Mike Poole

I'm waiting for: Atlantic Storm Nathan - ramped as Storm of the Century by the Daily Express, making landfall as a slight breeze and a bit of drizzle.

A word on the model verification statistics, here's the 5 day graph: There's clarification on what the PR... models are: PRX: Experimental T1534 Semi-Lagrangian GFS run by NCEP NCO PRHW14: Experimental T1534 Semi-Lagrangian GFS run by NCEP EMC New GFS run in two different places maybe? I'm rather dissappointed if so, I've had my eye on the PRHW14 most of the year and it's a bit better than GFS, close on UKMO but still short of ECM - if this is now the highest resolution model, it is a bit underwhelming.

Steve, thanks for the forecast, and all the analysis in the previous thread. It's well reasoned and I hope that in 5 years time long range forecasts of this nature are the norm. Good luck, love to see some snow in January!

This is an utterly compelling thread! The OPI evolution is simultaneously both fascinating and maddening! I've been giving some thought to the wild swings we've seen - on Friday and again today. Some thoughts: I'm taking as read that the OPI is as stated in Riccardo's post i.e. that today's value is average of 12 days actual data + 10 days GFS forecast data. The swing today from the 06Z to the 12Z was from -0.64 to -3.15. Given the GFS can forecast pretty well up to 4 days out, the change must largely come from 6 days out of 22. What could explain this? I think the answer must be that this is a highly non-linear index - the translation by Interitus a few posts above seems to suggest this regarding the angular position of this axis parameter. So I conclude that a few days contribute massively to the negative values we see and most others much less so. Given at day 12/22 we are still seeing massive swings suggests that the values south of -3 have probably arisen mostly from the forecast part rather than the 'banked part' of the index, and the forecast ones from earlier in the month didn't verify. On that basis I'd guess we'd finish up about -1.5. Which is nice.

I presume its based on GFS because the data is freely available. Whether to use an ensemble mean is more interesting - its the mean of a large number of entirely physical realisations, but the mean itself is not physically reasonable - it could not have occurred in nature - so I don't think it would be useful for this OPI index which looks to be highly dependent on detail.

PRHW14 is the new upgrade to GFS which is currently being tested, I believe - has been for a few months. I've been keeping my eye on the stats recently and while a couple of months ago it seemed to have similar performance to GFS, it seems to have upped it's game recently. The ECM's poor recent day 10 verification stats were commented on in here over the last couple of days, but it's rather gone under the radar that at day 10 PRHW14 has performed best by some distance recently for the northern hemisphere:

Interesting, so to be clear the upgrade to the GFS this year is not the FIM? I understand that on the model verification charts the GFS upgrade is denoted as PRHW14 (see below) is this the FIM or a more mundane upgrade to GFS?

Relatively new to Netweather and my first post on the MOD. Why? I've noticed a new model on Meteociel that looks as though it will be worth keeping an eye on, the FIM. Here's its take on Sunday: Here's what Wikipedia says about this model (quote): The Flow-following, finite-volume Icosahedral Model (FIM) is a numerical weather prediction model currently under development at the Earth System Research Laboratory. The FIM is being developed as a candidate to eventually supplant the Global Forecast System, the United States's current medium-range forecast model. The FIM was originally slated to become operational some time in 2014 (as of spring 2014 the model is still testing); the GFS will continue to be run and maintained for several years afterward, much in the same way the GFS and its predecessor, the Nested Grid Model, ran concurrently for several years. The model currently produces similar results to the GFS, but runs slower on the NWS's operational computers. Its three-part name derives from its key features: "flow-following" indicates that its vertical coordinates are based on both terrain and potential temperature (isentropic sigma coordinates, previously used in the now-discontinued rapid update cycle model), and "finite-volume" describes the method used for calculating horizontal transport. The "icosahedral" portion describes the model's most uncommon feature: whereas most grid-based forecast models have historically used rectangular grid points (a less than ideal arrangement for a planet that is a slightly oblate spheroid), the FIM instead fits Earth to a truncated icosahedron, with twelve evenly spaced pentagons (including two at the poles) anchoring a grid of hexagons. The FIM runs as a multiscale model, with a suffix number indicating the model's horizontal resolution. FIM7 operates at a spatial resolution of approximately 60 km, FIM8 at 30 km, FIM9 at 15km and FIM9.5 at 10km. The FIM7 and FIM8 both run twice daily (0z and 12z) with 6-hour temporal resolution out to 14 days. The FIM9 runs four times daily, also with 6-hour steps, out to 7 days. (FIM9.5 is not currently in operation.) Unquote! I think it will be interesting to see how this model performs on two levels as a possible successor to GFS. First, does the novel geometry of the model overcome any of GFS biases, second this model seems to run 14 days but without the drop in resolution at 8 days - will this be better at picking up trends than GFS? Time will tell no doubt.

I've always liked snow and hot weather, but what caused a keen interest in the weather was for many years I organised the fixtures for a large rounders competition on a campus in Oxfordshire - and in the summer months would try to predict what the weather was going to do for rearranging games etc when it rained. I gradually became more and more interested - I am a physicist and am generally interested in areas of science that are complex and with some depth - there's plenty going on with the weather to maintain the interest. Have learned a lot from posts on this forum - please keep them coming!

This is a good one for me, I think in Oxfordshire this was the moment we changed from having no snow, virtually ever, to the way the weather has been in the last few years. (new poster, so hope this pic appears!!) This channel low dumped Wantage with 5 inches, and our office was closed - trouble was we had an international meeting - one guy coming from Germany! So I braved the 7 mile journey (and abandoned my car) German guy having no problems with his journey naturally...health and safety meant we had to leave the office and adjourn to the pub! We're really not cut out for it, we british are we? And it snowed another 4 inches the next night!

Thanks ABNS! Now just tying to work out how to correct my dodgy maths - but maybe this year is going to be a 110% winter! I thought it was possible to edit posts though! Sussed it now!!

Hello everyone! Been lurking here for a while and really enjoy reading everone's posts in various threads, time to make some comment of my own! I can honestly say I'm looking forward to winter - for me there's only one good thing about winter and that's snow and cold weather - and I reckon I've suffered from SAD (seasonally affected disorder) for years. But for the last couple of years the netweather MOD thread has seen me through, either excitement with the potential for interesting weather, or just making the dark wet dull stuff fly by! My thoughts for winter (early ones) are as follows: I usually look at at least 5 CFS runs per week and this model is consistently going for northern blocking - as others have pointed out. So it's looking cold - but how cold? Some long range models suggest not that much colder than average, so that has me thinking coldish and snowy, rather then v cold and dry. Lots of discussion about solar activity and arctic sea ice - I think there is lots of uncertainty about these but they are only pointing to towards a colder outlook for the UK, so at this early stage I'm saying: 70% Colder than average 20% Average 10% Warmer than average But that's subject to change when we see how the stratosphere sets up in November! Mike