Atlantic Storms - Spring 2012

[Robbie Garrett]

Looks set to be quite an active period coming up...having a look at todays 06z runs!!

STORM 1 - Monday 9th April 2012 - Thursday 12th April 2012

STORM 2 - Sunday 15th April 2012 - Thursday 12th April 2012

ECMWF

Edited April 5, 2012 by Robbie Garrett

[Zenarcher]

Yes it does seem we are in for a more unsettled period however I wouldn't say storm 1 & 2 more of a wet and windy day.

[Aaron]

Doesn't look very wet here.. the Pennines.. god damn the Pennines (except in winter!)

[Robbie Garrett]

Decent looking 'storm' low pressure Monday, with some fairly decent rainfall.

Secondary low trying to form on Tuesday...

Friday 20th Delivering a bomb situation, nearly??

Providing a fairly windy weekend,....

Edited April 6, 2012 by Robbie Garrett

[Robbie Garrett]

Monday brought some fairly decent rainfalls, I take it anyone has the totals?? Was blustery but not too bad.

Sundays 15ths storm, ends up on the GFS later than scheduled for next Tuesday.... looks very potent,

[Zenarcher]

The UKMO and ECM both develop this system slightly different one to watch though.

[Zenarcher]

Models still very unsure on this low pressure system even at 96 to 120 hours.

ECM: shows a tight low of 980mb to the West of the UK creating severe gales across Ireland and Western parts of the UK.

GFS: The 12z run had a very deep low to the West of Scotland bringing storm force winds but has completely changed on the 18z the low has moved up to Iceland but still brings a short period of windy weather for Scotland.

UKMO: Not keen on developing any low at all until Tuesday which is placed over England this would bring a wet and windy day but nothing stormy.

NOGAPS: Agrees with the UKMO.

JMA: Agrees with the 18z GFS.

GEM: Doesn't develop a low like any of them.

[Robbie Garrett]

Yeah the models seem to be in confusion.

However...

This storm..

Sort of gets stuck over the north of the country.

##

AND then by the Wednesday, another storm is brewing... but the track is what's interesting me.

Going to be likely very very very wet next week, and a tad windy but not exceptional.

[Zenarcher]

Yes still some large disagreements this morning. I'm not paying much attention to Wednesday yet because we still don't know about Monday/Tuesday.

GFS: The 00z run showed a low over Scotland bringing wet and windy weather the 06z has kept it in the same area but has moved it slightly more North and also has moved over to agree slightly more with the UKMO this is us finally starting to edge towards agreement now.

ECM: Disagrees with all the runs today still showing a tight low to the West of the UK this would bring storm force winds to Western parts of Ireland and Scotland.

UKMO: Still not keen on developing any low at all we do end up with a shallow low over the UK it would bring just a wet and windy day.

NOGAPS: Has a rather tight low sitting to the South of Iceland on its 06z run it would bring windy weather to Scotland.

GEM: A very similar run to the UKMO.

Overall we are starting to see somewhat agreement come into place between UKMO GFS and GEM meanwhile the rest gain very little support.

Another update on this after the 12z runs.

Edited April 12, 2012 by weathermaster

[Zenarcher]

Starting to see the models agreeing but we still have some large disagreements yet. I suspect on Friday morning or this time tomorrow we will know for sure.

12z runs

GFS: Shows a deep tight low of 975mb to the West of Scotland. This would bring severe gales across Scotland and storm force winds for Ireland. Bear in mind the GFS commonly over does the low pressure systems. One thing to note is it has moved over and agreed with the ECM.

ECM: Remaining very consistent and is starting to pick up some agreement now. It has a 975mb low as well although the center is not as deep as the GFS and its further out away from the UK this would bring severe gales just to Ireland.

UKMO: Amazingly its still not keen on bringing in a low like the ECM and GFS and remains the same as this morning.

NOGAPS: Backs up the UKMO model.

JMA: Gives support to the UKMO as well.

GEM: Agrees with the ECM and GFS although the low it makes is not as deep only 980mb.

So yesterday we had most of them on their own but now we have 3 against 3 another 12 or 24 hours and we will know which ones are correct.

Edited April 12, 2012 by weathermaster

[Robbie Garrett]

975mb in April, that's pretty low isn't it? What's the lowest recorded in the UK for April??

[Aaron]

I had a pressure reading of 978mb or around there a few days ago.. so nothing exceptional.

[Zenarcher]

975mb in April, that's pretty low isn't it? What's the lowest recorded in the UK for April??

I'm not sure on the lowest recorded in April but it will be a lot lower than 975mb. I remember near the end of May last year a 975mb low passed over the UK. So even in May something like it can happen.

Edited April 13, 2012 by weathermaster

[Robbie Garrett]

Thanks guys,

Quite a difference in strength and track between the GFS and ECMWF

[Zenarcher]

Yeah the 06z run seemed a bit of an outlier and now the GFS 12z agrees on a very similar path to the other 12z runs so far today.

[Zenarcher]

A quick summary on the 12z runs,

GFS: Shows a tight 975mb low to the West of Scotland which eventually weakens and moves over Ireland.This would bring gales or severe gales across the UK and storm force winds for Ireland.

ECM: Does the same as the GFS although the low takes slightly longer to weaken as it passes over Ireland. ECM has been the most consistent model out of them all with this.

UKMO: Only has the low at 985mb so not as strong this would bring gales to those in the Western parts and severe gales for Ireland.

NOGAPS: Agrees with the UKMO.

JMA: Also agrees with the UKMO. But it has to be said this model has done the worst on picking this low up as it only picked it up today!

GEM: Its the only model that's brought the low closer into Northern Ireland. Severe gales would occur on its run for Ireland and gales in the West coasts.

Overall we have learned a lot more today. All of the models excluding GEM have the low to the far West of Scotland. The depth seems to be around the 975mb to 985mb range. How fast it will weaken is also a bit hazy at the moment.

Edited April 13, 2012 by weathermaster

[Robbie Garrett]

What's the reason for this weakening?? tropical cyclone in birth nature?? feeding off the ocean?? (seem that way, but probably not)

[Zenarcher]

What's the reason for this weakening?? tropical cyclone in birth nature?? feeding off the ocean?? (seem that way, but probably not)

A small area of low pressure starts getting carried in the jet stream once it leaves and goes into the colder air it deepens. The reason why it weakens is because of high pressure building up in the Atlantic and over our North forcing it down South over Ireland.

The problem the models are having at the moment is how much cold air will it get when it leaves the jet stream for example ECM pushes it into colder air making it go to 975mb but the UKMO has it going into less colder air making it a 985mb.

Edited April 13, 2012 by weathermaster

[Zenarcher]

A summary on the 00z runs,

GFS: Both its 00z and 06z runs have gone against most models this morning by having the low closer and more South than any other model. This would bring severe gales for Scotland and storm force winds for Ireland.

ECM: Has the low further out and not as deep as yesterday now at 980mb. Its solution would have gales for Scotland and severe gales for Ireland.

UKMO: Completely agrees with the ECM on both depth and positioning of the low.

NOGAPS: Another model agreeing with the ECM.

GME: This model is a short range one now as we get closer it can get used. It also backs up the ECM.

JMA: Backs up ECM.

GEM: Agrees with the GFS.

Overnight and this morning we now have better agreement over its depth and positioning. 5 Models agree with each other that the low will be further out and around 980mb bringing gales and severe gales across Western parts of the UK. Only 2 models want to bring in the low a bit closer and deeper this would bring severe gales and storm force winds for the Western UK.

[Zenarcher]

A updated summary on things at the moment.

12z runs.

GFS: It has moved the low out slightly but still closer to the UK than most of the other models. On the 18z very little changes appear on it at the moment the GFS seems confident about it.

The five others: ECM, UKMO, GME, JMA, and NOGAPS all have the low more further out and less tense and deep looking they also seem confident and refuse to change as well.

GEM: Agrees with the GFS.

Overall very interesting weather model here will we see 5 models collapse to their feet and say yes GFS and GEM your right or will it be the other way around?

[Robbie Garrett]

What interesting is GFS was showing this since 5th April

[Coast]

I'm not paying much attention to Wednesday yet because we still don't know about Monday/Tuesday.

Hi-res charts coming through for midday Tuesday now:

Going to see where this first hits the UK; Ireland? Scotland or Northern England????

Or will it crash into the English Channel??????

[Robbie Garrett]

I am pretty sure it may follow the route of the Monday/Tuesday Night storm. Surely it's because the jetstream is headed that way?? (English Channel)

[Robbie Garrett]

A bit more than a windy day for south west Ireland.

[Zenarcher]

For those looking for a detailed description for Monday to Wednesday look here http://forum.netweather.tv/topic/73030-model-output-discussion-15th-april-onwards/page__st__20#entry2291990