Model Output Discussion 07/02/2021 17:12 >>>· Page 9

BJBlake
Advanced Member

09 February 2021 08:17:45

And more specifically different materials conduct that heat better or worse. A concrete path will be fairly thick and concrete conducts heat quite well so the bottom of the concrete will be able to carry heat from the warmer soil quite a few inches below the surface (depending on the thickness of the concrete and sub base etc).

Tarmac seems to be a better insulator so often you will see the snow settling on tarmac but melting on adjacent concrete paving slabs etc.

I may be wrong but that is my best understanding of why it happens. I know that certain surfaces around my garden always melt the snow even if it’s very cold. The concrete path around the house is one of them.

Originally Posted by: Rob K

yes same here - probably part of it too.

Brecklands, South Norfolk 28m ASL

Whether Idle
Advanced Member

09 February 2021 08:19:31

#202

My view is that a backtrack away from the mild push will begin this evening and will be consolidated tomorrow, with huge inter model variance for 15 February, in terms of weather experienced on the ground.

Cold air in winter becomes very hard to shift. Models will get to grips only at very short notice.

FI is close range presently.

Dover, 5m asl. Half a mile from the south coast.

BJBlake
Advanced Member

09 February 2021 08:20:29

#203

I have set up a snow depth report thread. We should see some spectacular depths over in the east.

Brecklands, South Norfolk 28m ASL

four
Advanced Member

09 February 2021 08:22:34

#204

And more specifically different materials conduct that heat better or worse. A concrete path will be fairly thick and concrete conducts heat quite well so the bottom of the concrete will be able to carry heat from the warmer soil quite a few inches below the surface (depending on the thickness of the concrete and sub base etc).

Tarmac seems to be a better insulator so often you will see the snow settling on tarmac but melting on adjacent concrete paving slabs etc.

I may be wrong but that is my best understanding of why it happens. I know that certain surfaces around my garden always melt the snow even if it’s very cold. The concrete path around the house is one of them.

Originally Posted by: Rob K

This may be involved but as others point out does not explain why the effect is not noticed overnight at the same temperature.
When we have snow cover one of the striking things is how bright it is even when it's overcast, because a lot of solar energy still gets through the clouds and some is at Infra Red end of spectrum we don't see but is very good at slightly warming darker surfaces particularly.
The slow thawing when below freezing effect is hardly noticeable in December but is often spotted later in the winter as the sun is already far more powerful.

North York Moors weather

Brian Gaze
Administration Topic Starter

09 February 2021 08:33:45

#205

This may be involved but as others point out does not explain why the effect is not noticed overnight at the same temperature.
When we have snow cover one of the striking things is how bright it is even when it's overcast, because a lot of solar energy still gets through the clouds and some is at Infra Red end of spectrum we don't see but is very good at slightly warming darker surfaces particularly.
The slow thawing when below freezing effect is hardly noticeable in December but is often spotted later in the winter as the sun is already far more powerful.

Originally Posted by: four

If that was the case you would see the snow melting in areas where the "sun was shining" and not "in the shade". I think it more likely that heat was being reflected back down from the clouds which gave melt in all areas.

Brian Gaze
Berkhamsted
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western100
Advanced Member

09 February 2021 08:33:53

#206

I have said from the beginning, the break to mild may not be as easy as shown today on the GFS / ECM.

It may happen that way and if it does then hats off to the GEM. Although I think the GEM performs at the same consistency as the GFS and ECM anyway?

Our natural climate pattern in this part of the world is for a west to east flow / SW to NE flow. The climate will want the revert to that pattern which is its default synoptic . However it’s not been able to do that much this winter due to different pressure cells being located in parts that aren’t ordinarily the norm.

Large parts of December and January had a Greenland HP and at least 50% of February will have a Scandi HP. This is relative in the CET which was average in December 4.8 and Cold in January 3.1.

At some point a more westerly feed will be established. With a massive LP sat in the Atlantic next week, I am confident that will make a push and at some point some of the waves will make it through

Worcestershire / Warwickshire Border
100m ASL
Twitter…..@Weather4u2

roadrunnerajn
Advanced Member

09 February 2021 08:48:01

#207

A family member living in Crete has just told me that they are expecting cold weather next week. That would tie in with the latest models this morning..

Germoe, part of the breakaway Celtic Republic.

Brian Gaze
Administration Topic Starter

09 February 2021 08:54:01

#208

I have said from the beginning, the break to mild may not be as easy as shown today on the GFS / ECM.

It may happen that way and if it does then hats off to the GEM. Although I think the GEM performs at the same consistency as the GFS and ECM anyway?

Originally Posted by: western100

Correct, but for a reason I've never understood it seems some people think there are big differences in performance. Often the favoured model is the one which shows the desired outcome. Rule no 1 should be to look for consistency rather than focusing on one because it may be considered marginally better.

Latest verification stats here:

https://www.emc.ncep.noaa.gov/gmb/STATS_vsdb/allmodel/daily/cor/cor_day5_HGT_P500_G2NHX.png

Brian Gaze
Berkhamsted
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sunny coast
Advanced Member

09 February 2021 08:55:09

#209

Decent output this morning with a trend away from prolonged cold, will be looking for a continuation of this for a few days now.

Originally Posted by: backtobasics

Latest bbc report still very bullish about cold into next week

Rob K
Advanced Member

09 February 2021 08:58:50

#210

If that was the case you would see the snow melting in areas where the "sun was shining" and not "in the shade". I think it more likely that heat was being reflected back down from the clouds which gave melt in all areas.

Originally Posted by: Brian Gaze

When it is overcast the light is scattered so even areas “in the shade” will still be getting the infrared radiation. So it’s probably a combination of reflected and scattered radiation ensuring that any exposed surfaces that can absorb the heat will do so.

It still doesn’t make total sense to me because I would expect dark tarmac to absorb more heat in this case than pale grey concrete, but the concrete melts snow more easily. Must be a combination of factors including heat capacity/conductivity.

Edited by user 09 February 2021 09:01:23 | Reason: Not specified

Yateley, NE Hampshire, 73m asl
"But who wants to be foretold the weather? It is bad enough when it comes, without our having the misery of knowing about it beforehand." — Jerome K. Jerome

Hippydave
Advanced Member

09 February 2021 08:59:30

#211

Correct, but for a reason I've never understood it seems some people think there are big differences in performance. Often the favoured model is the one which shows the desired outcome. Rule no 1 should be to look for consistency rather than focusing on one because it may be considered marginally better.

Latest verification stats here:

https://www.emc.ncep.noaa.gov/gmb/STATS_vsdb/allmodel/daily/cor/cor_day5_HGT_P500_G2NHX.png

Originally Posted by: Brian Gaze

And just to back up my earlier thoughts, day 10 here:-

cor_day10_HGT_P500_G2NHX.png (800×800) (noaa.gov)

I'd be surprised when things filter through if GFS doesn't take a dip due to flipping in the run up to the cold spell but I guess it depends on whether it was just locally it got things wrong or globally. Generally though it had been performing very well (new and old). GEM verifying worse of the big 3 but not an enormous amount in it.

Home: Tunbridge Wells
Work: Tonbridge

MRayner
Advanced Member

09 February 2021 09:01:56

#212

Sitting at - 12.6 C now, and with 2 more nights to come like this, I will be glad to see the warm air arrive !!!

Location Whisky 🥃 country, Cragganmore ,Moray, 440 AMSL

Quantum
Advanced Member

09 February 2021 09:11:55

#213

ICON6Z hangs on a bit longer. Uppers of -14C just off the coast on Saturday.

vs 0Z

2023/2024 Snow days (approx 850hpa temp):
29/11 (-6), 30/11 (-6), 02/12 (-5), 03/12 (-5), 04/12 (-3), 16/01 (-3), 18/01 (-8), 08/02 (-5)

Total: 8 days with snow/sleet falling.

2022/2023 Snow days (approx 850hpa temp):

18/12 (-1), 06/03 (-6), 08/03 (-8), 09/03 (-6), 10/03 (-8), 11/03 (-5), 14/03 (-6)

Total: 7 days with snow/sleet falling.

2021/2022 Snow days (approx 850hpa temp):

26/11 (-5), 27/11 (-7), 28/11 (-6), 02/12 (-6), 06/01 (-5), 07/01 (-6), 06/02 (-5), 19/02 (-5), 24/02 (-7), 30/03 (-7), 31/03 (-8), 01/04 (-8)
Total: 12 days with snow/sleet falling.

Rob K
Advanced Member

09 February 2021 09:13:17

#214

Looking at the WRF, quite a decent snow to rain (freezing rain in the east) event for much of the south on Friday to Saturday.

Would be pretty rare for the SE areas currently lucky enough to have deep lying snow, to have frontal breakdown snow arrive on top of solid existing snow cover

Yateley, NE Hampshire, 73m asl
"But who wants to be foretold the weather? It is bad enough when it comes, without our having the misery of knowing about it beforehand." — Jerome K. Jerome

The Beast from the East
Advanced Member

09 February 2021 09:13:25

#215

Latest bbc report still very bullish about cold into next week

Originally Posted by: sunny coast

Always behind the curve using yesterdays output.

Disappointing today but its been in the GEM for some time and this model has been superb recently

"We have some alternative facts for you"
Kelly-Ann Conway - special adviser to the President

The Beast from the East
Advanced Member

09 February 2021 09:18:45

#216

ICON is a slight upgrade, but just delaying the inevitable

Its possible the block could fight back, but it needs to start showing up by tonights runs

"We have some alternative facts for you"
Kelly-Ann Conway - special adviser to the President

CField
Advanced Member

09 February 2021 09:21:12

#217

Simple theme this winter down south anyway cold week mild week,cold week mild week etc

I should know been on a week on week off rota on the gritters in Kent.The guys on the cold weeks have consistently earnt a fortune while the guys on mild weeks ( me) earnt peanuts and to see that forcast this weekend next week is a particular kick In the teeth

Favourite snowstorm
Famous channel low
Dec 31st 1978
Hastings East Sussex
Foot of level snow severe drifting
Next day max temp -4 degrees Celsius

ballamar
Advanced Member

09 February 2021 09:22:10

#218

Small old school chance of a snow to rain back to snow as the cold pushes back. Chances are not great but the pattern is an unusual one having som decent cold in place. Next couple of days should make some interesting viewing. I have had my snow fix so anything else would be a bonus

The Beast from the East
Advanced Member

09 February 2021 09:30:39

#219

Simple theme this winter down south anyway cold week mild week,cold week mild week etc

I should know been on a week on week off rota on the gritters in Kent.The guys on the cold weeks have consistently earnt a fortune while the guys on mild weeks ( me) earnt peanuts and to see that forcast this weekend next week is a particular kick In the teeth

Originally Posted by: CField

To try and be positive, if the block doesnt sink it could come back again later. Even if we have a mild week. Seems unfair to get paid depending on the weather conditions!

"We have some alternative facts for you"
Kelly-Ann Conway - special adviser to the President

doctormog
Advanced Member

09 February 2021 09:44:29

#220

I notice that the 06z ICON stubbornly hold on to the -10ºC t850s here until 120hr.

Aberdeen
Current conditions (personal WS)

sunnyramsgate
Advanced Member

09 February 2021 10:04:34

#221

Carol Kirkwood seems to think that the cold will hang on into next week that was at 7ish this morning

Saint Snow
Advanced Member

09 February 2021 10:05:54

#222

Carol Kirkwood seems to think that the cold will hang on into next week that was at 7ish this morning

Originally Posted by: sunnyramsgate

A few days before this chilly snap started, Carol Kirkwood was playing down the chances of cold and snow for anywhere.

Martin
Home: St Helens (26m asl) Work: Manchester (75m asl)
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