Convective / Storm Discussion - 4th October onwards 2013

[Jane Louise]

I am moving house so cannot get easy access to charts. I am free to storm chase on Sunday but i am now hearing a lot of talk about Sat and not Sun. Could someone fill me in on whether Sunday is still looking good please.

Hi Supacell. Sunday is looking better then tomorrow! tommorows potential is more for those who live by the coast and more to the West and SW. I'm not included once again Lol.. shall keep you more updated soon as we know more. Good luck with your house move.

[Supacell]

Hi Supacell. Sunday is looking better then tomorrow! tommorows potential is more for those who live by the coast and more to the West and SW. I'm not included once again Lol.. shall keep you more updated soon as we know more. Good luck with your house move.

Thanks Jane Louise for that, good news then for my chasing on Sunday. Its good to have opportunities so late in the season. Would be great if you could get a storm. House move going ok so far :-)

[Jane Louise]

Thanks Jane Louise for that, good news then for my chasing on Sunday. Its good to have opportunities so late in the season. Would be great if you could get a storm. House move going ok so far :-)

You're welcome I always say when it comes to storms to never give up lol. I will get a storm one day I'm a 100% sure of that  good your house move is going ok let's hope you get a storm too.

[Panayiotis]

Well the best thunderstorm I saw this year was in January so I never give up! Here's hoping tomorrowSunday will deliver,its looking very good for Southern England and Wales with high CAPE values, -2/-3 lifted index and  a trough on each day to act as a trigger, I would say theres quite a high chance of something interesting (storm related in UK) over the next 2 days!

Edited October 18, 2013 by Panayiotis

[wimblettben]

Not really bothered if I don't get anything more this year now as we have done pretty well and that lightning we had in the distance on the 4th of October was quite impressive.

 

I highly doubt that it will be anything near as good as that was if something does happen over the next few days.

[poseidon]

Kent clipper tomorrow....?

 

12GMT:

 

 

15GMT:

[Panayiotis]

Looking good out west!  

[Guest William Grimsley]

Hi Supacell. Sunday is looking better then tomorrow! tommorows potential is more for those who live by the coast and more to the West and SW. I'm not included once again Lol.. shall keep you more updated soon as we know more. Good luck with your house move.

Yeah, I think that the coasts of SW England including the S Coast are likely to see more showers than on Saturday. But, even so, I still feel Saturday has a good chance of seeing some showers/thunderstorms.

[Convective]

Holy lord above. Not seen one like this for a LONG time!

 

[Convective]

I must admit, I have found great difficulty in forecasting this one for some reason. For that reason, the overall confidence in this one is lower than usual. An update will be issued should one be required.

 

[Panayiotis]

Yes I think Sunday early hours will provide the best chances for a night show, just hoping that if it does occur we/I will be awake!

[Guest William Grimsley]

I must admit, I have found great difficulty in forecasting this one for some reason. For that reason, the overall confidence in this one is lower than usual. An update will be issued should one be required.

 

HELL YES! WOW!

[Guest William Grimsley]

Yesterday was wet and cool with a strong wind, here. High Rainfall Rate Yesterday: 14.8 mm/hr 21:47 High Hourly Rainfall Yesterday: 3.2 mm 19:27 Rainfall Yesterday: 8.6 mm High Temperature Yesterday: 15.3°C 14:50 High Wind Gust Yesterday: 23 mph 12:27 High Wind Speed Yesterday: 12 mph 12:49.

[Guest William Grimsley]

Not really bothered if I don't get anything more this year now as we have done pretty well and that lightning we had in the distance on the 4th of October was quite impressive.

 

I highly doubt that it will be anything near as good as that was if something does happen over the next few days.

Do you look at charts, Ben? They are more significant than last time!

[Evening thunder]

Already some activity to the SW:

(I think this image will self update through the morning)

 

Oh and yes please!

 

Although oddly a town nearer to me that's 3 miles away from Honiton and my location, shows much less thunder

 

Though I think the more important thing is on the Met Office forecast maps there are a reasonable number of thunder symbols and lots of heavy shower symbols from the early hours and through tomorrow, even if the text forecast for the SW only says isolated showers?

 

Edit: to avoid any confusion I'm at home in east Devon this weekend, not up in Surrey, hopefully this increases my chances of seeing something.

Edited October 19, 2013 by Stormmad26

[Guest William Grimsley]

Already some activity to the SW:

(I think this image will self update through the morning)

 

Oh and yes please!

Honiton thunder forecast.png

 

Although oddly a town nearer to me that's 3 miles away from Honiton and my location, shows much less thunder

Ottery forecast.png

 

Though I think the more important thing is on the Met Office forecast maps there are a reasonable number of thunder symbols and lots of heavy shower symbols from the early hours and through tomorrow, even if the text forecast for the SW only says isolated showers?

 

Edit: to avoid any confusion I'm at home in east Devon this weekend, not up in Surrey, hopefully this increases my chances of seeing something.

Yes, quite a bit of lightning towards the Scilly Isles, at the moment. As you say, it is looking like one hell of a light show in places, this weekend.

 

EDIT: The lightning seems to have stopped over the W English Channel. But, still some activity near Brest, now.

Edited October 19, 2013 by William Grimsley

[TropicThunder]

The BBC has the lightning symbol for 4 of the next 5 days in Southampton! We have missed out on most of the 'events' over the last few months, so really hoping to see something good to end the season. Good luck to all. 

[Nick F]

Storm & Convective ForecastIssued 2013-10-19 08:02:30Valid: 19/10/2013 0800z to 20/10/2013 0600z

THERE IS A RISK OF THUNDERSTORMS FORECAST

SynopsisAn upper-level trough will slowly move in from the Atlantic today, surface low pressure system stays just west of the UK, with cold front clearing east of the UK this morning with an unstable returning Polar maritime (rPm) flow spreading in behind.

 

... IRELAND, SOUTHERN and WESTERN BRITAIN ...

 

Lapse rates will steepen from the southwest through the day, as increasingly cold mid-level temperatures spread in from the west atop of moist southerly flow following cold front clearing eastern Britain this morning. GFS indicates 300-500 j/kg MLCAPE spreading inland in response to the steep lapse rates, though the extent of its CAPE values so far inland seems questionable given lack of a forcing mechanism - with greatest instability likely offshore and along southern/western coasts due to sea temperatures still warm from the summer. Therefore Ireland, southern and western coastal counties will be most at risk of deep convection forming offshore moving increasing onshore through the day. Wind shear will be modest, 20-30 knts - so no organised severe weather is anticipated, though showers/storms will likely organise and may move inland along forecast shortwave-trough moving in across Ireland and western Britain this afternoon/evening ... which may bring an enhanced risk of localised flooding. Stronger instability offshore and along southern/western coasts along with possible localised veering of surface winds may allow strong updrafts to rotate with a risk of waterspouts/brief tornadoes not ruled out.

 

Issued by: Nick Finnis

 

[Coast]

 

 

Storm ForecastValid: Sat 19 Oct 2013 06:00 to Sun 20 Oct 2013 06:00 UTCIssued: Fri 18 Oct 2013 16:17Forecaster: TUSCHYA level 1 was issued for parts of C France mainly for isolated large hail, excessive rain and an isolated tornado event.

A level 1 was issued for a small part of S France mainly for isolated large hail and an isolated tornado event.

 

SYNOPSIS

 

A flat and transient omega-like pattern has established over Europe. A weakening upper trough over SE Europe remains in place with only a low-end motion to the east. Numerous vortices over the far E-Atlantic steer a warm/humid air mass far to the NE while a stout branch of the polar vortex over N-Norway/Sweden advects a cold airmass to the south. A deep baroclinic zone (e.g. in excess of 20 K difference at 500 hPa between Germany/N-Norway) is the result with an evolving 40 m/s mid-level streak over the Baltic Sea.This kind of pattern results in a bisection of Europe from the North Sea to Greece. Areas to the east will feel the influx of cool/cold and dry continental air from the N whereas areas to the west see a gradual recovery of moisture, both due to advection of a modified subtropical air mass and a moistening W-Mediterranean air mass. Hence thunderstorm probs. over E/NE Europe remain confined to offshore and coastal areas with isolated/weakly electrified storms. Scattered and stronger storms however occur over far W Europe.

 

DISCUSSION

 

... Ireland and United Kingdom ...

Ingredients for thunderstorms will be in place with some iffy signals however. Behind a ENE-ward moving front (already transforming from a cold front into an occlusion from N to S) seasonable BL moisture remains in place. Mid/upper jets also reveal a good placement for some lift in addition to a weak vort.max. crossing the area of interest from SW to NE between 12-18Z. However, forecast soundings show a meager depth of the BL moisture with constant drying above. Therefore onshore turbulent mixing next to some temporal heating lower confidence in adequate CAPE build-up well inland. Coastal areas (SW-ward facing) will see best moisture and at least 300 to 700 J/kg SBCAPE. Some veering in the lowest 2 km AGL is present along the coastal areas with 50-100 J/kg 0-3 km CAPE, so an isolated spout/short-lived tornado is possible. Effective PWs also approach 20 mm, which could lead to some heavy rain and 15-20 m/s 850 hpa flow should ensure gusty winds with stronger convection.

 

We expanded the lightning areas far offshore. Despite more hostile conditions for electrified storms with this type of air mass, approaching cooler mid-level air should increase the CAPE disperal in the mid-level graupel layer a bit. Hence confidence in more activity compared to yesterday has increased. We also splayed the eastern part of the 15-% lightning area all the way to Denmark to cover a few elevated thunderstorm events beyond 12Z. This also includes parts of N France . This activity will be non-severe.

 

 

[VillagePlank]

My take on Sunday morning for the SE

 

http://forum.netweather.tv/topic/78128-south-east-east-anglia-regional-weather-discussion-111013/?p=2809347

[Coast]

No words this morning Dan?

 

 

Forecaster: DanValid: 2013-10-19 00:00:00 - 2013-10-19 23:59:00

 

 

 

 

http://ukasf.co.uk/storm-forecasts/286

 

 

[staplehurst]

No words this morning Dan?

 

 

http://ukasf.co.uk/storm-forecasts/286

 

Was typing away... 

 

 

 

Synopsis

Upper trough over Central Europe continues to shift eastwards, allowing an upper trough over the Atlantic to approach from the West. At the surface, a cold front/occlusion continues to exit to the North Sea (albeit with a wave over SE England this afternoon) while cooling occurs aloft in western areas.

 

DiscussionIn the post-frontal airmass, scattered showers and a few thunderstorms are forecast to develop through today as diurnal heating allows LSTs to match those of neighbouring SSTs. A couple of shortwave troughs will enhance shower activity/organisation (one developing from the Ireland/Northern Ireland border - Pembrokeshire - Cornwall at midday, and migrating northeastwards thereafter through the remainder of the forecast period). 

Surface moisture reduces as showers move further inland, so a gradual decrease in instability and hence activity is expected as these troughs/showers migrate further inland. Nonetheless, ample CAPE around coastal areas (500-800 J/kg), steep mid-level lapse rates and ELTs down to -30 to -40C should allow some occasional lightning to occur from best-organised cells. Given such instability, and cold air aloft, hail is possible in stronger cells perhaps up to 2.0-2.5cm in diameter. Low-level wind veer near coasts may allow a funnel or waterspout to form, while some quite gusty winds are expected near and within heavy showers.

Most lightning activity will retreat to the coasts during this evening and overnight as land temperatures fall, but it is possible given 2 defined shortwave troughs that some sporadic lightning may occur along these line of showers even in eastern areas if enough remnant instability is present. Given main upper trough (axis) is still located over the Atlantic today, it is likely that Sunday may produce more widespread lightning activity compared to today... 

[poseidon]

SkyWarn.....

 

Last Update: 0045UTC Saturday 19th October 2013  

SKYWARN UK SEVERE THUNDERSTORM WATCH #033ISSUED: 0045UTC SATURDAY 19TH OCTOBER 2013

SKYWARN UK FORECASTS THE POTENTIAL FOR SEVERE THUNDERSTORM CONDITIONS AS FOLLOWS:STRONG, POTENTIALLY DAMAGING WIND GUSTS - SOUTHWEST & SOUTHERN ENGLAND, MIDLANDS, WALES, SOUTHWEST SCOTLAND AND IOMBRIEF, POTENTIALLY DAMAGING TORNADOES - SOUTHWEST ENGLAND, SOUTHERN MIDLANDS, WALES

IN EFFECT FROM 1000UTC UNTIL 1900UTC SATURDAY 19TH OCTOBER 2013

MODERATELY UNSTABLE POST-FRONTAL AIRMASS, WITH ORGANISED CONVECTION IN STRONG LOW TO MID LEVEL WINDS

DISCUSSION:THERE IS GOOD-ISH MODEL AND PARTNER AGENCY CONFIDENCE IN THE POSSIBILITY OF SEVERE THUNDERSTORM RISKS THROUGH THE PERIOD. ORGANISED CONVECTION SHOULD APPROACH THE SOUTHWEST AND WALES BY LUNCHTIME, ALONG A SURFACE SHORTWAVE AND WITHIN AN ENVIRONMENT OF 800-1200J/KG CAPE. THIS IS EXPECTED TO BE QUITE ORGANISED GIVEN DIRECTIONAL AND SPEED SHEAR IN THE LOWEST 3KM, WITH THE POSSIBILITY OF STRONG GUSTS AND BRIEF TORNADOES. A BROKEN LINE OF CONVECTION IS EXPECTED TO MOVE THROUGH WALES, WITH FURTHER CONVECTION DEVELOPING IN THE CHANNEL AND IRISH SEA, BY MID AFTERNOON WITH LESS HELICITY BUT ENOUGH VERTICAL SPEED SHEAR TO SUSTAIN STORMS LONG ENOUGH FOR STORMS PHASING THROUGH MORE ORGANISED MODES. RISK OF STRONG GUSTS AND A LOWER POTENTIAL FOR TORNADOES EXISTS THROUGH THE REST OF THE WATCH AREAS. THIS WATCH MAY BE UPGRADED. PLEASE MONITOR WEATHER AND TRAVEL INFO AS NECESSARY.

SPOTTER ACTIVATION IS REQUESTED AND SPOTTERS ARE REQUESTED TO REPORT ALL FACTORS EXCEEDING ACTIVATION CRITERIA.

[Supacell]

Just had a quick look at the charts and forecasts. I think my best bet would be to load up the car with petrol, sleeping bags, food and head to the south coast for an overnight show followed by a spout/tornado risk in the morning.

[poseidon]

First lightning cluster near Cornwall coast.