I Think we are in for a high mold Autumn........
...
It is also an La Niña year!
This winter is expected to be a Very Cold this winter because of it!
How far is Casablanca? It could be a nice warm place for Christmas!
As part of the wider El Niño Southern Oscillation, La Niña is characterised by the development of
cooler than average sea surface temperatures (SSTs) in the eastern Pacific Ocean.
Sometimes dropping by around 5°C below normal, this oceanic cooling can cause
droughts in some parts of the world, and
intense storms in others. It is only the third 'triple dip' La Niña since records began, back in 1950.
According to the BoM, this event is forecast to be
weak to moderate in strength, peaking during the Southern Hemisphere's spring and easing during summer.
“During La Niña events, waters in the eastern tropical Pacific Ocean are
cooler than normal, and waters in the western tropical Pacific Ocean warmer than normal," said Dr Andrew Watkins, head of long-range weather forecasts at the BoM.
"This causes
changes in wind, cloud and pressure patterns over the Pacific. When this change in the atmosphere combines with changes in ocean temperature, it can influence global weather patterns and climate."
Global weather impacts of La Niña
La Niña events have widespread impacts on both seasonal weather patterns and the climate, as the changes in SSTs have
knock-on effects on large scale circulation patterns.
For example, the phenomenon tends to bring
increased levels of rainfall for parts of northern South America, southern Africa and many areas in southern and eastern Asia.
Map of average sea surface temperature anomalies during La Niña (cooling indicated by blue), overlaid with Walker Circulation anomaly. Credit: NOAA Climate/Fiona Martin.
These wetter than average conditions are particularly notable in
Australia, where rainfall during local summer can be as much as 20% higher than normal, resulting in
severe flooding. Elsewhere, the southern
United States and
Mexico usually see comparatively dry, warm conditions, which can lead to drought.
Does La Niña affect the UK?
The consequences of La Niña in Europe are much less obvious, with the only clear impact, according to the Met Office, being a tendency for slightly
drier than average weather in the Iberian Peninsula during autumn.
In the UK, there is a tendency for La Niña years to favour high pressure in the mid-Atlantic during late autumn and early winter. This can promote
intense, cold conditions due to the blocking of the Atlantic weather systems that typically deliver mild air.
Conversely, in late winter, the weather can turn milder as La Niña
drives the jet stream closer to the North Pole. This can also result in stormier conditions, with increased rainfall.