of the date-line. Below the surface, temperatures also remain significantly cooler than average, with some areas more than 4°C cooler than normal. Trade winds in the western Pacific remain stronger than normal and cloudiness near the date-line continues to be suppressed. These indicators, together with the Southern Oscillation Index (SOI), which has been positive since April, are consistent with the developing stages of a La Niña event.
The majority of climate models surveyed by the Bureau suggest current patterns and trends will continue, with a significant likelihood of further ocean cooling beyond La Niña thresholds before the end of the southern winter.
Historically, about 35 to 40% of El Niño events (such as occurred in 2009/10) are followed by a La Niña within the same year. The combination of current trends and model outlooks suggest the chance of a La Niña in 2010 is now clearly more likely than not.
Information about the historic relationship between ENSO events and Australian climate can be viewed here.
Next update expected by 21 July 2010 | print version
The following data is from the Ag research service in Lubbock, TX and was compiled by Dr, Steven Mauget and Dr. Dan R Church and looks at the yield impact of wheat and corn yields for both La Nina and El Nino events.
The full research can be found at:http://www.lbk.ars.usda.gov/WEWC/ensoag.aspx
Table 1: Effects on Corn Yield After El Niño (6+) and La Niña (6-,10-) July-August-September Periods. Illinois | # Harvests | Below Normal | Near Normal | Above Normal | Significance |
After Warm JAS (6+) | 12 | 0 | 3 | 9 | 98.81% | After Cold JAS (6-) | 18 | 10 | 5 | 3 | 99.46% | After Cold JAS (10-) | 8 | 6 | 1 | 1 | 99.50% | All Years (1881-1994) | 114 | 31 | 37 | 46 | |
After Warm JAS (6+) | 12 | 0 | 4 | 8 | 96.23% | After Cold JAS (6-) | 18 | 8 | 6 | 4 | 91.61% | After Cold JAS (10-) | 8 | 3 | 4 | 1 | 88.71% | All Years (1881-1994) | 114 | 29 | 32 | 39 | |
After Warm JAS | 12 | 2 | 4 | 6 | 79.80% | After Cold JAS (6-) | 18 | 7 | 8 | 3 | 94.86% | After Cold JAS (10-) | 8 | 5 | 2 | 1 | 93.60% | All Years (1881-1994) | 114 | 36 | 37 | 41 | |
After Warm JAS | 12 | 2 | 3 | 7 | 86.60% | After Cold JAS (6-) | 18 | 7 | 8 | 3 | 97.45% | After Cold JAS (10-) | 8 | 3 | 5 | 0 | 98.48% | All Years (1881-1994) | 114 | 34 | 35 | 45 | |
After Warm JAS (6+) | 12 | 3 | 0 | 9 | 98.33% | After Cold JAS (6-) | 18 | 6 | 7 | 5 | 86.07% | After Cold JAS (10-) | 8 | 2 | 3 | 3 | **** | All Years (1881-1994) | 114 | 30 | 36 | 48 | |
Table 1. Entries show the number of total and below, near, and above normal corn harvests after July-August-September periods marked by extreme S index conditions. "All years" entries indicate those same counts for the (1881-1994) population of harvests for each state. 6+ (6-) indicates SSTA conditions above (below) the highest (lowest) sextile of the historical distribution. 10- indicates SSTA conditions below the lowest decile; i.e., in the lowest 10% of values. Significance levels apply to the bold and underlined entries in each row. Thus underlined near and above normal counts shows a tendency to near and above normal harvests at the corresponding significance level, etc.
Table 2: Effects on Winter Wheat Yield After El Niño (6+) and La Niña (6-) November-December-January Periods. Kansas | # Harvests | Below Normal | Near Normal | Above Normal | Significance |
After Warm NDJ (6+) | 19 | 3 | 5 | 11 | 98.65% | After Cold NDJ(6-) | 20 | 11 | 7 | 2 | 94.55% | All Years (1909-1994) | 86 | 32 | 25 | 29 | |
After Warm NDJ (6+) | 19 | 2 | 6 | 11 | 99.05% | After Cold NDJ (6-) | 20 | 14 | 3 | 3 | 99.95% | All Years (1909-1994) | 86 | 31 | 27 | 28 | |
After Warm NDJ (6+) | 19 | 0 | 8 | 11 | 99.04% | After Cold NDJ (6-) | 20 | 13 | 5 | 2 | 99.59% | All Years (1909-1994) | 86 | 32 | 26 | 28 | |
After Warm NDJ (6+) | 19 | 5 | 5 | 9 | 89.89% | After Cold NDJ (6-) | 20 | 11 | 2 | 7 | 94.55% | All Years (1909-1994) | 86 | 32 | 26 | 28 | |
After Warm NDJ (6+) | 19 | 5 | 5 | 9 | 92.00% | After Cold NDJ (6-) | 20 | 11 | 4 | 5 | 92.99% | All Years (1909-1994) | 86 | 33 | 26 | 27 | NA |
Table 2. Entries show the number of total and below, near, and above normal winter wheat harvests after November-December-January periods marked by extreme S index conditions. "All years" entries indicate those same counts for the (1909-1994) population of harvests for each state. 6+ (6-) indicates SSTA conditions above (below) the highest (lowest) sextile etc. Significance levels apply to the bold and underlined entries in each row. Thus underlined near and above normal counts shows a tendency to near and above normal harvests at the corresponding significance level, etc.
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La nina
