Astronomy, Photography and Weather

General Category => Weather & Atmospherics => Topic started by: martinastro on November 16, 2009, 04:31:35 pm



Title: Significant Storm For Ireland & UK Sat-Sun Nov 21st/22nd
Post by: martinastro on November 16, 2009, 04:31:35 pm
New thread started to cover a very interesting situation for the weekend. GFS, and other models, are currently predicting a significant Atlantic storm expected to affect Ireland, N. Ireland and Scotland, and perhaps W. UK on Fri/Sat. Gales inland and severe gales over coastal areas are possible. It's s little far away yet but according to forecasters the models have been consistent with this feature. Wave prediction websites are also going for huge waves over SW Ireland which may attract surfers from around the world. Worth keeping an eye on this one.

Update, latest gfs indicates the storm could be even worse with hurricane force gusts over Scotland.


Title: Re: Significant Storm For Ireland & Scotland Sat Nov 21st
Post by: Padraig OBrien on November 16, 2009, 06:16:13 pm
Some saying Hurricane winds for Dublin City!!!! Good lord


Title: Re: Significant Storm For Ireland & Scotland Sat Nov 21st
Post by: martinastro on November 16, 2009, 06:41:16 pm
I just hope it doesn't get downgraded, still 5 days to go....its' going to be wet and windy anyway no matter if there's a big storm or not.


Title: Re: Significant Storm For Ireland & Scotland Sat Nov 21st
Post by: martinastro on November 16, 2009, 07:13:36 pm
Latest GFS has moved the centre of the storm further S and E with 100mph winds for W. Ireland.

Check out the convective maps for N. Ireland and UK for Wed and Thur - the significant tornado parameter is black in colour with phenomenal wind shear...I've NEVER seen that before!!!.


Title: Re: Significant Storm For Ireland & Scotland Sat Nov 21st
Post by: brianb on November 16, 2009, 07:13:56 pm
Quote
its' going to be wet and windy anyway
Defeatist - I hope it's dry, calm & clear.


Title: Re: Significant Storm For Ireland & Scotland Sat Nov 21st
Post by: martinastro on November 16, 2009, 07:20:23 pm
lol, Brian, I very much doubt it will be dry and clear...but who knows...you could be correct. I noticed that the BBC Newsline weather stayed well clear from taking about the weekend.


Title: Re: Significant Storm For Ireland & Scotland Sat Nov 21st
Post by: martinastro on November 16, 2009, 07:30:08 pm
Never seen charts like these before!. There's a powerful tornado and supercell signature for nearly two days during mid week.

(images deleted)

All this means nothing of course unless there's instability and lift in the first place to generate cbs which can take advantage of shear.


Title: Re: Significant Storm For Ireland & Scotland Sat Nov 21st
Post by: Padraig OBrien on November 16, 2009, 09:15:44 pm
If it does hit us that hard god help Ireland


Title: Re: Significant Storm For Ireland & Scotland Sat Nov 21st
Post by: martinastro on November 16, 2009, 09:46:28 pm
Check out the latest chart!

(http://i36.tinypic.com/vfi4j5.jpg)


Title: Re: Significant Storm For Ireland & Scotland Sat Nov 21st
Post by: jjb on November 16, 2009, 09:50:25 pm
Looks like it is going to be rough for a ween of days good idea to keep a  camera happy just in case something happens.


Title: Re: Significant Storm For Ireland & Scotland Sat Nov 21st
Post by: markt on November 16, 2009, 10:36:45 pm
Crikey, sounds rough!  Will keep my eye on that one...


Title: Re: Significant Storm For Ireland & Scotland Sat Nov 21st
Post by: paulster78 on November 17, 2009, 04:11:51 am
This is damn exciting stuff at the minute but id say the models will never hold for fri/sat and we'll end up with some drizzle!  (hope im wrong tho  :) )


Title: Re: Significant Storm For Ireland & Scotland Sat Nov 21st
Post by: martinastro on November 18, 2009, 01:34:14 am
This is the latest, if this chart actually came to pass there would be risk of loss of life in SW Ireland...

(http://i48.tinypic.com/w0lsvt.jpg)

However, as Paul said, these are just models and are not to be trusted this far out...we could just end up with rain on our face...but let's wait and see.


Title: Re: Significant Storm For Ireland & Scotland Sat Nov 21st
Post by: martinastro on November 20, 2009, 04:18:32 pm
A discussion is started for this coming Sat/Sun convective outlook for UK & Ireland.

 Period of interest;

Current forecast synopsis would suggest potential for a split front during late Sat night into Sun morning. Then post frontal troughing through the Sunday period. Whilst the UKMO synopsis no longer shows a defined split along the frontal boundary the GFS model would tend to differ for later within the passage of the cold front; SE UK. The secondary 'surface' feature looks to develop within a vorticity rich environment with better instability potential.

A number of surface troughs are progged to then traverse both the UK & Ireland through Sunday under continued strong vertical shear profiles and deep upper cold pooling aloft.

Certainly another windy and convective weekend in store, with the potential for thundery activity!



Title: Re: Significant Storm For Ireland & Scotland Sat-Sun Nov 21st/22nd
Post by: martinastro on November 21, 2009, 11:41:25 am
UKww Weather Warning for Heavy rain and severe gales


Issued Saturday 21/11/2009 1015BST

Areas affected: N & W half of Wales, NW England, SW & W Scotland, N Ireland

Valid from: 1200GMT Saturday 21st November - 2359GMT Sunday 22nd November


--------------------------------------------------------------------------------

General evolution:


The weather during this Warning period will be dominated by a major, deep (962mb Sunday 1800) Atlantic low pressure system that will move NE towards NW Scotland later Sunday. On its southern flank, more moist SW winds will bring fronts eastwards during the forecast period. High pressure over Europe means that a steep pressure-gradient will remain a feature throughout.


Forecast:
Wet and windy again sums up the forecast with gale to severe gale-force winds causing problems at times: however, the key feature is further heavy rainfall that will occur initially in the forecast period. Latest model guidance suggests totals of 40-45mm for W Wales and NW England but the Lake District and hills of SW Scotland: adding in a factor for enhancement over the mountains and these figures could be exceeded by 50% or more giving 80mm+ in places. The ground is already saturated so that run-off will be very high, leading to further widespread standing water on roads and rivers/streams in full spate. Prone flood-plain areas are very likely to see more -possibly serious- flooding leading to disruption . Road travel is likely to be adversely affected and driving conditions will be hazardous throughout the period. Winds will increase in the far W and NW later on Sunday with severe gales affecting northernmost N Ireland and W Scotland with gusts to 65-70mph possible.

This forecast period ends on the evening of Sunday 22nd November but readers should be aware that another round of severe weather looks likely to affect western & NW parts again by midweek with further rain & very windy conditions a cause for concern - more on that nearer the time.
 

Issued by DJW for UKww, 1015GMT 21/11/2009


Title: Re: Significant Storm For Ireland & Scotland Sat-Sun Nov 21st/22nd
Post by: martinastro on November 21, 2009, 04:04:18 pm
(http://i48.tinypic.com/34il5ky.jpg)

SEVERE THUNDERSTORM WATCH 2009/009

A TORRO TORNADO WATCH has been issued at 14:30GMT on Saturday 21st November 2009

Valid from/until: 14:30 - 15:00GMT on Saturday 21st/Monday 23rd November 2009 for the following regions

**NOTE THAT THIS IS AN UPGRADE FROM THE PREVIOUS DISCUSSION***

Parts of (see map)

Eire

N Ireland

THREATS

Wind gusts to 70mph; hail 10-15mm diameter; CG lightning; isolated tornadoes

DISCUSSION

Unstable, strongly sheared environment will be in place across the area for the next couple of days (hence the unusually long validity period. This will bring showers and thunderstorms from time to time, with a risk of severe wind gusts. This is especially true on Sunday as a deep low pressure system moves through, although there are some question marks over how much of the activity will be convective as this moves through. In addition, hail and CG lightning are likely. A small risk of tornadoes exists although the main risk will be strong winds.

PLEASE NOTE THAT FURTHER WATCHES MAY BE ISSUED LATER ON, FOR PARTS OF GREAT BRITAIN...A RISK OF TORNADOES/STRONG WINDS EXISTS FOR SOUTHERN PARTS LATER TONIGHT AND FOR A TIME TOMORROW MORNING

Forecaster: RPK.


Title: Re: Significant Storm For Ireland & Scotland Sat-Sun Nov 21st/22nd
Post by: martinastro on November 21, 2009, 04:20:03 pm
Some serious t-storms moving up Ireland now - here's the lightning...

(http://i45.tinypic.com/n1vt44.gif)


Title: Re: Significant Storm For Ireland & Scotland Sat-Sun Nov 21st/22nd
Post by: Padraig OBrien on November 21, 2009, 04:29:43 pm
Thanks Martin for above,

Heavy shower here atm small rumble of thunder before it came in distance really squally
 behind it


Title: Re: Significant Storm For Ireland & Scotland Sat-Sun Nov 21st/22nd
Post by: martinastro on November 21, 2009, 06:20:32 pm
Seen big convective lines at dusk over Maghera passing by the Moon, they were the left overs of that thunderstorm earlier in the SW, got some images of the clouds. This could be a late night, I suspect distant storms will be seen for 100's of miles, at least the flashes will be visible. Sun might be a chase day!

Just seen RTE news, the flooding in the Republic is unbelievable!...more bad weather into next week too. This is fast becoming an historic weather event.


Title: Re: Significant Storm For Ireland & Scotland Sat-Sun Nov 21st/22nd
Post by: paulster78 on November 21, 2009, 06:58:02 pm
Those are really devastating floods its going to be hard times for alot of people coming up to Christmas.  Yeah Martin tomorrow looking good for some nice showers/t-storms, must get the batteries charged.


Title: Re: Significant Storm For Ireland & Scotland Sat-Sun Nov 21st/22nd
Post by: martinastro on November 21, 2009, 07:03:54 pm
Paul, check out the sferics charts, the entire W coast of Ireland and Atlantic sea board is packed with lightning. Someone is getting a good show tonight, hoping they will move inland, in either case looking forward to some night flashes among the stars. Hoping to see something on Sun, I would be happy enough with a good gust front. With that phenomenal shear around the enviornment will be perfect for tornadoes if strong convection can form. Best of luck.

Yes, the situation in the ROI and Cumbria is horrific!


Title: Re: Significant Storm For Ireland & Scotland Sat-Sun Nov 21st/22nd
Post by: martinastro on November 21, 2009, 07:06:43 pm
(http://i46.tinypic.com/nmxjqo.jpg)

SEVERE THUNDERSTORM WATCH 2009/010 (PLEASE NOTE SW009 IS STILL IN EFFECT)

A TORRO SEVERE THUNDERSTORM WATCH (AREA B) has been issued at 17:45GMT on Saturday 21st November 2009

Valid from/until: 17:45 - 23:59GMT on Saturday 21st/Sunday 22nd November 2009 for the following regions

Parts of (see map)

W Scotland

Wales

W England

S England

THREATS

Wind gusts to 60-70mph; hail 10-15mm diameter; CG lightning; isolated tornadoes

DISCUSSION

Unstable, strongly sheared environment will be in place across the area for the next couple of days (hence the unusually long validity period. This will bring showers and thunderstorms from time to time, with a risk of severe wind gusts. A small risk of tornadoes exists too. A trough will cross southern parts of England tomorrow morning, enhancing the tornado risk. A tornado watch may be issued later this evening to cover this risk.

FORECASTER: RPK



Title: Re: Significant Storm For Ireland & Scotland Sat-Sun Nov 21st/22nd
Post by: paulster78 on November 21, 2009, 07:18:56 pm
Wow, thats alot of lightning. might go out to see if i can view any distance flashes.


Title: Re: Significant Storm For Ireland & Scotland Sat-Sun Nov 21st/22nd
Post by: martinastro on November 21, 2009, 07:20:33 pm
Go for it, I might try that too. Best of luck.

here's the storm on SAT24 - beautiful. You can see the anvils on those t-storms over Ireland! The big one to the SW must have been a severe storm, check out the anvil about 3 times the length of Lough Neagh with an overshooting top.

(http://i47.tinypic.com/2ilf2xc.jpg)


Title: Re: Significant Storm For Ireland & Scotland Sat-Sun Nov 21st/22nd
Post by: martinastro on November 21, 2009, 07:30:03 pm
latest lightning

(http://i47.tinypic.com/ilwsuo.gif)


Title: Re: Significant Storm For Ireland & UK Sat-Sun Nov 21st/22nd
Post by: Padraig OBrien on November 21, 2009, 07:56:59 pm
Observing a lot of lightning flashes from a storm out in the irish sea huge anvil on it lighting up


Title: Re: Significant Storm For Ireland & UK Sat-Sun Nov 21st/22nd
Post by: martinastro on November 21, 2009, 08:03:16 pm
Thanks for the report, those look like organized multicells, that's now W and E Irish coastal regions getting storms now. Some of those are probably severe, just a pity they are not inland. Tempted to go out to look for flashes now.


Title: Re: Significant Storm For Ireland & UK Sat-Sun Nov 21st/22nd
Post by: paulster78 on November 21, 2009, 09:01:50 pm
Was about to head out but alot of cloud has rolled in here so visibility not so good. Hoping the freshening wind will blow a few of those cells close to the sligo coastline a bit further inland. Been a long time since i seen a night time storm.


Title: Re: Significant Storm For Ireland & UK Sat-Sun Nov 21st/22nd
Post by: martinastro on November 21, 2009, 11:20:46 pm
I drove out to the middle of nowhere and did a long cold watch, only seen one flash of lightning to the south, however the sky was darn dark with incredible stars, I was watching for aurora activity too. Car was shaking pretty good in the wind. Hoping to see something cool on Sun, car and camera are at the ready.


Title: Re: Significant Storm For Ireland & UK Sat-Sun Nov 21st/22nd
Post by: martinastro on November 21, 2009, 11:21:52 pm
Sunday's outlook from Tony Gilbert...

(http://i47.tinypic.com/2psrehs.jpg)

Slight Risk of isolated Thunderstorms & Severe Gusts UK & Ireland 00Z Sun- 12Z Mon

Slight Risk of Tornado Development central south UK through to E. Anglia 10Z-17Z Sunday

A complex forecast with several areas at risk of thunderstorms with hail and severe gusts, though pretty much spread out over a large area. Regions at risk of isolated stronger convection are relatively sparse in nature and would be almost impossible to mark with separate convective boxes. Prime attention ATM is given to the risk of a tornado event red box during Sunday. Sharp surface trough expected to develop along the English Channel during Sun morning triggering some heavy rain and convective showers inland within a highly sheared environment. PV is stacked vertically and a breakaway upper trough influences lift in the region. ATM there looks to be some restriction regarding the dry intrusion which looks to remain offshore. This is the missing link and is the reason behind issuing a 'Slight' risk instead of a  'Moderate' risk for tornado genesis!....the potential here nevertheless should be regarded as high priority; Streamlining is actually shown to bow around part of this trough. This is not a common prediction for surface troughing as I can recall. Possible suggestive of some very localised low pressure building at surface! The potential for low level directional shear under these conditions could be exceptional!!

A further risk extended into Mon morning as a cold front and TP moves east bringing another round of thundery showers along the English Channel. Though based on a calculation of storm steering winds this potentially strong convection looks to remain just offshore! A small variation in wind vector could just as easily bring this lot ashore am Mon.



Title: Re: Significant Storm For Ireland & UK Sat-Sun Nov 21st/22nd
Post by: paulster78 on November 22, 2009, 01:21:07 am
Check out the hook winding up just off the west coast, pretty mean looking.

(http://i613.photobucket.com/albums/tt215/paulster78/storm221109.jpg)


Title: Re: Significant Storm For Ireland & UK Sat-Sun Nov 21st/22nd
Post by: martinastro on November 22, 2009, 01:37:24 am
wow! - that looks nasty!


Title: Re: Significant Storm For Ireland & UK Sat-Sun Nov 21st/22nd
Post by: Padraig OBrien on November 22, 2009, 07:26:27 am
The latest from Estofex

Storm Forecast




Storm Forecast
Valid: Sun 22 Nov 2009 06:00 to Mon 23 Nov 2009 06:00 UTC
Issued: Sun 22 Nov 2009 05:35
Forecaster: SCHLENCZEK
A level 1 was issued for parts of the Bay of Biscay, S UK, NW France and the British Channel mainly for severe wind gusts and tornadoes.

A level 1 was issued for N Ireland and N UK mainly for severe wind gusts and to a lesser extent for tornadoes.

SYNOPSIS

The dominant feature for convective activity on Sunday is a low pressure system over the British Isles. A 965 hPa surface low has developed ahead of a shortwave trough west of Ireland. Another upper trough over the Irish Sea will affect most parts of the UK and the North Sea during the period and is associated with the cold front of the surface low. This cold front stretches from the Strait of Gibraltar via southwestern France and the Netherlands towards S Norway at 06 UTC. West of the Bay of Biscay, a small area of convective clouds is associated with a weak thermal wave and an upper vort-max south of the low pressure system, affecting W France and S UK in the next few hours.

An upper ridge over the central Mediterranean will provide stable and warm conditions in most parts of the Mediterranean and central Europe.

DISCUSSION

...Bay of Biscay, W / NW France, British Channel, S UK...

About 500 J/kg MLCAPE are forecast in the vicinity of an upper vort-max which will cross the area between 06 UTC and 12 UTC from the west to the east. In this environment, strong vertical shear (20 m/s DLS, 15 m/s LLS) is expected given 30 m/s at 850 hPa and up to 40 m/s at 500 hPa. Convective cells will tend to merge into small bowing segments with severe wind gusts as main threat. SRH1 / SRH3 increases to values near 200 / 300 mē/sē over W / NW France and some short-lived mesocyclones are likely. Locally enhanced LLS near the coastlines may allow a few isolated tornadoes with an isolated strong (F2 - F3) tornado not completely ruled out. There is no area with much higher probability of tornadoes in the models which precludes a LVL2 in this case. The associated upper level feature will undergo substantial weakening after landfall and the threat of tornadoes will diminish in the eastern parts of this LVL1 area. Nevertheless, isolated convectively enhanced severe wind gusts will be possible there.

...Ireland, N England, Scotland...

Another area with low-end instability is located in the wake of the bent-back occlusion west of Ireland. Multicell storms may organise into narrow lines with bowing segments that will cross parts of Ireland / northern UK on Sunday morning / afternoon. Tornadoes appear less likely than in the other area of discussion as deep layer shear reaches only values of 10 - 15 m/s which is probably not sufficient for deep mesocyclones but an isolated tornado cannot be ruled out as strong ( >15 m/s ) LLS and about 300 mē/sē SRH1 are forecast. The main threat in this region will be damaging (33 m/s) gusts that are convectively enhanced. Most of the wind should be due to the intense gradient flow with 35 - 40 m/s forecast at 850 hPa. As the surface low occludes, the severe wind gust threat will decrease to the northeast.



Title: Re: Significant Storm For Ireland & UK Sat-Sun Nov 21st/22nd
Post by: paulster78 on November 22, 2009, 11:39:54 am
Some real heavy and squally showers hitting me now


Title: Re: Significant Storm For Ireland & UK Sat-Sun Nov 21st/22nd
Post by: markt on November 22, 2009, 12:52:53 pm
This certainly is some rough weather we're having at the moment!   :o


Title: Re: Significant Storm For Ireland & UK Sat-Sun Nov 21st/22nd
Post by: martinastro on November 22, 2009, 04:47:43 pm
I have been up to Lough Neagh in Ballyronan and there's plenty of flooding, the jeti's are covered in water and the shore looks like a tsunami had hit it with debris washed so far inland that logs and sticks have passed beyond the swings, there must have been serious flooding there recently. It sure is a wild day, although  extremely disappointing with a convective point of view, I didn't see any convection at all, clouds just looked like thick soup. Quite a let down so far...more wet weather on the way though so anything is possible.


Title: Re: Significant Storm For Ireland & UK Sat-Sun Nov 21st/22nd
Post by: Padraig OBrien on November 22, 2009, 05:55:19 pm
Had some flooding experience myself today  i was literally standing in the middle of a lake


Title: Re: Significant Storm For Ireland & UK Sat-Sun Nov 21st/22nd
Post by: paulster78 on November 22, 2009, 10:54:11 pm
As Martin said bit of a no-show for any convection today, thought at the very least id see a few updrafts or cbs but just a blanket of cloud.  >:(   Although there was some heavy rain and impressive gusts associated with the showers. It was probably a lot worse cause all i did was look out at it through the window.


Title: Re: Significant Storm For Ireland & UK Sat-Sun Nov 21st/22nd
Post by: martinastro on November 22, 2009, 11:21:46 pm
I agree with you Paul, it was a damp squip and such a let down after that big build up earlier in the week. I was looking at the CAPE charts last night and there was no instability over NI at all so I couldn't understand why we where included in the risk maps.

Drove around after dark taking video of the gales but that was about it apart from some heavy showers and squalls. Seen one dark anvil in the dusk sky going over the Moon but that was the end of it.


Title: Re: Significant Storm For Ireland & UK Sat-Sun Nov 21st/22nd
Post by: brianb on November 23, 2009, 11:32:31 am
Quote
it was a damp squip
A bit more than "damp". Rainfall during the "shower" that ran continuously from 10:30 am till late evening was around 40mm, more than the whole of the previous week combined. And the wind ... yeah, we've had worse, but here it's very unusual to get such a sustained, gusty wind from that direction. It's penetrated the seals on my kitchen skylight, first time I've had a problem in 16 years.

Quote
such a let down
I'm very grateful it was no more severe than it actually was.