Model Discussion - 10th March Onwards

[picog]

GFS 06z looks like it will bring some much needed rain to the drought areas over the coming 14 day's, with the hosepipe bans now just 2 days away this rain will be welcome news to Gardeners ect

http://www.jp2webdes...o.uk/ds/gfs.htm

To me that looks settled in the reliable timeframe — no real rain there for the areas that need it?

Edited April 3, 2012 by picog

[Polar Maritime]

GFS 06z looks like it will bring some much needed rain to the drought areas over the coming 14 day's, with the hosepipe bans now just 2 days away this rain will be welcome news to Gardeners ect

http://www.jp2webdes...o.uk/ds/gfs.htm

Yes Gav, things are looking much better on the GFS percipitation charts to top us up in time for summer.

Let's just hope it's enough to keep us out of the danger zone.

http://www.meteociel.fr/modeles/gfse_cartes.php?ech=6&code=0&mode=2

[Summer Sun]

GFS 12 remains unsettled for a good period of its run, with ample chances for rain in the areas in need

http://www.null/ds/gfs.htm

UKMO also looks unsettled

http://www.null/ds/ukmo.htm

All in all there is going to be plenty of rain around during the first half of this month, maybe even the second but for now that's too far out

[KTtom]

A progressive trend away from settled conditions and temperatures in the 70's for the next 10 days or so, getting to feel a little embarissed standing in the middle of the front lawn with a hose pipe in March! (sorry for those in the SE, plenty of water in Wales )

Looking like a fair swathe of the country will even return to winter tonight especially for hilly areas of Wales where some will see their first snowflakes of the year...don't you just love the Brittish Weather!

[Summer Sun]

ECM is unsettled for all its run tonight

http://www.null/ds/ecm.htm

[Cloud 10]

Yes,a very unsettled run from the ECM this evening,that high pressure just to our west at +96hrs

is yanked away west in double-quick time!

Must be the BHO at work. (Bank Holiday Oscillation )

+96> +144>

[summersnow]

Model output generally starting to agree on supporting a much less settled and cool/cold pattern for some time to come. Any suggestion of a quick return to HP residing over he UK seems to be fading with each model run. It looks in fact, like a pretty classic spring mix for most, albeit a bit on the chilly side!

Edited April 3, 2012 by summersnow

[damianslaw]

Models showing an unsettled theme in the main for the foreseeable future. The weekend should see average temps with driest brightest conditions for the south and southwest, however, by Easter Monday a deep low anchored to the NW will quickly cast the mid atlantic/azores high aside way out to the west - a position it hasn't been for absolutely ages, enabling a much colder polar maritime feed of air to descend down across the country wrapped around a trough feature - so next week could be a chilly cyclonic one, with lots of useful rain, further snow on higher ground in the north, with the potential for another arctic reload as the low heights move into the N Sea.

All three models are showing this set up, confidence must be high for a generally cool/cold unsettled week next week after a slightly milder drier period over the easter period. Its an uninspiring outlook for those on easter holidays in this country wanting some fine warm sunny dry weather, especially after the glorious conditions of the last 2 weeks.

On a personal note - there is much interest in the synoptics, with each day bringing something different, rain, wind, snow, cold.

[johnholmes]

On a personal note - there is much interest in the synoptics, with each day bringing something different, rain, wind, snow, cold.

indeed its a real mix of April type weather from the 'heat' of last week to the cold this week.

[Glacier Point]

.. and the enquiring mind might be tempted to ask what has driven such a dramatic switch around... especially one which was clearly advertised across long range forecast tools and non-NWP methods over two weeks ago ?

It's text book stuff -

The centre of tropical thunderstorm activity has shifted eastwards towards the Dateline in the Pacific and correspondingly, there is a large upstream anticyclone over the Indian Ocean directing Rossby Wave trains.

http://www.cawcr.gov...stDandNpass.gif

The MJO is centred in phase 7 (central Pacific) and is forecast to amplify in phase 8 over the coming week (again major influence on Rossby Wave pattern):

http://cawcr.gov.au/...Last40days.html

During mid March there was a large spike in tendency in relative angiular momentum which have transferred poleward:

http://www.esrl.noaa...d.sig.90day.gif

Net impact - as per tonight's output, mean trough centred over the UK.

Edited April 3, 2012 by Glacier Point

[Snowyowl9]

12 years to the day since a snowy hilly setup like this with strong NE-lys.

http://www.wetterzentrale.de/archive/ra/2000/Rrea00120000404.gif

http://www.wetterzentrale.de/pics/Rtavn181.png

http://www2.wetter3.de/Animation_12_UTC/30_30.gif

Lets see what tomorow brings.

[johnholmes]

.. and the enquiring mind might be tempted to ask what has driven such a dramatic switch around... especially one which was clearly advertised across long range forecast tools and non-NWP methods over two weeks ago ?

It's text book stuff -

The centre of tropical thunderstorm activity has shifted eastwards towards the Dateline in the Pacific and correspondingly, there is a large upstream anticyclone over the Indian Ocean directing Rossby Wave trains.

http://www.cawcr.gov...stDandNpass.gif

The MJO is centred in phase 7 (central Pacific) and is forecast to amplify in phase 8 over the coming week (again major influence on Rossby Wave pattern):

http://cawcr.gov.au/...Last40days.html

During mid March there was a large spike in tendency in relative angiular momentum which have transferred poleward:

http://www.esrl.noaa...d.sig.90day.gif

Net impact - as per tonight's output, mean trough centred over the UK.

I like the post Stewart and the explanation but I'm struggling to see some of your proof I'm afraid. Probably just me not thinking straight?

MJO phase 7 suggests a 500mb pattern not really like we see on the 12z output for today?

The 500mb anomaly charts, see my comments on No 6, were less than conclusive about how the upper air pattern would evolve 14-15 days ago. Its only over the last 4-5 days that they are 'singing from about the same hymn sheet' and have firmed up on the pattern of upper ridge in the Atlantic, probably about 30+ west and far enough north to allow a n of west 500mb flow as the trough that was over Scandinavia tend s to edge west into the uk. Although I suspect this will move a bit east with time as will the ridge?

Nor did any of the other sometimes used indicators, AO NAO appear to give much support at times?

Edited April 3, 2012 by johnholmes

[Cloud 10]

Net impact - as per tonight's output, mean trough centred over the UK.

....which looks like being a treat for fans of convection.

April showers?

Ecm mean day 10 Gefs mean day 10

CPC 8-14 dayer

Even the stubborn NAEFS is on board

[Glacier Point]

I like the post Stewart and the explanation but I'm struggling to see some of your proof I'm afraid. Probably just me not thinking straight?

MJO phase 7 suggests a 500mb pattern not really like we see on the 12z output for today?

The 500mb anomaly charts, see my comments on No 6, were less than conclusive about how the upper air pattern would evolve 14-15 days ago. Its only over the last 4-5 days that they are 'singing from about the same hymn sheet' and have firmed up on the pattern of upper ridge in the Atlantic, probably about 30+ west and far enough north to allow a n of west 500mb flow as the trough that was over Scandinavia tend s to edge west into the uk. Although I suspect this will move a bit east with time as will the ridge?

Nor did any of the other sometimes used indicators, AO NAO appear to give much support at times?

Phase 7 composite MJO:

ECM ensemble mean for the next 5 days:

But it's more about the MJO evolving towards phase 8 in the next weeek John, composite as below:

http://raleighwx.ame...Phase8500mb.gif

which is indicative of increasing westerly inertia coming off the wave in the Pacific. The Southern Oscillation Index has notably tanked negative of late, further underlining this eastward shift the centre of tropical thunderstorm activity.

The CPC has stated low confidence in the last 7-10 days, although CFS weekly, ECM 32 dayer and indeed most global model MJO forecast ensembles have been sweet on a mean trough, and the non-numerical assessment (global wind oscillation composites for phases 4-5-6 (higher angular momentum) gave this tacit support. The GEFS and associated AO and NAO products (CPC as well?) have jumped around a lot in the last 14 days.

Edited April 3, 2012 by Glacier Point

[damianslaw]

.. It's more about the MJO evolving towards phase 8 in the next weeek John, composite as below:

http://raleighwx.ame...Phase8500mb.gif

which is indicative of increasing westerly inertia coming off the wave in the Pacific.

The CPC has stated low confidence in the last 7-10 days, although CFS weekly, ECM 32 dayer and indeed most global model MJO forecast ensembles have been sweet on a mean trough, and the non-numerical assessment (global wind oscillation composites for phases 4-5-6 (higher angular momentum) gave this tacit support.

The last time we saw the mean trough anchored over the country was probably last summer - it usually means copious amounts of rain, a good thing for the drought stricken areas.

The persistency of high pressure anchored over and to the south of the country has been notable for its longevity.

[Alex]

Phase 7 composite MJO:

ECM ensemble mean for the next 5 days:

But it's more about the MJO evolving towards phase 8 in the next weeek John, composite as below:

http://raleighwx.ame...Phase8500mb.gif

which is indicative of increasing westerly inertia coming off the wave in the Pacific. The Southern Oscillation Index has notably tanked negative of late, further underlining this eastward shift the centre of tropical thunderstorm activity.

The CPC has stated low confidence in the last 7-10 days, although CFS weekly, ECM 32 dayer and indeed most global model MJO forecast ensembles have been sweet on a mean trough, and the non-numerical assessment (global wind oscillation composites for phases 4-5-6 (higher angular momentum) gave this tacit support. The GEFS and associated AO and NAO products (CPC as well?) have jumped around a lot in the last 14 days.

Is this a pattern you see persisting for sometime or is there light at the end of the tunnel I.e is May / June doomed?

The reason for my worry is that we seem to lock into patterns for a good 3/4 months these days.

[Robbie Garrett]

The persistency of high pressure anchored over and to the south of the country has been notable for its longevity.

Good riddance!!

Is this a pattern you see persisting for sometime or is there light at the end of the tunnel I.e is May / June doomed?

The reason for my worry is that we seem to lock into patterns for a good 3/4 months these days.

Nothing is certain, but the CFS long-range has been hinting at a wetter few months coming, with high pressure not to far away. It all depends on the angle of the jet-stream, which for us is influenced by conditions out over the pacific. The jetstream is tracking south, so it's likely to remain unsettled and very cool. If anything, don't worry about Summer yet.. it's 2 months away.

Even if we did get locked into this said pattern for 3-4 months, end of September 2011/Early October 2011 is a very good example that you don't need longer days to get some good temperatures and nice weather going. I'd probably say the pattern would stay for at least April/May but it could stay till end of July as the CFS predicts.

Edited April 3, 2012 by Robbie Garrett

[Weather Wizard]

Quite big diffrences at 144h on the 18z high pressure further north

[ribster]

ECM is unsettled for all its run tonight

http://www.jp2webdes...o.uk/ds/ecm.htm

Indeed, not quite the 3 day blip is it, don't think the models have read your script!

[johnholmes]

Phase 7 composite MJO:

ECM ensemble mean for the next 5 days:

But it's more about the MJO evolving towards phase 8 in the next weeek John, composite as below:

http://raleighwx.ame...Phase8500mb.gif

which is indicative of increasing westerly inertia coming off the wave in the Pacific. The Southern Oscillation Index has notably tanked negative of late, further underlining this eastward shift the centre of tropical thunderstorm activity.

The CPC has stated low confidence in the last 7-10 days, although CFS weekly, ECM 32 dayer and indeed most global model MJO forecast ensembles have been sweet on a mean trough, and the non-numerical assessment (global wind oscillation composites for phases 4-5-6 (higher angular momentum) gave this tacit support. The GEFS and associated AO and NAO products (CPC as well?) have jumped around a lot in the last 14 days.

thanks for that Stewart and, yes, NOAA have ben marking model output generally low for a while, much as I suggested about the anomaly charts. I'd agree that a trough sitting around for some time in the UK area seems the most likely outcome.

Edited April 4, 2012 by johnholmes

[SMU]

Heavy snow over the East once again

S

[Polar Maritime]

A very wintry outlook going by the GFS this morning, with a very cold Northerly showing by the weekend. And then another Easterly.

[mezzacyclone]

Prolonging the mid-atlantic ridge

http://www.eldoradoc...-anomalies.html

leaves a more polar-maritime NWesterly influence for the mid-term IMO? NAO`s/AO`s trending slightly more neutral in hindsight but I can`t view any validity of an easterly onset? which in itself goes against the grain of the usual Siberian blast we endure in April , excluding last years very settled start that is.

[Polar Maritime]

Prolonging the mid-atlantic ridge

http://www.eldoradoc...-anomalies.html

leaves a more polar-maritime NWesterly influence for the mid-term IMO? NAO`s/AO`s trending slightly more neutral in hindsight but I can`t view any validity of an easterly onset? which in itself goes against the grain of the usual Siberian blast we endure in April , excluding last years very settled start that is.

An Easterly is showing on the GFS albeit later in the run.

And the same with ECM

[Summer Sun]

We are certainly in an unsettled pattern now and just in time for those in the south who are just hours away from Hose pipe bans, the 10 Pecipitation outlook shows that there will be rain around for those in need of it

All the models this morning point to only one thing and that is unsettled weather during the first half at least of the month giving ample Opportunities for rainfall