Model Output Discussion 26/08/2012

[ANYWEATHER]

Ecm and gfs are"almost" joining hands in with there prediction for the weekend. I think there will be upgrades to this as time as gone by and perhaps this system will spawn some severe weather. No one knows at this stage but its certainly one that has kept the computer models on there toes!!

Edited September 20, 2012 by ANYWEATHER

[Zenarcher]

Looking at the ECM 12z 3 hour data at the wind speeds,

6am Monday looking windy across South Western England and through the channel 30 to 45mph.

3pm Monday the windy weather moves across all of England and Wales bringing 30 to 40mph winds and things start getting interesting over Northern Scotland with the wind speeds being 35 to 45mph.

12am Tuesday the wind slowly drops over England but across Scotland and Northern Ireland they see an increase with Northern and Western Scotland seeing the worst with 45mph to 55mph winds.

12pm Tuesday Northern England and Southern Scotland see winds around 35mph while the worst of the wind remain far out West as the low pressure system slowly weakens so do the winds.

Looking at the previous ECM run from this morning it looks very similar to this evenings run so consistency there but the UKMO has also shown consistent runs on it's theory. I think the fax charts tonight will be interesting from the Met Office. Hopefully tomorrow we will start to get agreement from all of the models.

Edited September 20, 2012 by weathermaster

[Geordiesnow]

As the BBC's videos about this low tells us, we can't be so sure what will develop until the low actually forms and it hasn't yet hence so much uncertainty in the forecasts.

I think if people prefer brighter cooler weather, then hope the UKMO is on the right lines, if people are after wet and windy weather then hope the GFS/ECM is correct, either way, its an autumnal outlook the models are showing.

If this low does indeed come off and ends up on our shores, if it gets tied into that low around Iceland, it could well stick around as the models seem to be indicating.

[Frank Trough]

Ecm and gfs are"almost" joining hands in with there prediction for the weekend. I think there will be upgrades to this as time as gone by and perhaps this system will spawn some severe weather. No one knows at this stage but its certainly one that has kept the computer models on there toes!!

i think it's worth noting that the UKMO recently seems to be a bit ahead of the game. Yesterday (was it? or the day before?) ECM/GFS were refusing to even spawn the secondary low. The GEM and UKMO did.

interesting whatever happens. A bit of fishing saturday and then sit back for a properly autumnal week ahead, whatever the eventual outcome is. Slightly longer term looks cool but less "dynamic" to me. Long way off, though. Unsettled is the theme in the medium term.

*edit* - as said above, the fax charts will be interesting. They don't always side with the UKMO output - The cold spell last february springs to mind when the 12z UKMO sunk the high but the FAX charts went with the GFS/ECM option.

Edited September 20, 2012 by Pharaoh Clutchstraw

[mrsmall]

Does anyone know what the verification stats are at the moment with the gfs? iirc last autumn it was overcooking lows and the ecm dropped them down before the gfs did?

[WhiteFox]

Ive got to say that the ECM is fascinating me tonight. The low develops over Biscay, moves north, develops some more, fills slightly, moves back over Biscay, develops again and then moves back north before filling for a final time. Can't say I've seen the like before. Lows filling in situ, yes, and lows developing, filling then redeveloping as they move to the east, yes, but never meandering as forecast by the ECM. Seems unlikely, but very interesting!

[damianslaw]

Certainly an interesting spell of weather ahead synoptic wise - all very uncertain at the 72 hour timeframe which is preety short. I suspect we may end up with a hybrid of what ECM/GFS and UKMO is showing, i.e. we will see some form of secondary low development but not quite the intense feature being suggested by UKMO, however, the low to the NW will most likely sink SE into the country and quickly absorb the 'secondary low' to bring very cyclonic conditions for early next week with a major complex low feature becoming very slow moving thanks to strong heights to the NW and NE 'locking it into position', consequently we would likely see some very high rainfall totals and some strong winds around the edges of the feature. I can't see the high holding out against the two low pressure attacks - it is quite a weak high.

I am enjoying this September for the variety of synoptics it has delivered so far - many recent Septembers have been preety uninteresting in terms of offering much variety, but this September so far has felt very traditional - starting off warm and dry but becoming unsettled and cooler as we have approached the equinox and now a good chance of a very unsettled autumnal latter third...

[legritter]

for all you new members posters etc ,welcome aboard ,fasten your seat belts and enjoy the roller coaster . we are looking down the barrel of a loaded weather gun , but the exact track of that weather bullet is still unknown ,its speed and how much it developes is still far from certain . IT could bring potentially heavy rain , also the possibility of some strong winds , it could just be an ordinary autumn low . looking at tonights data and charts it does appear to be something of significance , with some very interesting weather around right throughout next week . remember we have some very talented posters on NET /WEATHER and although some of it gets technical, there is always someone to help, if you dont understand just ask , well its coming up to FAX TIME when the professionalls at exeter met office publish the latest forecast charts all carefully and lovingly created by hand . if your new on NET /Weather also take a look at the latest GFS charts about to finish the run soon .regards

[peterf]

dont start till 22.30 during summertime,but like you state some very interesting runs to come.

Edited September 20, 2012 by peterf

[Chris W]

I can't remember seeing lows come from the south too often so this is very different territory for me - I have a couple of question points:

- Coming from the south, over potentially warmer waters (and interacting with land over Portugal/Spain perhaps) than usual when coming from the west, how does this develop the storm differently to a 'normal' south-westerly autumnal low?

- This may be well-related to the first question, but since this low from the south is spawning directly from Nadine (it seems) then how would the more tropical characteristics and nature of Nadine feed into it? Is it just a question of it having more moisture and energy?

It does seem from what others have posted here that something will develop over the weekend and into Monday, it's just a question of how intense and the specific track. I see that the Met Office have early warnings out mostly covering the south at the moment.

[peterf]

where's it gone lol?

[Zenarcher]

Big change in the 18z just amazing,

Here is the difference at just 48 hours,

Again at 72 hours,

90 hours seems the 18z follows the UKMO,

[peterf]

METO site dropped it 2 hours ago for my location.

[peterf]

I'll wait for the 06z run in the morning i think.

[Zenarcher]

GFS 18z and UKMO 12z side by side,

Met Office fax chart shows that they are going with their own model tonight,

[pyrotech]

Does anyone know what the verification stats are at the moment with the gfs? iirc last autumn it was overcooking lows and the ecm dropped them down before the gfs did?

You can get stats for each model. What i have noticed is generally the Gfs seems to not overcook lows anymore on regular basis. Infacr in 5 day plus period i believe ecm has had them deeper over last 8 months. What i also notice s Gfs showed this scenario with Nadine. Around 10 days ago and then dropped the idea to bring it back again now. If you watch Gfs deep in fi with its lows and more so tropical storms it does this regularly especially on its 18z run. I actually think if gfs kept some of its fi. Scenario right thru the run up ot would out do the other models. It is almost like it looks at ecm, desides that its made a mistake and jumps on band wagon.

I suppose if any model was 100% right we would have a lot less to discuss. Personally i find each one has its own merits. One tip for ne members is with gfs, to compare changes run to run use same model run time. Ie diference on 18z to 18z not different run times. I prefer the 18z run as personal preference but which ever run 00z, 06z, 12z or 18 only compare like for like. Take note of others in fi but best compared at same time each day. That is not so much at reliable timeframe. Reliable time frame changes and on a system like current scenario i suggest 18 - 36 hours is where reliable timeframe is. Some days it can be 3 - 5 day or possibly more.

[AWD]

GFS 12z run brings the LP back, rather deep too, with strong winds likely across many parts for a time.

UKMO does too have a depression come up from the SW, but on this run the depression deepens over the North Sea, so winds wouldn't be an issue here, just some wet weather about.

The GEM Model has an outcome similiar to the GFS, in that the depression deepens over the UK and eventually sits over Ireland, with strong winds for a time for many, and heavy rain.

The Nogaps Model also has a deepening depression hit our shores from the SW, although not as windy as the GFS/GEM outcome.

So, currently now we have all models ( although we do await the 0z ECM output ) bring a depression up from the south west and deepen it arround our shores. The UKMO is currently on its own deepening the depression over the North Sea without it really affecting the UK. All other models above show it deepening over the UK providing somw wet and windy weather for all. Still it seems we have uncertainties about the weather from Sunday afternoon onwards, but currently one has to favour the wet and windy scenario.

Damn, wrong thread, Mods Can you move to the Model Output thread please!

Edited September 21, 2012 by AWD

[Gibby]

Good morning. Here is the morning look at the 00z output of the forecasting models of GFS, UKMO and ECM.

Things still look a little undecided between GFS, UKMO and ECM on the exact track of the depression at the end of the weekend. What is agreed that a Low pressure of sorts will move NE from Biscay by the end of Sunday. Until then a cold front will move South over the rest of Southern Britain today before clearing overnight. Saturday will see high pressure ridging down over Britain in cool air. Sunday sees this High slowly displaced by an increase of breeze and falling pressure from the SW through Sunday. Rain will move into southern areas later.

GFS takes the depression up over Southern England and merge with an Icelandic Low to become an intense Low complex over Scotland on Monday. This then swings SW then East over the South again through the week filling and ending up just to the SE of Britain by the weekend. All through this period rain and showers will occur everywhere, the emphasis of which gradually transfers towards the East and South later on. In FI this morning things improve for all for a while as a ridge crosses slowly East and South over next weekend. Thereafter a trend to more unsettled weather is shown as Low pressure troughs down from the NW though a notable cold high pressure does return by the end of the run.

The GFS Ensembles this morning show average 850's over the period with rain at times from a mostly unsettled pattern over the UK. the second week though is shown to be less wet than the first. The operational was a cold outlier right at the end.

The Jet Stream is shown to dig South to the West of the UK interacting with the warm sub tropical air to the SW aiding the formation of Low pressure which is driven NE on the flow which moves across Southern Britain. The flow thereafter generally maintains a position South of the UK if in a weaker form later.

UKMO for midnight on Thursday shows Low pressure over Germany with a cool NNE flow over Britain bringing cloudy damp weather for many in a raw and cold breeze.

ECM shows Low pressure to the NE with a cool Northerly flow too at the same time point before complications from the South could bring rain back to here by the end of the week before a simplification of synoptics occurs towards the end of the run of High to the South and Low to the North with rainfall becoming most prominent in Northern areas while Southern Britain become drier and milder as winds turn South of West.

In Summary leaving Sunday's low pressure aside the weather looks like being very unsettled and cool next week with rain or showers at times for all in innitially very strong winds. As time passes pressure is shown to want to build, albeit slowly so rainfall events should become less frequent with some longer brighter spells although ECM and GFS have different evolutions of arriving to that point.

[legritter]

just a very quick post from me ,there is potential for a nasty area of low pressure Sun /mon ,with endless possibilitys and at this stage [range ] it could be almost anywhere that gets hit .its also a fair possibility that our friends across in europe could cop it worse than us . it will be interesting to see what happens on the eastern and s/eastern flanks of this low . but as usual at this stage its what type of child is spawned ,a very quick developer with a bite or ,a flabby one and slow moving ,just my take on things this morning ,but interesting times ahead ,cheers .

[AWD]

These long range EC model runs seem to be "flip flopping" a lot lately.

Latest EC 32 day signalling a cool/unsettled picture throughout the opening first half of Oct. Precip at/above avg, temps near/below avg.

I swear the last EC 32 run suggested higher pressure and more settled conditions early October. This latest update sort of backs up the Meto outlook now.

[shedhead]

just a very quick post from me ,there is potential for a nasty area of low pressure Sun /mon ,with endless possibilitys and at this stage [range ] it could be almost anywhere that gets hit .its also a fair possibility that our friends across in europe could cop it worse than us . it will be interesting to see what happens on the eastern and s/eastern flanks of this low . but as usual at this stage its what type of child is spawned ,a very quick developer with a bite or ,a flabby one and slow moving ,just my take on things this morning ,but interesting times ahead ,cheers .

Yes, certainly a very interesting and rather complex situation developing for the 2nd half of the weekend. Even at this short range options vary from remaining dry away from Channel coastal counties, to 60-70% of England and Wales seeing heavy rainfall and potential problems with flooding. Still would not like to try and call this one definatively, but I'd suggest areas southeast of a line from Torbay to the Wash currently look most prone to some significant totals.

Edited September 21, 2012 by shedhead

[johnholmes]

These long range EC model runs seem to be "flip flopping" a lot lately.

Latest EC 32 day signalling a cool/unsettled picture throughout the opening first half of Oct. Precip at/above avg, temps near/below avg.

I swear the last EC 32 run suggested higher pressure and more settled conditions early October. This latest update sort of backs up the Meto outlook now.

May I ask where are you seeing the ECMWF 32 day outlooks? Or are you commenting on comments from someone who does have access?

have access

[AWD]

May I ask where are you seeing the ECMWF 32 day outlooks? Or are you commenting on comments from someone who does have access?

have access

Reviews from Matt Hugo

[ribster]

Reviews from Matt Hugo

Can I start quoting what Alex Deakin has been saying then (and not credit him with saying it), thought the idea was to post your own thoughts, not regurgitate what someone else has been saying.

Edited September 21, 2012 by ribster

[AWD]

Can I start quoting what Alex Deakin has been saying then (and not credit him with saying it), thought the idea was to post your own thoughts, not regurgitate what someone else has been saying.

Can if you want.

I haven't been told not to as long as its model based which it is, and provides an insight into what the models that many of us haven't got access too are suggesting.

Edited September 21, 2012 by chionomaniac
removed unneccesary comment.