MattTarrant
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Posts posted by MattTarrant
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1 minute ago, Windblade said:
What this is showing is that the storms are not dying over the channel so sea temps are warm enough to sustain them on their journey over. This bodes well for the southeast later.
Elevated storms so not routed in the boundary layer hence sea level temperatures can be ignored.
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10 minutes ago, The PIT said:
Times like the this you watch the radar. Storms are very difficult to predict and you should have learnt by now they have a habit of forming not in the right place. Also if you read the forecast it said it may have to be adjusted south. BTW no need to shout.
I will refrain from shouting, though as has been mentioned initiation has been consistently modeled in the late afternoon/early evening in North Wales/North West England due to slow development of convergence zones and as forcing mechanisms increase. An upper level warm nose has capped convection, though this will likely be eroded as heights lower from the west and convergence causes strong uplift.
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1 minute ago, The PIT said:
Looks a bust for here and looking at the radar it looks like the south and east of here have the best chances.
READ THE UK CONVECTIVE FORECAST
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9 minutes ago, Harry said:
Oh yes @MP-R that’s what we’re talking about! More of that would be amazing.
On the Kent ‘plains’ here it’s a very promising start - cloudless skies aiding hopefully many hours of good insolation! The little bit of breeze we have here feels quite warm too.
Elevated Storms are not routed to the boundary (surface) layer so insolation is not really a contributing factor.
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3 minutes ago, Ben Sainsbury said:
Well here are the Euro4 for 9pm and midnight. Much of North Wales and West Midlands actually miss out, very different compared to NMM Model. According to Euro4, CS/SE England into East Midlands look a treat.
Convective initiation, as has been mentioned is relying strongly on the 850hpa - 900hpa warm sector being eroded. Euro4 is suggesting sufficient cloud levels to prohibit insolation, hence sporadic development.
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1 hour ago, Daniel* said:
Up scaled but often not enough, it’s such a common occurrence and it can be seen all corners of the country. H-res not even right with the ‘now’. As to record it will be a step too far seeing how 1949 panned out, but UHI is more ‘intense’ than then with more urban sprawl. I think we’ll see 28C reached fairly sure, up there with 1949. And I think we’ll outdo 2011 on face value it doesn’t look as good as now.
You raise a notable point of interest regarding deficiencies within the +1/2 hr time range. This for me constitutes a significant barrier to verification capabilities, observational frameworks do require greater investment to prevent deviation at such short range. These deficiencies represent themselves frequently in warm/hot synoptic episodes, even seen in the most recent cold spell. This rhetoric was indicated somewhat at the Met Office (Visit Day).
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4 minutes ago, Man With Beard said:
And here's the actual. Big differences!
As mentioned in a previous post, AROME seems to have had a slightly better handle on localised urban heat. Here's what is has for 4pm tomorrow (sorry doesn't seem to cover Scotland): heat generally east of high ground, 24-26C for many and 26-28 in London (A really close look at this chart has a tiny area at 28C or above around Heathrow - incredible definition!!)
ARGEPE similar this time
compared with other models which are 1C/2C lower
Finally, I guess the April record is probably safe but not 100% unreachable: 29.3C.
It would seem unrealistic to reach such a record, though more pertinent here is the high res models tendency to upscale heat rapidly within the 24 hour range. London is frequently up-scaled as the dynamics of urban heat containment are controlled with greater accuracy! The models ability to locate sea mist formation is an area of interest also, with some coastal regions suffering short notice downturn in weather prospects (for most people).
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24 minutes ago, mb018538 said:
Where exactly are you getting 23c as a max from?? BBC are forecasting 26c on Thursday at 3 days away, you think they are going to be that wrong??
I bet that comment would be reversed if it was snow being anticipated, just a caution to stop such bold language use.
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16 hours ago, Interitus said:
Interesting answer, however wavelength and amplitude are separate distinct wave characteristics
I never intended to directly define wavelength, my answer was portended to help Mike
with his questions.
Wavelength in it self is does not require much talk, I intended to discuss around the topic to help promote Mike's wider thinking.
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On 4/3/2018 at 20:16, Mike Poole said:
I've wanted to post in this thread for a while, but have been sidetracked by the actual weather following the SSW, but with the current rain, drizzle and generally rubbish weather, I'm taking a break from the MOD! I think this thread is excellent and look forward to following it avidly.
I've tried to read up on teleconnections, particularly the GWO and AAM, but feel there are still some major gaps in my understanding that maybe you folks could help with. So two questions for today:
1. The phrase 'seasonal wavelength changes' is one I've seen regularly in posts relating to teleconnections. I'm unsure what this means, although I assume it relates to the meandering of the jet stream in some way. So could anyone please provide an explanation of: the wavelength of what is changing, how does it change, why does it change, and how might that impact the UK at various times of year?
2. A lot of discussion I've read has been related to winter. I'd like to know what teleconnections can tell us about summer, I know the strat is out of play, but what can give an indication of summer weather patterns a few weeks in advance?
Thanks in advance and very best regards.
MikeGood Evening Mike
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Seasonal Wavelength Change : With regard to the notion of teleconnections, this relates (as you mentioned) to jet stream undulation/amplitude. Winter is characterized through a high poleward temperature gradient, resulting in increased upper atmospheric zonal winds (Jet Stream). High velocity upper atmospheric winds rarely reflect themselves in a meridional (high amplitude) setup, partial reasoning at least why winter weather is dominated by interchangeable surface setups (Unsettled). In summer months, with the considerable weakening of the polar vortex the temperature gradient is far less pronounced, resulting in lower upper atmospheric zonal winds (Jet Stream). This can and usually translates to a more amplified pattern being seen in the upper winds. In short, summer is characterized by short wavelength (increased amplitude) jet stream (Slower Aswell) setups and this is reversed in winter months.
A possible approach to this (for beginners), is to consider why blocked surface patterns gain so much interest in the winter period. It will have weak correlation with fanatical hopes of snowmageddon, but on a serious note it provides respite from the broad continuum of strongly zonal conditions. Wavelength changes can change more abruptly on reduced timescales, these being induced by changes in the global wind oscillation (GWO), MJO phases etc.
An interesting line of thought, especially since the turn of the millennium regards an ever increasingly undulated jet stream in both winter & summer potentially related to arctic temperature sensitivity. Here are a few links to research papers for you :
https://ams.confex.com/ams/94Annual/webprogram/.../Extended Abstract.pdf
http://iopscience.iop.org/article/10.1088/1748-9326/10/1/014005/pdf
Feel free to message me with any specific queries
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4 minutes ago, Bring Back1962-63 said:
I just wanted to say that I have recently taken on some additional business commitments which will take up the small amount of free time that I have available for an extended period. I will now only be able to post very occasionally and perhaps not at all during the next few months. Needless to say, I will not have any time to develop this learning thread as I had wished to. I apologise to anyone who was expecting to see greater activity on here. I hope that others will continue to contribute to and support this thread with questions and answers. Perhaps someone might like to respond to @Mike Poole and his queries in the post just above this message. This is exactly what this thread is intended for.
David.
Good luck with these extra commitments
I will attempt to do the occasional post, though as with you my time will be constrained when back studying next week. I will hopefully formulate a response to Mike in the upcoming days
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On a separate note, I will be transferring across a detailed update to the 'Hurricane Tutorial' written back in 2005 in preparation for the upcoming North Atlantic Hurricane Season. It should be fully updated and available on here within two weeks, anyone interested should occasionally check in the Hurricane Tutorial thread and possibly any new thread for the upcoming season where it will likely be added to.
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1 minute ago, Leon1 said:
http://www.dsgc.co.uk/what-is-happening-now/webcam
Wowzer! Didn't expect there to be a covering after this much rain. A dusting now appearing there!
The intensity of this system is impressive. Even very wet and warm surfaces can see snow settle on them given very heavy wet flakes.
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1 minute ago, Leon1 said:
Met Office says it will get down to 4c at 17:00 but next chance for snow now will be sunday night
Yes Sunday night has some potential, probably a 1 - 3 hour window where some wet snow is possible under evaporate cooling. Obviously Exmoor/Mendips/Chilterns will likely see a transient wet covering before transition to rain.
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Just now, Leon1 said:
Does anybody think the temperatures will dip here too? Just rain here - 6.5c from 7c in the last 30 mins and at 52 meters asl
No unlikely, not sufficient for wintry precipitation anyhow. Its 3.1 here will little bit of sleet, but other than that a very wet afternoon.
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7 minutes ago, Evening thunder said:
A rather miserable day, light rain has gradually got more moderate. In fact now there's occasional but definite traces of sleet on the window, temp 4.1C but going down.
These webcams http://www.dsgc.co.uk/what-is-happening-now/webcam suggest it's turning to sleet/wet snow on the Blackdowns with a temp of 1.4C at 280m
Met Office forecast update also shows snow up there and even sleet at 1C down here at 4pm now.Indeed would now expect some wet snow to come down to low levels at times in the next few hours. Temperature here in Wellington now falling and currently around 3.3.
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1 hour ago, Nick L said:
I think those charts are not snow depths, but falling wintry precip. The chances of accumulating snow on low ground through the Midlands on Monday is very small, the timing would be wrong for it. Accumulating snow in the day time in April is extremely difficult.
Given sufficient intensity I would assume snow will settle, just devoid of any significant impacts to major travel routes. Considerably transient though with sub surface temperatures too high.
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Unlikely now to be anything in Swansea (at least giving decent depth), with limited covering overnight now almost fully melted. Bravo to ARPEGE & EURO4 for its correct predictions. Thhe band is weakening already so HIRLAM looks somewhat wrong.
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3 minutes ago, JamesL said:
Jeeeeeez still goin on about Derek? Really?
What used to be a decent forum has become a total farce.
Get a grip people, you must all lead incredibly boring lives to still be talking about Derek after 2.5 weeks.
He would be flattered to know that you're still talking about him.
Im done here.
Over and out
James you are one of a few who analyse charts instead of hopecasting so please join me in trying to increase that number.
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4 minutes ago, MidnightSnow said:
Don't want to be an attention grabber, but the HIRLAM is awesome.
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16 minutes ago, Seasonal weather required said:
Matt , This is how world wars start ....
To clarify ,Mr winter 17/18 has been all talk and no action so far .
Bottled it , all huff and bluster but no substance .
Very last chance this weekend or it’s thrown into the bin , black bag waste ,to go to landfill with the last 4 winters .
I think for Swansea, It's been an average to decent winter. I think we now be in double figures of days where snow has fallen at some point (rare). It may not have delivered in depth but there is essentially only 1/2 ways Swansea would receive notable depth. These would be from a front from the west engaging with in situ cold, unlike these two cold outbreaks which have & will be to 'clean' for us (Unlikely to see much tonight/tomorrow 1/2 cm).
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2 hours ago, Seasonal weather required said:
If I can build that snowman tomorrow for my daughter then I will tick off winter 17/18 as a pass or grade C.
At the moment this winter is somewhere between F and E .
Last time I went to bed early on that Thursday night after a few hours of lamposting ,watching the swirling powder crap fall expecting to see a good 5cm + blanket in the morning.
Woke up , dashed to the curtain and then it started , the biggest ever let down , WTF ? , it just went from bad to worse as I thought ok don’t panic we still have All Friday to go , but nothing , nada .
This time expectations are as low as they can be .
Winter 17/18 you have been warned, you have one last chance to scrape through with a low pass grade or you will be rejected .
So far you have been all talk and no action , this weekend is judgement time .
You saying I have been all talk & no action?
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2 minutes ago, andymusic said:
What, with an amber warning already over south eastern Wales likely to turn RED
'There is the potential for 5-10 cm of snow to fall quite widely'
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2 minutes ago, andymusic said:
nope 20cms plus all round me-thinks
Charts? With the exception of forced ascent along the Eastern Brecons (20/25cm), 5 - 10 cm would be the sensible prediction.
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7 minutes ago, Seasonal weather required said:
After the last ssw in 2013 the summer was very good - hopefully it will be the same this year .
I wonder if anyone has checked Ssw and the following summer years to see if there is a pattern ?
Maunder minimum, ice melt cutting off the usual under water current flows , Andy’s snow shaker , in 20 years time we will be one of the leading nations at the Winter Olympics .
Costa , Greggs , Joes ice cream etc all on the top of Pen Y Fan , Ibis ,premier inn etc in place of that dodgy burger van at the bottom of the ski lifts .
How good is Joe's Ice Cream place?
Model output discussion 14/04/18
in Forecast Model Discussion
Posted
One would conclude that it will be a slow transition to notably sunnier conditions, this change being pronounced when/if a continental feed forms. One certain though is a warming trend with temperatures trending around or just above average and feeling very pleasant indeed.