Model Output Discussion

[KTtom]

Latest UKMO T+72 fax shows the alantic lows slightly futher south than the previous run and the ridge extending down to Iceland is stronger.

Although the front introducing the milder air is further north. Pretty in much with the mid day forecast on BBC. I really think this week is nailed on now, any interest for snow (apart from Wednesdays transient event) has to be what happens after next weekend.

[BLAST FROM THE PAST]

Quite amusing to see so many believe that FI [beyong t96/120] is absolutely spot on correct because it is a mild theme. With the flip flop we have seen last couple of days how on earth can anyone believe FI?. Very interesting change to the ECM at t96....don't look beyond with huge confidence. T120 to 144 just does not look right at all....interesting short term development though from the ECM. The energy will go towards the southern arm down the line, so wait for more changes. I'm talking synoptic pattern here and not rip roaring easterly and I'm keeping my eyes to N and NW currently.

BFTP

Edited January 31, 2010 by BLAST FROM THE PAST

[andymusic]

Although the front introducing the milder air is further north. Pretty in much with the mid day forecast on BBC. I really think this week is nailed on now, any interest for snow (apart from Wednesdays transient event) has to be what happens after next weekend.

and wednesday's transient event could be very interesting - who knows - anyone fancy an upgrade!

[MR EXTREMES]

ok sorry alittle of topic.

i could not believe my ears a minute ago on bbc news 24 weather the fella said turning milder then at the end of the forecast he suspects that it wont be long before colder weather returns.

i wonder what models hes watching lol but thats what i call a ramp from a forecaster.

[Ben_Cambs]

ok sorry alittle of topic.

i could not believe my ears a minute ago on bbc news 24 weather the fella said turning milder then at the end of the forecast he suspects that it wont be long before colder weather returns.

i wonder what models hes watching lol but thats what i call a ramp from a forecaster.

Looking at the ECM at T+240, it gets rid of the Bartlett Scenario? If that turns out to be the case what happens after will be very uncertain. This quote from GP on the other thread sums it up for me

The evolution thereafter will be dictated by the location of any height rises forced by the stratospheric warming

[igloo]

ok sorry alittle of topic.

i could not believe my ears a minute ago on bbc news 24 weather the fella said turning milder then at the end of the forecast he suspects that it wont be long before colder weather returns.

i wonder what models hes watching lol but thats what i call a ramp from a forecaster.

certainly not looking at the models we have at our disposal would not be to surprised if it was yesterdays GFS runs

[MR EXTREMES]

Quite amusing to see so many believe that FI [beyong t96/120] is absolutely spot on correct because it is a mild theme. With the flip flop we have seen last couple of days how on earth can anyone believe FI?. Very interesting change to the ECM at t96....don't look beyond with huge confidence. T120 to 144 just does not look right at all....interesting short term development though from the ECM. The energy will go towards the southern arm down the line, so wait for more changes. I'm talking synoptic pattern here and not rip roaring easterly and I'm keeping my eyes to N and NW currently.

BFTP

i agree blast theres more to this than meets the eye and to be honest i think id rather see this weeks developements now,

because im sure theres something beyond fi that could be intresting although im not expecting deep cold of december jan.

but certainly the term winter returns with a sting in its tail rings true.

ive seen snow falling in april so if winter was to return mid feb or 3rd week in feb it would still be rather exciting with cold still in europe i cant see the alantic getting that far west to be honest.

Looking at the ECM at T+240, it gets rid of the Bartlett Scenario? If that turns out to be the case what happens after will be very uncertain. This quote from GP on the other thread sums it up for me

absolutely ssw event still to take effect so 14 to 28 days is said to be the timeframe,

i expect it could be around 15 days it happen last winter and was pretty quick in coming although this time it seems a slower evolution.

where the heights go will be the key and to be honest after what we have seen so far this winter i would not be suprised if it turned out like jan.

[chionomaniac]

Quite amusing to see so many believe that FI [beyong t96/120] is absolutely spot on correct because it is a mild theme. With the flip flop we have seen last couple of days how on earth can anyone believe FI?. Very interesting change to the ECM at t96....don't look beyond with huge confidence. T120 to 144 just does not look right at all....interesting short term development though from the ECM. The energy will go towards the southern arm down the line, so wait for more changes. I'm talking synoptic pattern here and not rip roaring easterly and I'm keeping my eyes to N and NW currently.

BFTP

I agree BFTP. The underlying signals do not suggest long term mild to me but I can see where the spanners have come from and it may take a little time. I feel that in any other winter that if we looked at the 12Z ECM that we would recognise a certain amount of potential that is behind the pattern. This is not +AO raging zonality after all and it will not take too much of a jet stream shift to allow those height rises to our north to dictate the pattern. There are little signs in the overall pattern that this could be the case and with the stratospheric downwelling patterns so volatile presently, there are still some very interesting model watching in the days to come.

[andymusic]

certainly not looking at the models we have at our disposal would not be to surprised if it was yesterdays GFS runs

don't think so - they'll be using the latest briefing info!

[bluearmy]

ok sorry alittle of topic.

i could not believe my ears a minute ago on bbc news 24 weather the fella said turning milder then at the end of the forecast he suspects that it wont be long before colder weather returns.

i wonder what models hes watching lol but thats what i call a ramp from a forecaster.

given the 15 dayer from earlier, i guess that quote gives us a insight into what the ecm ens mean is showing. the current nwp med term has flipped from several days ago. looking at the 12z's, the 00z's may have overdone the atlantic energy past the meridian. the overall background pattern in the NH is conducive to cold for nw europe. the energy going into the atlantic this week from the gulf shortwaves will drive the trough too far to our north introducing milder air. at some point the strong northern blocking has to get into greenland and w canada as it retrogresses from siberia - maybe this is when a west based -NAO drives the jet south which allows any cold air/blocking to our east/northeast to retrogress west. this is the theory - maybe what we have seen played out during the past week was a plausible route to cold but it couldnt forsee the gulf shortwave conveyerbelt starting up. i recall the short term forecast pattern in the eastern pacific was very volatile from a NOAA dicussion earlier in the week. the gulf shortwave generation is very dependant on what happens of the US west coast. there must be strong reasons why the whole ens suite of GEM,GEFS/ecm plus GFS/GEM and ECM ops were showing the evolution to cold in the med term - my guess is the pattern in the eastern pacific was incorrectly modelled. maybe there is now a strong consensus on the likley pattern in this area lowering the potential for this energy to be entering the atlantic beyond next weekend. couple this with the likelihood of the easetern canadian block forcing the jet south and perhaps we can see reasons for the dropping ens mean beyond next weekend having forecaster confidence.

[andymusic]

Ian Ferguson keeps on about the meto keep the beeb up to date with regular briefings - and that's just their regional forecasters - for news 24 I expect they try even harder to get the briefings smack up to date!

[smich]

I'm puzzled guys. The AO and NAO forecasts are not predictive of what the models are going to show, they are reactive to the current output, right?

Given what the current models are showing since the "turnaround" today, how come AO still shows as tanked and NAO still largely negative with just a couple of positive members?

With both negative, I thought this was the holy grail, and it certainly was during recent cold spells this winter. What's different this time?

The SS warming event should be even more in our favour! Is the Pacific to blame?

Just thinking out loud as it were...

smich

[Snooz]

I agree BFTP. The underlying signals do not suggest long term mild to me but I can see where the spanners have come from and it may take a little time. I feel that in any other winter that if we looked at the 12Z ECM that we would recognise a certain amount of potential that is behind the pattern. This is not +AO raging zonality after all and it will not take too much of a jet stream shift to allow those height rises to our north to dictate the pattern. There are little signs in the overall pattern that this could be the case and with the stratospheric downwelling patterns so volatile presently, there are still some very interesting model watching in the days to come.

Thank you for a voice of reason. I had just managed to get close to the end of thread and was about to give up on it yet again!

(a plea, please could some of you put your [oft repeated] opinions or IMBY posts in the regional threads??)

chionomaniac, your post means I click out with at least some idea of whats actually going on regards MO.. thanks!

[Burygirl]

I never post in here because I have not got the experience or intelligence of you guys regarding the weather but really enjoy lurking and Reading all the posts but could someone more knowledgable answer a novice question? The so called beast from the east came up almost overnight as has the latest mild scenerio. What makes everyone so certain that it won't switch back again?

[SP1986]

Smich it's to do with east and west based NAO, west based NAO and we end up on the west of the trough, east and eastern side, it that terms NAO is relatively pointless in that situation but you are right -NAO and -AO can and have delivered some memorable winters.

I'd say as far as history dictates, with -NAO and -AO, east based NAO's are more common than western NAO's/

[Lewis]

I never post in here because I have not got the experience or intelligence of you guys regarding the weather but really enjoy lurking and Reading all the posts but could someone more knowledgable answer a novice question? The so called beast from the east came up almost overnight as has the latest mild scenerio. What makes everyone so certain that it won't switch back again?

I'll do my best to answer the question, but i'm pretty much certain a model buff will give a better answer, anyhow here go's;

The models was showing an easterly, and a lovely one it was. This was way out of time frame (FI) which means fantasy island. We had mixed signals across the EUROS and the American models. At one point for a couple of runs, did all the models actually agree on the easterly but this was way out in FI.

Another thing was the position of the block, the GFS was holding the block, yet the ECM was allowing it to breakdown with the Atlantic pushing through. Generally, you can tell a pattern by looking into FI , but of course the chances are a much lower % of that pattern happening. Things can change, but as we are now closer to the time frame (near enough reliable time frame) that the models was showing the easterly, the chances are pretty much 0, as we have a completely different pattern developing now.

Hope this helps

[SP1986]

I never post in here because I have not got the experience or intelligence of you guys regarding the weather but really enjoy lurking and Reading all the posts but could someone more knowledgable answer a novice question? The so called beast from the east came up almost overnight as has the latest mild scenerio. What makes everyone so certain that it won't switch back again?

welcome, I guess youve been enjoying the snow your way?

The easterly was being shown for a while and was for much of time supported by the signals. One model however the UKMO suggested the easterly would not occur, so actually although all the models have agreed recently, the UKMO model has had this latest idea for a while.

I think a lot of people are hoping it'll switch back again, personally I'm sceptical it will but I don't think anyone would be wise to write off an easterly in the future, it may happen in 2 weeks?

[lukemc]

Hi,

Is it the case that the current teleconnections that are predicted at the moment are not supportive of a long term mild pattern for example I read a post saying the AO/NAO is progged to go deeply negative (or one of them was) - wouldn't that be more likely to result in a cold pattern in about a weeks time for mid February? Also again I ask what is the state of play with respect to the Polar Vortex - I have noticed no one has mentioned this in the last few days there does not to seem to be any organized PV over the Greenland area or predicted to be in the near future in any of the model output. (feel free to correct me if I am wrong on this). Now earlier in the winter (early December) I have read posts saying that the lack of any organized PV over Greenland makes it easier for a cold pattern to set up. Looking at just these factors alone I have been surprised by some of the posts I have read on weather forums that seem to imply that we will be stuck in a mild pattern for weeks on end! Another thing slightly OT but does anyone think a white Valentines Day could well be a possibility at the moment (do they take bets on that like they do with a white Xmas) - and when was the last "white" Valentines day - how common are they?

Luke

[andymusic]

I never post in here because I have not got the experience or intelligence of you guys regarding the weather but really enjoy lurking and Reading all the posts but could someone more knowledgable answer a novice question? The so called beast from the east came up almost overnight as has the latest mild scenerio. What makes everyone so certain that it won't switch back again?

nobody can say the models will or won't for certain (unless they had a time machine) - it is quite feasable that they could flip again - it's the cold blocking that interests me - who will win the fight between the atlantic low and the blocking cold - that's why the models are at 6s and 7s + now this extra spanner as well with this extra energy out of the states (but we'll see just how much energy that is once it arrives)

The guy at the end of country file weather said the same thing. Perhaps they know something we dont lol.

they just get the same meto briefing

[swilliam]

Quite amusing to see so many believe that FI [beyong t96/120] is absolutely spot on correct because it is a mild theme. With the flip flop we have seen last couple of days how on earth can anyone believe FI?. Very interesting change to the ECM at t96....don't look beyond with huge confidence. T120 to 144 just does not look right at all....interesting short term development though from the ECM. The energy will go towards the southern arm down the line, so wait for more changes. I'm talking synoptic pattern here and not rip roaring easterly and I'm keeping my eyes to N and NW currently.

BFTP

I agree re the seeming belief that now that FI is mild it is going to happen. There is Paul B and others telling us that we will have double digit temps next weekend - if we were saying it would be v cold would we be saying this - I doubt it. We have people talking about record max temps for Feb - have they gone mad! It would be nice to have some balanced posting on here (both sides)

Looking at the ECM ensembles it is clear that the op was very much at the top - especially in FI where people are ramping up the mild. This explains why the Meto are suggesting the possibility of a return to cold after or over next weekend.

I suspect that as was suggested earlier it only needs a small amount of undercutting to get blocking to the NE and return of a continental flow. It is clear to see on both the UKMO 144 and the ECM 192 that small changes could induce this.

Presumably this is what happens on the large number of ECM cold ensembles

The GFS has started overblowing the Atlantic LPs so is less likley to happen

Edited January 31, 2010 by swilliam

[pj cov]

I love your posts! So realistic, true and sensible. Would I be right in thinking if the model runs we have seen today came off, post mid-week that is, weather like that of early Feb 04 would be the case. Rather showery and breezy but not soaking and much milder than the northerly we had had the week before.

can anyone here,,hand on heart,,actually remember feb 2004,,,,i can barely remember feb 2010,,,and it hasnt even happened yet......

[Ben_Cambs]

Good to see from the De Bilt Dutch ensembles that a prologned mild spell is not supported. A majority of members go for cold in the long term

[Ian Fergusson]

The guy at the end of country file weather said the same thing. Perhaps they know something we dont lol.

Hi Kent:

Nope.

Nothing other than I've already posted earlier on this very thread in terms of the UKMO standpoint. Will it prove correct? Who knows. But that's for the future.

I would add that the GM (the raw basis for our medium-range BBC graphics) often sees modifications made each day on the basis of Arpege, GFS, etc., so it's hardly a myopic standpoint being adopted at Exeter's Ops Centre. I'm sure the other national models are often being adapted based on UKMO output, too. Good science, I'd suggest.

After all, the essential business at Exeter is (peer reviewed: please note this key point) science and - unlike religion - science of any discipline should always be open and willing to accept tweaks or even massive U-turns representing new collective thinking / conclusions.

[Burygirl]

thank you for replying! Yes it's been lovely here! Went sky diving yesterday v. Cold but amazing views near coast! Back to lurking again! Thais again

[kent]

nobody can say the models will or won't for certain (unless they had a time machine) - it is quite feasable that they could flip again - it's the cold blocking that interests me - who will win the fight between the atlantic low and the blocking cold - that's why the models are at 6s and 7s + now this extra spanner as well with this extra energy out of the states (but we'll see just how much energy that is once it arrives)

they just get the same meto briefing

OK but why would established BBC forecasters put their heads in a noose and predict colder weather returning after next weekend. It doesnt seem logical to me to predict what we would classify as FI if they didnt have some degree of confidence. Regardless of the fact they do not usually commit themselves to that far out normally.