Don't just blame El Nino for weather
The weird warm weather much of the country has been experiencing in November and December is not unexpected. In fact, it fits many past strong El Nino patterns and was what was forecast to happen. Yes, El Nino is by SOME measures the strongest (warmest water temps) on record. But beware
media hype, El Nino is NOT a storm system or a jet stream monster that's going to reek havoc and release the hounds of hell. It brings both good and bad weather. It can help the drought in California but with too much of a good thing (flooding/mud slides).
The strong 2015 El Niño event is near its peak. While sea surface temperatures remain close to record-high values, some El Niño indicators are now showing signs of easing.The 2015–16 El Niño is strong, and likely to rank in the top three events of the past 50 years. Presently,
several key indicators fall short of their 1997–98 and 1982–83 values, both in the ocean (e.g. sub-surface temperatures, which have peaked around +8 °C this year, compared to +12 °C in 1997–98), and atmosphere (e.g. SOI, for which monthly values peaked around −20, while 1982–83 had several months at −30).
While
El Nino is impacting global weather patterns, it is far from the only weather driver and not always the primary one.
Right now something else is more likely the reason the coats and gloves have been gathering moths. The warmth is "
really associated with the strengthened polar vortex," said Mike Halpert, deputy director of the
Climate Prediction Center at the National Weather Service. "It is much more likely the Arctic Oscillation." "
Arctic Oscillation" is a change in
air pressure (oops! no CO2, just
PV=nRT) at the North Pole that affects how far south cold air travels from the Arctic.
First, it is important to
understand (
science "boy" with a mall "b") a phenomenon called the polar vortex. The polar vortex is a ring of cold winds that swirls around the north pole (there is one at the South Pole, as well).
Low pressure (
PV=nRT, temperature difference drives pressure and wind speed) keeps those winds — and the cold air they carry — wrapped around the poles. At the furthest perimeter of this vortex is a
jet stream of fast-moving, cold air. But the pattern varies —
high pressure in the Arctic can push the winds away from the pole and down to the the mid-latitude regions of the planet, where most people live. Other times, the pressure at the Arctic can be so low that the vortex is especially tight, and a greater portion of cold air than normal is trapped near the pole. Those fluctuations make up the Arctic Oscillation.
When pressure at the Arctic is exceptionally high, the AO is "negative," when pressure is low, it is "positive." The cold weather in the early months of 2014 was largely attributed to that shifting of the polar vortex away from the Arctic and toward the equator — a "
negative" Arctic Oscillation. Over half of the United States was covered in snow, and some regions saw record cold temperatures.
Currently, the Arctic Oscillation is
exceptionally positive, and the polar vortex has been stronger than average. The cold air that would otherwise chill the northern regions of the country is staying around the Arctic. So, regions that would normally be receiving snow at this time of year are
unseasonably warm. Only a few mountainous regions in the country have seen snow. Judah Cohen, a meteorologist with Atmospheric and Environmental Research, echoed Halpert's comments in a recent blog post.
A positive Arctic Oscillation pattern "has resulted in
very mild temperatures across northern Europe, the Eastern United States and to a lesser degree East Asia," Cohen wrote. However, he noted that the
pattern is slowly transitioning, and "temperatures are likely to cool from their very elevated levels."
El Nino is almost certainly affecting weather and precipitation in the Northeast and elsewhere in the United States to some extent; much of the rain seen across the South is consistent with El Nino, for example.
No two El Nino seasons are ever exactly alike, but are often similar. Halpert said the Climate Prediction Center projects that the strong El Nino will maintain its strength through the winter before gradually weakening in spring.
"For California, El Nino means that there is a pretty favorable tilt toward a wetter winter from January through March," Halpert said, but added that
"this is not a guarantee" since weather and climate are complicated and can be affected by many factors.
Plenty of winter is expected as we get deeper into the new season, IF the analog years I've selected are correct.
Longer-term high latitude boundary conditions
favor a negative bias to the AO including extensive Eurasian snow cover and low sea ice extent in the Barents-Kara seas. The key will be how strong the
energy transfer from the troposphere to the stratosphere (
PV=nRT) is in late December and how much the polar vortex is perturbed. If the energy transfer does NOT significantly weaken the polar vortex, the AO will likely remain mostly positive and then mild temperatures will dominate the mid-latitudes.
Strong El Ninos have accompanied both no snow and heavy snow in winter in Georgia.
http://www.wsbradio.com/weblogs/kir.../2015/dec/13/dont-just-blame-el-nino-weather/
Not one mention of climate change, global warming or CO2 levels. What is interesting to note is the energy transfer from the troposphere to the stratosphere (cooling). Radiative forcing transfers energy from the atmosphere back to the surface of the earth (warming). Strange that the CO2 levels are increasing without the effect of warming the earth consistently day to day, week to week, month to month, year to year for 17+ years.