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Paul

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Everything posted by Paul

  1. It may be weather, it may be climate but it's definitely not model discussion! I've just started a winter speculation and chat thread so this sort of stuff can continue in there.
  2. As we're starting to see more chat about the upcoming winter in other threads, here's a dedicated one for everyone to get their teeth into...
  3. @knocker & @johnholmes - thought this article may be of interest
  4. Yeah, I think a lot of home type stations can struggle with the sun affecting temperatures, things blocking the wind readings etc.
  5. Ah, yeah a bit more going on now! Used to be an aerial, a decoder and a pc for the basic NOAA ones.
  6. Love these sat pics, reminds me of when I was doing it way back in early the days of Netweather. Unfortunately my decoding unit overheated and kind of melted itself though!
  7. Yep, had mine on today. A bit earlier than I'd like but is what it is!
  8. Not too much change on the UKV 12z, 80mph gusts looking possible close to the west coast of Ireland overnight. Tomorrow morning up to early afternoon looks like the peak time for gusts of 50mph or so in the SW.
  9. After a break last winter, SACRA will be back for the winter of 2019/2020
  10. Winds picking up on the west coast of Ireland now, 54mph the high gust currently, but that'll be beaten this evening I'm sure.. https://www.netweather.tv/live-weather/map
  11. And off we head again, for those (on both sides) who have nothing to add other than snipes and digs at others, maybe just don't post and wait until you have something constructive to add to the discussion...
  12. Oops, sorry I didn't intend to leave it half an hour before opening this new thread! As ever, please keep to discussing just the model output in this thread. If you're wanting comment on the upcoming winter, please head to the winter speculation thread: For Autumn weather chat or to have a good moan or ramp, please use the Autumn thread. As seasonal winter forecasts start to come through (or if you're wanting to post your own), please head over to the seasonal forecast thread. Other assorted, useful / interesting threads: Stratosphere and Polar Vortex Watch Met Office forecasts Snow and ice in the Northern hemisphere Have a weather or meteorology question? Head over to our brand new Q & A forum. There are also loads of guides and learning info over in our nearly as new Learning and Research area. Model Output And Charts On Netweather: UKV (Extra subscribers) GFS GEFS Ensembles ECMWF ECMWF EPS NetWx-SR (3km) NetWx-MR (9km) Met Office (UKMO) Fax GEM GFS Hourly Model Comparison Golbal Jetstream Stratosphere
  13. Yes, afraid this is a limitation of the gust data currently, the Met Office only supply it to 36 hours. They do plan to sort it and bring it into line with the rest of the data but I don't have an eta yet.
  14. It's not looking too bad in the London on Thursday. https://www.netweather.tv/weather-forecasts/uk/7-day/18351~London Worth staying up with the latest forecasts when you have a chance though, in case of any last minute changes.
  15. If the aim is to make people more aware of an impending storm, then changing the name the day before it's due seems odd to me.
  16. And for anyone who'd like to learn, take a look at John's Skew-T guide in our shiny new learning area
  17. If you have questions about the weather or meteorology, feel free to ask them here.
  18. Paul

    Dewpoint

    Dewpoint: The strict definition for this is:-The temperature to which the air must be cooled in order that it is saturated with respect to a water surface and for this to occur at its existing pressure and humidity content. Dewpoint may be measured indirectly from wet- bulb and dry-bulb temperatures with the aid of humidity tables. More often now it is produced by some kind of calculator or computer programme taking these basics into consideration. Dew forms on clear nights when there is little or no wind at the surface. It can occur on summer nights but is most prevalent during the long nights from autumn through to spring. Dew forms on surfaces whose temperature falls to below the dewpoint of the air in contact with it. From what has already been said it should be clear that the dewpoint is always below the surface temperature. As in many things to do with Meteorology there is a caveat. Remember that the definition is 'become saturated with respect to a water surface'. There are a very small number of occasions when, with temperatures falling, the relationship becomes to that with respect to ice. In these few instances, briefly, the dewpoint may be a fraction higher than the air temperature. Dewpoint is really a measure of how much water vapour there is at any one time. Obviously the higher the air temperature then the higher the dewpoint can be. Compare the temperature in winter say of 3C with that on a hot summer day, maybe 25C. Obviously much more water vapour is possible with higher temperatures. This is partially responsible for the intensity of thunderstorms in summer compared to those of winter, and to the Tropics having much more intense downpours than in Temperate latitudes. The frost point is that temperature at which the air is saturated with respect to an ice surface. Dew point is closely associated with humidity. Thus in warm frontal zones the humidity is high. The arrival of a cold air mass will usually bring a sharp drop in the dewpoint. Dewpoint is an important tool for forecasters to use when forecasting many weather phenomena, be it thunderstorms, human comfort levels, or the likelihood of snow or frost. by John Holmes
  19. Paul

    Windchill

    Weather forecasters use an index to try to indicate how the average person will feel in the wind, this is known as wind chill. The skin is our largest organ and is vital in temperature control. When we are hot we sweat, this removes excess heat and cools us down. When we are cold, the skin warms a thin insulating boundary of air, trapping in body heat and keeping us warm. There are 2 ways in which wind cools the skin, firstly it disturbs the insulating boundary layer of air, and secondly it increases the evaporation of moisture from the skin - this takes body warmth with it. When the wind chill is below -50°C on an exposed forehead unconsciousness can occur in minutes, also skin may freeze within 30 seconds when the wind chill is -75°C. Individual differences The effects of wind chill affect people differently. Wind chill is based on the average person; however there are a number of factors that can cause differences in how we feel in a cold wind. Extreme cold can cause both frost bite and hypothermia. Depending on your build, you can be more susceptible to one than the other. If you are tall and thin you will probably feel cold sooner than shorter stockier people because you have a greater surface area of skin compared to their mass. People with greater insulation are more likely to suffer frost bite but less likely to suffer hypothermia, as they lose body heat to their cooling skin more slowly. Young and elderly people have less developed and less effective body temperature control systems, so they are at particular risk from the cold. In Canada, where wind chill effects are very important, they have a 'Cold Weather Policy' where children are kept indoors when wind chill reaches a certain level. If you have damaged blood vessels, which carry heat around the body, you are also more likely to feel the cold. This can be the case if your iron levels are low which can happen when taking some medications. Metabolism rates can also have an impact on how cold you feel, as slow metabolism can result in poorer circulation. Some medical conditions, or even medications, can also have an effect on how we feel in a cold wind. If you have diabetes and have peripheral neuropathy (a disorder of the nerves) you may find that you sweat more on your face and neck - from which we lose a large proportion of our body heat. If your blood glucose levels are high this can also damage the nerves in your legs and feet, which means that cold may not be felt as easily - this makes you more likely to suffer frostbite when it is very cold. If you take Beta-Blockers they can also increase the likelihood of frost-bite because they cause blood vessels to constrict, and this results in colder hands and feet. Avoid the chill Apart from staying inside on windy days, there are simple things that you can do to lessen the effects of wind chill. Drink plenty of water to hydrate your skin inside and outside (dehydration affects your ability to regulate your body temperature) and if you apply moisturiser to wet skin this seals in the moisture and prevents heat loss. When you go out in the cold make sure you wrap up well - wearing a hat and scarf can help keep in the 40 - 50% of heat that would otherwise be lost through the head and neck, mittens help keep hands warmer than gloves, and by wearing several thin layers of clothes you help create more insulating layers of boundary air. Before going out if you eat a light snack rather than a big meal you will ensure that less blood goes to your stomach to aid digestion leaving more to circulate to the extremities of your body like fingers and toes. If you wear waterproof clothes in wet weather they prevent the increase in heat loss from damp skin and clothes - heat loss occurs about 20 times faster from wet clothes than dry clothes. When the wind is strong the body can react as if it is under attack - this creates the 'stress hormone' dopamine. The body can't sustain stress like this for long, which is why you may feel exhausted at the end of a windy day.
  20. As promised - a more comprehensive look at what data goes into the GFS. All of these types of data from around the entire globe are input into the model on each run. There are obviously different availabilities of some types of data (like for instance flight data will be more available during daylight hours as flights occur more often at that time). But bear in mind that as the data is worldwide - there will be more data available from different parts of the globe at different times. The net result is probably that each model run has a similar amount of raw data fed into it. As you can see there is a fair bit of raw data used... Surface data - Land Synoptic - restricted (WMO Resolution 40) manual and automatic Synoptic - fixed manual and automatic Synoptic - mobile manual and automatic Aviation - METAR Vertical soundings - other than Satellite Rawinsonde - fixed land Rawinsonde - mobile land Rawinsonde - ship Dropwinsonde Pibal NEXRAD Vertical Azimuth Display (VAD) winds Single Level Upper-air data (other than satellite) Flight level reconnaissance aircraft data Automated MDCRS ACARS aircraft data (from ARINC) Automated MDCRS ACARS aircraft data (from ARINC) via AFWA Manual AIREP format aircraft data Manual PIREP format aircraft data Automated AMDAR format ASDAR/ACARS aircraft data European ASDAR/ACARS Data Aquisition System (E-ADAS) aircraft data (originally in BUFR) NOAA Profiler Network (NPN) winds Profiler winds originating from PILOT (Pibal) bulletins Japanese Meteorological Agency (JMA) profiler winds Cooperative Agency Profiler (CAP) winds RASS temperatures from NOAA Profiler Network (NPN) and Cooperative Agency Profilers (CAP) Vertical soundings - satellite GOES/NESDIS-processed 5x5 field-of-view soundings/brightness temperatures GOES/NESDIS-processed 1x1 field-of-view soundings/brightness temperatures Surface data - satellite QuikSCAT products DMSP/SSM-I - operational products derived at FNMOC DMSP/SSM-I - Neural Net-3 products derived at NCEP DMSP/SSM-I - processed brightness temperatures NASA/Tropical Rainfall Measuring Mission (TRMM)/TMI) Single level upper air data - satellite GOES/NESDIS infrared derived cloud motion (from NESDIS server, originally in BUFR) GOES/NESDIS water vapor imager derived cloud motion (from NESDIS server, originally in BUFR) GOES/NESDIS visible derived cloud motion (from NESDIS server, originally in BUFR) INSAT/India infrared derived cloud motion INSAT/India visible derived cloud motion INSAT/India water vapor derived cloud motion GMS/JMA infrared derived cloud motion - low density (originally in SATOB format) GMS/JMA visible derived cloud motion - low density (originally in SATOB format) GMS/JMA water vapor imager derived cloud motion - low density (originally in SATOB format) METEOSAT/EUMETSAT infrared derived cloud motion (originally in BUFR) AQUA/TERRA MODIS infrared derived cloud motion AQUA/TERRA MODIS water vapor imager derived cloud motion Surface data - sea Sea level pressure bogus Ship - manual and automatic Buoys in FM-18 format (moored or drifting) Buoys in FM-13 format (moored) Land-based CMAN station Tide gauge reports in CREX format Radiances - satellite measured AQUA/AIRS, AMSU-A, HSB processed brightness temperatures GOES NESDIS-processed 11x17 field-of-view imager (clear sky) brightness temperatures NOAA-14/HIRS-2 (High resolution InfraRed Sounder-2) NCEP-processed brightness temperatures NOAA-14/MSU (Microwave Sounding Unit) NCEP-processed brightness temperatures NOAA-15,-16,-17,-18/AMSU-A (Advanced Microwave Sounding Unit-A) NCEP-processed brightness temperatures NOAA-15,-16,-17/AMSU-B (Advanced Microwave Sounding Unit-B NCEP-processed brightness temperatures NOAA-15,-16,-17/HIRS-3 (High resolution InfraRed Sounder-3) NCEP-processed brightness temperatures Physical/chemical constituents POES/NESDIS Solar backscatter ultraviolet radiances
  21. The 15z UKV (the 03z and 15z runs go to 120 hours, the others to 54 hours) has ex-Lorenzo a bit further north as it makes landfall. It then fills fairly quickly as it moves southeast, with the centre over the Isle of Wight as it clears. Here's the difference between the 3z and 15z
  22. The model and stratosphere threads have now been moved over into the general / seasonal weather forum, as per the plan above. https://www.netweather.tv/forum/forum/1-general-weather-discussion-autumn/
  23. The UKV is the met-office's hi-res (1.5km) model. So, it's likely that the forecaster(s) doing the fax charts will take it into account more often than not. https://www.metoffice.gov.uk/research/approach/modelling-systems/unified-model/weather-forecasting
  24. Take your pick this morning when it comes to ex-Lorenzo. GFS, ECM and UKV all handling it very differently. GFS ECMWF: UKV: Most of the GFS ensembles go for something similar to the GFS or ECM with maybe 3/20 members taking it along the lines of the UKV. Wouldn't want to place much money on the most likely outcome at the moment.
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