Boxing Day Snow Event Thoughts And Reports.

[Paul_1978]

About 1" in Wakefield. Shame it's not gonna be a long snowy spell.

[Mapantz]

Some strong gusts near the South coast at the moment.

 

http://www.xcweather.co.uk/

I was just looking at that on my phone and thought the same. It's not that bad here. In fact, it's barely windy! It might be slightly protected due to the direction. It'll be different as it swings around to the NW though.

[johnholmes]

well even low lying Doncaster has moderate briefly heavy snow with 3-4cm lying, roads are well covered, fortunately not a lot of folk out, rain and snow at 1900 turned to snow about 2000 with moderate briefly heavy at times from about 2100, current T=0.0C.

 

the radra suggests it should stop or ease off before long.

 

Obviously the low is much further north than I suggested (maybe 100 or so miles it looks on the 2200 chart) it is also deepening quite a bit which is one factor in increased ppn and intensity.

Edited December 26, 2014 by johnholmes

[Polar Maritime]

A few pics of mine from here, Still moderate snow and drifting a little.

 

Edited December 26, 2014 by Polar Maritime

[roys]

still snowing hear in sheffield about five inches laying dosent seem to be letting up, kids will have fun in morning playing in snow.

[johnholmes]

still snowing hear in sheffield about five inches laying dosent seem to be letting up, kids will have fun in morning playing in snow.

 

could you put your town in your avatar for future reference  please?

any idea of your height please, and welcome to Net Wx.

Edited December 26, 2014 by johnholmes

[Cloud 10]

still snowing hear in sheffield about five inches laying dosent seem to be letting up, kids will have fun in morning playing in snow.

 

Has  The Pit  dismantled the shield?.

[Polar Maritime]

Very heavy again, Near on a foot outside.

[Vorticity0123]

After the tour across the UK, the low pressure area currently located somewhere close to London is bound to bring some quite significant amount of rain and snow for the Benelux. As has been observed over the UK, the Benelux is also going to experience a north-south split in the type and amount of precipitation, with the Netherlands (especially the middle- and southern parts) will be experiencing quite some snow, while Belgium will see a mix of rain and snow (probably more snow to the north and east in Belgium).

 

Low pressure tracks toward the Benelux

 

To place this into perspective, below is the wind and surface level pressure chart of tomorrow morning from the Harmonie model (Dutch mesoscale model):

 

Harmonie 10 m wind and MSLP 18 UTC run, T+14 h.

 

The core of the low pressure area is located directly over the center of Belgium at 09:00 local time (08 UTC).

 

The low pressure area also contains quite a strong wind field, with the northwestern edge of France probably having a sustained 8 BFT for some hours. Over land, winds could also edge up to 5 BFT, about 200 kilometres north of the center.

 

Temperature structure of the system

 

Furthermore (perhaps more interesting) is that the wind blows from land north and east of the low pressure area, while winds from sea are being experienced on the western and southern half of the system. This has also some consequences for the temperature, and more importantly (for snow), the dewpoint. Therefore, the dewpoint temperatures forecast at the same timeframe is given here:

 

Harmonie dewpoint temperatures 18 UTC run, T+14 h.

 

Over the whole Netherlands, and over extreme eastern Belgium, the dewpoints are just at the edge for snow/rain, being at 0*C. On the other hand, the dewpoints over the central part of Belgium are much higher, up to 5*C (as a result of the winds from sea and the influx of warmer at the center (?) ). Yet they are lower again over the western part of Belgium (about 0*C again). This difference is better visible when taking a look at the 850 hPa temperatures at the same timeframe (the chart is from Meteociel, because the Harmonie model does not have the 850 hPa temperatures):

 

WRF NMM 850 hPa temperatures 18 UTC run (T+14).

 

For the time being, I assume that the position of the low pressure system is identical (which is not exactly the case, but does fulfil the conditions to make comparison possible).

 

As can be seen from the image, sub -4*C 850 hPa temperatures encompass the northern, southern and western extent of the low pressure area. However, the center of the low pressure area does contain somewhat higher 850 hPa temps (even higher than -2*C just to the west of the center, check the Harmonie output at the first image). The reason for this is unknown to me, but most likely it has something to do with the frontal structure of the low. If anybody knows the answer, it would be greatly appreciated!

 

Precipitation analysis

 

Then, finally, to what it all comes down of course: the snow itself. Check the Harmonie output for the precipitation amounts of the same timeframe as given above:

 

Harmonie 10 m precipitation amount 18 UTC run, T+14 h.

 

The main precipitation zone lies over the southern half of Holland. There is also some scattered precipitation over Belgium. However, a few hours prior to this, the precipitation zone was lying over Belgium as well. As the dewpoints are around zero over Holland and over the extreme eastern part of Belgium, and considering that the precipitation expected is going to be pretty intense (more than 1 mm/h at many places in the Benelux), this will be mainly snow at the areas mentioned before.

 

The Harmonie model can also indicate where the precipitation will be wintry and where rain. For that forecast, check the link below:

 

http://www.weerplaza.nl/gdata/weerkaarten/harmonie/charts_harmonie_pcptype_bnl_15.png (Harmonie 10 m assessment of kind of precipitation, 18 UTC run, T+14 h.)

 

The red dots indicate wintry precipitation, while the blue dots indicate rain. This image agrees with the statement given above.

 

Conclusion

 

Ultimately, summing this all up, snow amount are forecast to vary between 0 in the north of Holland, up to more than 10 cm in the center and south of Holland and eastern Belgium. However, any change in the track of the low pressure could completely change this forecast, especially with such a precarious situation. Very exciting times lie ahead!

 

Sources:

http://www.weerplaza.nl/weerkaarten/harmonie/?tau=15&element=pcptype

http://www.meteociel.fr/modeles/wrfnmm.php?ech=3&mode=21&map=0

^1:https://twitter.com/weerplaza

Edited December 26, 2014 by Vorticity0123

[roys]

blowing like a blizzard here now in sheffield, 5 to midnight.

[Muffelchen]

Well it's all over for tonight here: no snow as the sleet has turned to rain and temp has risen to 2.5°C with a DP of 1.5°C. Looked promising (in spite of me knowing better!) with the temp dropping to 0.8°C but it was not to be. Don't really get it here in these set-ups, they always end up with sleet. Best easterly snow is with a strong, cold continental feed picking up moisture from the N Sea and producing heavy (sometimes thundery) snow showers. Depressions tracking East to the south of us in marginal situations never produce the goods although often do so to the west and this was the case tonight.

 

Back to model watching again... Won't be posting over on the model thread though: way too dangerous :w00t:

[roys]

think we could end up with 8 or 10 inches if this keeps on maybe more.

[ChezWeather]

blowing like a blizzard here now in sheffield, 5 to midnight.

Same here, small flakes being blown at quite an angle.

 

6 Inches at least now on the roads, still coming and looking at the radar we have at least a couple of hours more yet 

[cuckoo]

Looking good for The Netherlands and West / South Germany tomorrow.  

[Daniel*]

Very good well written post vorticity - bit IMBY (jokes aside)

your charts highlight potential for sleet/snow showers towards (South East & East Anglia) Fax indicates this, so those that missed out today which was yesterday - might manage some flakes and to be truthful I will be content with that after the dismal 20 or so months. Good day for some...

[Sainsbo]

With all of the talk of snow it seems the wind aspect of this system was forgotten about. Gusts of over 110mph have been recorded on the south coast, with 80-90mph gusts reported inland, according to the map posted on Twitter, courtesy of Meteogroup.

 

And not even a yellow warning out for the wind from the MetO!

 

[LadyEv06]

For the past hour or so myself and other locals have witnessed blue and green flashes in the sky - I'd say lightning but none of the radars have detected any. Can anyone shed some light?

We've had around 7in of snow in 6 hours, still coming down heavy and the wind has really picked up.

Edited December 27, 2014 by LadyEv06

[alexisj9]

For the past hour or so myself and other locals have witnessed blue and green flashes in the sky - I'd say lightning but none of the radars have detected any. Can anyone shed some light?

We've had around 7in of snow in 6 hours, still coming down heavy and the wind has really picked up.

Power flashes may be, the wind is a lot stronger than forecast for sure.

Edited December 27, 2014 by alexisj9

[Captain Shortwave]

No snow as of yet, but gale force winds and a lot of rain which has caused localised flooding.

[ihatecoldweather]

Yellow wind warning now

[Fingers]

Evening all. The warm sector took us up to 10'c this evening but a massive drop of 4'c in 51 minutes since midnight is fairly impressive! Very strong gusty winds here too.

Looking forward to some calm frosty nights this week.

[East_England_Stormchaser91]

For the past hour or so myself and other locals have witnessed blue and green flashes in the sky - I'd say lightning but none of the radars have detected any. Can anyone shed some light?

We've had around 7in of snow in 6 hours, still coming down heavy and the wind has really picked up.

I can vouch for this! bright blue flashes to my West!

[bazookabob]

Would love to know why none of the roads in South Yorkshire we gritted, including the M1! Having got stuck on the road between it and Rotherham, we eventually gave up and decided to head back to Leeds, having had our snow fix, only to find conditions on the M1 were even worse, and there was still not a single gritter out. 2 and a half hours to get home instead of 40 mins. But at least it snowed I suppose!

 

[Daniel*]

For the past hour or so myself and other locals have witnessed blue and green flashes in the sky - I'd say lightning but none of the radars have detected any. Can anyone shed some light?

We've had around 7in of snow in 6 hours, still coming down heavy and the wind has really picked up.

Downed power lines due to the sheer weight of the snow? Struggle to explain the green flashes mysterious

[LadyEv06]

I can vouch for this! bright blue flashes to my West!

MetO tweeted saying no lightning detected over the UK so what the heck is it

Downed power lines due to the sheer weight of the snow? Struggle to explain the green flashes mysterious

The flashes seem to be away from any power lines though. I've certainly never seen anything like it in my life