Astronomy, Photography and Weather

General Category => Weather & Atmospherics => Topic started by: martinastro on October 29, 2009, 02:48:29 pm



Title: Atlantic Storm This Weekend
Post by: martinastro on October 29, 2009, 02:48:29 pm
Looks like another Atlantic storm will affect many parts of Ireland and UK on Sunday. A very deep low will produce heavy rain and gales, with possibly severe gales in exposed coastal areas. The track of the low isn't certain yet but it could be a SW to NE mover. A nasty cold front from this system might have convective potential with a risk of line convection, possible squall lines, scattered lightning, and a risk of tornadoes over England (?). Looks like  a lively weekend to come. Will post more information on this when it comes available including any convective outlooks.


Title: Re: Atlantic Storm This Weekend
Post by: martinastro on October 29, 2009, 04:25:24 pm
Weather advisory out for NI on Sun...

http://www.metoffice.gov.uk/weather/uk/ni/ni_forecast_warnings.html?day=4


Title: Re: Atlantic Storm This Weekend
Post by: rjgjr on October 29, 2009, 04:41:13 pm
Good luck with any photo ops! Try and stay dry.


Title: Re: Atlantic Storm This Weekend
Post by: martinastro on October 29, 2009, 05:41:58 pm
Thanks Richard, I will do my best. There's going to be a lot of rain and wind this weekend and into next week with possibly two more lows moving across. The Jet Stream is over Ireland and UK so bad weather is a promise. I'm hoping for some sunset convection photo opps with mammatus but it would be tough to get the timing. We will see what happens...


Title: Re: Atlantic Storm This Weekend
Post by: martinastro on October 30, 2009, 01:22:19 am
(http://i37.tinypic.com/sena61.jpg)

Storm Forecast
Valid: Fri 30 Oct 2009 06:00 to Sat 31 Oct 2009 06:00 UTC
Issued: Thu 29 Oct 2009 20:03
Forecaster: TUSCHY

SYNOPSIS and DISCUSSION

Robust ridging atop most parts of Europe persists throughout the forecast. A progressive trough, affecting Ireland and Scotland during the late night hours and another one over SE-Europe spark isolated to scattered thunderstorms. Sticking with the ingredient based forecasting method, nothing severe is expected, next to strong wind gusts over Ireland and Scotland.

A prolonged (mostly stratiform in nature) rainfall event evolves around Istanbul and southwestwards during the forecast. Convective coverage increases during the night but expected strength and late increase of thunderstorm probabilities preclude a level 1 for now. Nevertheless, a 20m/s front parallel LLJ and a more or less stalling boundary  oint to isolated high rain amounts.



Title: Re: Atlantic Storm This Weekend
Post by: martinastro on October 30, 2009, 01:49:07 am
From Irish Weather Network...

A Weather warning of Severe gales for Sunday 1st November.

During the early hours of Sunday morning, a deepening area of low pressure will approach from the SSW. The track of the LP is key to where the winds are strongest initially. The track atm looks set to move through the southern half of the country and out into the Irish sea.

Winds will back southerly Halloween night and begin to strengthen. By midnight, S'ly gales will become established in the south and SE. Winds will pick up quickly in the southern 2/3 of Ireland into the small hours on Sunday.

The track of the LP exits Ireland on the east coast and wind will veer W'ly and increase further to become gale to severe gales. Strongest winds this time in the north.

As the area of LP moves into Scotland, another small LP of what looks likely to become complex moves down from the NW and wind begin to pick up again after a slight lull during Sunday afternoon. Winds again becoming widespread W to NW'ly gale to severe gale with higher gusts.

Accompanying the winds, there will be heavy rain with some places receiving upto 40mm during Sunday. Flooding looks likely.


Title: Re: Atlantic Storm This Weekend
Post by: markt on October 30, 2009, 09:46:32 am
It certainly looks like it's going to be a rough un'!


Title: Re: Atlantic Storm This Weekend
Post by: martinastro on October 30, 2009, 10:52:16 am
It has been a very nasty night and morning here (still is) due to strong winds and intense rain fall. That cold front is a beast.


Title: Re: Atlantic Storm This Weekend
Post by: paulster78 on October 30, 2009, 01:49:54 pm
Yeah its a monster i had to look at a world satellite image to get a full view of it!  Rain very heavy here now!


Title: Re: Atlantic Storm This Weekend
Post by: martinastro on October 30, 2009, 03:58:31 pm
GFS update is very confusing and actually downgrades the entire event with the low several hundred miles further south than previously predicted turning Sunday into a windy day rather than a stormy one. Everyone is waiting for the next update to see if this is a real pattern or not.

Today is certainly very nasty, I thought it was bad here but check out the radar for the Republic of Ireland...nasty!.


Title: Re: Atlantic Storm This Weekend
Post by: markt on October 30, 2009, 07:20:41 pm
Rain not quite reached me yet, but we have friends staying over this weekend so no doubt it will get us when we go out later on this evening!


Title: Re: Atlantic Storm This Weekend
Post by: martinastro on October 30, 2009, 07:37:04 pm
Frontal system has moved through here and it's drying up...it has been a nasty night and day. Loads of lightning over the Atlantic W of Ireland at the min. Post frontal airmass is quite unstable so heavy showers and coastal storms are a possiblity over the next day or two. TV forecast is still go for Sunday's storm but I think UK, England etc will get the strongest winds. Will wait and see what the experts say.

I'm hoping to catch a few moonbows soon.

Best of luck Mark.


Title: Re: Atlantic Storm This Weekend
Post by: JohnC on October 31, 2009, 12:43:05 am
I'm off here on Sunday. Takes two and a half hours. I'll have to wait for the  heavy rain to pass through before photographing out of the car though. Porth Cawl is between Cardiff and Swansea.

http://images.google.co.uk/images?hl=en&source=hp&q=porth+Cawl+lighthouse+wales&btnG=Search+Images&gbv=2&aq=f&oq=


Title: Re: Atlantic Storm This Weekend
Post by: martinastro on October 31, 2009, 12:53:18 am
Best of luck John, I hope you get some sweet images!

(http://i33.tinypic.com/2m4yaaf.jpg)

Storm Forecast
Valid: Sat 31 Oct 2009 06:00 to Sun 01 Nov 2009 06:00 UTC
Issued: Fri 30 Oct 2009 23:15
Forecaster: KOROSEC
A level 1 was issued for SW England towards Britanny mainly for severe wind gusts.

SYNOPSIS

Strong ridging over much of Europe persists while a deep trough enters western Europe during the day. Along with this trough, a rapidly deepening surface low with a cold front approaches British Isles by Sunday 06z. An elongated trough over eastern and southeastern Europe becomes more pronounced and a weak surface depression forms over southern Turkey and eastern Mediterranean sea.

DISCUSSION

... SW England towards Britanny ...

As the deep trough digs into the British Isles, a new surface depression forms on its southern edge. Its expected to reach southwestern UK by Sunday morning. Some differences between GFS and ECMWF models exist, where GFS has the low deeper and slightly faster/more to the east than ECMWF. While the convection is limited only the the narrow zone south of triple point, highly sheared environment (25m/s 0-6km shear, above 200m^2/s^2 of SREH in the lowest 3km layer) seems favorable for severe wind gusts along the rapidly moving cold front. Most of the wind gusts should be non-convective, however. A level 1 was issued for SW England area and southwestwards towards Britanny where higher probabilities for a few severe gust events exist. More to the north, quite steep lapse rates behind another low north of UK will overspread the region. Numerous showers should form in the cold airmass, while steep lapse rates could result in a couple hundreds J/kg of MLCAPE and allow some electrified convection as well.




Title: Re: Atlantic Storm This Weekend
Post by: martinastro on October 31, 2009, 06:24:32 pm
I was chasing today, the convection was really great for this time of year with superb updraughts and large multicells near Maghera, Tobermore, and Draperstown. I caught a poor contrast funnel cloud over E Maghera from a line of cu. Plenty of anvils and mammatus about to. I didn't hear any thunder as some of the convection was distant but according to the sferics charts the cells I seen did produce lightning. Nasty showers too. Images are a disaster today lol.

Reading interesting reports from the Republic of Ireland about mad roation and a funnel close the ground.



Title: Re: Atlantic Storm This Weekend
Post by: martinastro on October 31, 2009, 06:37:02 pm
Just found out TORRO had a tornado warning out today, Paul Knightly said the cells over N. Ireland had mesocyclones present. Observers in Dublin reporting the best t-storm they have ever seen with constant thunder.


Title: Re: Atlantic Storm This Weekend
Post by: paulster78 on November 01, 2009, 01:30:50 am
Some serious rain falling over the republic right now, I wonder will it be as intense by the time it reaches us here in the north!!


Title: Re: Atlantic Storm This Weekend
Post by: Padraig OBrien on November 01, 2009, 01:37:57 am
Heavy rain here now atm


Title: Re: Atlantic Storm This Weekend
Post by: martinastro on November 01, 2009, 01:42:25 am
Here's a video clip of some of the convection here today....

http://www.youtube.com/watch?v=JVDOPRcfKdE

Yea, the ROI are getting hammered!, I'm eager to see if those reds and whites will appear over NI. No sferics so far but I'm sure those strong radar echoes are from embedded cells in the front. Will be interesting to see what happens in the morning. Still waiting to see what ESTOFEX say.


Title: Re: Atlantic Storm This Weekend
Post by: martinastro on November 01, 2009, 02:43:19 am
(http://i33.tinypic.com/a0lbq1.jpg)

TORRO TORNADO WATCH 2009/007

A TORNADO WATCH has been issued at 23:20GMT on Saturday 31st October 2009

Valid from/until: 0430-1600GMT on Sunday 1st November 2009 for the following regions:

Parts of (see map)

England & Wales

S Scotland

Isle of Man

Channel Islands

Eastern Eire

THREATS

Tornadoes and wind gusts of up to 70mph; isolated CG lightning.

Rapidly developing Atlantic depression will move NNE late tonight and through tomorrow, the most likely track is through the Irish Sea into S Scotland. Close to the storm's centre, a marked dry intrusion/frontal fracture may allow some convection to develop, in a highly sheared environment. Marked low-level shear brings the risk of isolated tornadoes - in addition, wind gusts of 60mph are possible, perhaps 70mph in places. There is a small risk that a sting-jet may develop, enhancing the wind risk.

To the south of the depression, a well-marked cold front will surge eastwards...this is likely to split, so rather intense precip, perhaps with lightning, could develop ahead of the surface front, althoug rather stable/saturated low-level air ahead of the front would limit the risk of convective gusts. The surface front looks fairly likely to be marked by a line of forced convection. Strong low-level shear ahead of this means that misocyclones may develop along this front, bringing a risk of locally damaging winds, and perhaps isolated tornadoes. At this stage it is not clear whether this convection will be deep enough for lightning.

Even at this late stage, the track of the depression is stil rather uncertain. This forecast may well be updated/amended in the morning, as the situation develops.

Forecaster: RPK.


Title: Re: Atlantic Storm This Weekend
Post by: markt on November 01, 2009, 08:47:54 am
Some very impressive colours on the rainfall radar this morning across the uk!  :o