An 'Excessively Abnormal' Negative Arctic Oscillation (AO) & Negative North Atlantic Oscillation (NAO) - An Indicative Sign Of Big Things Coming To The UK & Ireland? Cold/Snow/Blocking
The exact signals that we need to be seeing for some even colder weather and widespread snow events throughout the second half of November, and into early/mid December are now starting to fall in place - with the Arctic Oscillation (AO) and the North Atlantic Oscillation (NAO) both doing exactly what they should be at this stage and in terms of our 5-6 month ahead calculations/forecasts.
The North Atlantic Oscillation (NAO) and the Arctic Oscillation (AO) are closely related and affect temperature patterns in the Northern Hemisphere. Factors such as the Siberian snow cover, and sudden stratospheric warming relate to these negative trends.
When the AO is in its negative phase (as above), it allows for an easier intrusion of cold Arctic air to lower latitudes. When the closely related NAO is in a negative phase (as above), it allows for cold easterly winds and cold winters in Europe, with a blocking situation that our forecasting parameters favour over Western Europe.
The impressive Siberian snow cover for this year also offers a high correlation for a negative AO throughout much of the upcoming winter and into next spring. We can therefore expect a significant amount of colder intrusions and prolonged diversions of the jet stream/blocking within this period.
If we look at the latest AO readings, it is really starting to trend towards an 'excessively abnormal' negative value from around the middle of November, and this will also be in response to the recent stratospheric warming over Siberia. The excessively abnormal value from the AO index is also important, as it indicates that higher than normal pressure is present over the Polar region and to what extent of cold we are looking at throughout this winter, and in terms of a big event like December 2010 or March 2013 (which were both forecast from several months in advance for the specific dates within our previous long range forecasts). When the AO/NAO turns negative like this, it becomes a good time to prepare for a number of Arctic intrusions and the potential for some widespread snow events (even to lower levels) across the UK and Ireland throughout the second half of November and into December.
Now this is something that the models have only just started to pick up on in the last 24-48 hours (the reason why there has been some opposition from other forecasters with our November/winter forecast). So be prepared for some backtracking from other forecasters who said this wouldn't happen. Unfortunately, when you have no other methodology or little understanding of forecasting the weather other than model watching, there is always the risk that it could come back and bite you at a later date.
So be prepared for falsified claims that we have said the coldest winter in 100 years is on the way or -27C in weeks as they backtrack - as subscribers know this has not been said in any of our reports.
As I also stated in one of the recent updates below, they do this out of fear and their own insecurity/inability to forecast long range weather events to their clients. They also choose to pass judgement on certain variables such as the headline alone (also very contradictory), without looking deeper into the content of what has actually been said within articles in "quotation marks" (the same and simplistic logic that they apply to their weather forecasting).
I even come across an article the other day from a competitor in Ireland that went as far as saying that we had said the coldest winter in 150 years. This is nothing but misleading drivel to make themselves feel or appear superior, and it is quite misleading information for the people who follow them too.
Another very recent example of our differing methodology to others + a colder than average November?
There are some indications that Bonfire Night could turn out to be the coldest of this century @ http://www.mirror.co.uk/news/uk-news/uk-weather-bonfire-night-set-4564096
Our UK & Ireland month ahead forecasts to subscribers from 10 days earlier also stated (when many models/other forecasters were indicating a mild and unsettled Bonfire Night):
This period will also begin to feel markedly cooler to what we have experienced throughout autumn to date. As we progress towards the middle part of this forecasting period (in or around bonfire night), there is the potential for a much colder flow of air to push in across the country and temperatures are likely to feature at a progressive near to below average within this period.
Temperatures are now also likely to fluctuate at near or below-average after Bonfire Night (not above-average or mild for the time of the year). If we then consider how things are likely to develop for the second half of November, it is now becoming very realistic that November will come in as a colder than the average month overall. Exacta Weather were the only ones that forecast this within our month ahead forecast to subscribers, and in advance of standard meteorology, as we don't rely on what computer models are indicating. However, every other forecaster who relies heavily upon computer models and have similar methodology to each other, indicated above-average temps for November as a whole, including the UK Met Office. In addition to this, our October month ahead forecast that was issued in advance of standard meteorology also opted for temperatures to be above-average for the month, but if you don't subscribe to our forecasts or listen to others with hidden agendas, then you won't know this.
Based on our differing methodology that has caused some variance among other forecasters/model watchers - the following information from our 5-6 month ahead forecast was provided voluntarily to various media for public consumption in relation to November/this winter in "quotation marks" only:
“Over the coming weeks and into NOVEMBER, it is likely to turn PROGRESSIVELY COLDER, even very cold at times, in particular, in parts of the north as northern BLOCKING becomes a somewhat more prominent feature. “This is likely to bring some significant snow across HIGHER GROUND within this period.
“A number of potentially very cold periods of weather and major snow events are likely to develop throughout this winter across large parts of the country, in particular, throughout the latter part of December and into January.
“The worst case and more plausible scenario could bring something on a similar par to the winter of 2009/10, the coldest in 31 years, or an event close to 2010/11 which experienced the coldest December in 100 years.
“February and into spring may also not escape an extension of these waves of cold and widespread snow at times."
(Published 10th October - when many said it would be mild until after Christmas).
Mr Madden warned to brace for a “shock to the system” with a “significant” snow event possible in weeks.
He said: “As we progress throughout NOVEMBER, it will begin to turn gradually cooler, in particular, WITHIN THE SECOND HALF OF THE MONTH as BLOCKING becomes a more prominent feature and the jet stream diverts further south.
“This will be due to expanding cold from the Arctic region, and this will also allow for the development of some much colder intrusions of air and snow for the UK.
“Some of the snow events are likely to be quite significant with blizzards across HIGHER GROUND, and a number of potentially notable snow events are also possible across some lower levels within this PERIOD (NOVEMBER AS A WHOLE), in particular, in some exposed coastal areas to the north and west of the country.
“We are also likely to see the development of some widespread frosts and rather extensive fog patches across the country within this period, and this will come as quite a shock to what we have experienced throughout this autumn to date.
“However, some spikes of milder conditions may also develop within this period, in particular, in some parts to the south of the country, and these will be accompanied by some rather windy and quite stormy conditions at times.”
(Published 26th October - when many were forecasting a mild start to November/November as a whole).
He said: “As we progress throughout November, it is going to become gradually colder across many parts of Ireland, in particular from around the MID-MONTH POINT when it is likely to become exceptionally cold at times. “This early start to what is likely to be a harsh winter is also likely to be accompanied by a number of potentially widespread snow events within this period and into the start of December. He continued: “The worst case and more plausible scenario could bring something on a similar par to the winter of 2009/2010, which was the coldest in 31 years, or an event close to 2010/2011, which experienced the coldest December in 100 years.
“However, the alternative and slightly more unfavourable scenario could see a winter period on a similar par to 2012/2013 developing, which would still support a colder and snowier than average winter throughout 2014/2015. “If any month could prove to be very severe or potentially record-breaking in terms of the cold and snow episodes that are likely to develop, then January looks like being the main contributor for this on current indications.” He added: “February and into spring may also not escape an extension of these waves of cold and widespread snow at times."
(Published 29th October - when many were still forecasting a mild start to November/November as a whole).
Netweather in particular, has had quite a lot to say about our winter forecast. However, they are now also forecasting a cold and snowy January due to a sudden stratospheric warming event within their preliminary winter forecast. It would also appear that they are quite uncertain about what is going to happen in the second half of November and into December.
Our forecast that was issued six months ahead of their forecast, and in every media article that we have appeared within over the last few months stated: January and into February could be particularly cold and snowy or potentially record-breaking due to an SSW event occurring.
The following media article from over 20 days in advance of the Netweather preliminary winter forecast release also stated:
“If any month could prove to be very severe or potentially record-breaking in terms of the cold and snow episodes that are likely to develop, then January looks like being the main contributor for this on current indications."
UPDATE ADDED: 5th November 2014 (08:32) - James Madden