Severe Storm System & Arctic Blast Thursday 5th Onwards

[Summer Sun]

There is now increasing confidence that an arctic blast will sweep across the UK later this week with snow falling in northern Scotland from Thursday

 

 

By Friday the arctic air will be across the UK with temperatures ranging from 0c in the northern Isles to 4c in the south

 

 

 

 

 

[NUT]

Thursday the change day might be interesting

[Snowshine]

The Snow Risk chances have decreased for much of England in the last hour. Earlier on much of Western England had a snow risk of 90% however now the highest snow risk is lower and much less widespread.

[Mark Neal.]

Well the end of the week will be colder, thats all that is almost certain!

Be good for many areas to see first snowfall of the season, especially the usual favourites, NW Eng,N Wales,Scotland, NE coasts... I'd do anything for a snow flurry ha 

[mike Meehan]

So who's in a hurry for a flurry?

[Summer Sun]

Yellow warnings for snow issued for most of Scotland

 

http://www.metoffice.gov.uk/public/weather/warnings/#?tab=map&map=Warnings&zoom=5&lon=-3.50&lat=55.50&fcTime=1386201600

[Roger J Smith]

This turns into a severe windstorm for Holland, northern Germany, Denmark and the Baltic region as the low bombs out to below 955 mbs in the southern Baltic Sea by Friday early morning. Scotland will see the developing stages of this, but it won't be quite as extreme there. Have to say that the 850 temps look a bit overdone given the maritime source of the northwest winds, in reality it may turn out 2-3 deg less severe for upper temps in the North Sea region but that won't affect the intensity of the winds which could easily gust above 80 mph in exposed locations from Holland to the Baltic states.

 

For Scotland, would say maximum wind gusts will be around 70 mph in northern Isles and central belt, of course could be way higher in upland areas, but fortunately this system peaks further east. The effects will be generally moderately severe in northern England (some gusts to 65 mph, some upland snowfalls), isolated moderate impacts in central England and parts of Wales and the southwest (some gusts to 60 mph, isolated snow streamers). In London and the southeast it just looks like a slight impact of colder daytime temperatures and moderate wind gusts near 50 mph. Northern Norfolk could also see some very strong gusts late Thursday and early Friday. There could be some severe wind damage in exposed locations across the North Sea in Holland and northwest Germany.

[Coast]

Looks like it's wind that will be the notable weather for many, especially in the East:

 

 

Wow!!

 

 

 

Gust up to 129 km/hr (80mph) in the North and East?

 

 

Northern England in a band through Blackpool, Bradford, Leeds and Hull gets some very big gusts:

 

 

Hang on to your hats up there.

[NL]

Well the end of the week will be colder, thats all that is almost certain!

Be good for many areas to see first snowfall of the season, especially the usual favourites, NW Eng,N Wales,Scotland, NE coasts... I'd do anything for a snow flurry ha 

Wont be the first snowfall of the season as we had snow fall although briefly on the 19th November.

[Thundery wintry showers]

The main "thrust" of the northerly looks like being shunted into the North Sea although there may be a feed of light showers moving down the Cheshire Gap and clipping the NE of Scotland and Norfolk.

[GulberwickWeather]

Already quite chilly up here and a quick change from yesterday. At 2am this morning it was a balmy 8.9C currently it's 2.9C and falling and the dew point is already below freezing at -0.3C. Could be fun on Thursday/Friday!

[Vorticity0123]

As there will be a possible storm system developing next Thursday and Friday, an outlook for the storm is given below:

 

The system is forecast to cause a possible 11BFT along the eastern UK, the Netherlands and Denmark on Thursday and Friday. This could possibly cause quite some damage in these countries.

 

For illustration, the Hirlam (a short-term high-res model) output of pressure on thursday 12Z is shown below:

It shows that a rather intense low pressure area (975 mb) drops from the north with a rather tight pressure gradient.

 

For the wind speeds, the GFS 12Z on Thursday 12Z is given below:

 

It shows an 11BFT over the North Sea, with a 10BFT scraping the easter UK and the north part of The Netherlands.

Six hours later. there is still a 10 BFT along the northern part of The Netherlands and Denmark.

 

 

On Friday 6Z, there is still a potent 8BFT in the northern part of The Netherlands, and a 9BFT in Denmark.

 

Along with this wind, there will also be high tide accompanied by "springtide" (when the moon causes the tide to have a higher amplitude). As from the KNMI, this could cause alarm levels to be reached in the Netherlands (concerning flooding). This means that there is a rather severe risk on flooding occuring there.

 

On top of this all, there is also snow forecast for the hills in the UK and the Netherlands:

Below is the GFS 12Z forecast for snow on Friday morning:

 

The amounts of snow falling are not very severe (only 3 cm max, may change somewhat in the short term), so the chances on a blizzard occuring are quite slim, luckily.

 

Though the severity of the storm is not set in stone yet, the potential of the system makes it worth watching.

 

Sources:

http://www.weeronline.nl/vakman-index/130/0

http://www.wetter3.de/animation.html

http://www.knmi.nl/waarschuwingen_en_verwachtingen/extra/guidance_meerdaagse.html

Edited December 3, 2013 by Vorticity0123

[Coast]

Can these all be gathered together in one place, as it's being discussed in these threads as well?

 

http://forum.netweather.tv/topic/75377-atlantic-storms-2013/

 

http://forum.netweather.tv/topic/78642-arctic-blast-december-5th-onwards/

[BurntFishTrousers]

And I thought a BFT was me

[Vorticity0123]

Can these all be gathered together in one place, as it's being discussed in these threads as well?

 

Thanks for the merging!

Edited December 3, 2013 by Vorticity0123

[sn0wman]

As there will be a possible storm system developing next Thursday and Friday, here is a topic about the storm.

 

The system is forecast to cause a possible 11BFT along the eastern UK, the Netherlands and Denmark on Thursday and Friday. This could possibly cause quite some damage in these countries.

 

For illustration, the Hirlam (a short-term high-res model) output of pressure on thursday 12Z is shown below:

It shows that a rather intense low pressure area (975 mb) drops from the north with a rather tight pressure gradient.

 

For the wind speeds, the GFS 12Z on Thursday 12Z is given below:

 

It shows an 11BFT over the North Sea, with a 10BFT scraping the easter UK and the north part of The Netherlands.

Six hours later. there is still a 10 BFT along the northern part of The Netherlands and Denmark.

 

 

On Friday 6Z, there is still a potent 8BFT in the northern part of The Netherlands, and a 9BFT in Denmark.

 

Along with this wind, there will also be high tide accompanied by "springtide" (when the moon causes the tide to have a higher amplitude). As from the KNMI, this could cause alarm levels to be reached in the Netherlands (concerning flooding). This means that there is a rather severe risk on flooding occuring there.

 

On top of this all, there is also snow forecast for the hills in the UK and the Netherlands:

Below is the GFS 12Z forecast for snow on Friday morning:

 

The amounts of snow falling are not very severe (only 3 cm max, may change somewhat in the short term), so the chances on a blizzard occuring are quite slim, luckily.

 

Though the severity of the storm is not set in stone yet, the potential of the system makes it worth watching.

 

Sources:

http://www.weeronline.nl/vakman-index/130/0

http://www.wetter3.de/animation.html

http://www.knmi.nl/waarschuwingen_en_verwachtingen/extra/guidance_meerdaagse.html

Excellent post, Vorticity. I believe Coast means that these three threads should be merged together, as they are basically discussing the same thing.

[Roger J Smith]

They might merge the threads, this one has a better title although northern Germany and Poland look set to take the strongest winds Thursday night.

 

I had a look back through the daily weather maps on wetterzentrale, only one other Dec 6 (00z) map had a low below 970 mbs over the Baltic region and that was in 1895 with a centre of about 957 mb indicated near Stockholm. The evolution was similar although a bit further north as to track. A map from 1940 also looked similar but less intense than the current model depictions. In the 12z suite, the range seems to be 954 to 965 mb and the location fairly consistent (Bornhom to Danzig).

 

Thursday night, winds could gust in excess of 140 km/hr in exposed parts of northern Holland, northern Germany, southern Denmark, and northern Poland into Lithuania. Direction of the strongest winds likely to be WSW veering to WNW. Temperatures with these very strong winds only 2-4 C then falling below freezing with hail or snow. I would expect some fairly heavy snowfalls (10-30 cm) to the north of the low in Shetlands, northeast Scotland, northern Denmark, south-central Sweden, Finland, Estonia, Latvia and western Russia. Winds associated with these heavier snowfalls would be SE backing to NE 50-80 km/hr. Sea enhancement could give very heavy amounts locally in northern Denmark.

 

This low will take days to fill over central Russia to northern Ukraine and this process will probably seal the fate of the December forecast further west as very mild Atlantic air flows in to fill the void. The current GEM model has an unearthly 14 C 850 mb temp at day ten. There could be inversion issues in some parts of eastern England but if the air mixes that would support highs of 18-20 C near the surface. Other models are not quite this extreme, however, the GEM had a fairly good depiction of the current situation days earlier than the GFS or ECM did.

[Liam J]

I've just merged both threads that were basically discussions on the same event, title also changed  

 

Please carry on folks 

[Vorticity0123]

I've just merged both threads that were basically discussions on the same event, title also changed

 

Please carry on folks 

Thanks for the merging!

[Vorticity0123]

I'll try to give a more in-depth analysis of the wind field and possible flooding (along with the WRF-model).

 

On Thursday afternoon, gales are expected to occur in the North Sea and possibly a small piece of eastern UK and northwestern Holland:

 

As the wind is not that severe yet, and the wind is from the west-southwest, no severe flooding will be expected.

 

 

 

Six hours later, a brisk west-northwesterly is shown. The average winds get up to 90 km/h in the northwestern part of The Netherlands:

Still, the risk on flooding isn't very high at that point for the Benelux, as it is slightly in the shadow of the UK (regarding the wind direction). However, the threat for Denmark could be more serious, because water can be pushed up toward Denmark itself.

 

Meanwhile, at Friday 00Z, the winds veer more toward the northwest, while reaching speeds up to 80 km/h. The risk for flooding for Holland is much higher at that point, as the wind is now fully from sea.

 

 

The explanation is that the North Sea functions as a kind of "bathtub". The water is, when a severe NW'ly is blowing, being pushed into the Norht Sea. There, the water piles up to give an increase in height of the water.²

 

Accompanied with this, there is also spring tide (as indicated in my previous post), which increases the risk on flooding. This is because the moon is at it's  "new moon" stage.¹

 

One positive point is that the most severe winds aren't northwesterlies. Otherwise, the storm could have caused major problems.

 

Sources:

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

1: http://en.wikipedia.org/wiki/Tide#Tidal_constituents

1: http://www.kalender-365.nl/maan/maankalender.html

2: http://en.wikipedia.org/wiki/Storm_tides_of_the_North_Sea

Edited December 3, 2013 by Vorticity0123

[The PIT]

Doesn't this belong under the Atlantic storms thread? I think that was Crewe was suggesting earlier. Two threads still discussing the same system.

[Liam J]

This thread is for discussing the wind event and the following cold plunge from the Arctic as the depression exits into the North Sea. Chat, analysis, local reports etc as events unfold. 

Edited December 3, 2013 by Liam J

[Roger J Smith]

I would support keeping this merged thread separate from the main storm thread because it could turn into a major weather event for the continent and links to it by NW members from those countries could then be more effective in giving specific information than asking non-English speaking readers to sort through a much larger thread with other references in it. Just my two cents anyway. This could be the lowest SLP ever recorded in Poland, I don't know what the previous record was or is, maybe somebody can enlighten us. Danzig or some nearby spot could be below 960 mb around 06z Friday.

 

My forecast is that the worst impacts from wind could be in northern Germany around Bremerhaven and Hamburg. The track is a bit far south for most of Denmark to see damage, although the southwest corner could get into the very strong winds. These winds will quickly translate east into northern Poland and there could be scattered damage anywhere in Germany and Poland from this. Kahler Astlen which is 800m above the surrounding plain could see some very strong gusts.  

 

Storm surge potential is rather high given that it will be 72h after new moon and 36h after lunar perigee. Agree with vorticity on his analysis, largest tidal surge is probable for Elbe and other estuaries in northwest Germany, possibly also around Kaliningrad and Baltic states' various west-facing ports.

[Weather-history]

. The current GEM model has an unearthly 14 C 850 mb temp at day ten. There could be inversion issues in some parts of eastern England but if the air mixes that would support highs of 18-20 C near the surface.

Hmmm, not convinced at all by that. The GEM model shows high pressure virtually over most parts of the UK and little wind, to get those sort of temperatures they are more likely under Fohn effect conditions. That does not look a classic Fohn effect. Further to that, length of day is close to the shortest and sun is at its weakest.

[Matty M]

The winds aloft over Scotland parts of Northern Ireland and Northern Britain will be something fierce on Thursday morning.

 

925hPa winds can reach the surface in these set-ups . And this to be looks like a dangerous situation which has been under forecast.

 

Fortunately most trees have lost their leaf in the affected areas so tree fall won't be as major a problem as it may have been.