Winter 2013/2014 Forecasts/Hopes/Discussion Thread

[Conor Sherwin]

                                                                SO IS THIS COLD AND SNOW      

[Weather of Mass Disruption]

Christmas day anybody?

 

The dream...   

[Dancerwithwings]

                                                                SO IS THIS COLD AND SNOW      

 

Yes (cold)....Because there's cold air in place but you would only know this by looking at the 850hpa charts..... below,

 

[Buriedundersnow]

                                                                SO IS THIS COLD AND SNOW      

 

 

yes conor that chart would be cold and snowy I have saved it and posted it here again incase it changes

 

 

here is the 850 temps

 

 

and temps at the surface or the 2m temps

 

 

here is the precipitation chart and as you see there is a front moving in so this would mean a considerable amount of frontal snowfall

 

 

at the top of the charts on meteociel you will see 850hpa and 2m temps and precipitation

Edited October 3, 2013 by Buriedundersnow

[Yarmy]

Yes (cold)....Because there's cold air in place but you would only know this by looking at the 850hpa charts..... below,

 

 

Yes, one needs to look at the Upp..  er, I mean 850hPa temps too.

[Conor Sherwin]

Christmas day anybody?

IS THAT COLD BUD

[Dancerwithwings]

Yes, one needs to look at the Upp..  er, I mean 850hPa temps too.

[Conor Sherwin]

                                                                    NOT ONLY ON CHRISTMAS DAY      

[feb1991blizzard]

You can tell by SLP and H500 charts alone when you get a bit of experience, you will get a feel for what is cold uppers, generally the higher the SLP, the higher the H500 you can get away with to maintain cold uppers, of course though you can even have uppers close to zero and still be cold enough for snow at surface if its a frontal incursion over trapped surface cold.

Edited October 3, 2013 by feb1991blizzard

[Summer Sun]

IS THAT COLD BUD

 

There cold at first but slowly easing through the day.

 

Your not going to get any consistent charts for Xmas day until well into December sometimes it can be just 48 hrs before we know whats going to fall from the sky

 

Could I politely ask you don't post in caps as its often referred to as shouting I know your not but just for future reference

[feb1991blizzard]

Check - meant higher- of course the lower the heights the better, ive found this stored away in my locker from last years forum - its very useful for the last few frames of the UKMO runs and the GEM 0z.

 

http://forum.netweather.tv/index.php?app=core&module=attach&section=attach&attach_rel_module=post&attach_id=146057

 

This table here is the easiest way to convert Heights / SLP to uppers, I am not qualified enough to know whether its an exact science or a guestimate but to me it seems about right usually.

[Dancerwithwings]

You can tell by SLP and H500 charts alone when you get a bit of experience, you will get a feel for what is cold uppers, generally the higher the SLP, the higher the H500 you can get away with to maintain cold uppers, of course though you can even have uppers close to zero and still be cold enough for snow at surface if its a frontal incursion over trapped surface cold.

Predicting snowfall by combining 500hpa with 850hpa charts

 

500hpa upper levels section temperatures need to be -25C or below with a damline preferably DAM 528 or lower. Snow can occur with a DAMLINE as high as 540 but lower/mid levels and surface conditions need to be lower. As for the 850hpa values, we need and demand -7C, generally a blue/cold green colour gradient. The key to remember here is that crystalisation at upper levels of -25 C or lower will fall rapidly into warmer lower levels melting as they fall, this melting releasing latent heat warming the surrounding environmental atmosphere. To know that when the ice crystals/graupel can reach the relatively low/mid levels close to the surface at a temperature of -7, ensures the precipitation is cold enough to fall the remaining short distance to the surface without melting. So the important parameters for snowfall so far are noted below:

500hpa – -25C or Lower & DAMLINE 528 or lower850hpa – -7C or lower

Edited October 3, 2013 by Dancerwithwings

[MR EXTREMES]

There cold at first but slowly easing through the day.

 

Your not going to get any consistent charts for Xmas day until well into December sometimes it can be just 48 hrs before we know whats going to fall from the sky

 

Could I politely ask you don't post in caps as its often referred to as shouting I know your not but just for future reference

tbh summer don't think any of us know until the day itself but its a chart of beauty and is possible as much as its inpossible.

[Yarmy]

Check - meant higher- of course the lower the heights the better, ive found this stored away in my locker from last years forum - its very useful for the last few frames of the UKMO runs and the GEM 0z.

 

http://forum.netweather.tv/index.php?app=core&module=attach&section=attach&attach_rel_module=post&attach_id=146057

 

This table here is the easiest way to convert Heights / SLP to uppers, I am not qualified enough to know whether its an exact science or a guestimate but to me it seems about right usually.

 

Cheers, bookmarked. That's useful for the UKMO as the 850 temps only go out to T72 for some reason.

[feb1991blizzard]

The way I think of it is if you see the dark blue colour on the H500 charts then anything much greater than 1000hpa surface pressure is likely to be brutal cold.

[smithyweather]

To be honest I will take the euro high set up, look at the ECM ensemble mean, there could be snow cover over most of the North-eastern half of Russia in 10 days time, certainly will be cold enough.

I think you've made that aware these days.

[sebastiaan1973]

Check - meant higher- of course the lower the heights the better, ive found this stored away in my locker from last years forum - its very useful for the last few frames of the UKMO runs and the GEM 0z.

 

http://forum.netweather.tv/index.php?app=core&module=attach&section=attach&attach_rel_module=post&attach_id=146057

 

This table here is the easiest way to convert Heights / SLP to uppers, I am not qualified enough to know whether its an exact science or a guestimate but to me it seems about right usually.

I placed this some time ago here at Netweather. It was made by Alwin Haklander. Working for KNMI, he has a PhD in meteorology.

 

http://repository.tue.nl/637579 his thesis

Edited October 3, 2013 by sebastiaan1973

[feb1991blizzard]

I placed this some time ago here at Netweather. It was made by Alwin Haklander. Working for KNMI, he has a PhD in meteorology.

 

http://repository.tue.nl/637579 his thesis

 

Cheers although unfortunately I cannot open PDF's on my computer at the moment, cheers anyway.

[johnholmes]

Predicting snowfall by combining 500hpa with 850hpa charts

 

500hpa upper levels section temperatures need to be -25C or below with a damline preferably DAM 528 or lower. Snow can occur with a DAMLINE as high as 540 but lower/mid levels and surface conditions need to be lower. As for the 850hpa values, we need and demand -7C, generally a blue/cold green colour gradient. The key to remember here is that crystalisation at upper levels of -25 C or lower will fall rapidly into warmer lower levels melting as they fall, this melting releasing latent heat warming the surrounding environmental atmosphere. To know that when the ice crystals/graupel can reach the relatively low/mid levels close to the surface at a temperature of -7, ensures the precipitation is cold enough to fall the remaining short distance to the surface without melting. So the important parameters for snowfall so far are noted below:

500hpa – -25C or Lower & DAMLINE 528 or lower850hpa – -7C or lower

I would suggest regarding that comment you read this link, it is usually reliable

http://www.theweatherprediction.com/habyhints/19/

 

to add to the proviso above there are at least 6 maybe 7 other parameters needed, assuming ppn is actually occurring for it to be snow and not sleet or rain. The 500mb temperature is perhaps the least important in these in a frontal situation, in a showery situation then obviously deep cold air at height will allow deeper convection.

Edited October 3, 2013 by johnholmes

[DAVID SNOW]

IS THAT COLD BUD

Great idea

[Dancerwithwings]

I would suggest regarding that comment you read this link, it is usually reliable

http://www.theweatherprediction.com/habyhints/19/

 

to add to the proviso above there are at least 6 maybe 7 other parameters needed, assuming ppn is actually occurring for it to be snow and not sleet or rain. The 500mb temperature is perhaps the least important in these in a frontal situation, in a showery situation then obviously deep cold air at height will allow deeper convection.

Great read..... Cheers

[feb1991blizzard]

Some sort of cold pooling at 168 on the ECM over Eastern Europe, not relevant to us yet as even if the trigger was to be pulled (which it wont yet), the bullet wouldn't be potent enough, however, it might help with a build up of snow cover over there.

[Mark Neal.]

Some sort of cold pooling at 168 on the ECM over Eastern Europe, not relevant to us yet as even if the trigger was to be pulled (which it wont yet), the bullet wouldn't be potent enough, however, it might help with a build up of snow cover over there.

May not be snowy or far from cold near here, but would help with the increasing Eurasian snowcover! 

[feb1991blizzard]

May not be snowy or far from cold near here, but would help with the increasing Eurasian snowcover! 

 

yes that's why I posted it, its a forlorn hope to get anything here yet but every little helps wrt forthcoming winter.

[feb1991blizzard]

http://www.youtube.com/watch?v=Z9wM3-RAmg0&feature=c4-overview&list=UU2wnqre5yOw-aFrYFegp_zQ