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Model Output Discussion 31/03/14 onwards.


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Comparing the 0z ECM temp mean with this morning's GFS 0z suggests the latter is an outlier compared to ECM enspost-14819-0-34676200-1398598074_thumb.g

 

D13 GFS op run is about 12c higher than the ECM mean!

 

It was at the top end in its own ensemble as well (NW): post-14819-0-61442100-1398598301_thumb.g

 

So probably an unlikely scenario and best ignored till sustained support.

 

The 06z Control looks to tie in closer with the ECM and the flip of the 06z op.

 

At T240 the Control:  post-14819-0-40181000-1398598605_thumb.p  Mean: post-14819-0-84304000-1398598694_thumb.p

 

At T288 on the Control another northerly blast: post-14819-0-86135500-1398599053_thumb.p

 

At T288 only four other members support the GFS 06z op for a MLB over the UK. From the London ens 850s the op is clearly at the top end of its members (in FI) and the control, the bottom end:

 

post-14819-0-64991600-1398600026_thumb.g

 

The majority of the suite are more similar to the control run (though not as cold). However it is the 06z run so I am not going to call a trend yet.

 

 

 

 

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As mentioned above, it seems like a considerable shift in synoptic setup is forecasted, with a general dominance of low pressure over and just to the west of the UK anticipated in just a few days time

With the buildup of high pressure from the southwest, it seems like an end will come to a prolonged wet period. More settled conditions will prevail for the next few days over the UK. How will the wea

Well this week sees a large heat plume building over central & most of Western Europe,the UK however sitting on the western periphery with the trough anchored to the SW of us & southerly flow

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GFS hinting at a colder spell but as it heads towards the reliable time frame the downgrades are already in full swing. I wouldn't be surprised by the time we get to Wednesday the cold spell will have become plain average which seems to be the constant theme this year. UKMO also indicates at cool down from the north at the present time.

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GFS 12z showing some very calm and benign conditions developing as the cold northerly wind dies down at the weekend. High pressure moving south to sit over the UK so temperatures will slowly recover to average values but nothing you could describe as warm until later on in the run. UKMO at t+144 looking like raising temperatures quicker than the GFS so if it was right it would become pleasant in time for the bank holiday weekend. Pleasing outputs from the 12z runs so far.

 

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UKMO once more shows pressure rising so a decent BH weekend is looking a good bet at the moment temperatures will be down compared to late it would feel pleasant in any sunshine but chilly overnight especially Friday night into Saturday which looks to be the coldest night of the week with a widespread frost probable unless we see any downgrades to the cold air over the next 72 hours

 

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GFS keeps the high going through-out the bank holiday weekend and to the end of the run again temperatures are likely to be down compared to late by day especially early on but given the strong May sunshine it would feel quite pleasant by day in any sunshine. Night time temperatures would be low at first but once the northerly flow gets cut off they should slowly rise after BH Monday

 

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GEM on the other hand is looking more unsettled and cooler from BH Monday unlike this morning we can't discount this run of course but it would be best to wait and see what ECM has for this period later on

 

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Edited by Summer Sun
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It just goes to show how a week away is still almost impossible to predict with any accuracy even in 2014. The GFS tonight is nothing like the charts I posted yesterday, and as SS says above, the GEM has thrown out a completely different run from this morning.

 

Do you think we will ever be able to predict a week out as accurately as we do for 24 hours today within our lifetimes?

 

It could be that more processing power is needed, but i just have this thought in my head that, perhaps the atmosphere and the Earth is just far too complex and fluid to ever be able to predict!

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Much more straightforward placement of the high now emerging. Gone is the low pressure sliding south out of Iceland keeping things cool.

 

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Edited by Milhouse
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It just goes to show how a week away is still almost impossible to predict with any accuracy even in 2014. The GFS tonight is nothing like the charts I posted yesterday, and as SS says above, the GEM has thrown out a completely different run from this morning.

 

Do you think we will ever be able to predict a week out as accurately as we do for 24 hours today within our lifetimes?

 

It could be that more processing power is needed, but i just have this thought in my head that, perhaps the atmosphere and the Earth is just far too complex and fluid to ever be able to predict!

That's why ensemble forecasting has become increasingly popular, especially as technology is improving as whilst operationals are still the best at picking out trends, they still tend to swing wildly after 7 days or so, ensembles are more consistent for the most part. Worth noting that the operationals are much more in line with the ensembles now with heights sitting just to the south west of the uk into week 2, no guarantees on a UK wide settled spell but certainly drier than average for most looks likely.

ECM looks fine for the entire weekend

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850s look decent from Sunday onwards so a recovery in temperatures would be in order.

 

That high does look like it might drift to the east/north eat of the UK on this run.

Edited by Captain shortwave
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ECM keeps the high going into next week like GFS does so GEM is seemingly on its own this evening for the breakdown on BH Monday

 

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A short colder snap later in the week before it becomes milder again from the west during the weekend, Friday into Saturday continues to be the coldest period with a widespread frost probably barring any changes

 

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The high starts to drift east slowly WC the 5th but we are always under its influence (see below)

 

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Edited by Summer Sun
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ECM keeps the high going into next week like GFS does so GEM is seemingly on its own this evening for the breakdown on BH Monday

 

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A short colder snap later in the week before it becomes milder again from the west during the weekend, Friday into Saturday continues to be the coldest period with a widespread frost probably barring any changes

 

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The high starts to drift east slowly WC the 5th but we are always under its influence most importantly as well is high pressure doesn't re-build over Greenland

The trend continues for dry weather.

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The trend continues for dry weather.

 

Exactly what the GFS precipitation data is showing from May 5th to 13th

 

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Ensemble pressure charts show the high could last for a lengthy period after the cold snap Friday into Saturday

Edited by Summer Sun
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No guarantee but looking like high pressure will become dominant later this week and into the following week .just a few adjustments and we could get the high eventually to our east or over us ,more runs needed but at this range its possible .so looking at all available info Dust off the barby but dont buy the steak just yet ,Today ,well felt and looked more like winter caught every shower going ,take care all .

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Slightly surprised by the ECM ens, very much backs the op in extending the dry settled weather into the following week. Odds starting to favour a return to the conditions that have most commonly effected the UK this Spring so far after a brief cold plunge at the end of the week. Though a long way to go of course.

Edited by Captain shortwave
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Well we've had the usual weekend wobbles in the various outputs, I wonder what tomorrow's and Tuesday runs will show? There are often too many model runs for us all to analyse hence the conflicting evidence provided by them. It is worth stressing the significance of watching the nearer-term to mid-term timeframes in the outputs for trends as these are often more reliable than attempting to determine any trend at ten days plus range. Invariably, it is as you were for the next few days, which in my patch is unwelcome as we've received nigh on two inches of rain in just the last few days. Signs of something drier beginning at the four to five day range and then perhaps a much warmer second week to May.

 

Maybe the post below is still a straw clutcher but perhaps, less in the way of precipitation will come about, as we enter May.

 

http://forum.netweather.tv/topic/79879-model-output-discussion-310314-onwards/?p=2960599

Edited by gottolovethisweather
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It looks like the initial blast of Artic air later this week ,will result in high pressure building across the Uk  and staying for some time,,, :happy:  :yahoo:  :yahoo:

 

Yes Anyweather, the HP influence hasn't gone away in the outputs and hopefully some of the larger rainfall totals will, even if I do like a good ole Thunderstorm, I would like some dryness too.

 

http://forum.netweather.tv/topic/79879-model-output-discussion-310314-onwards/?p=2960613

Edited by gottolovethisweather
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Not too surprised too see the colder shot getting watered down but its annoying as it shows yet again a Northerly stright from the Arctic seems something that is so hard to get nowadays and plus it looks like we may spend another day suffering from this stubborn low pressure system. 

 

It would be nice to have the cooler shot and then a build up of pressure which would result in brighter and drier weather if albeit quite chilly at night but it is certainly a strong trend for things to settle down and for pressure to hopefully eventually build over the UK. 

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It just goes to show how a week away is still almost impossible to predict with any accuracy even in 2014. The GFS tonight is nothing like the charts I posted yesterday, and as SS says above, the GEM has thrown out a completely different run from this morning.

 

Do you think we will ever be able to predict a week out as accurately as we do for 24 hours today within our lifetimes?

 

It could be that more processing power is needed, but i just have this thought in my head that, perhaps the atmosphere and the Earth is just far too complex and fluid to ever be able to predict!

 

 

Well 30 years ago the 24 hour forecast was as accurate now as we can go out to 4 days. So that is some achievement in itself! In the near future though, more computing power would not give us anywhere near the accuracy we have for 24 hours for a week out. A lot of other things need to be improved before that!Incidentally, within the next year or so, we will indeed have more computing power here at the Met Office (as a new supercomputer is soon to be purchased, the most expensive yet!)

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No great shocks from the GFS 18z. It maintains the cooler shot for Friday and Saturday and also then builds pressure over us and gives us a settled bank holiday Monday. A lot of support now for a nice one!!

 

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Met office don't think high pressure will stick around for more than a few days at the end of the week ahead, but fortunately its next weekend that looks fine with sunny spells and light winds but turning colder after midweek from the north with sharp frosts and even some wintry showers to the east and especially northeast of the uk, then a fine weekend with pressure rising but then lowering heights from the northwest bringing unsettled weather to all areas after the bank holiday, especially the north and west.

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Not a bad bank holiday weekend.

 

 

Will the high bring average temperatures, warm weather or hot weather?

 

At this time of year you'd maxima reach the high teens in the south but if uppers are cold then you'd see cold nights.

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Unseasonal cold later in week, shame we have had to wait since last spring for a sniff of arctic air. I think there will be some damaging frosts with temperatures well below zero celsius in rural areas.

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A real good watch the northerly slam progged on Friday cut off by some progressive solutions with the ridging. When is FI again these days.

 

Either way it is a winner, if the Northerly re-asserts by 12z tomorrow we have some fantastic synoptics with the sun vs cold airmass, or we lose this Atlantic junk as HP sets in a la UKMO 144.

 

Rusty as not been paying attention closely, Nino did catch the eye on twitter tho lurking with menace.. 

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