Dam

[dhillcrest]

Hello all. As a total novice, indeed imbecile, what does 'dam' mean and what does it imply as in 500-1000 hPA, 516 dam on the snow farecast chart here?

There is just so much I would want to understand but don't know where to start. Could anyone recommend a site which gives a retards guide to meteorology symbols and charts?

May we all live in igloos by March. Thanks all.

Oh, and mods, please remove this if it's in a bad place.

cheers :blush:

Oh embarrassing - just found the netweather guide. I await my removal.

Best wishes

[Mesoscale]

Hey and welcome! basically its the depth of a layer in decameters between the 1000 - 500 hpa (1 Dam = 10 metres) the thicker the depth the less likely the chance of snow! we want it as thin as possible for snow!

[johnholmes]

Hello all. As a total novice, indeed imbecile, what does 'dam' mean and what does it imply as in 500-1000 hPA, 516 dam on the snow farecast chart here?

There is just so much I would want to understand but don't know where to start. Could anyone recommend a site which gives a retards guide to meteorology symbols and charts?

May we all live in igloos by March. Thanks all.

Oh, and mods, please remove this if it's in a bad place.

cheers :blush:

Oh embarrassing - just found the netweather guide. I await my removal.

Best wishes

this link takes you to what DM or Dam lines are about along with other explanations, understanding the GFS output etc, lots more if you look further into the main link

enjoy

sorry I seem to have lost it somehow and only just come back to this thread but I see Paul has come to the rescue further down, I'll now post in the other link regarding how to use GFS to do your own forecast?

apologies again.

http://forum.netweather.tv/topic/64122-basic-gfs-charts-how-to-understand-and-use-them/

Edited November 23, 2010 by johnholmes

[Guest]

The 528 metre line is generally regarded as the dividing line between snow and rain.

'Ere, I've just checked, I don't get the thickness levels or the 850 millibar temps on my local forecasts - Am I missing something here?

Edited November 23, 2010 by mike Meehan

[dhillcrest]

The 528 metre line is generally regarded as the dividing line between snow and rain.

'Ere, I've just checked, I don't get the thickness levels or the 850 millibar temps on my local forecasts - Am I missing something here?

Thank you all. @ Mike, the dam and 850 temps are on the netweather snow forcast .

Best wishes to all,

[Paul]

Hello all. As a total novice, indeed imbecile, what does 'dam' mean and what does it imply as in 500-1000 hPA, 516 dam on the snow farecast chart here?

There is just so much I would want to understand but don't know where to start. Could anyone recommend a site which gives a retards guide to meteorology symbols and charts?

May we all live in igloos by March. Thanks all.

Oh, and mods, please remove this if it's in a bad place.

cheers :blush:

Oh embarrassing - just found the netweather guide. I await my removal.

Best wishes

Welcome to the site

If you scroll down beneath the snow forecast there's a brief explanation of the two techie terms in there:

Snow forecast information

You may not be familiar with a couple of the items within the snow forecast, the first one 850hpa temps is the temperature at approximately 1.5km above the ground. Generally this temperature needs to be at -5°c or below for snow to be likely. The other term is 500-1000hpa, this is a measure of the height or 'thickness' between these two points in the atmosphere (HPA is a measure of air pressure, so these points move up and down dependant on conditions). In general for snow to be likely, this value needs to be showing 528dam or less.

There's also a good guide written by John here:

http://forum.netweather.tv/topic/57486-how-to-understand-what-is-meant-by-dam/

[Cakie]

dhillcrest

You have proved that no question is a daft question (my mantra at work) I still don't have the full understanding of the Dam but will read up yet again

[Guest]

Thank you all. @ Mike, the dam and 850 temps are on the netweather snow forcast .

Best wishes to all,

Thank you, that is so useful