Lewis
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Posts posted by Lewis
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First UK storm forecast since back from 2 weeks of storm chasing in the US mid-west. Not expecting anything like we saw in the Plains tomorrow, but the parameters for severe weather look eye-catching nonetheless - with a strong jet. vertical shear and instability overalpping across S, central and E England.
Storm & Convective Forecast - Issued 14/06/2012 22:00
Click for full size
Valid: 15/05/2012 06:00 - 16/05/2012 06:00
Headline: ... THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FORECAST...
Synopsis
Deep upper trough and accompanying intense upper-level jet moving in from the Atlantic has spawned an unseasonably deep low (circa 985mb) to the SW of the BI this evening. This low will drift NE to be invof SW Rep. of Ireland at 12z Friday - with wrap around occlusion across Eire, occluded frontal zone across southern Scotland an unstable rPm SSW flow across England & Wales.
... E WALES, N ENGLAND, MIDLANDS, E and CENTRAL S ENGLAND...
A moist SSW flow will be present at the surface on Friday while colder air at mid-levels spreads in from cold upper trough to the W (500mb temps falling to AOB -20C) - which will allow low-mid level lapse rates to steepen ... with GFS indicating 300-700 j/kg CAPE to develop broadly across England and into E Wales by the afternoon. Scattered heavy showers and thunderstorms will therefore likely develop across England and E Wales in response to steepening lapse rates, solar heating and forcing likely from a shortwave trough or two moving through in the strong upper southwesterly flow. 500mb winds approach 70-80 knts towards SE England coupled with fairly strong vertical shear in the lowest 6km (30-60knts) - will favour storms to develop into bowing line segments or even one or two supcercells - given sufficient instability indicated by models. Such storms maybe capable of damaging wind gusts, moderate size hail, torrential rain, CG lightning ... and possibly one or two tornadoes - especially across S/central/E England - where vertical shear, low LCLs, dry mid-level incursion and backing surface winds will be most favorable for rotating updrafts into any storms. There is some question marks though on extent of this severe threat across England given possible frontal development towards SE England in the afternoon which could hamper convective development here - with a more narrow corridor of severe convective potential possible from SW/Central-S England towards Midlands/E England as a result. Storms will be driven by diurnal heating, so should fade after dark.
Issued by: Nick F - Forecaster for Netweather
Thanks Nick for such an informative read.
Hope you had a good time in the states, would be nice to see the UK get some severe thunderstorms tomorrow, I have a funny feeling that Lincolnshire is the place to be tomorrow, so I think i'm going to position myself further South tomorrow, whilst avoiding the A15!
Lewis
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Anyone in the East Yorkshire area that wants to chase tomorrow hit me up: info@designhull.com or add me to facebook
http://www.facebook.com/eastyorksforecaster
I'm back on the road! so more chasing to come =D
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I wonder where UKMO will go from Monday high pressure get's very close to the south west but will it move further up during the week?
I don't think HP will come in to play within the next 10-14 days looking at the models, it'll come close but no cigar.
Possibly at the end of the month is when we could see HP establishing.
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Loosing intensity already
Give it chance lol, there's a trough pushing through during the early hours which will enhance the precipitation.
lewis
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If Harry and the pit re referring to the 2007 floods, it was 25-50mm of rain predicted over a large area 48 hours in advance, then a flash warning came in force at about 5:30-6am that morning warning of rainfall up to 100mm.
I'm 100% certain because me and my lass had a break up that night so i hit the southern comfort and I woke up and saw the heavy rain during early hours and knew it was serious rain, checked the forecast and teletext.
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Well it's raining heavily now.. my Sky signal has gone despite rain not been that heavy
Sorry mate. I'll bring your dish back when I'm finished with it.
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12z NMM has the heaviest precipitation across London for a time showing intensity increasing as it pivots on it's NW flank, as it does this and start to fizzle out southwards, the heaviest of the precipitation will be SW of London around Surrey to Brighton.
Highest rainfall totals for an area in the South?
I'm going for Farnham to get 78.4mm
Lewis
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Hi guys,
Was incredible yesterday didn't get chance to come online as I was busy buying a new car, so i'm back on the road now for storm chasing, just need some storms!
When I went to pick my car up, I had seen the storm Muff and Reef was talking about, they was on all mighty rumble followed by a few IC lightning. Was not in the perfect line of sight to see any +CG but the storm had quite a base too it, some impressive rainfall totals too.
Was looking back at the posts from yesterday and Supacell got it spot on.
They seems to be mininmal amounts of CAPE out there today around the 100-150 mark, with a LI of +1 possibly 0 in places.
Showers will continue through the early evening, small chance of some showers becoming heavy across Pennine areas and more organised. But showers in the North East and close to Eastern coastal areas gradually dying out.
Something to keep an eye on this evening for Kent, running through to London & the Home counties and parts of EA running in to East Midlands, a trough on the fax charts is expected to push through tonight and during the early hours of tomorrow, the NMM is showing the precipitation to be very potent indeed with some impressive returns.
I think they may be some elevated thunderstorms tonight across these regions/ thundery in nature for Southern parts of EA, Kent, SE England/London, running through to the East Midlands.
Just looking at the latest radar and there's a potent little cell just West of Beverley, flicked back some time frames and it's hardly moved at all, no doubt some impressive rainfall totals there.
Lewis
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Yeah, insolation, when the sun heats the land causing convection. I might not have spelled it right though. Anyway, it's raining again now so it doesn't matter.
I think you mean evaporation, the sun heats the land and water that's on the ground evaporates and then condenses forming water droplets/clouds, with rapid surface heating and other factors this aids rapid convection.
Evaporative cooling.
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Another photo of the lightning from the storms over the Midlands the other day!
Midlands? Looks more like Spain.
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It has been raining continuously now for about 21 hours although I have not checked how much has fallen. At times the rain has been very heavy and thundery. Getting home at 18:15 last night it was really black over Beverley and I was certain we were going to have thunder - it was very warm at the time. Still pretty warm at 14.1 degrees C so there is some energy in there, if the sun ever comes out.
Hints of June 25th 2007 at the monent although the rain is not as heavy but there are similarities......
Hi Muff,
Certainly been a very wet and soggy 24 hours or so.
I was posting in the model output the other day and was comparing this month to that of 2007, I just hope to god we don't get it the same, I have a feeling we are going too see some very heavy spells of rain/wet weather over the coming couple of weeks.
Just looked at the radar now and there's a potent piece of precipitation heading your way or just about over you now, any thunder inside of that?
Regards
lewis
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Afternoon storm lovers,
Not much in the way of a risk today for many areas, although a small window of opportunity for North Western areas, running through to central parts of Northern England, and possibly Eastern Counties of Yorkshire, and Northern Lincolnshire this afternoon.
We have low pressure in charge centered across Northern England.
Winds strengthening on it's southern edge gusting to 40-50mph for a time.
Below is the chart which shows some heavier pulses of rain/showers for Northern areas, and it also shows the cloud cover.
Temperatures expected to be around the 10-11c mark in the North West, slightly warmer as you head South Eastwards in to Yorkshire with expected temperatures to be around the 14-15c mark.
Surface temperatures around 10-13c for most, with some higher values creeping in to the pennine areas and Yorkshire
Dew point temperatures again 10-11c quite widely, higher values across Yorkshire
Now the all important "CAPE and LI Values chart"
The above chart shows some values across Yorkshire, and the far North West of England running in to Scotland.
Conclusion
With a lot of cloud cover, and lack of surface heating, thunderstorm development will be very low, although sharp showers may form for the above mentioned areas. If there's breaks in the cloud later this afternoon some sharp showers may form and become heavy and on the thundery side.
There is minimum energy out there, although being under lower pressure may enhance development for a time for the mentioned areas where conditions become favorable.
Over-all the risk of any severe thunderstorms is basically non existent, but there is a small risk of localised thundery showers.
Quick map below of the areas that may see something develop during the latter part of this afternoon;
Lewis
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After reading through what felt like an eternity of spot the high pressure I decided to take a look at the models long term, as most of you already know I don't like long term forecasting unless your GP it's very hard to make predictions and be good at them!
So after looking at the models, the "GFS and the ECMWF" the GFS shows a constant pattern of low pressure over the U.K or close by no doubt having an affect on our weather, by no means is high pressure in charge or looking like it's going to come in charge any time soon.
There's light at the end of the tunnel no doubt but you have to go to the last few frames of the GFS to see pressure building from the near continent.
GFS
ECMWF
I feel as though we are just in one of them patterns that we need to ride out, after a lovely mid-may I kind of expected June to be a write off, a very unseasonable feel to the weather for another 2-3 weeks I feel, once we get out of this pattern here's hoping to some lovely temperatures, a beer garden and a pint of bulmers crisp premium blend. Feels a long way off after been out and about today but it'll come
We all have our favorite weather preference but I like most like any weather, but at the end of the day the weather will do what the weather wants to do.
The past 10 days or so has reminded me of winter on the model threads, a reversal from the pattern of wanting to see heights to the north but only this time to the South in the form of high pressure.
The below chart taken from the GFS at +T81 clearly shows how messy things are out there, and slight changes will make such a difference.
Plenty of rain, average temperatures to come for a time, it will feel pleasant at times for some areas, and we will see some convection knocking about, far from boring weather, just not nice to have it this time of the year I suppose.
At least were getting some much needed rain.
Anyhow, if High Pressure is not showing on them model charts soon i'll open up Photoshop and make some for you guys, I might go one step further and make a my own Phantom high pressure model.
Good night Netweather
Lewis
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I was talking about a large storm last night for N Lincs and Yorkshire, here comes the bad boy, tapping on Nottinghams door now
Lewis
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Lincolnshire and Yorkshire looking very favorable early evening onwards.
Lewis
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Just done a quick video forecast, and already 2 rumbles of thunder from this cell;
Lewis
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Have towers building quite rapidly here in East Hull.
The NMM runs from yesterday was suggesting a lot of cloud cover, certainly not the case up to now, although cloud cover is increasing slightly.
NMM continues to show massive cape and LI values, with cape around the 900-1100 values with a lifted index of -4, there is sufficient energy across this part of the region until sun down.
Looking like an interesting day.
Lewis
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8.55pm Tues
Moderate Risk of Scattered Thundery Showers Ireland & UK 09Z-21Z
Stronger Organised Convection Possible (as per yellow box)
Irregularities between models now much less obvious. GFS, NMM and WRF now pretty firm on the potential for a widespread thundery regime through Weds, Hence a Moderate Risk level is more appropriate!
An unstable environment builds within the post frontal sector. A number of surface troughs expected to develop from quite early on Weds morning. Relatively weak upper trough nudges eastward increasing lift with a number of moderate strength PVA Max's looking to further increase lift along the northern periphery of the upper jet stream. Some marginal overlay of vertical shear to instability looks to take place for southern UK as per yellow box. Though based on the forecast vertical wind profiles I do not ATM see this support developing supercell characteristics on any storm building in this sector (though this could change)! Whilst Deep Layer Shear would appear strong, the vertical velocities are not showing cloud tops reaching this level. This will means that any building storm cell will be unlikely to tap into this strong upper motion. Lack of convergence right across the board and the low level shear looks rather weak ATM with fairly straight lined winds at all levels. So not ready to suggest any risk of tornado development. Though this cannot be entirely ruled out.
Prime regions where lightning could be more prolific might be around W.Midlands later in the day. Also likely to be a risk of strong gusts (non severe). Confidence is fairly good for results ATM. Certainly worth a heads up and requires careful monitoring.
It would only take some minor changes within the models to increase the severe aspect of this outlook.
This post has been edited by Tony Gilbert: 05 June 2012 - 21:19
Interesting he goes for West Midlands, when all models clearly show it's East Mids, SE, Lincs and Yorkshire (Eastern areas)
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Storm from the other month, larger picture to that in my signature, more of this please tomorrow
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I honestly think N Lincolnshire and Hull/Humber area will be battered by a massive storm tomorrow afternoon/early evening.
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No mention of NW england then, what a surprise! I think it looks good for here as well, unless the wind turns too westerly or northwesterly tomorrow in which case we're buggerd.
There is a chance of some heavy showers, but not as a higher risk than other areas mentioned Chris.
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They may be uncertainty with regards to our longer term pattern, but there's no uncertainty that during the short term we are going to experience a more fresher, low pressure dominated pattern of weather, with some possible convective weather for central & eastern parts tomorrow.
Another change is occurring now as a LP system off the Atlantic becomes established and moves North Eastwards towards the United Kingdom.
There is currently an area of precipitation giving moderate to heavy rainfall for central southern regions and the South East, this area of precipitation will continue to edge North Eastwards during the course of this evening exiting East Anglia during the early hours.
As we head further North, they may be a period of precipitation overnight tonight for Central and more Eastern parts of England, pushing through to Northern England.
The heaviest of the precipitation is more likely to be across central areas, mainly pennine areas.
Overnight tonight temperatures will be much more respectable than of late, with temperatures expected to be 10-11c quite widely, with the highest of the temperatures across the South East where they could reach 12-13c, although locations experiencing prolonged rainfall may have lower temperatures, of around 8-9c.
As we head in to tomorrow morning it will be a cloudy, dreary start for many, with extensive cloud cover, very little in the way of breaks to start off with.
Throughout tomorrow temperatures will be a little up on today with highs of around 15-16c quite widely, with some areas possibly hitting 17-18c.
Throughout the course of tomorrow showers will develop fairly quickly, heavy in places with localised thunderstorms. I'm keeping an eye on a trough tomorrow drawn on the fax charts for the South East and East Anglia, they could be some very sharp showers with thunder and lightning developing tomorrow, then as we head in to the afternoon and early evening the risk extends Northwards across the East Midlands, Lincolnshire and then through to East Yorkshire/Humber area.
As you can see on the below image, some energy is available from the word go in the form of moderate levels of CAPE and a negative Lifted Index, covering a bulk of Eastern and central England, and also parts of Wales.
As we head in to the early evening tomorrow CAPE and LI values become more prominent across N Yorkshire, East Yorkshire, Lincolnshire, East Anglia and the East Midlands;
These showers may become more organised and slow moving giving torrential downpours for many of these parts, and also the risk of some moderate to severe thunderstorms with frequent lightning.
Although cloud cover will be rather extensive, and it's a feature that many members may think will play a big part tomorrow of conditions not being favorable for thunderstorms, as always this is always a possibility, a risk we run with, but with an approaching trough, I think this will aid the activity and be the trigger in terms of convection.
Dew Points are favorable, in the low to mid teens, although it would be good if we could hit maybe 14-15c, something we need to keep an eye on tomorrow morning and as the afternoon develops.
As we head on through the week the unsettled theme will continue with weather fronts making their way in off the Atlantic, South Western and Western areas look to bear the brunt, with Ireland possibly taking a battering from a deepening area of low pressure, something to keep an eye on no doubt.
But it's certainly an unsettled spell of weather to come for many of us
Regards,
Lewis
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They may be uncertainty with regards to our longer term pattern, but there's no uncertainty that during the short term we are going to experience a more fresher, low pressure dominated pattern of weather, with some possible convective weather for central & eastern parts tomorrow.
Another change is occurring now as a LP system off the Atlantic becomes established and moves North Eastwards towards the United Kingdom.
There is currently an area of precipitation giving moderate to heavy rainfall for central southern regions and the South East, this area of precipitation will continue to edge North Eastwards during the course of this evening exiting East Anglia during the early hours.
As we head further North, they may be a period of precipitation overnight tonight for Central and more Eastern parts of England, pushing through to Northern England.
The heaviest of the precipitation is more likely to be across central areas, mainly pennine areas.
Overnight tonight temperatures will be much more respectable than of late, with temperatures expected to be 10-11c quite widely, with the highest of the temperatures across the South East where they could reach 12-13c, although locations experiencing prolonged rainfall may have lower temperatures, of around 8-9c.
As we head in to tomorrow morning it will be a cloudy, dreary start for many, with extensive cloud cover, very little in the way of breaks to start off with.
Throughout tomorrow temperatures will be a little up on today with highs of around 15-16c quite widely, with some areas possibly hitting 17-18c.
Throughout the course of tomorrow showers will develop fairly quickly, heavy in places with localised thunderstorms. I'm keeping an eye on a trough tomorrow drawn on the fax charts for the South East and East Anglia, they could be some very sharp showers with thunder and lightning developing tomorrow, then as we head in to the afternoon and early evening the risk extends Northwards across the East Midlands, Lincolnshire and then through to East Yorkshire/Humber area.
As you can see on the below image, some energy is available from the word go in the form of moderate levels of CAPE and a negative Lifted Index, covering a bulk of Eastern and central England, and also parts of Wales.
As we head in to the early evening tomorrow CAPE and LI values become more prominent across N Yorkshire, East Yorkshire, Lincolnshire, East Anglia and the East Midlands;
These showers may become more organised and slow moving giving torrential downpours for many of these parts, and also the risk of some moderate to severe thunderstorms with frequent lightning.
Although cloud cover will be rather extensive, and it's a feature that many members may think will play a big part tomorrow of conditions not being favorable for thunderstorms, as always this is always a possibility, a risk we run with, but with an approaching trough, I think this will aid the activity and be the trigger in terms of convection.
Dew Points are favorable, in the low to mid teens, although it would be good if we could hit maybe 14-15c, something we need to keep an eye on tomorrow morning and as the afternoon develops.
As we head on through the week the unsettled theme will continue with weather fronts making their way in off the Atlantic, South Western and Western areas look to bear the brunt, with Ireland possibly taking a battering from a deepening area of low pressure, something to keep an eye on no doubt.
But it's certainly an unsettled spell of weather to come for many of us
Regards,
Lewis
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Very nice SKEW-T charts
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UK Convective General Discussion & Forecasts - June 6th 2012>
in Storms & Severe Weather
Posted
Kicking off 9am onwards further south, and around 1pm onwards further north.
I've done a quick image below areas in the red greatest at risk of severe thunderstorms/tornado potential. Areas inside the black have the lower risk, but a general risk of localised thunderstorms.