omendoza 1 Posted May 10, 2021 Share Posted May 10, 2021 First image taken from the Browser shows at least two or more SIGMETs (Isolated Embedded Cumulonimbus) over the UK and France Please login to display this image. Now, second image shows the Flight Map where we see two SIGMETs that by a stretch could be considered a few of the above ones but for sure the dimensions nor the locations match. Please login to display this image. Does this mean there is an issue reporting the SIGMETs above Europe or am I doing something wrong Link to comment Share on other sites More sharing options...
srcooke 421 Posted May 11, 2021 Share Posted May 11, 2021 An aviation weather expert can elaborate further, however the browser image is a Significant Weather Forecast valid for 6hr whereas the map is displaying SIGMET, an in-flight advisory which in general has a 4hr validity except for certain criteria. Link to comment Share on other sites More sharing options...
Mklemme 9 Posted May 11, 2021 Share Posted May 11, 2021 The Sig Wx Chart is generally used for planning purposes, is a forecast and is issued around 16-18 hours before its validity time. So the chart valid at 12Z on a particular date will have been issued c. 18Z the previous day. SIGMETs are actual advisories of active or expected occurrence of potentially hazardous weather and as noted by Stephen have a much shorter time span of out to 4 hr. SIGMETs can be thought of as updates to what the Sig Wx chart has forecast. Thus if SIGMET conditions forecast on the Sig Wx chart are still expected to occur, then nearer the validity time a SIGMET will be issued for these conditions but with more precise information as to severity, location, movement etc; conversely if SIGMET conditions forecast on the Sig Wx chart are later not expected to occur then no SIGMET will be issued. Also note that there are differences between what Sig Wx charts depict v. what SIGMETs are issued for (eg Sig Wx charts will depict areas of moderate or severe icing and turbulence whereas SIGMETs only cover severe conditions). To the OP's question, the fact that the SIGMETs cover a much smaller area (bottom pix) than what is depicted on the Sig Wx chart (top pix) probably means that the actual CB/TS conditions forecast in the Sig Wx chart turned out to be much more localized and SIGMETs were only issued for those specific areas (assumes the two pix are relating to similar time frames). It could also be a PFPX depiction issue (ie more SIGMETs were actually issued but weren't depicted on the PFPX map) but this could only be verified by comparing with a third-party provider such as Sky Vector or one of the weather agency websites. In my experience, depiction of SIGMETs in PFPX is fairly spotty, but perhaps it's something to do with my setup. Link to comment Share on other sites More sharing options...
ahuimanu 36 Posted May 11, 2021 Share Posted May 11, 2021 The value of the data subscription is waning over the years as the product is more and more neglected. Meanwhile, Navigraph invests in Simbrief. I am disappointed in the erratic nature of the data service and general support for PFPX. Link to comment Share on other sites More sharing options...
jpgmultimodal 61 Posted May 11, 2021 Share Posted May 11, 2021 Hi, There is a difference between significant weather charts, SIGWX: https://aviation.meteo.fr/affiche_image.php?time=1620745520&type=sigwx/uk/smpz_eur&date=20210511180000&mode=img&comment= and SIGMET (SIGnificant METeorological Information): https://www.aviationweather.gov/sigmet With PFPX it shows on the map the SIGMET but not the SIGWX. SIGMETs are only for dangerous phenomenas forecasted or observed (turbulence, icing, CBs). The SIGMETs (if any) are given by the weather center like Shannon, Gander, New York in plain language every 30 minutes on HF frequencies and I believe nowadays by computerized transmissions. Regards, JP Link to comment Share on other sites More sharing options...
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