Identify the issuing advisory centre
Environment and Climate Change Canada's Montreal Volcanic Ash Advisory Centre page presents its ash products. A Montreal-issued product does not necessarily mean that the source volcano is in Canada. The issuing centre, source volcano and area shown by the product are separate facts. Preserve all three before describing an image as a Canadian eruption map.
The Environmental Emergency Response service directory places the VAAC among specialist atmospheric products. The purpose of an ash advisory differs from that of a general weather forecast or a geological volcano catalogue. A coloured polygon in one of these products should not be copied onto another map without its original legend, time and vertical extent.
Read observation and forecast fields separately
The Montreal product interface contains the available advisory information and graphics. Check the product issue time and whether a displayed position describes an observation or a forecast. Read any altitude or flight-level notation in its original context. Two overlapping polygons at different valid times or altitudes are not necessarily two separate eruptions.
For a research comparison, start with the volcano name and advisory identifier, then place the observation and forecast frames in chronological order. Keep their valid times beside each image. If a later product replaces an earlier one, link the current message rather than presenting an old screenshot as a new observation. The retrieval time of the website cannot substitute for the advisory's own issue time.
Do not infer operational or surface conditions
These specialist products are not personal travel advice or a complete flight briefing. An altitude-specific ash-cloud estimate is not a prediction of deposits at every ground location underneath it. Likewise, a volcano's ground alert level and an aviation status code serve different purposes. The US volcanic-ash guide explains that distinction using USGS source products.
The PocketWorld volcano overview provides available source-labelled volcano records and global context. It does not reproduce the complete Montreal VAAC archive, all active advisories or every altitude-resolved forecast. A reference marker should not be mistaken for current unrest, and a missing global record does not establish that a specialist advisory has been cancelled.
A useful summary names the centre, source volcano, product, issue time, valid time and vertical reference. Include the original advisory link and keep any source uncertainty intact. For operations, use the responsible aviation and emergency authorities and their current products. This page is an explanatory reading guide, not a routing tool, live warning service or claim that every Canadian airspace location has been assessed by the selected graphic.
Data sources
References are linked beside the explanations above. This evergreen guide does not report current incidents.