The daily pressure tendency charts available by this page are based on the 1800 hrs UTC weather observations. To access the chart please right click on the link below for the appropiate day and chart area, then click on "save as" to download that chart. All charts are in GIF format.
I have been studying & experimenting for several years with regard to possible weather effects on radio propagation and in particular skywave propagation. In the course of my research I found that high pressure over areas and especially as this high pressure was moving into a particular area was causing skywave propagation enhancement from that area. This propagation effect was shown to be as a result of rising pressure in that area, hence the use of pressure tendency charts here. Research was carried out using aero and marine navigational Non Directional Beacons in the frequency region of 280 to 500 kHz. The purpose of these charts is for Radio Amateur and SWLs to be able to either predict, using the simple instructions below, areas where likly radio propagation enhancement may occur on a nightly basis or to study the reception results from a previous night by comparing them with the appropiate charts.
Please note that all charts will be overwritten automatically after a week (for example Sunday's chart will be overwritten the following Sunday). Also note that although charts will be uploaded as soon as possibleafter 2200 UTC there may be occasions where this is not possible due to my workload, ISP problems and site access for the appropiate data. When this happens the chart will be uploaded as soon as possible afterwards and usually within 24 hours. Charts for other areas and times (0600, 1200, 1800 or 2400 UTC) can be requested by e-mailing me and they will be sent direct and requests will be actioned as soon as possible.
Basic instructions for using as a weather based propagation forecast tool.
These charts are based on pressure tendency. Areas of risng pressure are shown using blue contours and areas of falling pressure use red contours. In order to predict geographical areas of weather based propagation enhancement we need to look for the blue areas. The area of prime enhancement is the leading edge of this blue area, usually the eastern edge in the northern hemisphere but not always so you may have to compare charts over a couple of days to guage a pattern.
These charts are based on 1800 UTC observations and not uploaded until approx 2200 UTC so it is possible the prime area of enhancement may have moved a little so a little bit of guess work may be required to estimate the current actual position. Often there may be several blue areas on the chart. The area that you may receive weather based propagation enhancement from will depend if there are other higher pressure rises between your location and the target area. Think of the blue areas as mountains and the red areas as valleys. If there is a higher "mountain" between you and another blue area you will not receive that other area. However it the reverse is the case then you may possibly receive from the more distant area.
The charts can also be used to compare a previous night's reception by comparing the chart for the evening before your reception period. For example if you were listening between 2300 Friday and 0100 Saturday use the Friday chart.
Please note that this service now only operates over the weekend (Friday to Sunday inclusive). Charts for other days and regions are available on request.
Friday - Saturday - Sunday
Friday - Saturday - Sunday
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