What an eruption looks like on forecast charts

This is a run of combined forecasts called an EFS for Mexico USA and Canada. Various runs are made with the models used and the combined output is shaved from a plate of spaghetti outputs to this one organised forecast.  The daily run goes out to the analysis time+360 hours in 24 hour intervals.


2014083100_024 Above is the last chart for August and the first for September 2014. The Lows or cyclonic systems are weak and ill defined. The anticyclones or highs are much stronger.

2014090100_024But the spell changes and the anticyclones split into smaller systems after forming ridges and leaking away.

2014090200_024Note that when an anticyclone declines, the air doesn’t join the cyclones but persists in much the same area as before -if it can.

2014090300_024In fact cyclones and anticyclones tend to follow routes defined by something divorced from what mere isobars show us.

2014090400_024What happens when three Lows (or three Highs) occur on such a chart is somewhere on the planet the isobars are operating deeper in the planet.

2014090500_024It could be that these subterranean pressure points coalesce or join up to form an earthquake of large magnitude or there might be a volcanic eruption of notable output.

2014090600_024In such cases the pressure systems are better defined than on these charts but (for volcanic eruptions) they tend to last longer. When they lie adjacent, such as the 5 Lows in the chart above, it is a sure sign of a significant event.

Look at the chart one above that. There are three Lows adjacent and also three Highs.

2014090700_024This one is a confusing signal. Generally when that happens the eruptions, if any, are low key or there are several low-medium sized earthquakes.

2014090800_024Take a look at what earthquakes were occurring on the dates of these charts and see what you can make of things:


2014090900_024As a general rule; when we get a series of alternate systems (H/L/H/L etcetera) there tends to be a series of quakes in the range of 5.5 to 6 .5 M.

2014091000_024You can usually see it all coming a few days in advance. But you can’t rely on these model runs because they are not changed by computed progression alone.

There is a lot of human input correcting what the meteorologist knows from previous experience won’t happen, or from simple gas physics, can’t happen.

2014091200_024But when three or more well defined systems line up as with the product above, then you should pay more attention than usual to what happens next.

2014091300_024If the chart is a one off, then the signal means a large eruption is due. If you check with other charts you can tell if this is an error or something else is happening off the page.

I called a dud on the above thinking it was a larger than usual quake due. But there must have been another adjacent low in the mix off-screen.

2014091400_024Volcanic activity had increased for these dates but it wasn’t widely reported until journalists stopped blathering about Iceland long enough to report what the Philippine authorities were doing about Mount Mayon.

2014091500_024Not that you would know it from these runs. But I have omitted all the charts from the NAEFS except these 24 hour forecasts.

2014091600_024A series of large medium sized quakes occurred with the above:

2014/09/17        6.7        M        Mariana Islands
2014/09/17        5.6        Mb        Vanuatu Islands
2014/09/16        5.6        Mb        Eastern Honshu, Japan
2014/09/16        5.6        Mb        New Britain, Papua New Guinea

More here.

2014091700_024From now on the volcanism gets serious:

2014091700_048 2014091700_072 2014091700_096Which brings us pretty close to the end of the spell. In the next thread I will discuss the same signal and what happens then, according to the Australian charts.



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