Model Output Discussion 31/07/14 onwards.

[Frank Trough]

Well ECM ensembles are finally seeing the bigger picture and only 10% no longer have Bertha to the SW at T48. Now the main variable is how intense it is and there are breezy members and gale force with ones in between. By T96 Bertha mixes with the core low in the trough and the new low deepens (again variations on that theme). By D5 the new low is filling at different rates according to its members.

 

ECM's track of the low Sunday:

 

 

It is in line with GFS, in that again certain parts of the SE will escape the rain.

 

GEFS offer similar variety with regard to Bertha, maybe slightly more have a weakening feature as it approaches the UK.

 

The GEM op also made little of Bertha, but like the rogue GFS run a day or so ago, this was likely to happen at one point as there remains a cluster showing this. Currently about 30% of GEM's 0z support the op, 70% support the GEM control:

 

 

 

UKMO have struggled with Bertha and this morning the Fax looks like it weakens Bertha as it crosses the Channel/South coast: 

 

Not sure this has much support anymore, yesterday this was showing up as an option, but today most have UK impact around SW crossing NE. Assuming we have reached some sort of consensus (based on ensembles) then UKMO and ECM have been disappointing in their guidance whilst GEM and GFS have been very consistent. Tonights runs should clarify this finally.

 

Afterwards it looks like there is no clear consistent sign of a return to higher pressure. ECM's warm D10 chart last night is now a distant memory. ECM mean at D10:

 

 

 

I suspect the greater impact Bertha has on our mid latitude location the longer our weather will be sourced from a cooler direction.

 

just wondering why would you base such a forecast at this range on the ensembles? I thought the ops were run at a higher resolution? Wouldn't they be more likely to get a grip on this at such short range? Mind you, the ops don't agree either so i'm clueless (as you've guessed).  

 

Also GEM didn't make anything of it last night either so todays 00z is not a one off. 

 

Edited August 8, 2014 by New Forest Gump

[Bobby]

NOAA also predicting Bertha to deepen significantly thus take the more northerly track

 

 

With the ECM now starting to come on board the channel runner idea doesn't look too likely now

[mushymanrob]

I'm a relative newbie when it comes to models... what does 'FI' mean? I've come up with a few possibilities but none of them work in context!

 

 

Fantasy Island!

 

fantasy island, where the outputs are very unreliable.... i prefer Forget It though ...lol.

[MR EXTREMES]

its also worth noting that if this were late autumn or winter fi would be rather interesting seeing that theres a cool push from the northeast on most of the models.

from a model perspective of coarse warmer air can be sucked round into the lower pressure systems but over all summer looking to be heading swiftly into autumn although of coarse sept can also throw in some warm settled spells, but so far models do seem to be growing in confidence of lower pressure dominance with the azores heights supressed to our south.

 

 http://www.meteociel.fr/modeles/ecmwf/runs/2014080800/ECM1-240.GIF?08-12

 

the ecm builds from t144 with that push from the northeast which is maybe bit to soon but interesting if this kind of setup proceeds into autumn and winter.

[knocker]

The 06 GFS

 

Midnight Sunday low 987mb centred over Cork with moderate rain stretching into Wales and SW.

 

Midday Sunday 984mb north Irish Sea.

 

Midnight Monday 984mb east of Wick with strong westerly winds over the UK

 

Summary

 

Damp and windy

Edited August 8, 2014 by knocker

[Jo Farrow]

or perhaps Kilo at 45N?

better still - both!

John have you had a go on the Pin the tail on Bertha in the forum http://forum.netweather.tv/topic/81104-competition-pin-the-tail-on-the-bertha/

[knocker]

Latest from METO.

 

http://www.metoffice.gov.uk/news/releases/archive/2014/BerthaStorm?utm_source=twitterfeed&utm_medium=twitter

 

 

[johnholmes]

John have you had a go on the Pin the tail on Bertha in the forum http://forum.netweather.tv/topic/81104-competition-pin-the-tail-on-the-bertha/

 

nope, too technical for me to work out how to do it Jo, happy with the middle track Exeter are showing?

[carinthian]

I was down at Gatwick during the late August storm of 1986. I remember 24 hours before the event the track was picked up with good accuracy to centre through Mid Wales and head in a NEly direction. A lot of rain with that one. So , I would expect a certainty degree of confidence by tomorrow morning. With the data available now, I would go Cornwall, Midlands, up the Yorkshire coast. However, there is a lot of warm air to be engaged in this system, so the balance could easily be altered with-in the forecast period to a more southerly course.

C

[IDO]

The track looks close to being resolved, SW approach driving NNE. Looking at the GEFS the op is the middle ground re intensity, with over 30% deeper. Still a cluster of 33% that continue to weaken the system: http://www.meteociel.fr/cartes_obs/gens_panel.php?modele=0&mode=1&ech=48

 

The op is 985 low at T48, the control is 990mb:  

 

JMA delays the deepening till later as it approaches the NE: 

 

GEM is similar to JMA:  

 

So getting there...

 

 

[Ǝssex Ǝasterly]

A bit off topic, but does anyone have a link to the real time surface pressure charts? I've never bookmarked it, would like to track bertha 

[Panayiotis]

Latest from METO.

 

http://www.metoffice.gov.uk/news/releases/archive/2014/BerthaStorm?utm_source=twitterfeed&utm_medium=twitter

See my prediction is that it follows the Alternative Track 2, the GFS has been showing this for quite a while now, however it does mean that a lot of the UK will be hit by strong winds and heavy rain:

Edited August 8, 2014 by Panayiotis

[Panayiotis]

A bit off topic, but does anyone have a link to the real time surface pressure charts? I've never bookmarked it, would like to track bertha 

http://meteocentre.com/analyses/map.php?map=eur_full&date=2014080817&size=standard〈=en&area=eur

[IDO]

Don't ask what happens post Bertha, the models suggest about five days of trough/LP dominated weather then we have:

 

GEM  D10:    GFS D10: 

 

Total extremes. The GFS is a cool wet run way out to D15 with snow for Iceland and Scandinavia! The GFS ccontrol isn't much better and the mean gives some credence to the GFS op: 

 

 

Hopefully wrong.

 

UKMO Fax joining others re track:    ECM downplaying Bartha at T48: 

Edited August 8, 2014 by i'm dreaming of...

[carinthian]

A bit off topic, but does anyone have a link to the real time surface pressure charts? I've never bookmarked it, would like to track bertha 

Hi,

 There is not much information in this part of the Atlantic. Storm centre currently 47N : 30W. You can follow the hourly progress by visiting UQAM Weather Centre and follow the surface analyses and observations  for the North Atlantic. You also have the facility to expand the picture. Pressure changes will become more apparent as the system heads towards Western Europe region with the greater availability of weather stations.

C

[Cloud 10]

  ECM downplaying Bartha at T48: http:////f1.nwstatic.co.uk/forum/public/style_images/master/attachicon.gifECM1-48.gif

 

Shows up better on the UK view.

 

[IDO]

Shows up better on the UK view.http:////f1.nwstatic.co.uk/forum/public/style_images/tctc91_simplify/attachicon.gifECU1-48.gif

GFS Op about 10mb lower and further north, so UK wide windy with isobars closer together: Most of the strong winds are as per usual south of the low and ECM has them in France at T48. Though I suspect later in the run Bertha deepens as it turns north. Edited August 8, 2014 by i'm dreaming of...

[Gael_Force]

UKMO at t+48

 

[knocker]

The ECM sequence with 900 wind speeds

 

[ANYWEATHER]

Bertha, does not really deepen any further as it encroaches on the Uk early Sunday.morning. Still think there could be some last minute changes, but gfs has been on the money

[knocker]

Bertha, does not really deepen any further as it encroaches on the Uk early Sunday.morning. Still think there could be some last minute changes, but gfs has been on the money

 

Not sure how you work that out as the 06 this morning had the low north Irish Sea at 12z Sunday. The 12z has it 985mb just west of Carlisle. Let's await and see if that's correct.

Edited August 8, 2014 by knocker

[IDO]

Only 36 hours away and arguably the two main models offer different solutions. ECM moderates the low as it run up the Channel before moving up the North Sea:

 

Though the ensembles are split 50:50 GFS op or ECM op development: http://old.ecmwf.int/samples/d/inspect/teasers/samplers/banner/mean_sea_level_pressure_and_temperature_at_850hpa!48!pop!od!enfo!enplot!2014080812!!/

 

Mean from ECM more like GFS: 

 

 GFS pushes it in from the SW and heads NE and deepens:  

 

UKMO fax has aligned to this rather than ECM which is unusual.

 

Looking further ahead the GFS was poor with a cooler wetter outlook. NOAA 8-14 days backs this up:  

 

JMA has just updated and their 16-23 August anomaly in line with the above as well: 

 

More settled for the last week August into week 1 of September, with an Atlantic ridge towards the west of Ireland: 

 

 

 

 

Edited August 8, 2014 by i'm dreaming of...

[Polar Maritime]

Bertha, does not really deepen any further as it encroaches on the Uk early Sunday.morning. Still think there could be some last minute changes, but gfs has been on the money

The GFS does tend to handle the West better long term (And has on this instance). But as say Knock says, Lets wait and see reg detail. Edited August 8, 2014 by Polar Maritime

[Ǝssex Ǝasterly]

http://meteocentre.com/analyses/map.php?map=eur_full&date=2014080817&size=standard〈=en&area=eur

 

Thanks! Much appreciated 

[damianslaw]

One of those situations of nowcasting - however, its noteworthy how ECM and UKMO have continuously moved to the GFS scenario. Yes GFS does tend to perform better when it comes to forecasting position of atlantic lows.

 

The channel idea appears to be loosing out to a track taking a more central path across the centre of the country, meaning more of the UK will be exposed to heavy rain and strong winds.

 

Next week looks distinctly unsettled and cool for the time of year with a definite early hint of Autumn..