Model Discussion 12Z 25/02/13

[Panayiotis]

Following on from my post its worth highlighting the current temps in the N Sea.

http://www.wetterzen...ics/Reursst.gif

Let me put its this way I wouldn't fancy a swim in Cromer!

Have to be honest if we do see an E,ly I would much rather see very cold upper temps involved otherwise it will be cold, overcast, miserable in my location and many others. Infact I would then prefer a very mild SW,ly.

You need a difference of 13C or more between the sea and the upper air temperature for instability for convection to take place that will mean. looking at those temps we need at least -8C uppers for that to happen. With the PV on the move to Siberia with part of it moving to N.Europe that may be possible if we get the easterly, even more so if we get a northeasterly, as the SSTs are warmer and there is a larger fetch.

Too far to know for sure but definite trend to colder conditions after next weeks warm up.

http://en.wikipedia....ake-effect_snow

Edited March 1, 2013 by Panayiotis

[Jason M]

Out to the end of high res the ensembles offer a decent level of support. As TEITS suggests an easterly actually looks probable tonight although whether its a cold one (in terms of uppers) is still very much open to question.

I particularly like this ensemble

http://www.meteociel.fr/modeles/gefs_cartes.php?code=20&ech=192&mode=0&carte=0

or how about this one

http://www.meteociel.fr/modeles/gefs_cartes.php?ech=192&code=17&mode=0&carte=0

perhaps some of this one then?

http://www.meteociel.fr/modeles/gefs_cartes.php?code=11&ech=192&mode=0&carte=0

this one any good?

http://www.meteociel.fr/modeles/gefs_cartes.php?ech=192&code=2&mode=0&carte=0

As you can see, no support whatsoever for an easterly tonight!

Not saying anything will come of it, but tonight a few of the ensembles are looking decent at 192 hours rather than 240!

Jason

[Jason M]

You need a difference of 13C or more between the sea and the upper air temperature for instability to take place therefore convection can occur that will mean. looking at those temps we need at least -8C uppers for that to happen. With the PV on the move to Siberia with part of it moving to N.Europe that may be possible if we get the easterly even more so if we get a northeasterly, as the SSTs are warmer.

Too far to know for sure but definite trend to colder conditions after next weeks warm up.

ah, but don't forget that IF this was to happen it would be well into March. Upper cold pool plus strong solar input will equal potentially violent showers forming over land. Lots of variables of course such as air pressure etc but were getting towards the point now where the north sea isn't the only player in town for convection.

Jason

[lorenzo]

Well late on this as Monday update from the NOAA PPT however they remain interested in MJO developments in the mid term / medium range, I guess circa 12th March > with an active MJO. Edit add pic..

JMA had this solution around 5 days ago which moved quickly through the stalled appearance of now until low amplitude phase 1, solutions that favour a blocky outlook in essence.

With the JMA almost an extension of the UKMO it is an interesting solution, albeit not evident on runs showing today with little MJO activity and a stalled outlook, perhaps this will kick on again.

The UK High it seems was an inevitable solution having not presented itself for so long, the promise of retrogression teased on many occasions without coming to fruition.

I guess what is noteworthy is that there are still cold synoptics on the periphery and this must surely be down to the period of flat EP Flux and zonal wind reversal courtesy of the SSW. Not delivering the spectacular everywhere but delivering sustained interest.

The MJO tease from NOAA is certainly one they seem bullish about, a jolt towards late 7-8 predicates blocking.Would be Just our luck to get the dream set up late in the season !!

Edited March 1, 2013 by lorenzo

[Panayiotis]

With the JMA almost an extension of the UKMO it is an interesting solution, albeit not evident on runs showing today with little MJO activity and a stalled outlook, perhaps this will kick on again.

Was it not the BOM? Great post however Edited March 1, 2013 by Panayiotis

[Thundery wintry showers]

One issue though is the atmosphere above the 850hPa level. During the late-February easterly we had 850hPa temperatures around -10C but we had a strong layer of dry stable air between the 650 and 850hPa level which meant that convective cloud sprouted up readily up until the 850hPa level, then hit a "dry lid" and spread out into stratocumulus. The proximity of high pressure and relatively high temperatures at the 500hPa level were also limiting factors. For this reason, I doubt that 850hPa temps of -8C from a dry continental easterly would be enough, though an east to north-easterly sourced from a fair way north would be a different story.

I can't remember seeing significant homegrown convection from an easterly in March before, because proximity of high pressure and relatively dry continental air tend to be limiting factors (though it is still possible to get a fair amount of convection over the North Sea under favourable circumstances- 17th/18th March 2001 in north-east England was a good example). Northerly types are a very different matter- we increasingly get homegrown convection from those as the season progresses.

Edited March 1, 2013 by Thundery wintry showers

[SMU]

Posts like this really get on my nerves. What is even more irritating is looking at who liked your post.

Did I say in my post when I highlighted the JMA that a big freeze is on its way? No I said the JMA would show this at +240. Furthermore I did say I wish the JMA was more reliable.

Let me say this is the model discussion thread and I was discussing what the JMA was showing.

What you got to understand TIETS is the agenda. Its so transparent.

Some people dont like it that people get excited by cold ( & warm ) -

Some people dont like it that some people on here forecast things without the models actually showing what they are forecasting- because its unconventional to go against what the overwheling model data is showing -

however thats being forecaster,- there arent many so forecasters on here- just people that interprete models.

I recall- such a day not so long ago when everyone wrote off the Jan cold spell- all the 'pros' on Twitter, & so on on here- & yet with no model showing cold out of them all except the ECM OP I forecast a full swing over night which they pretty much did except the woeful GFS.

Which again neatly reminded of us how mediocre the GFS is in certain forecasting situations.

s

[Jason M]

One issue though is the atmosphere above the 850hPa level. During the late-February easterly we had 850hPa temperatures around -10C but we had a strong layer of dry stable air between the 650 and 850hPa level which meant that convective cloud sprouted up readily up until the 850hPa level, then hit a "dry lid" and spread out into stratocumulus. The proximity of high pressure and relatively high temperatures at the 500hPa level were also limiting factors. For this reason, I doubt that 850hPa temps of -8C from a dry continental easterly would be enough, though an east to north-easterly sourced from a fair way north would be a different story.

I can't remember seeing significant homegrown convection from an easterly in March before, because proximity of high pressure and relatively dry continental air tend to be limiting factors (though it is still possible to get a fair amount of convection over the North Sea under favourable circumstances- 17th/18th March 2001 in north-east England was a good example). Northerly types are a very different matter- we increasingly get homegrown convection from those as the season progresses.

Feb 2005 saw some homegrown convection at times and that was earlier in the season than this. The sun really packs a punch by mid march. Ice days would be completely dependent on sustained cloud cover though. Its an interesting trade off in early mid march between the benefits of the extra solar input through added instability and the fact that ever colder uppers are needed.

Jason

Edited March 1, 2013 by Jason M

[lorenzo]

Steve, am not sure that folk have agendas tbh, I certainly dont, and nor am i aware of any of the team that have any pre planned ideas to support one idea or another.

I do think that no one would ever contest that you are a couple of steps ahead of the majority ( 99%) of folks due to your expertise /experience at reading charts - maybe this leads to you seeing folk not posting about what may happen because you can see an evolution others have not learned to see ? Not having a dig at all btw, just shooting the breeze. Really don' think folk post up in any manner to support one idea or another or with bias?

[LomondSnowstorm]

One issue though is the atmosphere above the 850hPa level. During the late-February easterly we had 850hPa temperatures around -10C but we had a strong layer of dry stable air between the 650 and 850hPa level which meant that convective cloud sprouted up readily up until the 850hPa level, then hit a "dry lid" and spread out into stratocumulus. The proximity of high pressure and relatively high temperatures at the 500hPa level were also limiting factors. For this reason, I doubt that 850hPa temps of -8C from a dry continental easterly would be enough, though an east to north-easterly sourced from a fair way north would be a different story.

I can't remember seeing significant homegrown convection from an easterly in March before, because proximity of high pressure and relatively dry continental air tend to be limiting factors (though it is still possible to get a fair amount of convection over the North Sea under favourable circumstances- 17th/18th March 2001 in north-east England was a good example). Northerly types are a very different matter- we increasingly get homegrown convection from those as the season progresses.

A notable exception for me was this:

The front brought rain to snow overnight from the second into the third with some classic sunshine and snow showers in behind. Had an inch here from the band overnight but the showers failed to lie, though further north there was up to a foot in places, and it was probably the best snow of the winter for eastern Scotland.

[Panayiotis]

Going on from posting over the last few days Im expecting a significant swing towards cold in the 144/168 timeframes of modellling in the next 24 hours.

S

What makes you think this Steve, last time it was the ECM showing the coldest of solutions when you said something similar to this and you were indeed right however this time its the GFS?

[lorenzo]

Was it not the BOM? Great post however

Thank you, the reason JMA cited as relevant was based on Ian F thoughts that the JMA held in high regard by UKMO, this was considering the solid resolution provided in resolving synoptics for a small Island not too dissimilar to the UK, I remember reading that UKMET held JMA in high regard, am sure verification stats will bear different results however when one model sniffs out something other than the huge suite of models with MJO predictions it is worth looking at (unless the Global Fail System - only kidding GFS love you for your dartboard lows).

[Panayiotis]

Again definite trend to colder conditions after next weeks warmer air arrives to the UK where possibly 13C could be reached later on in the week,especially in the SE. Also once again the control diving down to become one of the coldest members, something which has been apparent today...

Edited March 2, 2013 by Panayiotis

[Snowman.]

but this simply comes back to the pointless argument of whether the ops should be believed or the ensembles. People pick and choose whether the ops should be followed or, suddenly, if the ensembles trend cold in winter then we should follow them.

where are the stats that back the idea that we should follow the ensembles in this situation?

To be honest I have no idea...

The ops are proved right some times and proved wrong too just a fact that we need to wait till its much more clear.

[Panayiotis]

Thank you, the reason JMA cited as relevant was based on Ian F thoughts that the JMA held in high regard by UKMO, this was considering the solid resolution provided in resolving synoptics for a small Island not too dissimilar to the UK, I remember reading that UKMET held JMA in high regard, am sure verification stats will bear different results however when one model sniffs out something other than the huge suite of models with MJO predictions it is worth looking at (unless the Global Fail System - only kidding GFS love you for your dartboard lows).

Yes the JMA is regarded highly by the Met but its the BOM which is an extension of the UKMO model.

These charts present the data model BOM ACCESS-G Australia. The maps are updated from 7am to run 00Z and 19h for the 12Z run. The model is based on the system of unified model UKMO.

Edited March 2, 2013 by Panayiotis

[SMU]

What makes you think this Steve, last time it was the ECM showing the coldest of solutions when you said something similar to this and you were indeed right however this time its the GFS?

yeah its odd-

Obviously I like picking out when i think cold solutions will show ( but then it has just been winter )-

I would like to think I still remain objective towards the models in the mid term outlooks, however it has been shown time over this winter that the GFS couldnt deal with the scandi high pressure scenario & undercutting.

Here we have another different solution, with the screaming -AO & cold bursting south, I dont see what other people see from the models, I look for plausability & seemless flows- the GFS is often cluttered & the interaction of low pressures poor.

Im expecting medium potential for cold surface air off the continent between day 9/10 - how deep that cold is is wild in variability-

the ECM not being on board yet is surprising, although it still in the territory of 'swing'

The GFS ops havent been cold- just a handful of ensembles- however the BIG thing to note is all the very cold ensembles look close to the UKMO 144 solutions....

Ive found a few posters ( some more senior ones) very stubborn this year, that in the face of posting clear obviously posts & links to the failings of the GFS in 'certain' situations that when exactly the same solution comes up they are still using that model for a credible solution- doesnt make sense.

FWIW in this scenario I dont see the ECM with a huge significant advantage over the GFS- so the playing field is fair.

As for the anomaly charts--- waste of time for the UK-- This point being perfectly illustrated in December when we had 2 weeks nearly of 3 week + height anomalies then 2 + week anomalies then + 1 week anomalies all from the NEAFS showing big anomalies to the NW & over Northern Scandi- all predicting easterlies-

Where did our weather eventually come from. the SW.-

I have not looked at the anomaly charts once & never will- whats the point.

At best a weak teleconnector to the global pattern with almost zero link to the surface conditions.At worst not even representative of what is going to happen- how many black hole charts over greenland have we seen this winter- LOADS. how many have varified.

A big fat Zero.

Also anomaly charts are V the base state. How many people actually know the base state pattern- especially over scandi!-

If you take the predicted cold pattern developing on the control- will that wedge of pressure even register on the anomaly charts!!!!

Edited March 2, 2013 by Steve Murr

[SMU]

FWIW I think the CMA & JMA are the plausable non extreme outcomes tonight-

S

[Panayiotis]

Thank you very much for that Steve, advice and information onboard! I hope you are right, you have been a great contributor along with others to this thread this winter.

Edited March 2, 2013 by Panayiotis

[Thundery wintry showers]

Re. homegrown convection from an easterly, I have to admit that I stand corrected, after reading some of the responses to my post.

It's more specific than that- the type of continental easterly with a strong belt of high pressure to the north and relatively high 500hPa temperatures & heights would struggle to see any sort of homegrown convection but, given a cold enough airmass, can produce a fair amount of convection over the North Sea. But if pressure and heights and temperatures in the mid to upper atmosphere are relatively low, then indeed, come to think of it, there's no reason why a cold easterly or north-easterly wouldn't be capable of seeing the sun generate some homegrown convection. Indeed, I'm reminded of the north-easterly of the 16th/17th May 1996, when a cumulus congestus drifted onshore in the Tyne and Wear area on the evening of the 16th and it sprouted into a cumulonimbus with heavy hailstones after it came onshore.

http://www.wetterzentrale.de/pics/archive/ra/1996/Rrea00119960517.gif

However, an easterly that struggles to generate much convection over the North Sea (e.g. due to a layer of dry stable air at the 600-850hPa level, like happened a week ago) won't generate much, if any, over the land either- the dry lid won't go away.

The main issue with the current setup is that I think we'd need quite a significant shift in the current synoptic pattern to generate a sufficiently unstable easterly type for significant convection over either the North Sea or inland. A few of the GEFS ensembles point towards that scenario but they are few and far between at the moment- most of the "easterly" options don't see the colder airmasses quite reach us.

Edited March 2, 2013 by Thundery wintry showers

[bluearmy]

In the end, verification will make us look like a prophet or not. I understand the points made on here. Its all about interpretation and insight. I have a current disagreement with john re the cpc output where our views differ. Neither of us is right or wrong. The nwp currently churning out runs that support both views. In a few days one of us will be proved right. But the beauty of this game is that doesn't make the other viewpoint incorrect at the time it was made.

[jules216]

i believe we are going to see the jet stream continuing running south of us and we are going to be stuck in a through with low preasure not clearing north east rather stuck in one place for days bringing more prollonged rain rather than mild showery type of westerlies, this was the story of past year or so and appart from a rare dry anticyclonic weather we are experiencing now, we will hit the reset button next week and most probably the reason behind the persisting southerly tracking jet steam lies in a very low solar activity, lowest cycle in a decade, sorry the last part is not quite related to the model thread http://www.meteociel.fr/modeles/gfse_cartes.php?ech=192&code=0&mode=5

[winterof79]

Continuation of a colder theme and blocking to the north/e ECM

http://www.meteociel.fr/modeles/ecmwf/runs/2013030200/ECH1-168.GIF?02-12

http://www.meteociel.fr/modeles/ecmwf/runs/2013030200/ECH1-192.GIF?02-12

GEM http://modeles.meteociel.fr/modeles/gem/runs/2013030200/gemnh-0-180.png?00

The METO do not see a s/e /e feed for no reason.

GFS not sure where its going yet

http://www.wetterzentrale.de/pics/MT8_Manchester_ens.png

[winterof79]

Not too spring like over Eastern Europe

http://www.meteociel.fr/modeles/ecmwf/runs/2013030200/ECH0-216.GIF?02-12

[Paul]

Locking this one, new thread here: