NOAA released its detailed monthly analysis of global temperature and precipitation this week. For the first time in six months, January was not the warmest of any corresponding month — just the second warmest — when air and sea temperatures were averaged.
Overview Of January Temperatures
During the last half of 2014, sea surface temperatures (SST) set new monthly highs, while land temperatures, while in the top ten warmest years, generally didn’t threaten the records.
In January, land temperatures were the second highest ever recorded, while SSTs were only the third highest for any January. The years with higher ocean temperatures both had strong El Niños.
Highlights Of The January Temperature Analysis
The Gulf of Alaska and nearby northeast Pacific Ocean were very much warmer than normal in January, continuing the trend of the past fifteen months. Adjacent areas of Alaska, western Canada, and the northwest US were influenced by the ocean water temperatures and recorded well-above-normal readings.
Surface temperatures are highly correlated with bulges in the jet stream, and the past 15 months have been characterized by a ridge in the jet stream over the eastern Pacific and western North America.
The corollary to this has been a pronounced dip in the jet stream over eastern North America (the polar vortex), and that shows up in colder than normal temperatures at the surface.
Waters of the equatorial Pacific continue to run above normal, as they have for about six months. This very modest El Niño — Decoded Science calls it El Niño Eggplant, though it does not quite get over the bar of NOAAs definition — has influenced the weather in the western US a couple of times, most notably in November, when southern California received considerable rain.
In January, however, the warm waters of the northeast Pacific were dominant, and little rain fell in all of California — in fact no rain at all in San Francisco. This was the first time San Francisco has had a rainless January.
The waters of the Gulf of Mexico, Caribbean Sea, and western North Atlantic were all above normal. Other things being equal, this would imply a busy hurricane season to come.
China recorded its warmest January, but records only go back to 1961. Nevertheless, China is a big place, and a record temperature over such a large area is significant.
Different Atmospheres For Different Hemispheres
Though the northern and southern hemispheres both measured well above average temperatures, there were significant differences:
- Land temperatures were third warmest in the northern hemisphere, but only 19th warmest in the southern hemisphere.
- Ocean temperatures were the warmest ever in the northern hemisphere and fifth warmest in the southern hemisphere.
- Land and ocean combined were second warmest in the northern hemisphere and seventh warmest in the southern hemisphere.
A Possible Explanation For The Differences Between The Hemispheres: Sea Ice
The extent of sea ice in Antarctica in January was the greatest on record. This would account for the cold temperature anomaly of waters in the southern oceans, and the relatively colder southern hemisphere as a whole relative to the northern hemisphere.
Arctic sea ice extent in January was the third lowest on record. Arctic temperatures as reported by the Danish Meteorological Institute continue to run about five degrees above the long-term average as they have every winter since 2006.
January Precipitation Highlights
Precipitation is highly variable from month to month. Nevertheless, we can discern some trends.
- Europe was mostly wetter than normal, with the exception of the Iberian Peninsula.
- Western Australia was dry.
- Portions of western and extreme southern Africa were dry.
- The northern and southern tips of south America were dry.
- Part of Argentina was extremely wet.
Precipitation In The United States
Aside from the very dry January in the US west, part of an ongoing drought, there were variations in the rest of the country.
Only parts of the southwest and mid-Atlantic received above-normal precipitation.
Much of the rest of the country was drier than normal, including the central plains, central Rockies, intermountain west, and midwest.
Nature’s Tug Of War Continues
El Niño Eggplant is fighting with the warm Alaskan waters for control of the weather pattern over the US west coast. This, in turn, determines the weather in the eastern US.
Northern and southern hemispheric polar areas have diverged in their temperature anomalies; this trend has been in place for years and is hard to explain.
The future of the climate is up in the air — but it would be foolish to bet against warm.
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