chionomaniac

Latest update: The stratosphere is cooling down as one would expect as we head through November. Both the temperature and wind anomaly at the 30hpa level are around average for this time of the year: The drop in temperature has not been linear, but I think this is to be expected: The prediction over the next 5 days is that the temps are going to drop further dipping below average: Both the ECM and NOAA have similar predictions for 5 days out: So nothing to get to excited about at present. If we follow the six week rule then it would appear that is a chance that the tropospheric vortex will be strong around the New Year With no major northern blocking. One of the reasons I am monitoring the stratosphere is so that I can make retrospective analysis later on in the winter, and see how much the stratosphere may have influenced the weather patterns we experience. Regards c

SB, I think the chart on that link shows the strength of the polar vortex from July to present day in the troposphere, not the stratosphere. To quote the NOAA : "The daily geopotential height anomalies at 17 pressure levels are shown for the previous 120 days as indicated, and they are normalized by standard deviation using 1979-2000 base period. The anomalies are calculated by subtracting 1979-2000 daily climatology, and then averaged over the polar cap poleward of 65°N. The blue (red) colors represent a strong (weak) polar vortex. The black solid lines show the zero anomalies." So what we have is a below average polar vortex which is translated into the negative AO presently seen in the blue bars. The stratosphere temps and wind anomalies haven't changed much since yesterday. Regards c

Latest data: Stratospheric polar temp back to average for this time of year after last weeks slight warming. Polar winds are about where they should be with no great anomalies: Future forecast for average temps in the stratosphere: So nothing to get too excited about at present. c

It's early days yet and at least the stratosphere temps aren't below average!

Just lost a post!!! To azores . The best chances of prolonged cold are with a negative AO( interlinked with a negative NAO). The AO is more likely to be negative with a warmer stratosphere. So whereas a warmer stratopsphere is not essential it is an important building block to help. You can compare previous cold winter spells to the average winter polar months stratospheric temps which can be found below (since 1955) http://www.geo.fu-berlin.de/en/met/ag/stra...pole/index.html Also NOAA data here http://www.cpc.ncep.noaa.gov/products/stra...ere/strat-trop/

The event in February was far greater. Firstly the stratospheric wind anomaly was great enough to reverse the polar winds as shown below: This time the reduction in stratospheric vortex is not strong enough to reverse. The net result is that the warming event in Feb was strong enough to filter right down to the tropopause layer. The present warming hardly takes us above average so not of major significance as of yet: c

I don't know the answer to that ( but would like to!). What I do know though, is that the warm anomoly is forecast to migrate east over Alaska, and reduce in intensity.

Oops!

Both the ECM and Japan models look similar for 3rd Oct so certainly something to watch.

Compared to last year:

Truth is AF, I don't really know! My take on it is slightly different - it could be right - it could be wrong - if someone here knows better I am willing to learn. I reckon that the winter default stratosphere pattern is a strong cold vortex similar to a spinning top. This spinning top will try and reach maximum speed but is prevented from doing so by intrinsic stratospheric friction and friction from the stratosphere radiating towards the equator. This friction generates a certain amount of heat. The vortex itself encourages the troposphere polar vortex below in a way as if a hoover nozzle was sucking from above. The statospheric vortex can also be interfered with from extrinsic factors such as those that GP mentions in his post above. These factors have the effect similar to putting a stick in the spoke of a wheel generating a sudden stratospheric warming event. I don't know whether it is the warming or the stopping of the wheel that affects the troposphere below, but I reckon it has the affect of turning the hoover off and the tropospheric polar vortex spins itself out, leaving pressure rises in the polar regions and a negative AO. I could be totally wrong though! Regards c

Every winter the temperature of the stratosphere above the North Pole to around 60 N cools rapidly. This cooling is influenced by strong cyclonic winds and has an affect on the troposphere below, which in turn influences our own weather. The greater the cooling in the stratosphere, the stronger the polar vortex in the troposphere. This has the affect of creating a more positive AO which leaves us experiencing milder wetter winters driven along by westerly winds. A less cool stratosphere will ultimately lead to a more negative AO and cooler, dryer winter weather. Effects of the Positive Phase | Effects of the Negative Phase of the Arctic Oscillation of the Arctic Oscillation (Figures courtesy of J. Wallace, University of Washington) Occasionally the stratosphere can undergo dramatic warming events. These occur when the cyclonic winds at around 60N slow down suddenly, halt or even reverse. http://en.wikipedia.org/wiki/Sudden_stratospheric_warmings This can have the affect of disrupting the polar vortex underneath (up to 6 weeks later) and creating a very negative AO with polar air flooding southwards. These are of obvious interest to us because it can create very cold conditions for us. A recent example of a Sudden Stratosphere Warming was at the end of Feb 2008. Remember the cold around 6th April around 6 weeks later. The following link gives the 30hp monthly mean North Pole temps since 1955. Interestingly figures are given for cold monthly means at the bottom of the table. These are temps I would like the stratosphere to avoid this upcoming winter! http://www.geo.fu-berlin.de/en/met/ag/stra...pole/index.html The idea of this thread is so that we can monitor the temps in the stratosphere over the upcoming winter. The data can be found here: http://www.cpc.ncep.noaa.gov/products/stra...ere/strat-trop/ And here: http://strat-www.met.fu-berlin.de/cgi-bin/diagnostics?1 Below is a chart showing the above or below average cooling around the north pole at the moment. The green is indicating that temps around now at that level of the atmosphere are cooler than average. And below is the wind anomaly chart over the north pole. This shows that there are around average winds at present: The full reasoning around why Sudden Stratosphere Warmings occur are complex and multifactorial. GP, the NW teleconnections guru has probably one of the best understandings in this field. He has suggested in the past that intense tropical convection in the Indian Ocean leads to powerful downstream anticyclones. This creates fast Rossby Wave Dispersal events which, if allied to a weak zonal wind anomaly, are a precursor to stratospheric warming events. The intense tropical convection is triggered by above average SSTs in that area. Further info from: http://www.appmath.columbia.edu/ssws/index.php Also current cooling graph: And forecast: http://strat-www.met.fu-berlin.de/cgi-bin/...mps&alert=1 Heres to a warm stratosphere this winter. c Further link: http://www.atmosphere.mpg.de/enid/2__Ozone/-_Cooling_nd.html Ps any other info / thoughts welcome on a subject I am trying to get to grips with!

I didn't know what ISA stood for but do now, so thanks John.

Cheers, I thought I had seen this somewhere before!

Whenever I would like to look at the weather certain places are experiencing, I can never find the right webcam. Is there a pinned page on nw with links to webcams that I have missed? If not would it be possible to start one? Would others find this useful? C

With a 20ft storm surge and very few areas above 20ft in Galveston what are these people thinking of by not leaving? Even those areas above 20ft will be subject to damaging gusts especially if Ike has a last minute intensification.

That graph is a little bit deceptive and I had to look twice! At first it looks like the eruption of Pinotubo was only slightly greater in terms of SO2 release than that of Hudson. A closer inspection of the left hand scale shows in fact that the eruption of Pinotubo was 5 times greater than that of Hudson. Is there any exact formula that can link ppm SO2 in the atmosphere to a precise reduction in global temperature? c

With last night registering at 14.6ºC and today (probably) low 20s, I reckon we may rise to 17.1ºc tomorrow, before the inevitable slide. I agree that once this occurs, it will prove difficult to rise higher than this as August is a cooling month.

Latest CET is 17.0ºC. Yesterday was 18.9ºC (max 22.7ºC, min 15.1ºC).

I am going to try and record each days provisional CET figures with maxima and minimum as soon as possible after they are released to see where the biggest end of months adjustments come from. CET up to the 1st is 17.0ºC Maximum is 20.5ºC Minimum is 13.4ºC c

Agreed, the CET values have been readjusted this week every next day.

Is this Watnall, Nottingham? If so, it appears max temp today was 27.0ºC by Met O data. http://www.metoffice.gov.uk/weather/uk/em/...her_graphs.html c

Just found this article which explains all! http://news.bbc.co.uk/1/hi/magazine/7525028.stm c

Hadley at 15.7C upto the 24th. Yesterday came in at 19.7C. Reef you were right about the adjustment for the 23rd, this is now recorded as being 18.7C (maxima 24.6C) which is the second adjustment this week. Odds on over 16.0C end figure now I reckon. c