Model Output Discussion - Spring Has Sprung

[Rain All Night]

 Mike Poole  LRD https://charts.ecmwf.int/products/plwww_3m_ens_tigge_upper_mean?area=Northern Extra-tropics&parameter=Geopotential 500hPa

This graph shows the quality of each ensemble's probability assessments (i.e. the proportion of ensemble member runs showing particular outcomes for 500hPa geopotential heights). For days 11-15, the days of the extended cluster charts (hours 264-360), the skill level is only slightly better (on average) than just looking at the climate average conditions and assuming that those will verify on the given dates!

Explanation: https://confluence.ecmwf.int/display/FUG/Section+12.B+Statistical+Concepts+-+Probabilistic+Data#Section12.BStatisticalConceptsProbabilisticData-ContinuousRankedProbabilitySkillScore(CRPSS)

Trivia: This is the only verification stats chart I am aware of that includes any DWD model (in this case, the ICON global ensemble, from which although the output data is made freely available by DWD, I'm not aware of any model enthusiast site that actually publishes it).

Edited February 15 by Rain All Night

[Rain All Night]

It's just occurred to me that the red solid line and the red dotted line on the graph above compare the ECM ensemble's performance in Autumn 2022 and Autumn 2023, before and after the ensemble's big resolution upgrade in June 2023. Interesting that this seems to have slightly improved its performance up to about to day 10, but then slightly worsened it (on average) beyond that!

Edited February 15 by Rain All Night

[minus10]

 LRD yes..take your point...i have probably been as guilty as others at taking pressure anoms too much at face value..need to use them in conjunction with other charts....

TIdbits has mslp contours and anomalies..

..this illustrates your point nicely with the low to the south of Greenland..however would be good if there was a chart that showed height anomalies together with mslp...i am not aware of one but i may have missed it...

 

[LRD]

 minus10 Don't get me wrong, I'm not having a pop at anyone who uses them. If it helps an individual interpret and come to their own conclusions then all good. There is more than one way to skin a cat. I just think they have to be used very carefully and with some scepticism

My personal tastes mean I don't like them, don't use them and take little notice of them. Temp and precipitation anomalies are a different kettle of fish of course. A massive pinch of salt should be taken with any pressure anomaly chart beyond 5-7 days. Even more salt than the everyday output

Edited February 15 by LRD

[Dennis]

 strato ideas 

[minus10]

 LRD wasnt suggesting you were mate..

[Dennis]

icon12z

Edited February 15 by Dennis

[Dennis]

change MJO 8-1

Edited February 15 by Dennis

[Dennis]

i dont give up...'when the puzzle is going to fit

 

[Rain All Night]

 Dennis It's very sweet of you to continue the chase on behalf of the UK, when you have already seen so much wintry weather in your location!

Edited February 15 by Rain All Night

[minus10]

 Dennis looks like you have been left on your own mate ! 

...good for you...keep flying the cold flag...

..edit see @Rain All Nightbeat me to it....

 

[damianslaw]

 Dennis Interesting to view the NAO which correlates well with mean temps so far this year, two dips in early Dec and second/third week Jan but otherwise positive territory.. there was an attempt at a third dip last week but alas it went up again. The outlook is something closer to neutral, correlating with temps trending closer to average by months end with perhaps injections of polar maritime air. Nothing overly cold on the horizon for rest of Feb but after a balmy mid third, temps look set to resemble more seasonal expectations.

The atlantic has reigned supreme for months and despite a weak PV it has overcome any weak blocking easily. The latter stages of next week hold possible interest to those who like stormy conditions, could become quite wet and wild. In the meantime fans of mild grey wet dank dreary skies will be happy, by latter part of Feb I think many though will be cursing them after nearly 4 months of them! This February likely to go down as exceptionally dull in western Britain. 

Edited February 15 by damianslaw

[Dennis]

gfs12z

 

Edited February 15 by Dennis

[Dennis]

GFS12z 

[LRD]

Thanks for those charts Dennis - looks like lots of chilly rain for the UK. Maybe some wintryness, occasionally, on northern high ground

Edited February 15 by LRD

[Dennis]

UKMO 12z

[Cambrian]

12z UKMO neatly captures the change over the next week, as a chunk of the PV circulation swings around through northeast Canada, through the south of Greenland to the Norwegian Sea. 

  

The 500mb temperature charts that we don’t often use, nicely show the replacement of the tropical maritime air over the UK and Ireland with a polar maritime air mass, that has followed the same path out of the Arctic through Canada and Greenland to get here, with some reasonable T850s to show for it. 

Should get rid of all this claggy stuff and eventually into some clearer air with decent lapse rates. Getting through to some proper cold sectors and seeing the tops of some beefy shower clouds, maybe the odd anvil, in a chilly northwesterly, bringing cold stuff down in the downdraughts sounds like a really good option right now. 

[Dennis]

well 

[WYorksWeather]

Tonight's GFS output looks pretty miserable, frankly. Not a lot to satisfy anyone. Looks less mild than of late - temperatures at 850hPa likely to dip a little below average at times, surface temperatures near average. Small diurnal ranges, and lots of cloud, wind and rain. Very little chance going by this of either further exceptionally mild spring-like conditions, or cold sufficient to deliver much wintriness.

[Ladyofthestorm]

 Dennis and Kirkcaldy Weather too 

I agree with you. Writing off more any cold weather is a full hardy narrative. Especially given the teleconnections. 

Just because an SSW didn't reverse the winds doesn't mean to say it can't stretch or distort the PV.

It happened already in January 

 

You have to remember easterlies are historically rare for us. 

 WYorksWeather trend is your friend. Down it goes 

[WYorksWeather]

 Ladyofthestorm All that's sufficient for is to make the rain feel colder. A couple of ground frosts maybe at best. There's nothing properly cold on the chart at all, just seasonal average or a little below.

[andymusic]

ecm 240 looking good

[Ladyofthestorm]

 WYorksWeather it's too early to call winter over, 2006, 2008, 2010, 2013, 2018 , and 2021  some pretty significant snow events in March and into April.

We often have a back end loaded winter . The PV is there to be stretched and distorted . 

 

 

 

[Kentspur]

Are white flags in or out now? A promising day 10 ECM gotta laugh  

Edited February 15 by Kentspur

[Johnp]

 andymusic Good for cold rain?

Edited February 15 by Johnp