Luke Best
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Posts posted by Luke Best
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Can someone help me here? How come the meto radar shows no precip over our area? Yet numerous people are reporting snow?
Hi Katie
Met Office radar is an hour behind. You can use the free netweather radar (http://www.netweather.tv/index.cgi?action=radar;sess=) for a more up-do-date picture of what is happening.
Cheers,
Luke
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Morning all!!
Well, I have to say I was a little concerned before I went to sleep last night as the snow was falling, but no settlement. I even had a dream that I woke up and looked out of the window to nothing....
However, my concerns were unfounded....
Its that beautiful slight where you can't tell which is the road and which is the pavement, the steps accross the road have merged into one and I can't see out of the back windows because the wind has covered them in snow!!
About 6 cms now, perhaps a bit more and still falling.... things are good!!
Haha - I looked out of the window at 5am to do some lamp post watching - only to find that the council have turned the lights off to save money... When the lights finally came on I saw the heavy snow settling and dozed off.
Next thing, I'm dreaming that it had all turned to rain and melted, and that I went out on my toddler's trike in search of snow and triked all the way from Christchurch to Poole. So relieved when I woke up!!!
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Where abouts Luke? You sound very very close to me!
Crofton Close - hoping the roads will be good enough to get me and the sledge (and the children......) to Queen's Park golf course in the morning!
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I live just back from the Fairmile pub! I think this one's nailed on Divadee - can't wait for tomorrow morning!
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Yes. It's an anomalous rise in WBFL: UKMO-GM had same issue yesterday for same time and area and was manually amended.
WBFL = Wet Bulb Freezing Level
Extract taken from http://weatherfaqs.org.uk/node/64:
Wet Bulb Freezing Level
Because evaporative cooling is so important in rain versus snow forecasting (see the main FAQ entries, here and here), the wet-bulb 0degC level is a better guide to snow-risk level than the actual ZDL. The wet-bulb is the lowest temperature to which air can be cooled by evaporating water into a sample, which is a mechanism often important in determining whether it will rain or snow at or near the surface. However, note carefully that advection, both cold and warm must be taken into account - the former is particularly important in marginal situations in the vicinity of a well-marked cold front.
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Hmmmm..... What's that 960mb dartboard low all about at T162??? One for the shredder methinks.
Oops - forgot to quote the original post:
Posted Today, 04:46
Xyplode, on 12 January 2013 - 04:40 , said:Post some charts please! im eager to see
http://www.wetterzen...s/Rtavn1087.png --> T108
http://www.wetterzen...s/Rtavn1327.png --> T132
http://www.wetterzen...s/Rtavn1627.png --> T162
Edited by Chris D, Today, 04:46.
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Slightly off-topic (sorry mods) but I read the following piece (written in 2003) on the TWO website and I think it serves as a timely reminder that we can trawl through model output all day long 'hunting for cold' but every now and again cold will simply arrive 'out of nowhere' (and this is true even now with powerful supercomputers churning through all of the available data).
Record Cold Spell of 1987: How It All Started
It is well accepted that the most severe spell of weather in southern England since the 'Little Ice Age' occurred in the unlikely year of 1987 in an otherwise 'average' winter.
So what brought about such a severe spell and why did it end as quickly as it started.
The story begins in the first few days of January 1987, looking at the surface chart a cold spell seemed miles away as a strong High of 1032mb sat over Spain with the U.K. and Western Europe in a strong Westerly flow, temperatures through most of Europe were above normal, however in Scandinavia and Northwest Russia it was intensely cold.
The first change occurred quickly on the 2nd as the Iberian High shifted Westwards and low pressure transferred into the North Sea, a brief Northerly swept south across the U.K. but it was hardly cold.
By Sunday 4th High pressure was back over France with the U.K. in another mild flow, however by now the models thought something was up and on the Countryfile forecast on the 4th the forecast was for a short but very cold Northeasterly outbreak mid week as low pressure crossed Holland. The models however predicted that the Arctic outbreak would be short and that milder westerly winds would take over again by the weekend.
The short cold spell was in fact a non-event as rising pressure over Ireland killed off the Arctic Airflow and by the 7th High pressure was centered over the Irish Sea and the weather cool and quiet.
By the 7th the models still couldn’t decide which way things were going to go and the Met. Office remained silent about prospects for the weekend.
Things then moved very quickly, a deepening low moved south across Norway on the 8th and into Germanyby the 9th and behind this low there was a massive rise in pressure over Scandinavia. At the same time a large pool of intensely cold air had swept out of Western Russia and was crossing Poland and East Germany, at last the models could see what was going to happen and early on the 9th the message went out: 'Very Cold later in the weekend'.
Meanwhile pressure continued to rise over Scandy reaching 1040mb over Finland by the 10th. Sub freezing air reached Eastern England on the afternoon of the 10th and this very cold air reached all areas by dawn on the 11th.
The Countryfile Forecast on the 11th was a 'classic' John Kettley saying "The only bright thing on this forecast is my tie!" He rightly predicted freezing temperatures and blizzards all week although even now the depth of the cold was being under estimated.
During the day temperatures kept on falling as snow showers became more intense, Monday 12th was probably one of the most remarkable days of the 20th Century as temperatures stayed below -5c throughout England and below -8c in several places in the home Counties.
The Weather Log for Jan. 1987 describes the 12th-14th as the coldest spell of weather in southern Englandsince January 1740.
Over the next few days the U.K. was swept by blizzards and freezing temperatures as an upper cold pool crossed England.
The models showed no sign of a break in the weather and on the Countryfile Forecast on January 18th the forecast was for a very cold but drier week, however within 24 hours this forecast went wrong.
During the 19th a warm front crossed the U.K. cutting off the continental feed and high pressure then formed in the warm sector.
By the 20th temperatures of 4c-6c were recorded over most parts and a steady thaw began. The next 10 days were dull and sunless the severe spell becoming a distant memory.
The interesting thing about the cold spell is the poor performance of the forecast models even up to +72 hours, O.K. computers are better now but I still think they would struggle with a similar chain of events.
In a 'New Scientist' Article of July 1987, a group of climatologist speculated that the Jan 1987 cold spell was partly due to GW and we could expect more frequent severe spells in the future!
That seems an awfully long time ago.
© Andy Woodcock, Jan 2003
So let's not get too down at the sight of a few blowtorch charts in FI, you never know what might be just round the corner. And finally, some eye candy from the height of the January 1987 episode:
From this:
To this:
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No, there isn't a caste iron reason why January is going to be dire....its all guesswork, no chart goes past New Year atm. The models are saying milder for the next week with Atlantic dominated weather but after that they don't all point the same way. If the charts can flip so massively like they did last week they can do it again. I'm not saying they will, just that they can....and with most of winter still to come nothing is certain.
I remember a couple of years ago there was cross-model agreement for zonal when quite suddenly a bitterly cold North-Easterly set in and blew for at least a week bringing copious snow showers with it. I've tried to dig out the charts but cannot find the event - if anyone can post these it would make really interesting viewing, especially with the current scenario in mind.
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Was that fast moving line of storms that affected Hampshire, Sussex and the London area the AltCas shower zone that Ian Fergusson was posting about
yesterday tp affect the West Country this morning? Only that it was around 100-150 miles further East that forecast/modelled yesterday.
I was out in the open all day and didn't see a radar image after 08.00 until this evening, however around the middle part of the day was very surprised to see a large bank of fast moving AltCas to the SE then E of Wiltshire - it was clearly the edge of that storm area.
I was in the New Forest and can confirm explosive mid-level growth of AltCas out of a bank of 'moisture'. (looked like the birth of a star in nebula)
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Hi Luke, when the temps are marginal, that is, a bit above freezing, any shift of the wind to onshore can be enough to lift the temp so that you get rain rather than snow, whereas the reverse is true, which is what seems to be happening now with an E to NE drift. But with such a slack pressure field as we have, you can get local winds changes due to local geography say, or small scale features such as the LP that might be nearby, as I mentioned earlier. The observing network is not dense enough to pick up these small features very well, plus we don't have the benefit of visible satellite which can pick up cloud patterns/motions, and therefore windflow, that the IR can't.
However, the cold air is spreading back, undercutting the frontal zones which on its own would favour snow rather than rain.
Many thanks for the detailed response OMM. Snowing hard now, albeit very small flakes.
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Probably because the cloud is a bit thicker. I noticed this afternoon that the temp DROPPED half a degree when the sun came out - weird. Now, as I said, I think we will see some wind shifts which may affect what happens on the coast. Shame it's dark because it would be possible to tell a lot more from the low cloud motion.
Hi OMM - what affects do you expect the wind shifts to have?
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All but stopped snowing here has settled on cars and grass but not pavements. Hoping for more about midnight. Can't see the radars as on phone. Can anyone see if we will get more at midnight?
I think (certainly hope) that we should do divadee - fingers crossed!
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Morning all. Temp here 1 and dp 1
It must of warmed up significantly last night as we don't even have any ice which I was very surprised at.
Hope the people who got snow get out and enjoy it today! Be safe and have fun xxx
Yes, the temperature rose to 6.6C in the early hours before falling back. Still above freezing though.
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Light rain just started in Bournemouth.
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morning all.
My first post on here and hope to follow with my first U.K. chase later.
In bournemouth and its hot and becoming very hazy from the Sw with a light Se wind. small cumulus visible to my S and Nw.
I have to work 11am - 2pm then 6pm onwards so hope to get out for a few hours this afternoon if anything goes within 1hr drive but thinking about getting my shift covered so I could go a bit further afield.
Thinking about heading Winchester way at about 2pm hoping for the best, what you guys think.
I'd stay put. I think the stuff further East is worth chasing this evening, but you say you have to work. IMO best stay on the coast in Bournemouth to see if we get anything early doors off of the Channel. Best of luck!
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just got back home from wasting my time waiting for a storm to arrive
i did see 2 flashes from the corner of my eye but didn't hear any thunder so i dismissed it as someone taking a photo.
still not giving up yet, but it won't be long.
I feel for you. I was on the clifftop at Highcliffe and saw nothing, although the atmosphere felt electric. Drove home and saw lightning twice as I was unloadingthe car. How lucky is that!
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are you to the east or west of weymouth?
About 30 miles east.
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NP
Don't give up yet still time for something to happen, I'm down at Christchurch quay looking over to the iow, fingers crossed
Hi - I'm in X'Church and we had 2 flashes about 15 minutes ago approx. 4 miles to the NW.
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BANK!
Looking around my area. The ensembles have been odd for a few days now.
Why that control is like that? any ideas.
Please could someone explain what the Control Run is - it's clearly a run in its own right and not a mean of the ensembles.
Cheers
Luke
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The GFS is the operational run. The GEFS are the ensembles which has a control run followed by 20 members. Just to confuse you further we also now have the GEFS parallel runs which also consist of a control run followed by 20 members.
Basically back in the 1990s they decided they also need to use ensembles to check the reliablity of the operational runs. What they basically do is slightly change the starting point (except control run). The main purpose is to rtry and take into account the kaos theory that applies in the climate but also these computer models.
The Kaos theory is why model output will always be uncertain beyond +144. Personally my view is they will never be able to take this into account despite increasing computer power.
P.S isn't a silly question. Never be afraid to ask as im always willing to help.
Hi TEITS
Another basic question... I understand the Operational and 20 members, but can you explain what the Control run is and how it's worked out for me? Also, has the parallel run now taken over from the old GFS model?
Cheers
Luke
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Hi Luke Id say its not so much a dry line as an upper level warm front. meaning that the upper section of the warm front is well..warm but surface temps are unaffected to a greater
extent. So if the ground level is 0oC or better -1oC or lower snow or possible freezing rain will fall, if the surface levels are at 1oC or more then mixing of the air occurs and
temps rise a little through the heights to you would see rain or wet snow. You will only be able to tell on the day. If you are at -1oC ( quite possible considering current temps) you are like to see snow especially if the wind direction there is ENE, ESE would be off the solent, and that could spell disaster with the temps a degree up. An easterly would be..well nail biting. Good luck
Hi PubliusEnigma - thanks so much for your response.
Luke
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Hi
I understand that the 'front' denoted in the attached map may actually be a dry line rather than a front. Given that the temperature of the air masses on either side of a dry line is usually fairly similar (and it is the undercutting of the moister air which causes convection), can anybody let me know what effect the dry line might have on my area (Bournemouth) in this set-up. I'd be interested in understanding more about this as the comments I've heard thus far have suggested a warm front that will bring slightly milder air bringing precipitation of a more transient nature to the extreme South Coast. Thanks in advance for your thoughts on this.
Luke.
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Big storm just passed through Bournemouth over the last hour. Preceded by torrential rain - lots of forked cc strikes and constant thunder.
Some very bright lightning from multiple cells. Now moving away East along South coast. Enjoy!!
South West/Central Southern England Regional Discussion 18/01/13 16z ------>
in Regional
Posted
Ah - apologies - I still have the old Met Office radar bookmarked. I see the new one is indeed updated every 15 minutes and is not an hour behind. That being the case, I have no idea!!