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In Depth Model Discussion and Summaries


Paul

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Posted
  • Location: just south of Doncaster, Sth Yorks
  • Location: just south of Doncaster, Sth Yorks

for some reason there is no reply to this topic on the model thread, any idea what the problem is Paul please?

anyway below is the morning ECMWF-GFS 500mb output and they show no sign of any pattern change again

http://www.meteo.psu.edu/~fxg1/ECMWF_0z/hgtcomp.html

Any hope for milder air is at least 10 maybe 15-20 days away unless something totally unforeseen develops.

Another air and ground frost this morning. I honestly do not remember a March quite like this and have no stats to show one way or the other beyond the 17 years data I have.

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Posted
  • Location: just south of Doncaster, Sth Yorks
  • Location: just south of Doncaster, Sth Yorks

I am not about to say the 500mb anomaly charts show a pattern change, however!

The output this morning from the ECMWF-GFS outputs is different from their issue yesterday. Not GFS it continues with the pattern it had been developing over the past 4-5 days. That is a gradual build of heights just north of the UK and the main Atlantic flow going towards Iberia and the Med. It does this again this morning much as the NOAA 6-10 and 8-14 did last evening. ECMWF has a different idea, from itself over the past few days and the other two. An instantaneous dismissal of the upper ridge or a shift of many hundreds of miles west with a fairly deep trough in its place allowing a marked northerly upper flow into the UK.

You all know my views on consistency with one another and themselves over several days for belief in any pattern showing, especially any marked changes. Just what ECMWF is up to I have no idea but it certainly is a change from its outputs over the past 5-7 days.

Time will tell, ask me again in 3 days or so?

anyway below is the output from ECMWF and GFS this morning.

http://www.meteo.psu...0z/hgtcomp.html

Edited by johnholmes
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Posted
  • Location: Lincoln, Lincolnshire
  • Weather Preferences: Sunshine, convective precipitation, snow, thunderstorms, "episodic" months.
  • Location: Lincoln, Lincolnshire

Dry and cold, but not quite as cold as recently, with broken cloud and sunny intervals looks to be the main story through to Tuesday, and as a general rule the south-east is likely to be the cloudiest and breeziest region while most other regions should have a fair amount of sunshine. With high pressure projected to stay closer to the British Isles than yesterday's runs suggested, most of Scotland, Ireland, Wales and the north and west of England will probably keep sunny intervals and broken cloud through to the end of this coming week, though East Anglia and the south-east will probably turn dull from Wednesday onwards due to the stiff north-easterly. Into next weekend the winds are forecast to back northerly, but with high pressure close by, it will probably remain generally dry, with the cloud probably easing over the SE.

The MJO is currently forecast to hover around phase 3 into April, and may eventually move to phase 4:

http://www.cpc.ncep....splume_full.gif

and the relevant composites show low pressure in charge, over and to the west of the British Isles.

http://raleighwx.americanwx.com/MJO/AprilPhase3500mb.gif

This is consistent with what we're starting to see in the GEFS and ECMWF ensembles, but the main hints of a pattern change are still at 7-10 days out.

Edited by Thundery wintry showers
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Posted
  • Location: @scotlandwx
  • Weather Preferences: Crystal Clear High Pressure & Blue Skies
  • Location: @scotlandwx

Spotted a great post by Dom on Americanwx, a pattern build using AO analog years. In short he highlighted the March years where AO significantly negative and looked at temperature profiles for first and second half of April, so in the interests of UK and Europe built some charts to reflect the same for us.

AO data here http://www.esrl.noaa...elation/ao.data

This in respect of this March being the lowest AO on record and going well beyond the previous lowest figure for 1958 of -2.8, final figure was predicted around -3.1.

Only 2 years were lower than -2.5 - 1958 and 1962

Total 5 years were lower than -2.0 1957 / 1958 / 1962 / 1970 / 1984

So using these dates here are the air temps for April spilt into first and second fortnight of the month, the pressure anomalies are interesting as high Pressure in or around the UK feature in nearly all the years bar one for the second period of April. Temperature profiles less bullish regarding a massive warm up but certainly markedly different from the colder phase of present if past years are anything to go by.

1957

Temps

post-7292-0-52753900-1364816927_thumb.gipost-7292-0-09654900-1364816935_thumb.gi

H5

post-7292-0-17673900-1364817211_thumb.gipost-7292-0-77251200-1364817220_thumb.gi

1958

Temps

post-7292-0-25301500-1364817041_thumb.gipost-7292-0-12318200-1364816968_thumb.gi

H5

post-7292-0-37664000-1364817227_thumb.gipost-7292-0-96460100-1364817228_thumb.gi

1962

Temps

post-7292-0-14938500-1364816973_thumb.gipost-7292-0-03841600-1364817098_thumb.gi

H5

post-7292-0-70923300-1364817237_thumb.gipost-7292-0-76791700-1364817246_thumb.gi

1970

Temps

post-7292-0-18963700-1364816981_thumb.gipost-7292-0-39057100-1364816995_thumb.gi

H5

post-7292-0-03579000-1364817267_thumb.gipost-7292-0-05824500-1364817275_thumb.gi

1984

Temps

post-7292-0-66830600-1364817008_thumb.gipost-7292-0-66341000-1364817023_thumb.gi

H5

post-7292-0-49926100-1364817285_thumb.gipost-7292-0-29634400-1364817285_thumb.gi

Looking at the GWO projections here and comparing with the composite phases, potential for something more cyclonic.

CFS / GEFS

post-7292-0-65076300-1364818197_thumb.pnpost-7292-0-24711700-1364818224_thumb.pn

Composites here, also a marked torque event in the Americas which if I read things right in the WB paper leads to zonal dispersion of waves.

post-7292-0-67737100-1364818177_thumb.gipost-7292-0-22957300-1364818161_thumb.gipost-7292-0-81921300-1364818178_thumb.gi

Hopefully someone else can take a read on the GWO charts as this is an area I struggle to get my head round even having read the WB paper a few times, it would be a shame to lose their forecast lead as they are an excellent predictor tool especially considering the MJO. Still High AAM predicted indicating the atmospheric Nino base state.

Edited by lorenzo
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Posted
  • Location: just south of Doncaster, Sth Yorks
  • Location: just south of Doncaster, Sth Yorks

re post 3

The signs remain for a change in upper air pattern within 10 days perhaps less than 10 days but it needs more concensus from the anomaly charts for a higher belief than I have today, I would say 60%.

It is is a good example of how the synoptic models will switch around but the anomaly charts much less so.

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Posted
  • Location: @scotlandwx
  • Weather Preferences: Crystal Clear High Pressure & Blue Skies
  • Location: @scotlandwx

Had a read through the MJO update late last night and CPC pretty clear on whilst the current signal has diminished slightly expectations are for the MJO to remain active for the next fortnight.

Some variation in the model predictions and will take another 7 days until the next update to get a good lead on how active / influential the MJO will be towards the 20th - 30th April. Plots http://www.cpc.ncep.noaa.gov/products/precip/CWlink/MJO/CLIVAR/clivar_wh.shtml#for

Phases 5 or perhaps 6 for April on the table.

post-7292-0-35441100-1364886247_thumb.gipost-7292-0-03213700-1364886262_thumb.gi

So whilst the phase for GWO indicates more cyclonic conditions, the MJO signals for HP anomaly, leaving us with a mystery to unfold in the medium range, QBO also potentially moving Westerly for the first time since July 2011 this month adds another variable, as do both strong signals for NAO and AO to move positive.

Best summed up by a solid confirmation the atmosphere is changing, not a flip but an erosion of the current conditions.

To visualise this,another tool that has become available on the PSD pages is the GEFS re-forecast dataset. This is an 11 member run of 10 ensembles and control, again the purpose being to filter out model bias via stripping out model tendencies.

Horizontal resolution of GEFS is T254 ( about 50km) out to 8 days. T190 ( about 70km) for days 8-16.

Link Here http://www.esrl.noaa.gov/psd/forecasts/reforecast2/

Supporting Paper http://www.esrl.noaa.gov/psd/forecasts/reforecast2/README.GEFS_Reforecast2.pdf

Teleconnections - predicted. NAO a standout here.

post-7292-0-69102500-1364887059_thumb.pn

Anomaly plots from GEFS reforecast 2

post-7292-0-71665100-1364887104_thumb.pn post-7292-0-28147000-1364887109_thumb.pn

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Posted
  • Location: just south of Doncaster, Sth Yorks
  • Location: just south of Doncaster, Sth Yorks

from model discussion my take on the pattern change for next week

Pattern change prediction-2 April 2013.pdf

two very interesting posts there from Lorenzo-having a much closer look now

Edited by johnholmes
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Posted
  • Location: just south of Doncaster, Sth Yorks
  • Location: just south of Doncaster, Sth Yorks

following on from the above

NOAA this evening

6-10 similar and 8-14 continues with trend of last 2 issues, note the building +ve heights over Iberia area helping with 500mb flow s of west into uk, heights just s of uk almost up to 564dm this run so milder, unsettled but this weather ending up more for nw to give nw-se split it would seem?

http://www.cpc.ncep.noaa.gov/products/predictions/814day/500mb.php

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Posted
  • Location: Nuneaton,Warks. 128m asl
  • Weather Preferences: Snow then clear and frosty.
  • Location: Nuneaton,Warks. 128m asl

A summary of prospects until mid-next week based on 00z outputs(copied from general thread).

Looking through the ens graph and ECM mean charts today there`s a strong signal now for some change in our weather type after this week.

First of all if we view the T84hrs latest fax taking us to Sat 12 noon we can see the cold easterly wind has finally died away as the northern high sinks down across the country.

Posted Image

Already we can see just out in the Atlantic the frontal systems linked to a developing area of low pressure waiting to come across the UK as we go into next week as the whole pattern moves east with our high finally giving way.

Next week promises to be more more unsettled then with rain or showers for many but with somewhat higher temperatures-especially at night-as a more westerly regime looks to take hold.

If we look at the ECM mean 500hPa and 850hPa charts for pressure and temps for day 8 this shows the pattern change.

Posted Image Posted Image

No great warm up yet it must be said but looking at that ens graph we can note the gradual rise in temps to possibly the dizzying daytime heights of double figures next week.

Posted Image Posted Image

Increasing precipitation is evident in week 2 underlining the more unsettled theme.

After the next few chilly days then something a bit more typical for mid-Spring next week is the current outlook.

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Posted
  • Location: hertfordshire
  • Location: hertfordshire

J. Holmes I e-mailed the Met Office in regards to my query IE temperatures on 24.03.13

and this was their response...

([email protected])

Add to contacts ([email protected])

From: 'Enquiries' ([email protected])

Dear Declan,

Please see below the response from our Forecast Service Delivery Team:

Declan

Thank you for your email.

The reason the 24th was so cold, is as Netweather.tv suggested some very low level cold air over the continent moved east during the day.

In winter, the temperature at 850mb can sometimes be a poor reflector of whether it is colder or warmer at the surface and this was one such occasion.

I hope this helps.

Kind regards,

James

Edited by cooling climate
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Posted
  • Location: West Sussex
  • Weather Preferences: Extreme cold & snow
  • Location: West Sussex

J. Holmes I e-mailed the Met Office in regards to my query IE temperatures on 24.03.13

and this was their response...

([email protected])

Add to contacts ([email protected])

From: 'Enquiries' ([email protected])

Dear Declan,

Please see below the response from our Forecast Service Delivery Team:

Declan

Thank you for your email.

The reason the 24th was so cold, is as Netweather.tv suggested some very low level cold air over the continent moved east during the day.

In winter, the temperature at 850mb can sometimes be a poor reflector of whether it is colder or warmer at the surface and this was one such occasion.

I hope this helps.

Kind regards,

James

Did the low level cold air move east or was it west CC?
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Posted
  • Location: Catchgate, Durham,705ft asl
  • Location: Catchgate, Durham,705ft asl

No real surprise to see that March 2013 had a record breaking negative AO with a

final value of -3.176 which easily beat March 1962 (-2.848) and is the most negative

spring month on record since at least 1950.

www.cpc.ncep.noaa.gov/products/precip/CWlink/daily_ao_index/monthly.ao.index.b50.current.ascii.table

The 500mb pressure anomaly chart for March 2013 tells the story.

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Posted
  • Location: Keyingham, East Yorkshire
  • Weather Preferences: Spanish plumes, hot and sunny with thunderstorms
  • Location: Keyingham, East Yorkshire

Good Stuff John. Its been a very captivating spell of model viewing this past few weeks watching the mild weather edge closer, but remain elusive until now. The ENS mean has been predicting high pressure to the SE of the UK for quite some time.

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Posted
  • Location: Lincoln, Lincolnshire
  • Weather Preferences: Sunshine, convective precipitation, snow, thunderstorms, "episodic" months.
  • Location: Lincoln, Lincolnshire

It is looking increasingly likely IMHO that we will move into a warmer and more changeable pattern into next week. While I've seen posts referencing a settled outlook, I don't see much evidence of one away from the south-eastern corner until at least 8 days out. I think the signals do suggest that high pressure will build over eastern and/or southern England at some point during the rest of April, promising an interlude of generally warm dry sunny weather, but we may find that, as with the upcoming change to warmer temperatures, it may end up being delayed until late in the month.

For instance if we take the MJO, Phase 5 is strongly consistent with a build of pressure over those areas:

http://raleighwx.ame...mbAnomalies.gif

...but the present MJO forecasts have it sticking around in Phase 4, which features a UK trough instead:

http://raleighwx.ame...AprilPhase4.gif

The MJO is only one variable of course, but I won't be surprised if the month's main warm dry sunny spell ends up falling around the 25th of the month rather than the 15th-20th as is currently being suggested by most GFS and ECMWF runs.

Friday could well be a day to watch for the convection/thunderstorm fans in the southern third of England, for to the south of a frontal system, some pretty high convective available potential energy has been shown by the GFS for a few runs:

http://cdn.nwstatic....69/ukcapeli.png

Sunday is looking increasingly likely to see the dry sunny weather largely restricted to East Anglia and the southeast in my view, though much of the rest of central and eastern England is likely to be markedly warmer than we've seen for a long time, and the change will be noticeable even though it will probably be mostly cloudy.

Next week's surface weather is up in the air. The GFS 18Z precipitation outputs are suggesting a persistent tropical maritime airflow with dull wet weather in the west and drier but mainly cloudy weather to the east of high ground, but the ECMWF 12Z has us in polar maritime air for most of the time, which would translate to some rain belts but also much brighter, showery interludes in between, and not many showers in eastern and southern England.

Edited by Thundery wintry showers
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Posted
  • Location: Heswall, Wirral
  • Weather Preferences: Summer: warm, humid, thundery. Winter: mild, stormy, some snow.
  • Location: Heswall, Wirral

GFS 18z ensures western areas will become wetter and remain fairly cool, whilst eastern areas may get the occasional settled patch with warmer temperatures. The setup would probably bring below average temperatures in the west, but average to above average at times in the east.

These conditions will certainly help the plants put on new Spring growth, but if the 18z is correct, it will be particularly dull and cool for the north and west.

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Posted
  • Location: just south of Doncaster, Sth Yorks
  • Location: just south of Doncaster, Sth Yorks

Perhaps time to post some 500mb charts in here to show how fairly consistent they have been and how they do seem to point to a NW-SE split in weather. The upper ridge is closer to the SE than the NW thus the further away from the SE you are the more unsettled the weather will be. Equally with the strength of 500mb flow it would indicate some quite windy unsettled weather even extending now and then well south.

The first chart issued on 13 April

post-847-0-90699900-1366185953_thumb.jpg

the second on the 15 April

post-847-0-32763200-1366185975_thumb.jpg

and the third on the 17 April is the ECMWF-GFS version along with my rough notes

post-847-0-51432300-1366185998_thumb.jpg

Wed 17 april

Ec-gfs

Some changes this morning on both=same idea and have made flow into uk s of west as trough is repositioned and flow is stron on both over most of country not just north, so on this if continued suggests not quite as cold but very unsettled

They are now both more like noaa in terms of +ve area and building heights but show flow uk is s of not in trough or even n of west as the two noaa show

so you can see there is reasonable consistency over a number of days, in fact this pattern has been showing on them for a week or more.

The idea of a fine and settled spell after this weekend, away from the SE is not supported by the anomaly charts.

Edited by johnholmes
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Posted
  • Location: just south of Doncaster, Sth Yorks
  • Location: just south of Doncaster, Sth Yorks

Indeed I would go further having had a look at this evenings NOAA output which has now shown a similar upper air pattern on 3 consecutive days, that is marked trough over e'ern half of UK with flow turning north of west at 500mb and some ridging showing south of Greenland as the +ve area stays in that area.

It is beginning to look from these charts, with ECMWF and GFS similar, that any settled weather north or south is going to be in short supply by month end and into early May.

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Posted
  • Location: @scotlandwx
  • Weather Preferences: Crystal Clear High Pressure & Blue Skies
  • Location: @scotlandwx

Met Office brief on the cold March conditions makes for a very interesting read, with Arctic Sea Ice extent the background theme to the paper below.

 

Good to see the re-analysis charts on there, also the MJO and Stratosphere get solid mentions for contributing to the negative NAO and March temp anomalies, 1962 is directly compared on H5s.

 

http://www.metoffice.gov.uk/media/pdf/i/2/March2013.pdf

 

 

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Posted
  • Location: Nuneaton,Warks. 128m asl
  • Weather Preferences: Snow then clear and frosty.
  • Location: Nuneaton,Warks. 128m asl

Met Office brief on the cold March conditions makes for a very interesting read, with Arctic Sea Ice extent the background theme to the paper below.

 

Good to see the re-analysis charts on there, also the MJO and Stratosphere get solid mentions for contributing to the negative NAO and March temp anomalies, 1962 is directly compared on H5s.

 

http://www.metoffice.gov.uk/media/pdf/i/2/March2013.pdf

Yes a good read that Lorenzo.

All of those possible contributory factors have been discussed on Net Weather in recent times so it's interesting to see that the M.O. are also focusing on these.

It`seems that the warmer Arctic with it`s resultant Summer ice losses is a big issue now and they are continuing to research on it`s effects on the NH patterns.

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Posted
  • Location: just south of Doncaster, Sth Yorks
  • Location: just south of Doncaster, Sth Yorks
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Posted
  • Location: just south of Doncaster, Sth Yorks
  • Location: just south of Doncaster, Sth Yorks

Also in the model thread but an interesting comparison with my last post in here just above!

what they appear to suggest for the BH weekend-perhaps?

anomaly chart ideas on mon 29 april 13.pdf

Edited by johnholmes
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