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Jane Louise

Convective / storm Discussion - 5th June 2014 onwards

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Valid From

Fri 6 Jun : 22:00 BST(In 11hrs)

Valid Until

Sun 8 Jun : 04:00 BST (41hrs remaining)

Advance Weather Warning For Severe Wind Gusts, Heavy Rain & Large Hail 

This warning has now been upgraded and updated to include Southern and South-east England. 

A large area of low pressure to the South-west of the UK will introduce a plume of warm and unstable air across the UK later this evening and overnight into tomorrow. 

There remains uncertainty with regards to the exact track of imported storms from France and not everyone will experience them, however the potential is for organised multicell structures across Southern England during the early hours of Saturday. 

During Saturday this risk will extend further North into the Midlands, Wales and later Northern England and Scotland. 

At present, the main risk is for severe wind gusts of up to 60-70mph around the systems as well as excessive rainfall with local flash flooding, large hail and F1/2 tornadoes. 

We will be monitoring developments across Spain/France closely today as if the storms develop closer to the surface level and access moist low-level air across the Channel this evening it is likely flash weather warnings will be issued for Southern England for tonight.

---END---

 

http://www.metcheck.com/UK/warnings.asp

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Post a pic :D

Here we go! These are a few lines of altocumulus castellanus clouds looking SSW from here.

 

post-21578-0-31676100-1402050470_thumb.j

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Should see my F5 button....

 

Posted Image

 

Come on metoffice

 

Posted Image

Aaargh still nothing yet, they must be on a coffee break......... I am about to give up

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Aaargh still nothing yet, they must be on a coffee break......... I am about to give up

 

I know, I'm ready for bed but determined to wait for the update first!

Edited by CreweCold

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I'm still fairly happy with the charts and the prospect of what might creep up in the early hours.post-15177-0-06122200-1402050766_thumb.ppost-15177-0-67744000-1402050777_thumb.pA small finger of cold ELT's edges up, and MLCAPE still not looking too bad, it's certainly enough to produce some elevated lightning- worth looking out to sea if you're on or near the coast. I'd put areas somewhere between Weymouth and Brighton in with a shout at first, and into Wilts and Berks, Surrey.I don't expect anything severe, the chances for that would be around the home counties and east Midlands, whether everything engages remains to be seen.I wouldn't overly worry about precipitation charts, anything could kick off later tonight.

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NMM 06z is looking rather fantastic. Li of -9 for parts of the southeast by the look of it, and some rather worrying precipitation totals.

 

Posted Image

 

 

Posted Image

Edited by Sainsbo

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need to give met office time to update there warnings

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It's quite surreal how different the NMM and GFS are. GFS Showing 1300J/kg and Li of -3, whereas the NMM is showing CAPE of 2600J/kg and Li of -7

 

Maybe they'll both be wrong, and we'll get a CAPE of 4000J/kg and Li of -11?  ;)

Once in range of the NMM then I'd ignore the GFS to some degree and stick with the higher res model. 

Edited by Liam J

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NMM 06z is looking rather fantastic. Li of -9 for parts of the southeast by the look of it, and some rather worrying precipitation totals.

 

Posted Image

 

 

Posted Image

 

Completely at odds with GFS over where the heaviest precipitation is likely to be. Looks nothing like the BBC forecast I've just seen either. That being said, the WRF has been pushing that CAPE east even quicker than the GFS!

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I know, I'm ready for bed but determined to wait for the update first!

It was updated 10 mins ago. :)

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MetO had changed me back to light rain. :(

 

*gives up* 

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It was updated 10 mins ago. :)

 

Oh aye, still no amber. Though they say, 'The focus is then expected to shift into northern England, southwest Scotland and eastern fringes of Northern Ireland during the afternoon'...

 

So I've no idea where the NMM WRF is picking up its precipitation signal from....unless it really does have the situation nailed. Unless it's overreacting to a signal RE surface based possibilities tomorrow afternoon.

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anyone "down south" or from around this way familiar with Combe Gibbet?

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The met office updated their warnings quarter of an hour ago..

post-15177-0-22047500-1402051663_thumb.p

The blanket warning still exists but the matrix has been updated.

Edited by Mapantz

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MetO had changed me back to light rain. :( *gives up*

Don't use that to determine how you're going to do! At the moment, I would say you're in a pretty good location for tomorrow.

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 My current thinking has changed somewhat from yesterdays thoughts.  The divergence aloft no longer appears enough to support an MCS in my view.

Atmosphere looks strongly capped at 850hpa, but the cap looks to weaken as the cold front approaches.

 

Which marginally shows up on the 850hpa temperature chart.

 

There is however another posible mechanims for storm initiation on the current model output and thats low level wind convergence, which will tend to pool moisture.

 

The pooling I think shows up on the thetae chart.

 

Low level winds are very difficult for the models to forecast even 24 hours out so expect some changes before the event.

 

I now expect some elevated storms to develop overnight out over the bay of biscay and trundle into the south of the UK in the early hours. Perhaps giving an early wake up call to those in the south.

 

As the day progresses then there is a chance that storms could become suface based (seems likely to me).

 

The Cap is likely to be back in place across the south by the afternoon as far as I can tell. Which could maybe break in the afternoon in the east.

 

Some SkewT's

 

 

 

Elevated storms ?

 

Highest convective precipitation.

 

Afternoon storms at peak heating ?

 

 

 

Its still too early to tell and higher level cloud cover could keep surface temperatures down. Considering how models have changed over the last day, I would not like to call it at the moment. Very slight super cell and tornadic activity form the midlands northwards possibly concentrated  around Lincolnshire and east midlands.

 

Models seem to always down grade convective activity risk at about 24 hours out and then slightly upgrade as the time line shortens. In my view there is now a greater risk of an isolated severe storm than yesterdays modelling would suggest.

 

 

Edited by BrickFielder

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Right that's me done, met o warning for me is mainly for heavy rain. Will look in later

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Its going to be a case of where and when upper forcing initiates the breakdown of the plume, i'm moving slightly Eastwards now and going with Mapantz around the Weymouth to IOW area, timewise (very tough) but still a couple of hours before midnight.

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The met office updated their warnings quarter of an hour ago..

Posted ImageScreenshot_2014-06-06-11-47-47.png

The blanket warning still exists but the matrix has been updated.

 

How long has the MetO warning said this? I'm sure it never said that yesterday when I looked  :cc_confused:

 

Heavy, thundery rain is expected to affect parts of the UK on Saturday. Some initial thundery outbreaks, possibly accompanied by frequent lightning, may arrive from around midnight, but it is later in the night and during the morning that the south will be at risk from more widespread thundery developments and locally intense rainfall. The focus is then expected to shift into northern England, southwest Scotland and eastern fringes of Northern Ireland during the afternoon, while parts of southern Britain see improving conditions. 

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Take a look at this peeps!!latest wrf nmm 06z breaks out I line of one can only assume is storms across the heart of england from 11pm tonight and 3am saturday morning!!so although chances have receded somewhat for tomorrow we might still actually get something better and thats a light show tonight!fingere crossed!here are the charts. ........

post-9030-0-29520600-1402051989_thumb.pn

post-9030-0-85153700-1402052015_thumb.pn

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