Model Output Discussion 31/03/14 onwards.

[Captain Shortwave]

Some consistency starting to show into week 2 now with heights slipping west allowing low pressure to dive into Northern and possibly Central Europe.

ECM

GFS

 

GFS ens

Not as bad, just a more mixed Bank holiday weekend, but concerning as there are some dire operationals appearing around the Easter period showing some quite unpleasant weather for many areas, GEM being the worst, ECM offering something more showery with the low further away and the GFS which looks more moderated in its evolution.

Edited April 9, 2014 by Captain shortwave

[Severe Siberian icy blast]

Some consistency starting to show into week 2 now with heights slipping west allowing low pressure to dive into Northern and possibly Central Europe.

ECM

GFS

 

GFS ens

Not as bad, just a more mixed Bank holiday weekend, but concerning as there are some dire operationals appearing around the Easter period showing some quite unpleasant weather for many areas, GEM being the worst, ECM offering something more showery with the low further away and the GFS which looks more moderated in its evolution.

But considering none of the models agree on the exact positioning of the low pressure/high pressure setting up , there's plenty of time for things to change and I'm sure it will.

In the mean time we have a good 7 days of high pressure and lots of sunshine which is in the reliable so quite a good outlook in the near term.

[Summer Sun]

Looks like UKMO had a minor wobble yesterday afternoon with high pressure back this morning giving the majority of us 5 or 6 days of decent weather it may not contain a lot of sunshine at times but the main thing is winds won't becoming from the north sea so it will be warmer than last week. As per the past few days the only probably exception to the dry weather at times is the far north of Scotland where you'll be closer to low pressure

 

 

 

 

[draztik]

It's beginning to look a lot like..... Easter?

 

days 8-13 temp anom / ecm control.

Edited April 9, 2014 by draztik

[049balt]

It's beginning to look a lot like..... Easter?

 

days 8-13 temp anom / ecm control.

Look at the poor sods in Russia, having to suffer a heat wave!

[Weather Boy]

But considering none of the models agree on the exact positioning of the low pressure/high pressure setting up , there's plenty of time for things to change and I'm sure it will.In the mean time we have a good 7 days of high pressure and lots of sunshine which is in the reliable so quite a good outlook in the near term.

 

True, but the consistent signal, particularly from the ops, has been for a low pressure dominated BH weekend and there is precious little reason at this point to think that the settled weather is going to hang on for that long.

 

Obviously it all could be wrong, but the form horse at the moment has to be unsettled and possibly chilly Easter weekend, with the north and east looking most vulnerable to some very disappointing weather, especially after what we are expecting in the nearer time frame.

 

As I said in my last post, though, it should be a lot clearer by Fri/Sat.  If they're still singing the same hymn then, surely it's brollies and woolies back out!

[Thundery wintry showers]

Looking over this morning's model outputs, it seems probable to me that the upcoming settled spell will have a NW-SE split similar to the one that we're having today, with areas from the Midlands southwards and eastwards having plenty of dry sunny weather, but a lot of cloudy wet weather in the north and west of Scotland, and mostly dry but cloudy weather over the rest of the country.  The main issue is that the models have revised the position of the ridging high further south over the last two days which means that the sunny conditions won't penetrate as far north and west as looked likely two days ago.

 

Friday is looking the most likely day to see the sunny conditions penetrate further north and west, as the high pressure ridges right across the south:

http://cdn.nwstatic.co.uk/gfsimages/gfs.20140409/06/54/h500slp.png

http://cdn.nwstatic.co.uk/gfsimages/gfs.20140409/06/54/ukmaxtemp.png

 

Yesterday I noted that the NOAA 8-14 day outlook was suggesting a continuation of this pattern over the Easter period but today it has moved more into line with the extended ECMWF outputs, showing low pressure to the north and north-east of the British Isles having a progressively larger influence. Some model outputs are hinting at possible northerly shots bringing sunny intervals and wintry showers, but these would be likely to be short-lived due to the consistent projections of low pressure around Iceland, which tends to spawn secondary lows which bring fronts at intervals and mix out the colder Arctic air.  The question remains how "sharp" this change may be- it is too far out to be able to say whether there will be significant windows of drier brighter weather in between any rain belts.

[johnholmes]

hi Ian

re this

Yesterday I noted that the NOAA 8-14 day outlook was suggesting a continuation of this pattern over the Easter period but today it has moved more into line with the extended ECMWF outputs, s

 

where is it please, I thought they only issued each evening (our time)?

[Thundery wintry showers]

Good point- the latest update was yesterday evening (08 April) so it will be based on the same set of atmospheric signals as last evening's models:

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

Similarly yesterday's more anticyclonic projection would have been issued on the evening of the 7th. 

 

I don't think the Easter weekend's outlook is certain yet but I do feel that the cooler cyclonic outlook has gained more support recently.

[knocker]

Regarding the ECM it certainly looks uncertain but to my unitiated eye there does seem a leaning towards to the cooler cyclonic.

 

 

[phil nw.]

Regarding the ECM it certainly looks uncertain but to my unitiated eye there does seem a leaning towards to the cooler cyclonic.

Yes looking at the latest runs that does seem to be the case overall.

 

Some differences showing how quickly a cooler north westerly unsettled setup arrives -the 06Z GFS Op brings this forward a little toT168hrs

http://www.wetterzentrale.de/pics/Rtavn1681.gif

 

The ECM/GFS mean charts a little later.

http://www.wetterzentrale.de/pics/Reem1921.gif

http://www.wetterzentrale.de/pics/Rz500m8.gif

 

It does seem that we have a continuing trend for this change to come about around next Weds/Thurs though.

What we cant be sure of i guess is how unsettle and cool it will be until the operationals get a handle of the sharpness of the wave pattern.

 

Looks much better for many of us until at least next Tuesday though with a lot of dry and bright weather about-just the odd dying front crossing from the nw with little rain left as they comes south.

[Captain Shortwave]

Hmm one difference from this afternoons runs so far is to develop a trough much earlier and further west than this mornings suite.

 

UKMO

 

Could go the same way here.

The interest comes from that this earlier trough development will preserve heights to the east of the UK. Given the amplified pattern, you could cut off the low and sink it towards Iberia with high pressure building over the top, the GFS does this

One thing is for sure, the models still don't have much of a clue on how to deal with where the mid latitude heights split and end up eventually.

 

Edit - GEM is terrible, heavy persistent rain and westerly gales for the Easter weekend. Not keen 

Edited April 9, 2014 by Captain shortwave

[Summer Sun]

After a settled start ECM shows things going downhill on Wednesday with low pressure moving in

 

 

Thursday sees the low remaining over the UK it could be cold enough for snow on the highest ground in the north

 

 

By good Friday pressure starts to rise slightly from the west so possibly a sunshine and showers type set up

 

 

Then Easter Saturday sees pressure rising for the south more unsettled for the north so a north south slip developing

 

 

Like GFS ECM is showing pressure rising near the UK just in time for the Easter weekend what affect this could have remains to be seen, a lot to be resolved over the next week

[Captain Shortwave]

Very poor inter-run consistency from the models at the moment. Really does come down to this.

 

Where does the low go? The orange arrows show something similar to the GFS where the low drops south east towards Iberia with heights remaining to the east and building over the top of the sinking low resulting in unsettled conditions being rather brief. The black line is akin to the GEM where it takes the low over the top of our ridge and dives south east much later bringing cooler weather and the stronger jet allows very unsettled weather to develop.

ECM is in between dropping the low through the UK.

The poor consistency between runs should pretty much tell the level of confidence, fair to say there is all to play for and that no weather type can really be discounted at the moment.

Edited April 9, 2014 by Captain shortwave

[phil nw.]

Yes very uncertain how that upper trough develops next week Captain.

The trend overall though seems to suggest around Wednesday for some sort of change to a more unsettled and cooler period.

http://www.wetterzentrale.de/pics/Rz500m7.gif

http://www.wetterzentrale.de/pics/Reem1921.gif

 

The main High cell retreating west as pressure falls across the UK.

Edited April 9, 2014 by phil nw.

[Winter Cold]

Would this be cold enough for snow in April? Wintry showers at least? On this run, Good Friday looks very cool at least....

 

[Summer Sun]

Would this be cold enough for snow in April? Wintry showers at least? On this run, Good Friday looks very cool at least....

 

 

Maybe on high ground but low levels would be pushing it I would think

[draztik]

Trend towards much cooler weather steadfast on tonights ecm output. The mean and control only going one way; below average conditions for all into Easter (&beyond?)

days 7-12 temp anom mean & control

days 10-15 mean & control

beyond this time period, cfs ensembles also trending below average, with days 15-25 showing a negative anomaly for the UK.

days 15 - 25 temp anom.

May also looks dicey; much to be resolved into the short term nevermind days 15-25... But certainly, if one is looking for signals, the cooler outlook is one we cant dismiss.

Edited April 9, 2014 by draztik

[Frosty.]

I'm with the met office regarding next week, a nw-se aligned jet profile with progressively colder and unsettled weather setting in by the middle of next week, much sooner than that the further north you are. I expect low pressure will swing south eastwards with bands of cold rain and stronger winds with wintry showers for hilly parts of the north eventually. Hints of settled weather returning beyond the end of next week, at least across the south of the uk. In the meantime, a good deal of fine and very mild weather for most of england and wales but with occasional weakening fronts slipping south eastwards with more cloud but little in the way of rain, the fronts more active across n. Ireland and scotland with persistent rain and strong winds interspersed with sunshine and scattered heavy blustery showers.

[Polar Maritime]

Yes Frosty, The trend continues to gain weight as the days pass, and with the met also keen it's a pretty safe bet now for a colder and more unsettled spell from mid-month.

[Frosty.]

Yes Frosty, The trend continues to gain weight as the days pass, and with the met also keen it's a pretty safe bet now for a colder and more unsettled spell from mid-month.

Yes PM, it's looking increasingly like a rather chilly and unsettled spell will arrive for all areas from the north west by tues/wed next week and persisting over the easter period. There is even a risk of snow for northern hills with a white easter above 1000 feet across central and northern uk. It's a shame about the timing since this weekend is looking generally fine and on the warm side for the time of year with temperatures into the mid to upper teens celsius whereas by the second half of next week they may struggle to reach double digits c...at least for the north.

[Captain Shortwave]

Kind of predictable really, rain and wind arrives for the bank holiday (try something new perhaps weather )
One shred of hope is there are quite a handful of ensemble members which develop the trough much earlier on a weaker jet and give a very different outlook,

Something like this for example.

We will see, but if the models firm up on low pressure returning over the next 24 hours, then Easter looks like being one for the brollies and wellington boots.

Edited April 9, 2014 by Captain shortwave

[The PIT]

GFS as a FI cool spell pushing south probably go the same as other cool spells and will get downgraded to average to slightly above average. This trend from Winter is still generally happening.

Edited April 10, 2014 by The PIT

[Captain Shortwave]

Well the ECM perhaps sniffing out something different this morning. 

 

Isolated in a sense but quite of few gfs ens were going for something like this over the runs yesterday. Again though the lack of consistency at 6/7 days out is rather concerning. Models still struggling with this.

In the end the ECM shows little rainfall in the south with pressure remaining fairly high, it becomes more unsettled the further north you go.

Edited April 10, 2014 by Captain shortwave

[phil nw.]

Well the ECM perhaps sniffing out something different this morning. 

 

Isolated in a sense but quite of few gfs ens were going for something like this over the runs yesterday. Again though the lack of consistency at 6/7 days out is rather concerning. Models still struggling with this.

It just seems a little slower than the GFS in bringing that trough in

 

http://www.wetterzentrale.de/pics/Recm1681.gif

 

but it does bring it towards us around a day later.

Not sure about UKMO this morning it looks a little flatter at T144 than the others but there is a suggestion of pressure falling around the UK local,

http://www.wetterzentrale.de/pics/Rukm1441.gif

 

like we keep saying the exact pattern coming towards Easter still not agreed and this uncertainty was reflected on upstream developments in last nights American discussions

 

http://www.cpc.ncep.noaa.gov/products/predictions/610day/fxus06.html

FORECAST CONFIDENCE FOR THE 6-10 DAY PERIOD: BELOW AVERAGE, 2 OUT OF 5, DUE TO  FAIR AGREEMENT AMONG THE TOOLS OFFSET BY RELATIVELY HIGH SPREAD AMONG THE  ENSEMBLE MEMBERS.  

and

FORECAST CONFIDENCE FOR THE 8-14 DAY PERIOD IS: BELOW AVERAGE, 2 OUT OF 5, DUE  TO RELATIVELY LARGE SPREAD AMONG ENSEMBLE MEMBERS AND THE EXPECTATION OF A WEAK  HEIGHT ANOMALY FIELD. 

we cling onto the hope that the probable change may not make Easter itself a washout.