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With the models under some degree of scrutiny I always forget which has higher resolution here and there and at what time frames. After some digging around put this together and hope it is some use as a point of reference, this is not my area of expertise so please edit, add to, correct, grow etc etc Data for numerical weather prediction is provided by observations from satellites, from the ground (both human and from automatic weather stations), from buoys at sea, radar, radiosonde weather baloons,, wind profilers, commercial aircraft and a background field from previous model runs. The gist of this is shown by this handy pic from a non-blacked out Wikipedia and ensembles depicted from UKMO website. UKMO Unified Model - Global Model 25Km Resolution 70 Vertical Levels 144 Hours UKMO North Atlantic and European Model NAE 12Km Resolution 70 Vertical Levels 48 Hours UKMO - Other 1.5km Resolution UK 70 Vertical Levels 36 Hours 4Km Resolution Surrounding Areas 　 　 ECM / IFS 16 /31km? unsure.. Operational / Deterministic run is Twice Hortizontal Resolution of Ensembles 240 Hours Operational 60 Vertical Levels Ensembles 40 Vertical Levels 51 member Ensemble suite http://www.ecmwf.int...techniques.html 　 GFS 35 km / 64 vertical layers High Resolution runs to 192 Hours / 7 days - every 3 hrs 70 km / 64 vertical layers Lower Resolution runs from 192 - 384 Hrs - every 12th hr 22 Ensemble Suite 9 including Control / Operational GEFS using current operational GFS -increase in horizontal resolution from 70 km to 55 km (T254) for 0-192 h, and 70 km (T190) for 192-394 hours -increase in vertical resolution from 28 to 42 layers for 0-384 hours http://www.emc.ncep..../GEFS/mconf.php

Please carry on here. Please be polite and try and justify your posts with reasoned analysis and charts where appropriate. No bickering, trolling or anything off topic. We are seeing a lot of postings with musings from twitter - please only post these if they are relevent to the models and are taken in context. Please quote the source and give a link - otherwise your post may disappear as this is not the rumour model thread. Thank you.

Good Afternoon. It is time for a new thread. Please keep to the topic and include relevent charts where applicable. All views are welcome but please do back them up with appropriate charts and links. Any off topic or trolling posts are likely to be deleted. Thank you.

Good afternoon all. I hope you are all having a very pleasant Sunday afternoon. Well, with the end of November rapidly approaching we are all wondering what the new season will bring. We have a multitude of signals suggecting that northern blocking is about to occur - but none of these have shown themselves in the reliable timeframe. So to recap and to help start this thread off, let's go through them all. The GFS and ECM have jumped repeatedly in their outputs recently - often this lack of consistency is indicative of a change of pattern - and certainly there are clues that this could occur. Currently, we are in a pattern that holds a trough to our Northwest for the next week or so. There are suggestions that this trough will hold position and lead to height rises over Scandinavia which could give rise to an easterly - but it looks as though the height rises in Scandinavia will be slowly pushed by the trough to our west moving westwards. There is numerous support for this occur in the 8+ day timeframe. Here are the comparison H500 anomaly charts for the 8-10 day comparing the ECM and GFS. Both are pushing troughing towards our SE - never a bad place for this to be! Other H500 anomaly charts go further with the suggestion that height rises will replace the lower heights to our NW in the longer timeframe. They are all pointing in the same direction. So is there anything else that can add credence to this scenario occurring? The ECM and GFS MJO forecasts are both heading towards phase 1 towards the end of the month. http://www.cpc.ncep....clivar_wh.shtml This is a good phase for support of GH blocking - in fact it is uncannily accurate when comparing to the anomaly charts above! Now to the strat. The cooling seen in the autumn has been a fly in the ointment for those wishing to see a -ve AO winter. However there are signs that things are on the turn. During the last week wave 2 activity has put pressure on the vortex creating a monkey nut shape to the vortex. I suspect that this is likely to reoccur towards the end of the month and numerous forecasts right up into the middle strat have appeared. Yet again this has appeared on the latest GFS 06Z run - with the only difference being that the split is stronger and earlier! 30 hPa chart at T+ 12 days The postion of the split vortex here is more conducive to NWern height rises and cross polar flows. Furthermore, these type of blocking patterns seen recently are precursers to stratospheric warming events, so that I wouldn't be surprised to see a stratospheric warming occuring after - into early December - how significant this will be is difficult to say currently but it will be useful down the line. So, with a lot of pointers suggesting blocking towards the NW of the UK we are likely to see a cold pattern emerge from the start of December. In fact I can see it repeating and building towards mid December as the vortex takes repeated hits. If these hits can damage the stratospheric vortex and lead to warming then it willl be the perfect start to winter. Besides the upper stratosphere, I haven't seen such pointers to a cold set up since the start of 2010 -and we all know what happened then. Let's hope a repeat is on the cards. Please keep on topic and be relevent as always c

I thought I would post a brief look at one aspect of Nov/Dec 2010, the record breaking cold spell that will remain a 'one-off' within all of our lives. Obviously we know what happened, but put simply, after the onslaught of very cold weather in the final week of November and first week of December, there was a brief rest-bite around the 10th to the14th; this milder spell was almost like the country surfacing for air before the cold air tightened its grip further; after this slightly milder period, the cold air dived back in across the UK from the North East until the close of the year. Okay, so the focus of what im trying to get at here is; This winter has been very very boring. I often check the GFS for signs of cold snowy weather, and i suspect many others do at this time of year, but even the charts past 192hrs+ haven't indicated much potential this year. So, what did the GFS charts hold for Nov/Dec 2010 7 days out? What did the GFS ensembles read 7 days out? Firstly, a brief look at the start of the cold spell: On 19th Nov, i took a screen grab of what the GFS was predicting for the coming Thursday 25th Nov (144hrs+). This 18z run really did start it all off- the cold weather plummeting down from Scandinavia was almost in the reliable time frame: So what happened? Well 5 days later i took a screen grab of the day (Thurs 25th) obviously this time it was a mere 24hrs away....it shows that the GFS was pretty accurate on its previous forecast... Focusing on the 10th Dec onwards, I took a couple more screen grabs from my phone while browsing the ensemble charts. The 850 temp ensembles (Using Cambridgeshire as the control point): On December the 9th the ensembles indicated a slight increase in temperatures (850's) between the 10th to the 14th, with a noticeable cold spell lasting to the 25th Dec. What is amazing here is that the mean (red line) was forecast to stay below -5 for over a week: I then took this screen grab 5 days later. As you can see, the consistency is still there, with the mean line still below -5 for the period: So, in summary: If cold weather is on the way, then i tend to look at the ensembles first. If the 850's 'mean line' is dropping away, and consistently (run after run) then i start to get interested. Obviously the operational and control charts are important, but the ensembles above clearly show the consistency and confidence of the GFS when something special may be on the way. Will that happen this winter? Paul

Right, new model thread. Please discuss the latest output. Please keep posts relevent, no off topic posts, and back up your posts with links/ attachments where appropriate. And please, please no trolling.......

GFS Founded: 1988. Updates Per Day: 4. Range: 384 Hours. Full Name: Global forecast system. Introduction Mainly called 'GFS' is a global numerical weather prediction computer model run by NOAA. The model is run four times a day and is only the only one of the three main weather models that updates this many times a day. It also produces forecasts up to 16 days out however it is arguable that only up to day 5 or 7 is accurate. How it works The model runs from 0 hours to 192 hours at a resolution of 27km. After 192 hours to 384 hours it is run at 70km resolution. The GFS collects weather observations across the world then processes everything into a supercomputer to make a forecast. History The GFS model was originally called the Aviation Model (AVN) until its name was changed to Global Forecast System (GFS) when the Aviation model was combined with the Medium Range Forecast Model (MRF). Extra Information It is the only global weather model that is available for free in the public domain. Many weather websites across the world use it's data. It is one of the best medium range models available. GFS Supercomputer Sources http://en.wikipedia....Forecast_System ECM Founded: 1975. Updates Per Day: 2. Range: 240 Hours. Full Name: European Centre for Medium Range. Introduction Also known as the ECMWF or ECM is an independent intergovernmental organisation supported by 19 European Member States and 15 Co-operating States. At its headquarters in Reading, England, one of the largest supercomputer complexes in Europe is linked by high-speed telecommunication lines to the computer systems of the national weather services of its supporting States. The Centre's computer system contains the world's largest archive of numerical weather prediction data. How it works ECMWF uses the computer modelling technique of numerical weather prediction (NWP) to forecast the weather from its present measured state. The calculations require a constant input of meteorological data, collected by satellites and earth observation systems such as automatic and manned stations, aircraft, ships and weather balloons. The ECM does the first 10 days at 16km resolution which is why it is generally the most accurate model. The data is fed into ECMWF's databases and assimilated into its NWP models to produce: 1. Medium-range forecasts, predicting the weather up to 15 days ahead. The medium range data can be found on websites across the web but they only go to 10 days. 2. Monthly forecasts, predicting the weather on a weekly basis 30 days ahead. 3. Seasonal forecasts up to 12 months ahead. Both the 30 day and seasonal forecasts are not available to the public for viewing. History ECMWF delivered its first operational medium-range weather forecast to its Member States on 1 August 1979. It was produced using the CRAY-1A. This used about 5 hours of CPU time to produce a 10 day forecast, which was more than 50 times faster then the CDC6600, thereby making the production of 10-day forecasts a feasible undertaking. ECM's Supercomputer Sources http://www.ecmwf.int/ http://en.wikipedia....ather_Forecasts UKMO Founded: 1854 and started computer modelling in 1959. Updates Per Day: 2. Range: 144 Hours. Full Name: Met Office. How it works It gathers information from weather satellites in space and observations on earth, then processing it using two IBM supercomputers. It has a resolution of 1.25 deg between 0h & 72h and between 96 & 144h 2.5 deg. History The Met Office embraced the computer age in 1959, when a Ferranti Mercury, nicknamed Meteor, was purchased. Capable of doing 30,000 calculations a second, it was a major step forward in the evolution of making weather forecasts. For the first time, scientists were able to regularly use numerical methods to make their forecasts. Extra Information The Met Office's Global Model forecast has consistently been in the top 3 for global weather forecast performance over the past few decades in independent verification to WMO standards. Today IBM supercomputer which can do more than 100 trillion calculations a second. Its power allows it to take in hundreds of thousands of weather observations from all over the world. Met Office Supercomputer Sources http://en.wikipedia....wiki/Met_Office http://www.metoffice.gov.uk/ NOGAPS Founded: 1982. Updates Per Day: 4. Range: 180 hours for 00z & 12z. 144 hours for 06z & 18z. Full Name: Navy Operational Global Atmospheric Prediction System. How it works The acronym NOGAPS has been used since 1982 to represent the Navy’s global numerical weather prediction system, which includes components for data quality control, data assimilation, model initialization, and model forecasts. While the nature of the components has changed considerably over the years, NOGAPS has been and remains the central engine that is the heart of the Navy’s environmental prediction capability. History It has been performing poorly in recent years compared to the other global models, so it has been removed from the consensus models that the National hurricane center uses as of 2011. Sources http://www.nrlmry.navy.mil/ http://www.wunderground.com/ JMA Founded: 1956. Updates Per Day: 2. Range: 72 hours for 00z. 192 hours for 12z. Full Name: Japan Meteorological Agency. How it works It has a resolution 2.5 deg x 2.5 deg. It like other weather models collects weather observations around the world then processes it using their own supercomputer to produce a forecast. History In 1968, the World Meteorological Organization designated the JMA as a Regional Specialized Meteorological Centre for Asia. In June 1988, the WMO also assigned the JMA as a RSMC for the Northwestern Pacific under its Tropical Cyclone programme. In July 1989, the RSMC Tokyo - Typhoon Center was established within the headquarters office, which dealt with the forecasting and dissemination of active tropical cyclones, as well as preparing a summary of each year's cyclone activity. JMA's Supercomputer Sources http://en.wikipedia....ological_Agency http://www.weatheron...ARCHIV=0&ZOOM=0 GEM Founded: 1991. Updates Per Day: 2. Range: 240 hours for 00z. 144 hours for 12z. Full Name: Global Environmental Multiscale Model. How it works The operational GEM model dynamics is formulated in terms of the hydrostatic primitive equations with a terrain following pressure vertical coordinate (h). The time discretization is an implicit two-time-level semi-Lagrangian scheme. The spatial discretization is a Galerkin grid-point formulation on an Arakawa C-grid in the horizontal (lat-lon) and an unstaggered vertical discretization. The horizontal mesh can be of uniform or variable resolution, and furthermore can be arbitrarily rotated, the vertical mesh is also variable. The explicit horizontal diffusion is -2 on all prognostic variables. History The GEM model has been developed to meet the operational weather forecasting needs of Canada for the coming years. These presently include short-range regional forecasting, medium-range global forecasting, and data assimilation. In the future they will include nowcasting at the meso-scales, and dynamic extended-range forecasting on monthly to seasonal timescales. The essence of the approach is to develop a single highly efficient model that can be reconfigured at run time to either run globally at uniform-resolution (with possibly degraded resolution in the "other" hemisphere), or to run with variable resolution over a global domain such that high resolution is focused over an area of interest. GEM's Supercomputer Sources http://en.wikipedia....ultiscale_Model http://collaboration...blic/index.html CFS Founded: 2004. Updates Per Day: 4. Range: 1074 hours. Full Name: Climate Forecast System Introduction The CFS is a long range model, it does 4 updates a day going out to 1074 hours. However it's long range forecast is capable of going out to 6834 hours ahead (9 months). How it works It has a resolution of 2.5 def x 2.5 deg. The systems works by taking reanalysis data (NCEP Reanalysis 2) and ocean conditions from GODAS (Global Ocean data Assimilation). Both of these data sets are for the previous day, and so you should be aware that before initialisation the data is already one day old. Four runs of the model are then made, each with slightly differing starting conditions, and from these a prediction is made. History Developed at the Environmental Modelling Center at NCEP (National Centers for Environment Prediction) in the USA, the CFS became operational in August 2004. Sources http://www.weatheron...ARCHIV=0&ZOOM=0 GME Founded: 2004. Updates Per Day: 2. Range: 72 hours. Introduction Global weather forecast model also known as the GME is from the German Weather Service. How it works It has a resolution of 0.25 deg x 0.25 deg. GME is the first operational weather forecast model which uses an icosahedral hexagonal grid covering the globe. In comparison to traditional grid structures like latitude-longitude grids the icosahedral-hexagonal grid offers the advantage of a rather small variability of the area of the grid elements. Moreover, the notorious "pole-problem" of the latitude-longitude grid does not exist in the GME grid. Sources http://www.weatheron...ARCHIV=0&ZOOM=0 ---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- This guide was made to give an easy, quick understanding of the weather models used across the world - weathermaster.

Are the weather models bias or just statistical number crunchers? Previously discussed here Please continue here.