Astronomy, Photography and Weather

General Category => Weather & Atmospherics => Topic started by: martinastro on March 15, 2010, 08:53:24 pm



Title: Late March T-storm Potential UK & Ireland 2010
Post by: martinastro on March 15, 2010, 08:53:24 pm
It's a little early to get too excited yet however the weather is taking a more interesting turn in the near future. First of all the high pressure is being replaced by several low pressure areas with Atlantic frontal systems arriving across UK and Ireland on Wed and Thurs on a SWly flow. These will deliver heavy rain and strong winds in places. The warm front will be light however the cold front could pack more of a punch with low end CAPE being forecasted by GFS. The convective maps are showing weak tornadic and supercell parameters so a tornado is possible if there's enough instabiliity and lift/forcing along the front, although this is low risk at the moment.

Of greater interest, behind the fronts a SWly or Sly mild unstable flow moves in bringing as much as 100 to + 600 CAPE and negative LI's for much of Ireland and S/W Britain for Mon March 22nd which should produce some beefy thunderstorms in places, perhaps wide spread in nature in the south and midlands. There may also be thundery showers on Sun night for parts of NW Scotland. It's too early yet for specifics and hopecasting but the set-up is there for unsettled weather and early Spring thunderstorms!. Here's Mon's chart. Things will change alot before then for better or for worse. Please continue any convective discussion/forecasts/reports on this thread. Thanks.

(http://i40.tinypic.com/2yv1ok1.png)


Title: Re: Late March T-storm Potential UK & Ireland 2010
Post by: markt on March 16, 2010, 08:35:05 am
FIngers crossed for some interesting weather!  ;D


Title: Re: Late March T-storm Potential UK & Ireland 2010
Post by: martinastro on March 16, 2010, 07:24:46 pm
Latest GFS has updated CAPE over NI for Mon, there could be activity on Sun also for those further S and W. Tony Gilbert says there's a slight chance of a t-storm on Sat/Sun due to post-frontal troughing and convergence. Time will tell. Others point out that the Sea temps are at their coldest for this time of year which can inhibit convection, however on the plus side the Sun is now strong enough to produce storms inland. Someone also pointed out that very thundery Springs often follow a cold Winter.


Title: Re: Late March T-storm Potential UK & Ireland 2010
Post by: Padraig OBrien on March 17, 2010, 03:07:53 pm
Some nice convection occuring in a sweltering 16.3c lol it s a lovely day here by the way

Happy St Patrick's Day to all on the forum from the Republic Of Ireland! :D


Padraig


Title: Re: Late March T-storm Potential UK & Ireland 2010
Post by: martinastro on March 17, 2010, 06:36:06 pm
Here's the latest GFS run for Mon.

(http://i43.tinypic.com/pt574.jpg)


Title: Re: Late March T-storm Potential UK & Ireland 2010
Post by: martinastro on March 17, 2010, 07:41:00 pm
Latest GFS is in, Monday looks good, now Tues looks even better!. If this actually happens I will be chasing on both days.


Title: Re: Late March T-storm Potential UK & Ireland 2010
Post by: paulster78 on March 17, 2010, 08:01:24 pm
Im trying to hold off getting too excited here for next weeks potential, would be great to see although im busy until 4pm on both mon and tue so it would kill me to miss out on the first storms of the year-even some decent convection would be a bonus. :)


Title: Re: Late March T-storm Potential UK & Ireland 2010
Post by: paulster78 on March 18, 2010, 02:14:23 pm
Some sferics embedded in this front over the Republic   http://andvari.vedur.is/athuganir/eldingar/ (http://andvari.vedur.is/athuganir/eldingar/) 


Title: Re: Late March T-storm Potential UK & Ireland 2010
Post by: martinastro on March 18, 2010, 04:18:12 pm
...and the border areas too, quite a few thunderstorms from that cold front - that was a surprise  :)


Title: Re: Late March T-storm Potential UK & Ireland 2010
Post by: martinastro on March 18, 2010, 07:47:32 pm
Look at GFS for Thurs, +600 CAPE and LIs of -3 :)


Title: Re: Late March T-storm Potential UK & Ireland 2010
Post by: Padraig OBrien on March 18, 2010, 08:26:51 pm
didnt have any thundery activity here today despite sferics but had some quite heavy rain was quite weird seeing rain, has been snow most recently lol


Title: Re: Late March T-storm Potential UK & Ireland 2010
Post by: martinastro on March 19, 2010, 02:45:19 pm
oh dear - complete downgrade for Ireland/NI. Upgrade for Britain. Bloody GFS!!


Title: Re: Late March T-storm Potential UK & Ireland 2010
Post by: Padraig OBrien on March 19, 2010, 09:57:25 pm
having some heavy rain atm here in Kildare


Title: Re: Late March T-storm Potential UK & Ireland 2010
Post by: martinastro on March 19, 2010, 10:04:39 pm
Looks like convective showers for Britain on Sat, some of which could be thunderstorms. Meanwhile GFS is back on for Mon's t-storm potential for Ireland/NI, although the CAPE is reduced. Still early days yet but we are entering a more realistic time frame.


Title: Re: Late March T-storm Potential UK & Ireland 2010
Post by: martinastro on March 19, 2010, 10:11:27 pm
Here's Mon's GFS from Netweather. We still have an unstable post frontal airmass with heavy showers and thunderstorms possible. Hopefully it will get upgraded again over the next few days.

(http://i40.tinypic.com/xfcda1.jpg)

(http://i40.tinypic.com/2qbrrc8.jpg)


Title: Re: Late March T-storm Potential UK & Ireland 2010
Post by: Padraig OBrien on March 19, 2010, 10:43:09 pm
Thanks for that Martin yes lets hope for a big upgrade


Title: Re: Late March T-storm Potential UK & Ireland 2010
Post by: martinastro on March 20, 2010, 12:07:07 am
Big upgrade tonight Padraig for much of Ireland on Mon, also looks like some potential for S Ireland and Britain on Wed followed by Britain again on Fri. Hope this upgrade continues over the weekend.

http://www.netweather.tv/index.cgi?action=nwdc;sess=


Title: Re: Late March T-storm Potential UK & Ireland 2010
Post by: paulster78 on March 20, 2010, 12:30:49 am
Yes hopefully it does the trend looks good now and has been more or less showing this setup for a few days now :)


Title: Re: Late March T-storm Potential UK & Ireland 2010
Post by: JohnC on March 20, 2010, 09:41:49 pm
Martin - What's the minimum CAPE value that would be meaningful ?


Title: Re: Late March T-storm Potential UK & Ireland 2010
Post by: paulster78 on March 21, 2010, 11:16:53 pm
Still some action possible tomorrow according to latest GFS for N.Ireland with 300-400 CAPE and LI of -1. Also showing potential for Friday but thats too far off for any reliable forecast.


Title: Re: Late March T-storm Potential UK & Ireland 2010
Post by: Padraig OBrien on March 21, 2010, 11:53:11 pm
had a lovely day today highs of 15.4c nice and mild a little bit of convection in the late afternoon had some big drops of rain falling out of nowhere but very light

Padraig


Title: Re: Late March T-storm Potential UK & Ireland 2010
Post by: martinastro on March 22, 2010, 01:58:20 am
HI Paul, ESTOFEX have a t-storm risk out for N. Ireland and Scotland on Mon here...

http://www.estofex.org/

As for minimum CAPE? - it always depends on the other ingredients. 2000 CAPE would be amazing, however 100 to 200 CAPE in a highly sheared enviornment could produce severe winds and a tornado which has happened many times before in the UK. There were even 3 funnel clouds in the Republic a few years back with 50 CAPE.


Title: Re: Late March T-storm Potential UK & Ireland 2010
Post by: martinastro on March 22, 2010, 02:21:02 am
In more detail...

(http://i42.tinypic.com/2guw5jb.jpg)

Storm Forecast
Valid: Mon 22 Mar 2010 06:00 to Tue 23 Mar 2010 06:00 UTC
Issued: Mon 22 Mar 2010 00:00
Forecaster: SCHLENCZEK
No threat levels have been issued.

SYNOPSIS

An upper cut-off low enters the W Mediterranean on Monday morning, moving towards Italy. Over central Europe, conditions will become more stable as an upper ridge approaches from SW Europe. Over the North Atlantic, a large low pressure system affects Ireland, the British Isles and Iceland during the period.

DISCUSSION

...N Ireland, Scotland...

Near the upper cold core of an embedded trough west of Ireland, upper level cooling will lead to a few hundred J/kg CAPE. Strong QG forcing and enhanced deep layer shear (20 - 30 m/s) may lead to a narrow convective line that will cross the area from the west to the east during the morning / afternoon. Some isolated convectively enhanced wind gusts are expected to occur but a level 1 seems not warranted, though.


Title: Re: Late March T-storm Potential UK & Ireland 2010
Post by: paulster78 on March 22, 2010, 12:28:59 pm
Just been blasted with hail and some impressive gusts of wind as the leading edge of this shower hit here.


Title: Re: Late March T-storm Potential UK & Ireland 2010
Post by: martinastro on March 22, 2010, 12:39:37 pm
Tornado discussion from TORRO for us today..

Lightning already in W Ireland


Title: Re: Late March T-storm Potential UK & Ireland 2010
Post by: scott86 on March 22, 2010, 02:00:17 pm
Quite a beefy hail shower has just passed lisburn, some of it near pea sized and strong wind gusts but no lightning.


Title: Re: Late March T-storm Potential UK & Ireland 2010
Post by: brianb on March 22, 2010, 03:41:17 pm
Yeah, vicious showers here too h8h8h8h8h8


Title: Re: Late March T-storm Potential UK & Ireland 2010
Post by: Paul on March 22, 2010, 04:39:49 pm
Magnificent Mammatus clouds over Antrim at lunchtime - pics when I get home! Also the view across the Lough looked pretty stormy earlier.


Title: Re: Late March T-storm Potential UK & Ireland 2010
Post by: Padraig OBrien on March 22, 2010, 06:08:02 pm
what a day its been here had some very heavy squalls today both with hail, but it was the second one that got interesting had very heavy hail in it windows damaged 3 miles west of me now just few reports mind you. Heard a a few rumbles of thunder about two o clock and then reports of thunderstorm over Dublin


Title: Re: Late March T-storm Potential UK & Ireland 2010
Post by: paulster78 on March 22, 2010, 10:44:23 pm
It was great to see some interesting weather hit our shores again with a squall line passing over here this morning producing some good downdraft gusts and decent hail, this was followed by a number of showers into the afternoon and a fair few lightning strikes recorded across Ireland and the UK including some in the vicinity of Belfast Lough. I wasn't able to get out to get any images but just grabbed a few from the house.

(http://i613.photobucket.com/albums/tt215/paulster78/Weather%202010/22-3-10.jpg)

(http://i613.photobucket.com/albums/tt215/paulster78/Weather%202010/22mar10.jpg)

(http://i613.photobucket.com/albums/tt215/paulster78/Weather%202010/22310-2.jpg)


Title: Re: Late March T-storm Potential UK & Ireland 2010
Post by: martinastro on March 23, 2010, 12:05:22 am
I have really enjoyed reading all the reports and images turned a lively day indeed.
My computer is damaged so can't get online much until it visits the comp doctor so using sister's iPod at moment.

Conor and I chased today for hours, we intercepted the midday non severe squall line which poduced intense hail and poweful gusts which shook the car while I was driving up glenshane, we watched it travel to the ne and could see the well developed rear of the gust front with great precip curtains. We saw 2 rope-like forms among the hail which lowered near the sperrins, too far away to be certain but could have been a narrow funnel, we will never know for sure what it was. The convective line had a huge back sheared anvil with tiny mamma with considerable length.

After this we got on more lovely cells with large anvils and the best mamma I have seen in a long time with huge White bags over maghera, it was an exciting drive trying to get a lace to pull over and shoot it but we got there in the end. From drumlamph we saw hail curtains rotating slowly at close range in front of us which was VERY cool and something I have never seen before. The double bows on the hail curtains were spectacular! We ended the day at 16.00 since on the road from 11.00. We had to drive back to conors to check the radar and at one stage used the comp at the library so we were semi blind. That. Squall line was the length of ireland, it split in two and the n section hit us yellow and pink radar echoes, it produced lightning over w and e parts of n. Ireland so the gfs charts, torro and estofex were correct all along. There was 400 cape although I think it was less than this however the wind shear made the big difference. It was our forts chase of the year and it was a success, we really had a good time.

I got images but regret not taking vid of the squall line, conor has a few images on the ukww. Keep updating this section with further convective news/chat/forecasts. Glad everyone enjoyed the exciting weather!


Title: Re: Late March T-storm Potential UK & Ireland 2010
Post by: markt on March 23, 2010, 07:14:43 pm
Sounds good Martin!  ;D


Title: Re: Late March T-storm Potential UK & Ireland 2010
Post by: paulster78 on March 29, 2010, 06:02:46 pm
Quite a few thunderstorm sferics showing up in the English Channel just off the south coast. Could be a rough evening for the SE!


Title: Re: Late March T-storm Potential UK & Ireland 2010
Post by: martinastro on March 29, 2010, 07:21:05 pm
That's really worth keeping an eye on as you said Paul. Looks like plenty of lightning about to hit the south coast of Britain...

http://andvari.vedur.is/athuganir/eldingar/


Title: Re: Late March T-storm Potential UK & Ireland 2010
Post by: markt on March 29, 2010, 08:04:37 pm
Theres quite a few flashes in the SE corner there! This could be an interesting low pressure system, lets see how it develops over the next couple of days  :)


Title: Re: Late March T-storm Potential UK & Ireland 2010
Post by: martinastro on March 30, 2010, 02:03:10 pm
TORRO have a convective/tornado discussion out for England today....

http://www.torro.org.uk/site/forecast.php


Title: Re: Late March T-storm Potential UK & Ireland 2010
Post by: paulster78 on March 31, 2010, 02:21:36 pm
A number of sferics showing up including in the Republic, the English Channel again and the atlantic.  The English Channel really is seeing alot of electrical activity this past week

http://andvari.vedur.is/athuganir/eldingar/ (http://andvari.vedur.is/athuganir/eldingar/)