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Nick F

Convective / Storm Discussion Thread - 27th Feb onwards

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Day 1 Convective Outlook

VALID 06:00 UTC Wed 29 Mar 2017 - 05:59 UTC Thu 30 Mar 2017

ISSUED 19:50 UTC Wed 29 Mar 2017

ISSUED BY: Dan

UPDATE 19:50 UTC LOW extended NE-wards to cater for medium level instability release overnight - chance of lightning in any one location considered very low

... IRELAND / NORTHERN IRELAND ...

On the forward side of an upper trough, strong deep layer shear overlapping some marginal instability (in the post-frontal environment) may be sufficient to allow a few scattered showers / weak thunderstorms to develop during Wednesday afternoon. Relatively low LCLs and backed/curved low-level hodographs gives the potential for a brief tornado, albeit low-level flow is quite slack.

... S WALES / SW ENGLAND ...

A low risk of some embedded elevated convection on the forward side of the frontal boundary within a higher WBPT plume during Wednesday evening and night.

http://www.convectiveweather.co.uk/forecast.php?date=2017-03-29

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13 minutes ago, Summer Sun said:

Day 1 Convective Outlook

VALID 06:00 UTC Wed 29 Mar 2017 - 05:59 UTC Thu 30 Mar 2017

ISSUED 19:50 UTC Wed 29 Mar 2017

ISSUED BY: Dan

UPDATE 19:50 UTC LOW extended NE-wards to cater for medium level instability release overnight - chance of lightning in any one location considered very low

... IRELAND / NORTHERN IRELAND ...

On the forward side of an upper trough, strong deep layer shear overlapping some marginal instability (in the post-frontal environment) may be sufficient to allow a few scattered showers / weak thunderstorms to develop during Wednesday afternoon. Relatively low LCLs and backed/curved low-level hodographs gives the potential for a brief tornado, albeit low-level flow is quite slack.

... S WALES / SW ENGLAND ...

A low risk of some embedded elevated convection on the forward side of the frontal boundary within a higher WBPT plume during Wednesday evening and night.

http://www.convectiveweather.co.uk/forecast.php?date=2017-03-29

Sounds plausible given the plume like set up. I'd say chances again tomorrow evening given the front will make a move East/North East.

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Day 2 Convective Outlook

VALID 06:00 UTC Thu 30 Mar 2017 - 05:59 UTC Fri 31 Mar 2017

ISSUED 20:31 UTC Wed 29 Mar 2017

ISSUED BY: Dan

... IRELAND / NORTHERN IRELAND / W SCOTLAND ...

On the forward side of an upper trough, strong deep layer shear overlapping some marginal instability (along or just behind the waving cold front) may be sufficient to allow a few scattered showers / weak thunderstorms to develop during Thursday afternoon / early evening. 

... SW ENGLAND / WALES / MIDLANDS / NE ENGLAND ...

Ongoing (low) risk of some elevated convection on the forward side of the frontal boundary within a higher WBPT plume during Thursday, as several pulse of showery precipitation from medium/high cloud bases nudge NE-wards - some evaporating before reaching the ground.

C8HOLHXWsAALVIH.jpg

http://www.convectiveweather.co.uk/forecast.php?date=2017-03-30

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A pretty interesting looking and potent storm moving out into the North Sea east of Newcastle at the moment. Shame it is not over land as it would be nice to see some pictures of it. Doesn't seem to be producing much in the way of lightning though.

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Day 2 Convective Outlook

VALID 06:00 UTC Fri 31 Mar 2017 - 05:59 UTC Sat 01 Apr 2017

ISSUED 18:41 UTC Thu 30 Mar 2017

ISSUED BY: Dan

Upper trough approaching from the Atlantic on Friday will serve to steepen lapse rates as cool air aloft overspreads relatively warm SSTs (and diurnally-heated land). The net result is a few hundred Jkg-1 CAPE, with bands of showery precipitation, perhaps isolated thunderstorms, moving N-wards and E-wards across Ireland into western Britain. Some small hail will be possible in the most intense cells

Better instability will be found over portions of Ireland, but with the proviso that excessive cloudiness may inhibit convective depth somewhat - hence for now have refrained from upgrading to SLGT. A few heavy showers are possible in E England during Friday afternoon, but convective depth looking marginal for lightning. French exports may get close to SE England during the first half of Friday morning and again late afternoon / early evening.

http://www.convectiveweather.co.uk/forecast.php?date=2017-03-31

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Thank you Summer Sun. Ireland and north west englnd/wales do seem to be getting the early spring storms at the moment. Lovely scenery up that way too which would make viewing any activity even more enjoyable. Good luck to our friends in that area and be sure to post any pictures! :)

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Some potent showers now sky very dark to my south over and above incoming darkness ,lol

 

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Torrential rain from the slow moving band in Irish Sea Wales area ,no sferics though.

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9 minutes ago, Flash bang flash bang etc said:

Every forecast so far this week has been either north south or west of our precise location.

A frustrating 2017 storm season for the central south begins in earnest...

Saturday has potential. Typical it's on a day I don't really want it. 

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What's this I read about possible imports from France tonight?

I'll admit it looks like they won't make it on shore by the sounds of it - but the odd flash bang will do me fine if there's a remote chance...

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Day 2 Convective Outlook

VALID 06:00 UTC Sat 01 Apr 2017 - 05:59 UTC Sun 02 Apr 2017

ISSUED 19:08 UTC Fri 31 Mar 2017

ISSUED BY: Dan

A sharp but weakening upper trough will slowly migrate eastwards across the British Isles on Saturday, its associated cold mid/upper levels helping to steepen lapse rates and generate several hundred Jkg-1 CAPE in response to diurnal heating. The forecast evolution is complicated somewhat by occlusion debris that may be affecting parts of western Scotland and northern England, bringing the risk of some persistent rain in places but more importantly extensive cloud.

Nonetheless, a typical day of April airmass convection is anticipated, with numerous showers developing during the day. Instability is sufficient for a few thunderstorms, although a lack of any significant shear will result in pulse-type modes with relatively short lifespans per individual thunderstorm. As a result, it is hard to justify upgrading any particular area to a SLGT at this stage - although current thinking would favour a zone from Devon across southern counties of England/south Midlands to southern portions of East Anglia (including London) as the area most favoured for lightning activity.

Some small hail is likely in the most intense cells, and given slack flow there will be scope for a weak funnel cloud / tornado etc, especially near convergence zones. Some cause for concern in eastern Scotland given low-level convergence / slack flow, which may result in prolonged heavy showers bringing the risk of some localised flooding.

http://www.convectiveweather.co.uk/forecast.php?date=2017-04-01

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Storm & Convective Forecast

convmap_010417.thumb.png.ef3924b53d1b3906cc6bb7bb65779606.png

Issued 2017-04-01 06:36:07

Valid: 01/04/2017 06z to 02/04/2017 06z

CONVECTIVE / STORM FORECAST - SATURDAY 1ST APRIL 2017

Synopsis

Upper trough will slide east across western Europe including the UK and Ireland today, bringing scattered showers and some thunderstorms across many parts today.

... E IRELAND, N. IRELAND, WALES, ENGLAND. S, CENTRAL and E SCOTLAND ...

Cold mid-level temperatures of the upper troughing moving across the UK and Ireland today will create steep lapse rates with surface heating in sunny spells, allowing instability to develop. GFS indicates up to 300-600 j/kg CAPE from late morning and through the afternoon across E Ireland, E Wales, central and S England - which will support the highest likelihood of thunderstorms, outside these areas thunderstorms will be much more isolated. Vertical wind shear will be rather weak at all levels, so any storms will be dis-organised and of the 'pulse type', i.e. updrafts aren't seperated from downdrafts which means that any one storm is shortlived. As a result, no severe weather is forecast, any storms may produce small hail, and slow-movement of cells may cause some minor surface flooding. Light winds and surface breeze convergence may support funnel clouds with stronger updrafts.

Issued by: Nick Finnis

 

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Out of absolutely nothing got a fairly sharp shower here. Just seemed to bloom out of nowhere

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Things starting to look more active across Northern England, numerous sferics along a line running from approximately Skipton to Newcastle.

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Convergence zone ,nothing here yet though sun might start  driving convection soon .

Edited by Mokidugway

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Second shower. They small on radar but mean business when they unleash themselves

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Sunny spells round our way. Very warm when it does. Things starting to perk up shower-wise over towards Basingstoke - looking good for later this afternoon hopefully some nice cloudscapes, hefty showers and a thundery bonus mixed in...

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It's looking extremely dark now to my West 

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Had a few rumbles of thunder from a cell just east of me about half an hour ago.

 

Looks to be a convergence zone near the NE coast.

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Hail from that storm near chester-le-street...Screenshot_20170401-134923.thumb.png.902a33954b9c63dc4decb174b320708e.png

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What started out as a bright day with blue sky and fluffy white cumulous has quickly changed to lots of low level convection and increasingly darkening skies. Keeping an eye/ear out for some rumbles this afternoon and some weak sparks. I'm not expecting anything too much out of today, looking at it as a bonus if we get anything.

 

@ Flash Bang Flash Bang - Try not to get disheartened my friend. I share your pain from last year which was an absolute joke as far as storms are concerned for my area, but we're right at the very beginning of the season, literally. Theres plenty of time, so lets see what this year brings.

 

 

Edited by Windblade

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36 minutes ago, Windblade said:

What started out as a bright day with blue sky and fluffy white cumulous has quickly changed to lots of low level convection and increasingly darkening skies. Keeping an eye/ear out for some rumbles this afternoon and some weak sparks. I'm not expecting anything too much out of today, looking at it as a bonus if we get anything.

 

@ Flash Bang Flash Bang - Try not to get disheartened my friend. I share your pain from last year which was an absolute joke as far as storms are concerned for my area, but we're right at the very beginning of the season, literally. Theres plenty of time, so lets see what this year brings.

 

 

Ah my hopes will be suitably tampered this year. Heading over to Italy in May (in fact booking it today) so there'll be some lovely storm opportunities out there.

i'm sure we'll get something today

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One of two flashes detected elsewhere but a dead duck here not really surprised though.

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