South East & East Anglia Regional Discussion - September 15th 2012>

[Coast]

Cheers K!

I'm reposting Liam Dutton's blog here to give an idea about the weather this weekend and how Nadine may or may not affect things:

As a weather forecaster, every once in a while I stare at the weather charts and just know that a particular forecast is going to be very difficult to get right.

Whilst this alone can be frustrating, it’s even more annoying when it happens over a weekend, because it’s when most people have time off and are outside doing things, for which the weather can potentially have a big impact. So here’s the headache for later this weekend. An ex-hurricane, now Tropical Storm Nadine, is lurking to the south of the Azores. Nadine was formerly a category one hurricane, but has now weakened and is drifting slowly around the eastern Atlantic.

What is certain is that Nadine itself won’t affect the UK, but what could happen is some of the energy and moisture associated with the storm could break away and spawn a new area of low pressure that will potentially arrive on our shores later this weekend.

Image copyright 2012 EUMETSAT – shows Tropical Storm Nadine (circled in red).

This is where the huge level of uncertainty lies. Weather computer models don’t tend to handle the remnants of former hurricanes or tropical storms very well when they arrive at our latitude. It’s often because of the huge amount of moisture and potential energy that they contain. If this is engaged by the jet stream, then they can explode to life spawning deep areas of low pressure bringing strong winds and heavy rain.

On the other hand, if the jet stream doesn’t engage with this moisture and potential energy, then low pressure is less likely to form and the end result can be very different.

How does the jet stream cause low pressure to form?

When the jet stream moves from west to east, as well as travelling in a straight line, it also bends around. In cases where it dips and curves in a broad U-bend shape, something called a trough forms. As the ribbon of air approaches the base of a trough, it slows down slightly as it goes around the bend, then accelerates once it has passed through it.

It’s the acceleration of the jet stream after passing through the U-bend that is a key factor because air high up in the atmosphere is sucked upwards and removed faster that it can be replaced at the surface. As a result of this process, air has a tendency to rise and pressure falls (forming an area of low pressure), resulting in cloud, wind and rain.

So how is this relevant for this weekend’s forecast?

At the moment, there looks to be a good possibility that a trough in the jet stream will interact with some moisture and energy tied in with the forward side of Tropical Storm Nadine. In the past few days, the weather computer models have disagreed on the eventual outcome, with some developing an area of low pressure that moves across us and others not.

However, today there seems to be more agreement amongst the various models which favour this interaction taking place, with an area of low pressure forming and moving over the UK later this weekend. How much uncertainty is there? Whilst the area of low pressure looks likely to form, I think the uncertainty lies in its track, how developed it will be, and when it will arrive. The latest information suggests that it may arrive across southern parts of the UK later on Sunday, before moving further northwards overnight into Monday.

This would bring a spell of rain and brisk winds, although the intensity of the rain and exact strength of the winds will depend on how developed the low pressure system ends up being.Despite Sunday’s forecast looking uncertain, it’s worth highlighting that most places on Saturday will have a fine day with sunny spells after a chilly start.

http://blogs.channel...st-weekend/2109

[Coast]

The gusty wind and rain seem to carry on into Monday in our region:

Wales gets soaked:

Bullseye!

There's bound to be a lot of helicity with the low circulating, but notice the blue ringed feature over the SE late Sunday/early Monday:

First of the hi-res charts coming into view now and the rain on HiRLAM is not insignificant for some of us here!

[NO LONGER POSTING]

Interesting look on things by the NAE

[Steve C]

Morning all.

That is very heavy rain indicated, Coast, especially as it's a 3 hour total! Looks like local flooding heaviness.

I'll be off for the weekend by lunchtime, so have a good weekend all, if I can't log in later.

[Snowangel-MK]

Morning,

Busy day for me, I'm not going to be around much today so in case I don't get chance to say it later....

[NO LONGER POSTING]

Coast, your the best man for this...

We have not had much rain recent months (I was away so don't know what you had then) the ground is very hard still...This rain coming...Will be falling on to hard ground, will surface run off be a problem here? In terms of the amount of rainfall falling in a short period of time...

[Coast]

Coast, your the best man for this...

I'm not sure I'm the best man for anything other than waffle!! Thank you anyway.

We have not had much rain recent months (I was away so don't know what you had then) the ground is very hard still...This rain coming...Will be falling on to hard ground, will surface run off be a problem here? In terms of the amount of rainfall falling in a short period of time...

I can imagine that low lying areas and those near run-off from the hills may see some significant accumulations if this rain comes as is being forecast in some models. As you say the ground is quite hard and the expected precipitation comes thick and fast on Sunday. I'm on heavy clay soil and have an incline to the house, but it does have a barrier wall to help. We will need to keep an eye on the radar through Saturday night and into Sunday to see what coming, but frankly we can't avoid it if we do get a deluge.

Netweather extras own NMM is just coming into range and has this lot on it's for first thing Sunday:

[Keraunic]

(I'm not sure I'm the best man for anything other than waffle!! Thank you anyway.)

Phooey! You're very good at this forecasting malarkey. So enough of this self depracation.

[Coast]

The caveat in this post is, it is the Daily Express

FIERCE gales and torrential rain will lash Britain at the start of next week as the tail end of a tropical storm arrives with a bang. Gusts of up to 80mph will bring the risk of structural damage while up to 3in of rain could trigger devastating floods.

Forecasters last night said Hurricane Nadine, currently over the Atlantic, will cause a deep low pressure system to hit the UK on Sunday. Although the main body of the storm will miss Britain the “child of Nadine†is likely to trigger a “nasty spell of weatherâ€.

The Met Office said much of the country should enjoy a warm and pleasant day tomorrow – but it will be the calm before the storm. Forecaster Helen Chivers said a swathe of warm air from the Mediterranean is gearing up to flood into the UK triggering the extreme weather.

We could see up to 40mm (1.6in) of rain. The worst weather will be in the South. Forecaster Helen Chivers. She said: “We are expecting a low-pressure system will be swept into the UK making it very wet and windy from Sunday and next week is looking very unsettled.“We could see up to 40mm (1.6in) of rain. The worst weather will be in the South. There is the potential for a very miserable day.â€

The Met Office has issued a severe weather warning for rain on Sunday and Monday in the South and Southwest. A statement said: “There is a risk that wet and windy weather will spread north-east on Monday.†It said the rain was likely to be heavy with potential for between 1 and 2in in places and up to 3in “more locallyâ€.

Jonathan Powell, forecaster for Vantage Weather Services, warned gusts of up to 80mph will be enough to damage buildings and trees. He said: “We are looking at winds of 70 to 80mph setting in from Sunday. And then autumn is really going to bare its teeth. It is time to brace for a real battering. “The storm will also bring torrential downpours and there is the risk of structural damage and branches coming down with the gusts. “Next week is looking grim as this severe weather continues.â€

Netweather forecaster Paul Michaelwaite said:

“Although ‘child of Nadine’ isn’t going to be a tropical storm, it’s likely to have a good amount of energy within it.â€

http://www.express.c...out-with-a-bang

[Keraunic]

Morning all.

That is very heavy rain indicated, Coast, especially as it's a 3 hour total! Looks like local flooding heaviness.

I'll be off for the weekend by lunchtime, so have a good weekend all, if I can't log in later.

Same to you, Steve. Hope the weather is decent for you.

[Sprites]

A nice start to the day out there and again this morning the sky is filled with contrails reminiscent of WWII in these parts (I imagine).

Did anyone in the SE hear the really odd sounding plane/planes at 5.45 this morning? It/they returned exactly an hour later and I went outside to see what it was, but there wasn't a trace of anything in the sky at that point? It sounded to me just like Concorde used to with those noisy Olympus 593's burning mega fuel? Definitely not the usual air traffic and nothing unusual appeared on flight tracker, so maybe military?

heard them take off from Lakenheath probably F15s , they came over here heading south

[Coast]

heard them take off from Lakenheath probably F15s , they came over here heading south

Great, thanks for that! It would explain the multi-engined, deep noise but they weren't in a hurry to get anywhere. Must be doing exercises, there are plenty of hot-spots in the World at the moment!

[Bluebreezer54]

That precipitation spike from the 23rd is starting to look like the Shard

I cant say I like that building, but the fact its clearly visible from my works canteen at Heathrow, and also from my location in Northwood, approx 25 miles away, is quite impressive.

Have a good weekend all. Quite warm and humid out here today. A taste of whats to come this weekend with Nadines offspring perhaps ?

Edited September 21, 2012 by Bluebreezer54

[Sprites]

Great, thanks for that! It would explain the multi-engined, deep noise but they weren't in a hurry to get anywhere. Must be doing exercises, there are plenty of hot-spots in the World at the moment!

yes theres pleny of potential armes deals around atm , i did wonder if they had gone to bomb London

Edited September 21, 2012 by Sprites

[Suburban Streamer]

as much as i like extreme weather, i do have cucumbers still growing and tomatoes still ripening in the garden so would appreciate if nadine's offspring would um get lost!

surely she's too young to be going on holiday on her own anyway?

[Coast]

OK, I don't want to be in anyway alarmist, but there are some interesting developments this morning that are worth keeping an eye on. Now just because Nadine is strengthening again it doesn't necessarily mean it will have a bigger impact on us, but read the following with some caution/criticism and we'll see how it pans out in the next 24 hours or so:

TS Nadine

Tropical storm Nadine strengthens as she moves away from the Azores. Currently winds are at 65mph, pressure is 981mb, and she is moving SE at 8mph. While the wind speeds have came up and the pressure has dropped her satellite appearance is dwindling. There is little convection on the NE half of the storm and overall convection is not extremely deep. The reason for strengthening is Nadine is probably getting some non-tropical energy as conditions are not good for strengthening. With the intensity uptick there is some changes in the forecast from earlier.

Nadine continues to be a confusing storm with this intensity jump. This was a surprise given Nadine should be weakening or at least maintaining strength earlier. Also satellite shows that Nadine is not doing good. The whole northern side of the storm is void of convection and there doesn't look to be improvement. In fact, satellite imagery is showing Nadine may be trying to turn extra-tropical which is something to watch. Wind shear is pretty strong over Nadine and SST's are cool so any rising of the winds isn't from tropical organization. I do believe in the next few days Nadine should transition to an extra-tropical storm. Shear could decrease for a little bit but I'm not totally sure if that will happen or what Nadine would even do. After that Nadine's future is up in the air.

Models are still split on where Nadine will go. They can not agree on where/when a recurve would happen. This has been the norm for the models over the past few days. In the short term models show an ESE movement, which is backed up by the current environment. There is little agreement between the global models after a few days. My forecast doesn't have a lot of confidence since models don't have a lot of agreement. I see Nadine moving ESE to SE over the next couple days and then everything is mostly unknown.

http://www.wundergro...tml?entrynum=34

[Team Jo]

OK, I don't want to be in anyway alarmist, but there are some interesting developments this morning that are worth keeping an eye on. Now just because Nadine is strengthening again it doesn't necessarily mean it will have a bigger impact on us, but read the following with some caution and we'll see how it pans out in the next 24 hours or so:

http://www.wundergro...tml?entrynum=34

Crumbs.

[Coast]

Just a note for all those that PM'd me after my post above, as Mr Fish once said......

It's not necessary Nadine that will be the influence on our weekend, but what she may spawn or interact with. What does seem certain though is that nothing seems certain!!!

[NO LONGER POSTING]

Hold tight if this came off :/

http://www.ssd.noaa....l/loop-vis.html one to watch IMO

After playing around with that Sat, it's hard to make out what they say the path is..But the blue line indicates it

Edited September 21, 2012 by Surrey

[Snowangel-MK]

Yellow Alert of Rain for East of England :

Hertfordshire, Thurrock, Essex, Southend-on-Sea & Suffolk

Yellow Alert of Rain for London & South East England :

Bracknell Forest, Brighton and Hove, East Sussex, Greater London, Hampshire, Isle of Wight, Kent, Medway, Portsmouth, Reading, Southampton, Surrey, West Berkshire, West Sussex, Windsor and Maidenhead, Wokingham, Oxfordshire, Buckinghamshire & Slough

Issued at: 1228 on Fri 21 Sep 2012

Valid from: 0600 on Sun 23 Sep 2012

Valid to: 2359 on Sun 23 Sep 2012

Wet and windy weather is expected to move north into some southern areas of England and Wales during Sunday. The public should be aware that heavy and persistent rain may cause localized flooding and also that strong easterly winds could also cause some disruption, particularly near English Channel coasts.

http://www.metoffice.gov.uk/public/weather/warnings/?regionName=se&from=rss&sn=2549507A-1484-7A8A-AAEF-E318C218D5B8_3_SE

Yellow Alert of Rain for East of England :

Bedford, Cambridgeshire, Central Bedfordshire, Essex, Hertfordshire, Luton, Norfolk, Peterborough, Southend-on-Sea, Suffolk & Thurrock

Yellow Alert of Rain for London & South East England :

Bracknell Forest, Brighton and Hove, Buckinghamshire, East Sussex, Greater London, Hampshire, Isle of Wight, Kent, Medway, Milton Keynes, Oxfordshire, Portsmouth, Reading, Slough, Southampton, Surrey, West Berkshire, West Sussex, Windsor and Maidenhead & Wokingham

Issued at: 1254 on Fri 21 Sep 2012

Valid from: 0000 on Mon 24 Sep 2012

Valid to: 2359 on Mon 24 Sep 2012

The area of more persistent and heavy rain is likely to move north into northern England, southern and some eastern parts of Scotland during Monday, when gales are also expected to develop. Both the heavy rain and very strong winds have the potential to cause localized disruption. However, there remains a large amount of uncertainty at present in the detail. The public should be aware of this risk and keep up to date with our forecasts.

http://www.metoffice.gov.uk/public/weather/warnings/?regionName=se&from=rss&sn=2549507A-1484-7A8A-AAEF-E318C218D5B8_3_SE

[Suburban Streamer]

http://www.metoffice...18C218D5B8_3_SE

interesting how they have extended the yellow warning zone northwards for sunday, compared to yesterdays warning. and the "likelihood" has increased a notch too....

[Coast]

Looks like the jet is getting behind her today:

During tomorrow it all starts moving her around:

It then rolls straight into our front door:

[VillagePlank]

Certainly wet and windy late on Sunday.

However, I am a little more concerned about what might happen Tues/Wed night/morning.

Given the mesoscale forecasts, it looks like it will be a watch and see what happens on the day (ie given the pressure lapse rates, the lack of higher instabilty parameters implies something slightly wrong/confused with how this is being modelled - ie is being regressed to the mean, automatically; whether that's the instability parameters, or the pressure lapse rates - well, that remains to be seen)

Edited September 21, 2012 by Boar Wrinklestorm

[Eskimo]

Very lucky we've been predominantly dry for the past few weeks, otherwise sunday-monday would cause some devastating flooding I would suspect.

[gottolovethisweather]

Very lucky we've been predominantly dry for the past few weeks, otherwise sunday-monday would cause some devastating flooding I would suspect.

It still could be an issue and of course the MetO are suggesting likewise.

Certainly wet and windy late on Sunday.

However, I am a little more concerned about what might happen Tues/Wed night/morning.

Although I cannot analyse such things as well as you, my post via the status updates was picking up on a similar trend.

Interestingly the GFS 06z suggested a flabby low with some deepening as it enters the North sea, the met ofice opinion is rather similar too. I feel the rain from this event and subsequent events WILL be the talking point.

Edited September 21, 2012 by gottolovethisweather