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Storm and Convective Discussion 10th June Onwards


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Apologies, UKPP = UK post processed, a suite we have here at the Met Office, which means our model output from the Unified Model has additional algorithms and corrections applied to the raw data to better fit reality. At the shortest lead times (the next 6 hours) Nowcast data will be blended, then UKV (which is the Met Office high resolution model for the UK, with a resolution of 1.5km), up to Euro4 for the longest lead time (the Met Office 4km gridded model covering the Europe domain). So what I was referring to earlier was post processed output from our highest resolution model, regarding the potential for isolated storms in the south east, and possibly more significant convective activity in Lincolnshire tomorrow evening.Post processed data at short lead times (close to a weather event) for site specific forecasting, are generally regarded as the most reasonable prediction of what will occur. Broadscale considerations are still taken into account though, as sometimes UKPP looks too much like reality as opposed to forecast!

 

Many thanks Mark.... :hi:

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Primary factors are, I would say;

 

1. Proximity of the lightning to the receiver 

2. Power of the lightning (voltage/amps) and whether the bolt is positively or negatively charged (notwithstanding proximity, positive are normally FAR more powerful and the thunder reflecting that)

3. Air temperature (not just a ground level but at different altitudes)

4. Humidity (not just a ground level but at different altitudes)

5. Windspeed and direction (not just a ground level but at different altitudes)

6. Background noise (i.e traffic, wind, rain, aeroplanes (unlikely), etc)

7. Topography - Thunder sounds very different on the coast (more like the gradual and smooth roar of a jet in my experience) compared to inland (more thumpy and intermittent) where it rebounds of hills, trees, buildings, etc

 

When you say 'length' do you mean duration or length from end to end?

Hi, thanks for input on this, I meant length as in time thunderclap is heard..

 

I remember a storm from when I was a kid, ever so weird thunder.. for the first half hour of the storm, I didn't see any lightning, there wasn't any visible, that's no reflection to the fact I was hiding under the bed!!!!

At first, I didn't think it actually was thunder... Basically it was a succession of single bangs! Literally a single muffled bang, no rolling/echoing/rumbling etc, and then 1 to 2 mins later another bang, gradually getting louder until my mum rescued me from under the bed and I did see lightning, very quick lightning, and virtually simultaneous bang, very loud bang! These close bangs lasted around 15 mins and they moved further away, and receded in loudness again, but still no rumbling...

Thinking about it now, we had large playing fields to the back of the house, I mean it took 10 mins to walk to any of their edges and beyond that in one direction were cornfields, and on another side were water sanitation lakes... Just wondered if it was the open spaces that caused the strange thunder sound now.....

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Many thanks Mark.... :hi:

 

re the comment this post included from Mark Canning, who it appears works in UK Met?

this link shows the GFS idea of instability with the skew-t diagram for 18z today over Lincoln, along with all the 'clever bits' taken from that skew-t=CAPE, CAP etc etc

http://www.netweather.tv/secure/cgi-bin/premium.pl?action=cskew;sess=27ba02bee611ad205d5f0499093ffc35

 

It does support the idea from Mark last evening

 

and of course as always take note of the forecast from Nick F

Edited by johnholmes
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Beeb regional forecasts do have the east more favored for any heavy showers this evening which does seem to tie in with other forecasts so even though I may see some showers hopefully they won't be as intense as further East

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Lincolnshire has an invisible physical link with the near continent. The residents of Lincolnshire have known of this link for years but they don't want the rest of the UK knowing about it. This link is the reason why they get so many storms.

 

yes ssh were hides before revealing.

 

Serious note this could cause us to have quite deluge if it comes off.

 

Noticed last night TORRO has said posted by smartie Interesting that it was possible rain wrapped from supercell.  Anybody who go out storm chasing did you find evidence  

 

http://www.ukweatherworld.co.uk/forum/index.php?/topic/103796-rfmi-tornado-damage-9-june-2014/

 

Having examined high resolution radar imagery, photos and model output we think (at TORRO) that the supercells on this day may well have produced at least one tornado.

However, radar imagery and model output suggests any strong ground circulation was likely wrapped in heavy precipitation.

Therefore could members in Nottinghamshire and North Lincolnshire, SW of the Humber, please look out for reports of unusual damage.

Likely track area extends from between Wolverhampton and Leicester towards Hull. 

 

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Extremely heavy and oppressive here today. 16°C coupled with 14°C dewpoint and 88% humidity all under a blanket of mid level cloud cover. Shame there's no energy for these conditions to tap into here today or else it would be erupting into storms.

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Very quiet out there a sheet of cloud not looking good I'm afraid unless there's going to be a bit of forcing.

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Yellow warning for heavy thundery showers out from the met office

 

Issued at: 1221 on Fri 13 Jun 2014

Valid from: 1500 on Fri 13 Jun 2014

Valid to: 2345 on Fri 13 Jun 2014

 

Scattered heavy, thundery showers are likely to develop across parts of northern England this afternoon then extend down into the northeast Midlands this evening. The public should be aware of the risk of localised surface water flooding.

 

Chief Forecaster's assessment

 

The airmass across northern and eastern England will become increasingly unstable through today as a complex set of fronts moves down from the northwest and temporarily weakens the area of high pressure. As a result, scattered thundery showers are likely to develop over northern England and drift southwards. As is usual in such situations, rainfall amounts will vary considerably across the area. Some spots could possibly have over 20 mm of rain falling in less than an hour and very locally 30-40 mm in 3 hours, whilst many other places will miss the worst.

 

http://www.metoffice.gov.uk/public/weather/warnings/#?tab=warnings&map=Warnings&zoom=5&lon=-3.50&lat=55.50&fcTime=1402614000&regionName=uk

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Think you're too far SW Will, the Western extent seems to be around Bristol and down towards Hampshire.

 

It would be utterly hilarious if something thundery turns up (at what has been short notice) over Wiltshire tonight a week after the much féted plume event which managed to avoid Wiltshire from all angles!!

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Bring on anything now I've done my exams. I don't mind when and where. Any chance for me this week?

No im afraid.

 

I cannot see storms developing any further W than say the central Midlands.

 

Im getting rather excited at the potential for my area this evening.

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Think you're too far SW Will, the Western extent seems to be around Bristol and down towards Hampshire. It would be utterly hilarious if something thundery turns up (at what has been short notice) over Wiltshire tonight a week after the much féted plume event which managed to avoid Wiltshire from all angles!!

Happens a lot here Andy. There could be a small chance tomorrow afternoon, certainly pockets of decent ml/sb cape about, with a weakening front straddling, there could be some hefty showers popping up.
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Some showers breaking out over NE'rn parts now, likely becoming more widespread and intensifying into late afternoon & evening. 

 

Posted Imageradar1.png

 

Aye winds picked up further south and I can see some very large cumulus developing around here. Definitely some instability starting to appear. 

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Aye winds picked up further south and I can see some very large cumulus developing around here. Definitely some instability starting to appear. 

Yeah, from no onwards is the time to start watching the radar for developments.

 

Some pretty heavy showers over Scotland atm as well. 

 

post-9615-0-98202100-1402669404_thumb.pn

Edited by Liam J
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Convection is really kicking off here now with towering cumulus. I would expect showers to break out more widely over the next couple of hrs.

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Can't argue with GFS prediction in its positioning of wind convergence with showers developing there.

post-5386-0-37432400-1402669730_thumb.pn

5 min netweather rainfall radar.

Edited by NL
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