Model Output Discussion

[ScottSnow]

Im not sure I agree.

If what we're seeing in the model output is going to bring a prolonged cold spell then we're going to need to see pressure rise over Scandi bringing an E,ly. If not slowly becoming milder is the likely outcome.

In my opinion with pressure forecast to remain high to the north of Britain the potential is there for the weather to remain on the cold side especially in the north. Admittedly lying snow would probably be confined to higher areas but maybe not exclusively so. The 'potential' is there for another shot of cold air from the east or north while pressure remains high in the Greenland/Svalbard area. The cold spells in Febs 01, 04, 05, and 06 all came at the end of Feb and I personally don't rule any real proper winter weather out until mid march.

Edited February 11, 2010 by Snow White

[Duane S.]

I've suddenly realised what a really weird situation this is. I don't know what trend I want the model runs to show any more! If that makes sense?

MJO seems to be thinking about scooting back to phase 7 which should be good for future propects I would have thought. All in all next week holds some true potential within it. I am certainly out of my comfort zone forecasting prospective events for this one!

[SP1986]

I've suddenly realised what a really weird situation this is. I don't know what trend I want the model runs to show any more! If that makes sense?

MJO seems to be thinking about scooting back to phase 7 which should be good for future propects I would have thought. All in all next week holds some true potential within it. I am certainly out of my comfort zone forecasting prospective events for this one!

MJO I assume is rather like the NAO/AO in what it shows is not indicative of the weather it will bring but instead reflective of the changes in visual processed models (as such as we can see, and decipher).

Therefore it could change with the next change in the models.

further adding to the complication to things

[sandstorm2]

MJO, NAO, AO Solar Activity, MMW, Split Vortices :blink:

I never imagined before I started haunting these boards that so many things impacted on our weather systems. Forecasters definitely don't get the credit they're due.

Several times recently I've been tempted to post my thoughts on future events before a member has introduced the complications of one or all of the above, and hastily thought better of guessing!

I don't even know where we stand anymore, I can't seem to pick out a trend, even with reading more experienced member's posts. Does anyone have any thoughts of what they would like to see the 12Z trending towards, whether it's snow, rain or otherwise?

Personally I want the models to trend towards a cold and snowy outlook and at the moment it is a knife edge situation, don't think we will know until 24hrs before the event next week

SS2

PS, think this should really be in the cold spell discussion thread.

Edited February 11, 2010 by sandstorm2

[Duane S.]

MJO, NAO, AO Solar Activity, MMW, Split Vortices :blink:

I never imagined before I started haunting these boards that so many things impacted on our weather systems. Forecasters definitely don't get the credit they're due.

Several times recently I've been tempted to post my thoughts on future events before a member has introduced the complications of one or all of the above, and hastily thought better of guessing!

I don't even know where we stand anymore, I can't seem to pick out a trend, even with reading more experienced member's posts. Does anyone have any thoughts of what they would like to see the 12Z trending towards, whether it's snow, rain or otherwise?

I know! Sometimes it really does get just too complicated...

You can throw the GWO (Global Angular momentum) into the mix as well as that can have quite a bearing on events downstream, i.e. what we experience. GP and Brickfielder are the guys in the know for that one.

It's worth mentioning though, that a lot of those oscillations / factors you have mentioned are tied in (directly or less so) with each other as opposed to being totally independant issues.

[remymartin]

The GFS looks farther east on the 12h. It just cant make its mind up

EDIT quite a bit farther.

Edited February 11, 2010 by remymartin

[cuckoo]

Its looking further East to me on the 12Z so far

[mountain shadow]

The GFS looks farther east on the 12h. It just cant make its mind up

About 100 miles further east, which is a massive difference for the small country at that timeframe.

http://charts.netweather.tv/gfsimages/gfs.20100211/12/81/airpressure.png

The GFS looks farther east on the 12h. It just cant make its mind up

EDIT quite a bit farther.

About 100 miles further east, which is a massive difference for this small country at that timeframe.

http://charts.netweather.tv/gfsimages/gfs.20100211/12/81/airpressure.png

[full_frontal_occlusion]

MJO seems to be thinking about scooting back to phase 7 which should be good for future propects I would have thought.

Going to stick my neck out and probably get it shot off but.....

Seems to me that the postioning and track of the low out to the west next week, is dividing snow-potential opinion on the boards wrt marginalty or major event.

It also seems clear that a South Westwards trajectory improves the prospect for Polar Maritime rather than returning Polar Maritime air?

The resident teleconnection and GWO experts may like to comment on the current set of data wrt AAM, Mountain torques and flux convergence but:

1) Relative AAM seems to have peaked although still very +ve:

2) Mountain torques have dropped to zero or are now -ve:

3) Frictional torque has gone -ve:

The torques generating the AAM anomaly and hence reverse zonal winds would therefore suggest the westward retrogression of that low pressure system should soon be arrested. That bodes well for the models to begin picking up on a a more favourable South easterly track for the low?

4) NAO indexes still show -ve deviation but is that not a function of the ensemble members which perhaps have not picked up on the AAM developments?

A better indicator is the copuling between the MJO and the NAO:

5) MJO is phase 8 transition to phase 1:

and could move to phase 3/4 within 7 - 10 days with it coupling to the NAO which should show signs of a returning to a more +ve index.

This is just my amateur interpretation but to me heralds a pattern change where the reverse zonal winds influence is diminished and we start to see more of an Atlantic feel once again but perhaps some fun times during the transition period starting wrt to that low tantalising us to the west next week.

Would welcome the resident experts comments. :blink:

ffO

Edited February 11, 2010 by full_frontal_occlusion

[Harsh Climate]

Its looking further East to me on the 12Z so far

I think thats a small improvement, but what we really want is for it to be further south, that may then allow for an easterly down the line :blink:

[sandstorm2]

About 100 miles further east, which is a massive difference for the small country at that timeframe.

http://charts.netweather.tv/gfsimages/gfs.20100211/12/81/airpressure.png

About 100 miles further east, which is a massive difference for this small country at that timeframe.

http://charts.netweather.tv/gfsimages/gfs.20100211/12/81/airpressure.png

is that better or worse for the cold?

[locneverstop]

Personally I want the models to trend towards a cold and snowy outlook and at the moment it is a knife edge situation, don't think we will know until 24hrs before the event next week

SS2

PS, think this should really be in the cold spell discussion thread.

I'll remember that for next time, I only posted it here as I know you guys can help me out with my little musings.

LP has moved back East again on GFS, maybe a possbility of this becoming more pronounced? I didn't catch the 18z yesterday, but I know yesterday's 12Z has the low further East.

Interesting to see how the rest of the run will unfold.

Edited February 11, 2010 by locneverstop

[Geordiesnow]

12Z is certainly not as snowy as the 06Z run but it is an interesting run as it brings the low further eastwards. If only the cold air was a little bit more stubborn then we might of seen quite a snowy run, as it is though, its a mixture of rain/sleet and snow it would seem.

Not a bad run for convective weather fans though, i'm sure some squally showers will develop as inland warming from the strengthening sun takes place.

[Optimus Prime]

If you'e on an oil rig out in the north sea you'd probably want the low over Scandinavia. Ireland you'd want it over England and England over the North sea.

All relative to peoples personal preferences. I'm guessing it'll end up over the north sea.

[mountain shadow]

Well the trough is actually about 300 miles further north east at T+120 which should be better for cold............but it isn't? with more milder air brought into the mix?

The snow charts are a mess with sleet/snow/rain/sleet/snow, down the country.

Model watching pointless for specifics at this range.

http://charts.netweather.tv/gfsimages/gfs.20100211/12/120/h500slp.png

[Thunder Snow]

Im not liking the 12z, the snowfest for the NW has downgraded me things.

[cooling climate]

As far as the GFS model is concerned the lows movement from t72 plus hours out

is obviously still to far for the model to accurately depict its movement, hence the

difference between the 06z and 12z run in such a relatively short time frame.

According to the changes between the two runs today from the GFS I suggest

sticking a pin in the chart you may turn out nearer the mark.

Edited February 11, 2010 by cooling climate

[mountain shadow]

Looks like a good run further down the line, with colder air coming south as the trough pulls into the Continent.

http://charts.netweather.tv/gfsimages/gfs.20100211/12/150/h850t850eu.png

[Iceberg]

Don't understand some of the comments re the 12Z, it's a stunning run upto T168.

A Major shift eastward, but it has bands of snow moving around the high for all.

[remymartin]

At 168h its a totaly different chart to the previous run. the low races to the north sea. its anyones guess at the moment

[TEITS]

At least with this run the LP slowly moves E keeping us cold.

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

Lets be honest the models don't have a clue what to do with this LP. Also how far S/E the Arctic HP moves is uncertain.

[mountain shadow]

Don't understand some of the comments re the 12Z, it's a stunning run upto T168.

A Major shift eastward, but it has bands of snow moving around the high for all.

Because even though it's shifted East it's not cold enough for lowland snow in my opinion. The proper cold is put back again.

[Rollo]

The difference between 6z and 12z at 174hrs is so vast as far as the UK is concerned that I feel that we will only get a really good idea at T+48 the way things are going.However watching the differances between each run is fun but I would not get exited yet a while.

[Iceberg]

But the proper cold is there !, it hasn't been on alot of runs come the 19th almost the whole country is sub 520 thickness, a slightly larger mild section, but...this quickly passes though with thicknesses showing snow for 98% of the country IMO.

[TEITS]

Because even though it's shifted East it's not cold enough for lowland snow in my opinion. The proper cold is put back again.

Swings and roundaputs comes to mind with the 12Z.

Still the chance of snowfall but what the 12Z is showing in the medium range is far more promising than the 06Z.