BornFromTheVoid

The Francis and Vavrus paper suggests that warming is increasing the 500hPa geopotential heights and 1000-500hPa thickness across the Arctic, with the strongest trends in Autumn and Winter, reducing the poleward thickness gradient and reducing the upper level zonal flow. This based on the NCEP reanalysis. The geopotential heights and thickness, I'd imagine, should be related to the 500hPa warming trends. Given that the Chung et al. paper suggests an Autumn cooling trend since 1998, and a weak Winter warming trend, for the 500hPa level, I think that would cast some doubt on the trends (or at least their statistical significance) identified by the Francis and Vavrus study.

Still very mild here, 10.9C, but surprisingly gusty considering how far south I am. This December seems to be going against every LRF I've seen, including my own. Still though, things can change. Remember how mild and unsettled November looked at first?

One interesting thing about this paper, is it would throw some additional doubt on the Francis and Vavrus theory of Arctic Amplification and its link with mid-latitude weather extremes.

I wouldn't go so far as to call it a strong recovery myself, temporary recovery for now, until it lasts long enough to be clearly beyond the year to year variation.

Surprised there been no mention of the sea ice yesterday or today, are the US "sceptic" sites are busy with something else? NSIDC extent is now just 11th lowest on record, and nearing the 99-03 average.

The highest attribution to the AMO I've seen has been just 30%, not to mention that sea ice extent and thickness were on downward trends from 79 to the mid 90s anyway. As for the global data, seems plausible. But looking at the data shows for total extent, a number of weeks ago we reached the highest point since 1996 (not current, or 1994 as suggested) and anomaly-wise, just the highest since 2009.

November Stats for Cahir, Co. Tipperary. Mean: 7.3C Avg Max: 9.6C Avg Min: 4.9C Max: 14.5C on the 11th Min: -0.3C on the 23rd Total Precip: 48.6mm Precip Days: 10 Largest Fall: 13.0mm on the 10th Autumn Stats Mean: 12.1C Avg Max: 15.2C Avg Min: 9.0C Max: 24.5C on Sept 4th Min: -0.3C on Nov 23rd Total Precip:265mm Precip Days: 43/91 Largest Fall: 24.5mm October 16th Autumn DataAutumn TempPrecip.xls

Agreed guys, beautiful morning, so nice to see blue skies and the sun again! The early hours of this morning saw the first measurable rainfall here since October 20th, quite a remarkable dry spell for late Autumn.

It's not like "desk-bound jockeys who make stuff up with computer models" is the height of fine manners. Lets not be hypocrites.

Sea ice seems to have been doing ok recently, but for a little context on the NSIDC chart Keith posted.

C'mon now, post up some pics!

I'd say today will average around 6.6C. After that, the 12z GFS op run has the CET at 6.3C to the 3rd (6.6) 6.1C to the 4th (5.6) 5.9C to the 5th (5.2) 5.4C to the 6th (2.9) 5.1C to the 7th (2.9) 5.2C to the 8th (6.0) 5.3C to the 9th (6.0) 5.2C to the 10th (4.8] So slightly above the 61-90 average and slightly below the 81-10 average to the 10th. Here's how it would look compared to the historical records and averages.

I used the analogues, but they rarely offer much in the way of a strong signal, and then consider the SSTAs and general predicted weather patterns when forming the CET guess. It's true that the temperature predictions weren't any better than climatology and I don't expect great accuracy is possible for such a small area, but as the general patterns weren't too bad and the very anomalous October was picked out well, I'm hoping the temperature predictions just require some more refinement and experience.

Didn't mean to bother you buddy! Of course it will snow and snow risk is 60% doesn't really make sense though. Here's an animation of the precip and upper air temps, from 6pm Thursday to 3am Friday, no snow shown and no -10C uppers. A few sleet showers are looking most likely now, but as I said, the ensembles do look better in general.

Having a look back at how my Autumn forecast fared, I think the patterns of each month were captured quite well. September ............... Forecast ...................... ........... ............. Actual October ...... .... Forecast ............ .............. .................. .............Actual November ....... .....Forecast............... ............... ................. ........... Actual Pattern wise, October and November were very good I think, with September being the weakest of the bunch but still not too bad. Looking at the scale for September though, there was no strong signal that month so it's not too surprising. Despite getting the general patterns quite well, the CET errors were 1.1C on average, being 1.1C out for Sept, 0.5C for October and 1.6C for November (though had I based my CET guess off the updated November forecast rather than the old one, it would have been 0.8C out, with an average error of 0.8C.). I think this shows how tricky it is to get the temperatures right for the UK. I only started trying this in May this year, so there is still plenty of room for progress, refinement and improvement, and as always, suggestions and comments are welcome!

Evelyn Cusack (Met Eireann Meteorologist and RTE weather presenter) has been debunking some forecast methods and LRFs in general on air in recent weeks. Here's a few examples http://www.youtube.com/watch?v=KXDMTgx6xNM (1:15 onward) http://www.youtube.com/watch?v=V-ehkocbOcY

Further downgrades today, with the latest GFS shows no snow for smithyweather.... ensembles are a little better though.

Here's how the daily values looked compared to historical averages.

Seems relevant here... Strong atmospheric chemistry feedback to climate warming from Arctic methane emissions The magnitude and feedbacks of future methane release from the Arctic region are unknown. Despite limited documentation of potential future releases associated with thawing permafrost and degassing methane hydrates, the large potential for future methane releases calls for improved understanding of the interaction of a changing climate with processes in the Arctic and chemical feedbacks in the atmosphere. Here we apply a “state of the art†atmospheric chemistry transport model to show that large emissions of CH4 would likely have an unexpectedly large impact on the chemical composition of the atmosphere and on radiative forcing (RF). The indirect contribution to RF of additional methane emission is particularly important. It is shown that if global methane emissions were to increase by factors of 2.5 and 5.2 above current emissions, the indirect contributions to RF would be about 250% and 400%, respectively, of the RF that can be attributed to directly emitted methane alone. Assuming several hypothetical scenarios of CH4 release associated with permafrost thaw, shallow marine hydrate degassing, and submarine landslides, we find a strong positive feedback on RF through atmospheric chemistry. In particular, the impact of CH4 is enhanced through increase of its lifetime, and of atmospheric abundances of ozone, stratospheric water vapor, and CO2 as a result of atmospheric chemical processes. Despite uncertainties in emission scenarios, our results provide a better understanding of the feedbacks in the atmospheric chemistry that would amplify climate warming. http://onlinelibrary.wiley.com/doi/10.1029/2010GB003845/abstract

Strong atmospheric chemistry feedback to climate warming from Arctic methane emissions The magnitude and feedbacks of future methane release from the Arctic region are unknown. Despite limited documentation of potential future releases associated with thawing permafrost and degassing methane hydrates, the large potential for future methane releases calls for improved understanding of the interaction of a changing climate with processes in the Arctic and chemical feedbacks in the atmosphere. Here we apply a “state of the art†atmospheric chemistry transport model to show that large emissions of CH4 would likely have an unexpectedly large impact on the chemical composition of the atmosphere and on radiative forcing (RF). The indirect contribution to RF of additional methane emission is particularly important. It is shown that if global methane emissions were to increase by factors of 2.5 and 5.2 above current emissions, the indirect contributions to RF would be about 250% and 400%, respectively, of the RF that can be attributed to directly emitted methane alone. Assuming several hypothetical scenarios of CH4 release associated with permafrost thaw, shallow marine hydrate degassing, and submarine landslides, we find a strong positive feedback on RF through atmospheric chemistry. In particular, the impact of CH4 is enhanced through increase of its lifetime, and of atmospheric abundances of ozone, stratospheric water vapor, and CO2 as a result of atmospheric chemical processes. Despite uncertainties in emission scenarios, our results provide a better understanding of the feedbacks in the atmospheric chemistry that would amplify climate warming. http://onlinelibrary.wiley.com/doi/10.1029/2010GB003845/abstract

You can get the dew point in the free GFS data too, it's in the last option "UK Surface Conditions Overview".

Didn't know you got snow in the last spell, did any of it stick? I agree though, would love to just see some snow falling myself!

Those snow risk charts aren't the most reliable, so I wouldn't be certain you'd see snow quite yet smithy. It will probably be a nowcasting situation for folks in the north and west.

I think stolen drones could be a problem, and signing for delivery, and delivering in cities, apartments, etc., still, nice idea. Perhaps they could stream video footage from it so you can watch your order flying to your address!?

Thought I'd have a look at what the CFS is suggesting for northern blocking this month. Here's the chart with the latest blocking data (chart explanation here http://forum.netweather.tv/topic/77743-winter-20132014-forecastshopesdiscussion-thread/page-117#entry2806211) The average of the last 2 months is 1.5, or between weak and moderate blocking (+ve SLP anomalies to the north). The frequency of the different categories (from -5 to +5) can be seen in the chart below. Moderate and strong +ve SLP anomalies were the most frequent outcomes projected by the CFS, totalling half of all forecast in the last 2 months If we take -5 to -2 as the negative SLP category, -1 to +1 as neutral and +2 to +5 as positive, the percentage of days with those categories forecast are 8.3%, 33.3% and 58.3% respectively. So going by the CFS, we should expect higher than normal sea level pressure to our north this December.