minnesotasmith
12-30-2007, 20:40
http://www.extension.iastate.edu/notes/detail.aspx?id=15947
from Iowa State University:
Extension Notes
Note DetailLa Nina Reaches Threshold
12/26/2007 10:09:00 AM
--------------------------------------------------------------------------------
La Nina Reaches Threshold 071226
La Nina conditions are now posing a significant
risk to US corn production in 2008. The 90-day SOI
threshold of 0.80 was met on Christmas day.
Threshold means that 54% of the time significant La
Nina conditions (defined as a 5-month average
exceeding 0.8) will develop. The 90-day threshold
gives a 20 to 60-day advance indication. Several
research groups see some indication that the
La Nina may diminish quickly and not pose a risk to
US crops. Never the less, it is now at the level
to be considered a risk. When the La Nina is in
place in June and July the risk of a below trend
yield in the US Corn Belt is 70%. This risk is
increased by scant subsoil moisture, the 19-year
drought cycle, and existence of drought in the area
of South Carolina. At this time the combined risk
is a 68% chance of a below trend US corn yield.
The USDA trend for 2008 has not yet been released
but will likely be near 151.6 BPA. The chance of
a near record high yield is at 15% (greater than
165 BPA) and of drought (below 135 BPA) is 35%.
The risk levels are the composite of the identified
climate risks and are expected to be updated in
late January. E. Taylor 26 December 2007
==================================================
More specifically what this means for 2008 hikers...
http://en.wikipedia.org/wiki/La_Nina
La Niña is a coupled ocean-atmosphere phenomenon similar to El Niño. During a period of La Niña, the sea surface temperature across the equatorial Eastern Central Pacific Ocean will be lower than normal by 0.5 °C. By definition, an episode of La Niña is a period of at least 5 months of La Niña conditions. The name La Niña originates from Spanish, meaning "the little girl", analogous to El Niño meaning "the little boy".
La Niña is the opposite of El Niño, where the latter corresponds instead to a higher sea surface temperature by a deviation of at least 0.5 °C. El Niño is famous due to its potentially catastrophic impact on the weather along both the Chilean and Australian coasts. Furthermore, La Niña is often preceded by a strong El Niño.
Effects of La Niña
Regional impacts of La Niña.La Niña causes mostly the opposite effects of El Niño, for example, El Niño would cause a wet period in the Midwestern U.S., while La Niña would typically cause a dry period in this area.
Also, the presence of La Niña is often quoted by the National Hurricane Center to be a cause for increased Atlantic tropical cyclone activity, partly because of higher sea surface temperatures in the Atlantic basin. The hurricane season of 1995 is also likely to have been influenced by that year's La Niña conditions.
[edit] Recent occurrences
There was a strong La Niña episode during 1988-1989. La Niña also formed in 1995, and in 1999-2000. The last La Niña was a minor one, and occurred 2000-2001. Currently, there is a moderate La Niña, which began developing in mid-2007. NOAA confirmed that a moderate La Niña developed in their November El Niño/Southern Oscillation Diagnostic Discussion, and that it will likely continue into 2008. According to NOAA, "Expected La Niña impacts during November – January include a continuation of above-average precipitation over Indonesia and below-average precipitation over the central equatorial Pacific. For the contiguous United States, potential impacts include above average precipitation in the Northern Rockies, Northern California, and in southern and eastern regions of the Pacific Northwest. Below-average precipitation is expected across the southern tier, particularly in the southwestern and southeastern states."[1]
from Iowa State University:
Extension Notes
Note DetailLa Nina Reaches Threshold
12/26/2007 10:09:00 AM
--------------------------------------------------------------------------------
La Nina Reaches Threshold 071226
La Nina conditions are now posing a significant
risk to US corn production in 2008. The 90-day SOI
threshold of 0.80 was met on Christmas day.
Threshold means that 54% of the time significant La
Nina conditions (defined as a 5-month average
exceeding 0.8) will develop. The 90-day threshold
gives a 20 to 60-day advance indication. Several
research groups see some indication that the
La Nina may diminish quickly and not pose a risk to
US crops. Never the less, it is now at the level
to be considered a risk. When the La Nina is in
place in June and July the risk of a below trend
yield in the US Corn Belt is 70%. This risk is
increased by scant subsoil moisture, the 19-year
drought cycle, and existence of drought in the area
of South Carolina. At this time the combined risk
is a 68% chance of a below trend US corn yield.
The USDA trend for 2008 has not yet been released
but will likely be near 151.6 BPA. The chance of
a near record high yield is at 15% (greater than
165 BPA) and of drought (below 135 BPA) is 35%.
The risk levels are the composite of the identified
climate risks and are expected to be updated in
late January. E. Taylor 26 December 2007
==================================================
More specifically what this means for 2008 hikers...
http://en.wikipedia.org/wiki/La_Nina
La Niña is a coupled ocean-atmosphere phenomenon similar to El Niño. During a period of La Niña, the sea surface temperature across the equatorial Eastern Central Pacific Ocean will be lower than normal by 0.5 °C. By definition, an episode of La Niña is a period of at least 5 months of La Niña conditions. The name La Niña originates from Spanish, meaning "the little girl", analogous to El Niño meaning "the little boy".
La Niña is the opposite of El Niño, where the latter corresponds instead to a higher sea surface temperature by a deviation of at least 0.5 °C. El Niño is famous due to its potentially catastrophic impact on the weather along both the Chilean and Australian coasts. Furthermore, La Niña is often preceded by a strong El Niño.
Effects of La Niña
Regional impacts of La Niña.La Niña causes mostly the opposite effects of El Niño, for example, El Niño would cause a wet period in the Midwestern U.S., while La Niña would typically cause a dry period in this area.
Also, the presence of La Niña is often quoted by the National Hurricane Center to be a cause for increased Atlantic tropical cyclone activity, partly because of higher sea surface temperatures in the Atlantic basin. The hurricane season of 1995 is also likely to have been influenced by that year's La Niña conditions.
[edit] Recent occurrences
There was a strong La Niña episode during 1988-1989. La Niña also formed in 1995, and in 1999-2000. The last La Niña was a minor one, and occurred 2000-2001. Currently, there is a moderate La Niña, which began developing in mid-2007. NOAA confirmed that a moderate La Niña developed in their November El Niño/Southern Oscillation Diagnostic Discussion, and that it will likely continue into 2008. According to NOAA, "Expected La Niña impacts during November – January include a continuation of above-average precipitation over Indonesia and below-average precipitation over the central equatorial Pacific. For the contiguous United States, potential impacts include above average precipitation in the Northern Rockies, Northern California, and in southern and eastern regions of the Pacific Northwest. Below-average precipitation is expected across the southern tier, particularly in the southwestern and southeastern states."[1]