Mage Shool 104

Tornadoes

Time for a bit of practical.

(Yea; I know you would much rather do the more interesting stuff but we can't manage with just plain theory all the time.) …

The USA post all the amateur official reports ahead of in-depth iinvestigations into their tornado reports. They run a course for storm watchers who post reports to the Stormwatch agency and these are collated and posted on the NWS site

SkyWarn

[ur=http://weather.gov/l]NWS[/url]

The NWS hold archives of these unofficial official reports going back many years. At the time of posting, this was the last date where tornadoes were involved:

http://www.spc.noaa.gov/climo/reports/111013_rpts.html


There were 10 tornado, 41 high wind, 5 hail and 56 reports in total.
The tornadoes are shown in red, hail in green and winds in blue.

Note there is one blue dot in the Mid-West, a region fairly thinly populated. OTOH in a flat plain reporters can view much wider landscapes than is the case in hilly areas. The graphic portrays the number of reports not the actual final account of them.

The biggest bugbear of course is that tornadoes travel across the north of Mexico and the south of Canada too but those countries have not felt the need to connect to the service or set up their own, which makes a truer study of the forecasting of tornadoes even more difficult than it might be.

It will be impossible to find, for example the positings of the moon and their times of phases in time for forecasting tornadoes in the next year or two, I imagine. But every day's total of weather reports as seen by the Storm Watch Group is shared with the rest of the world. So that is at least a start isn't it?

Items such as strong winds and precipitation are reported and thus collected and posted to the archive. And for making a 24 hour forecast that is enough.

This is a picture of the Atlantic the day before the tornadoes at about the time of the relevant tornadoes. Of course, the Atlantic forecast gives plenty of warning by at least 5 days The situation of interest concerns the development of three pressure systems:

1. An High of 1016 millibars over Greenland in the centre top of the chart.

2. A Low of 986 immediately below the Greenland High. (Centre of chart between Newfoundland and Scotland.)

3. An High 1027 to the south-west of the Low forming a tornado spell sandwich. This High must always be to the south west. The one on this chart is over Biscay on the west of France.

The next day the pressure in the centre drops by about 5 millibars. Pressures may not always be the same but usually the central system, the Low is about 980 to 985 and drops 5 millibars by the next day:

Note the legend on this chart indicates it is from the same date as the preceding one. But if you go to the link indicated and play with the archive page loader you will see for yourself it is a different chart. There is no means of telling which chart is actually is though.

Another interesting point is that the thick black lines on the last chart show what are called Occluded Fronts. These are depicted with icons that are composed of triangles and semicircles arranged and look like cartoon mice.

On other parts of the line(s) they appear on alternate sides of the line.
This is to show which direction on a map the weather system approaches, or approached from. A triangle or series of triangles indicate a cold patch, and semicircles indicate warm air. Where they meet and are thus on the same side of the line, they are mixed.

This is called an occluded front. And they indicate something about earthquakes.

More later when you get used to things.

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7 thoughts on “Mage Shool 104

  1. I'm not sure I included the link to WetterZentrale. Bernard Burton keeps a far better selection of North Atlantic charts on this page.It only goes back to the beginning of this year. None the less it will be worth looking at a selection of tornado events to see their development in more detail. Which awaits a better man than I to get organised.Maybe in the next few weeks?

  2. This is the official page foer the Met Office's North Atlantic charts. They are forecasts not reanalyses. http://www.metoffice.gov.uk/weather/uk/surface_pressure.htmlA reanalyses is a computation of the actual fdata that occurred. In other words, using the same model drawing tools as the forecasters use, the true data is fed into the computer after the fact and the corect analysis is tuned out.They do something similar for preparing a model run to make the forecasts with. All the best data available sopme few hours before the next forecast is due is put in the machine and compiled.What happens next is a work of fiction. And sometimes it comes true.

  3. I suppose I should have started with an introduction to the North Atlantic Chart. No excuses. Sorry.Here is the full gamut from 1 pm on the 18th October 2011:

  4. Take a look at the Low just off Norway in the chart above and compare it to what the MetO are showing for it in 48 hours time (two days from Tuesday 18th October 2011.) Note the previous comment posted hosts an Analysis chart the +12 though +84 charts are Forecasts. This was the one for T+48: Note that the original had a tripple centre and wasn't in an hurry to dispose of any ashore.Now they are wondering up into the Arctic. One will build up off Siberia and one will go to the Mackenzie River. I can't remember what will happen to the other.At T+84 there is a large anticyclone over the west of Europe that built up from a ridge stretched out of the Azores:This is all very interesting but it doesn't seem to lead to any tornadoes. However there does appear to be a resurgence of an High over greenland just sparking off. What do you think?Lows pull apart and congregate according to their own weird laws, his wonders to perform.

  5. Here are the earthquakes of Magnitude 5 and over as of today Tuesday the 18th October 2011:6 18/10/2011 05:05 NEW BRITAIN REGION, PAPUA NEW GUINEA5.2 18/10/2011 01:39 JUJUY, ARGENTINA 5.3 17/10/2011 19:51 NEW BRITAIN REGION, PAPUA NEW GUINEA5 17/10/2011 06:03 SOUTHEAST OF TAIWAN 5.4 16/10/2011 17:16 SIMEULUE, INDONESIA5.2 16/10/2011 13:44 NORTHERN XINJIANG, CHINA5.5 16/10/2011 09:47 KURIL ISLANDS5.1 16/10/2011 04:24 VANUATU5 16/10/2011 01:21 KERMADEC ISLANDS REGION 5.2 15/10/2011 22:24 SOUTH OF THE FIJI ISLANDS 5.1 14/10/2011 18:00 KERMADEC ISLANDS REGION6.1 14/10/2011 06:10 AMURSKAYA OBLAST', RUSSIA6.5 14/10/2011 03:35 EASTERN NEW GUINEA REG, PAPUA NEW GUINEA 5.3 13/10/2011 17:53 MARIANA ISLANDS REGION5.3 13/10/2011 15:06 NORTHERN PERU5.3 13/10/2011 04:13 OFF THE COAST OF OREGON6.1 13/10/2011 03:16 SOUTH OF BALI, INDONESIA 5.1 11/10/2011 17:13 EASTER ISLAND REGION5.6 11/10/2011 13:05 PAPUA, INDONESIAThey are all related to the initial post. See how the ones arounf Papua New Guinea and Indonesia have migrated according to the Low invollved with them in the North Atlantic?Here are the accompanying maps from the links on ther NEIC page:

  6. This is interesting:7.4 Mag. 2011/10/21 KERMADEC ISLANDS REGIONT 48 looked the most promising, though by T84 the isobars had spread out a lot. (A ober.)Ah well back to the original subject…PS forgot to mention the GDACS page. It has improved immensely since last time I was there:http://www.gdacs.org/index.html

  7. I have gone way off track with this and am about to abandon the thread and start again.But I think I had best just park this here before I go:23 Oct 2011 6.0 M. EASTERN TURKEY5.1 M. EASTERN TURKEY5.6 M. EASTERN TURKEY5.6 M. EASTERN TURKEY7.2 M. EASTERN TURKEY5.3 M. PALAU REGION22 Oct 20115.0 M. TARAPACA, CHILE5.0 M. KERMADEC ISLANDS REGION5.0 M. SOUTHWEST OF SUMATRA, INDONESIA5.1 M. SOUTHWEST OF SUMATRA, INDONESIA21 Oct 20117.4 M. KERMADEC ISLANDS REGION6.1 M. HOKKAIDO, JAPAN REGION

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