UK Convective General Discussion & Forecasts

[Lauren]

You should get a hobby.....

You know what I meant

[Coast]

I'm not about for a couple of days, so here's an early look at what may be on offer:

Blimey, that's heading toward Jane Louise's house!!!

Hmmm covers a big area:

Oh nice, more rain!

The best action reserved for the French again?

[Harry]

Errrr, yes of course the best action is reserved for the French.....

[Coast]

Errrr, yes of course the best action is reserved for the French.....

Another vintage year for them?

[sunny scunny]

I'm not about for a couple of days

Really? Are you ill

[Coast]

Really? Are you ill

Well, no more than usual

No, long weekend away down West - I bet that's where the storms will be now!!!

[Andy Bown]

Well, no more than usual

No long weekend away down West - I bet that's where the storms will be now!!!

That would be good!

[A.J]

That would be good!

What?...the idea of Coast being off the forum for a couple of days, or the chance of storms in the west?

[Sprites]

What?...the idea of Coast being off the forum for a couple of days, or the chance of storms in the west?

im surprised there hasnt been any MetO severe lack of thunderstorm Netweather member warnings lately!

[Andy Bown]

What?...the idea of Coast being off the forum for a couple of days, or the chance of storms in the west?

LOL !

(The latter)

[A.J]

im surprised there hasnt been any MetO severe lack of thunderstorm Netweather member warnings lately!

Ah, the Met office Netweather Member Severe Suicide Watch ™ will almost certainly be back for the (lack of) snow season

[Sprites]

Ah, the Met office Netweather Member Severe Suicide Watch ™ will almost certainly be back for the (lack of) snow season

pmpl , i hope its a mild winter , i can remember when snow was a an unusual event here.

[Stuart]

Last Updated: 22:59 Thursday, 15th September 2011

Valid: 00:00 Friday, 16th September 2011 - 23:59 Friday, 16th September 2011

Areas Affected:Severe: Northern Ireland, N parts of the Republic of Ireland. Slight: the northern half of Ireland, N Wales, NW England, S Scotland.

Synopsis:Low pressure centred south of Iceland will extend an occluded front to the southeast, this will push across Ireland and into western Britain during the day. This will be followed by an upper trough that will help to trigger showers over Ireland and potentially NW Britain in the afternoon.

Discussion:

An interesting set-up on Friday. An occluded front will produce some showery rain during the morning, but this should clear away to the east during the middle part of the day allowing for some sunshine into the afternoon.

A negatively tilted upper level trough with 500mb temperatures of around -23C will push into Ireland and western Britain during the afternoon, providing unstable air aloft. This will produce modest CAPE values 300-500j/kg during the afternoon, highest of which will be over N Ireland. ELTs will be -20C across the area, but as low as -35C over parts of N Ireland for a time during the afternoon.

Surface winds will be south to southwesterly for much of the day, but they will veer around to the west or northwest into parts of Ireland later in the afternoon. 0-6km shear values will be in the region of 30-40kts, this along with 0-1km shear values of 20-25kts will produce the potential for a few tornadoes into the afternoon coinciding with the largest amount of instability. Shear values also lend themselves to the potential of some large hail, with values in the region of 1.5-2cm.

It should be stressed that overall potential for this severe weather remains low. Instability is marginal, and large amounts of cloud may linger into the afternoon limiting surface insolation.

Showers are not likely to be severe outside of the the zone in northern parts of Eire

http://ukasf.co.uk/storm-forecasts/106

[ZONE 51]

Thundery weekend-period friday 16th - sunday night 18th sept.

all areas/regions are at risk from heavy showers through the above period some may contain hail.

friday the western and northern areas most at risk from thundery torrential downpours, some thunderstorms may develop with squally gusts of wind, any hail that does fall should be of standard size but there is the risk of larger hail in the bigger storms if they do develop.

saturday thunderstorms becoming more widespread with the potential for hail, squally gusts of wind and hail, these even extending into Southern areas/South East, these could last well into the evening.

Sunday further risk of widespread downpours or thunderstorms.

-

flooding may become a local problem in any intense or prolonged activity.

Edited September 16, 2011 by ElectricSnowStorm

[ZONE 51]

http://www.ukweather.freeserve.co.uk/nwp.htm -

if anyone would like a link to every model and all data the above link is provided!

all models and links on one page.

[Sprites]

http://www.ukweather.freeserve.co.uk/nwp.htm -

if anyone would like a link to every model and all data the above link is provided!

all models and links on one page.

thanks for link, theres lightning in north-west France now, i expect its moving east though.

[Cheese Rice]

Alot of thunder here with the odd flash of visible lightning. Heavy rain too.

Since when was this forecast....

[Coast]

Quietening down now, nothing much in prospect for some days although next Sunday and Monday may be worth keeping an eye on down South (not a big beady eye though!)

[Stuart]

Thank Coast for that

Edited September 20, 2011 by Stuart

[Costa Del Fal]

Front peeped up over me in North Worcestershire at around 1pm with some very heavy rain for a time. All dry and clearing up now though.

[ZONE 51]

Just thought that i would let you know GFS 18z showing unstable air running across the-far North, this being Scotland mostly, CAPE/Lifted index reveals enough potential for thundery downpours/storms along with other elements to help with the thunderstorm risk, this might change by time the next run is in, but its worth keeping watch on this, cant look in depth now as not got time but im sure some early members would post up the charts. the risk being wednesday(today)through into the night hours.

Edited September 21, 2011 by ElectricSnowStorm

[Lauren]

Two random questions......

What happened to the rainfall radar on MetO?

You know the colour the sky goes when it's going to snow (that sort of odd grey-yellow colour). Why does it do that?

[Harry]

Two random questions...... What happened to the rainfall radar on MetO? You know the colour the sky goes when it's going to snow (that sort of odd grey-yellow colour). Why does it do that?

Re the MetO rainfall radar - it appears to be working ok my end. If you're referring to the MetO Invent showing predicted rainfall, I think that was just a trial (though I found it quite useful myself)

Re snow - as a guess I would say it's due to the nature of the precipitation within the cloud. Like with storm clouds before hail you get a greeny-greyish tinge. Storm clouds are dark because of their density along with the often bright, reflective cloud tops. This restricts the amount of light travelling through the cloud, giving us the shades of light to dark grey (or sometimes black/deep blue). The green I suspect comes from the way the ice refracts sunlight through the cloud. The higher the levels of ice, the more towards the green spectrum light is shifted. The yellowish tinge you have observed is probably the same phenomena, with a slightly different tinge caused by the different water : ice ratio associated with snowfall.

I'm sure there are more knowledgeable chaps who will shed more light (along with I suspect a few comments that this is the wrong thread)

Edited September 21, 2011 by Harry

[Lauren]

Re the MetO rainfall radar - it appears to be working ok my end. If you're referring to the MetO Invent showing predicted rainfall, I think that was just a trial (though I found it quite useful myself)

Re snow - as a guess I would say it's due to the nature of the precipitation within the cloud. Like with storm clouds before hail you get a greeny-greyish tinge. Storm clouds are dark because of their density along with the often bright, reflective cloud tops. This restricts the amount of light travelling through the cloud, giving us the shades of light to dark grey (or sometimes black/deep blue). The green I suspect comes from the way the ice refracts sunlight through the cloud. The higher the levels of ice, the more towards the green spectrum light is shifted. The yellowish tinge you have observed is probably the same phenomena, with a slightly different tinge caused by the different water : ice ratio associated with snowfall.

I'm sure there are more knowledgeable chaps who will shed more light (along with I suspect a few comments that this is the wrong thread)

Thanks Harry and yes, I was referring to the Invent predicted rainfall. I found it useful too! Are they likely to bring it back?

[Coast]

Thanks Harry and yes, I was referring to the Invent predicted rainfall. I found it useful too! Are they likely to bring it back?

The content will be regularly changed and is being continuously developed so things might not always work as expected. Met Office Invent should not be used to make operational or personal decisions.

http://www.metoffice.gov.uk/public/pws/invent/

I think they are moving to a Beta version of their whole site, so may be moving and updating features and pages a bit:

http://www.metoffice.gov.uk/public/beta/