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Model Output Discussion 1200 hrs 15/11/14


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It all unravels because it blows up the shortwave and this phases with upstream energy. As soon as you get this phasing you lose the dig south of the trough which helps to build the ridge towards Greenland, the UKMO is pretty similar with a blown up shortwave.

 

Because the models don't want to send that shortwave se then its crucial that it remains shallow, both the ECM and GFS do that, the GFS love child  P and the UKMO don't, sum total not great.

 

I would still urge some caution regarding all the outputs good or bad for cold, there are some uncertainties with events in the eastern USA which do effect how the jet exits the eastern USA past T120hrs.

 

Talking about the US have you seen the upgrade chart  for Tuesday.

 

"Familiar pattern w/blocking ridge over Alaska & deep trough over Great Lakes. Tuesday upper-level snap-shot"

https://twitter.com/RyanMaue:

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Talking about the US have you seen the upgrade chart  for Tuesday.

 

"Familiar pattern w/blocking ridge over Alaska & deep trough over Great Lakes. Tuesday upper-level snap-shot"

https://twitter.com/RyanMaue:

Yes some amazing Lake Effect snow totals there. The pattern however is changing and good agreement for the deep cold to subside as high pressure moves east towards the eastern USA, the Alaska heatwave looks like coming to an end as low pressure sets up there.

 

There is a window of opportunity afforded to the UK to get high pressure in a more favourable location for cold, I'm fairly confident of colder conditions but not sure if this will be a more se surface cold flow or whether a helpful shortwave will do the business and act as the trigger to deliver deeper cold with a chance of snow.

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Sorry guys but i don't see a noteworthy cold spell just yet, the cold pool won't be extensive enough over europe and what we'll get is a surface chilly feed  but nothing like December 2010, late December onwards is when bonechilling cold usually visits our shores.

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Interesting that the ECM deter was on the warm side of the EPS spread for Berlin days 9-10, indicating the cold pool dropping down from Finland/Norway could perhaps be more advanced in its SWly movement on many of the EPS members than the deter suggests.

 

post-1052-0-67081900-1416180109_thumb.gi

 

London 12z  EPS not quite so exciting for cold, though average max temp generally tailing off in single figures from now on, a gentle downward trend unless we tap into some deep cold air.

 

post-1052-0-23977800-1416180145_thumb.gi

 

However, for the UK to benefit from any cold pool that does drop into eastern Europe via the 'back door' over Finland/Norway on the east side of the block, we really need to see the northerly arm of the jet loop right round our block and return SW to get that cold pool moving towards the UK. Not really happening on 18z GFS op and certainly not the parallel - with the stronger upper flow diving south towards the Black Sea rather reaching southwest on the eastern side of the block.

 

Having said that, 2m temps dropping off nicely on GFS op by day 10 in the dry E or SEly flow off the continent, ovenright frost risk increasing by then too.

 

But, long way to go until the block's position/shape will be anywhere near resolved before we get near 25/26th  when the potential window that's been showing for a colder easterly developing. Bearing in mind that any of the cold easterly charts showing are always around the day 10 mark of recent days runs too!

Edited by Nick F
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GFS18z operational backs the GEM somewhat with a warmish plume moving north next Thursday/Friday (likely cloudy at this time of year) however by next Sunday we import dry continental air and so would see a clearer, cooler flow at the surface which persists well into FI..

 

Rtavn1441.gif

 

Rtavn1927.gif

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Last nights NOAA anomalies

 

The 6-10 Has the HP Scandinavia, the Canadian trough stretching SE to a weak low west of Portugal. A weakish Alaskan HP and LP in the Pacific and no amplification upstream. Depending where the surface HP settles rather dictates the flow over the UK but looking in the easterly quadrant.

 

The 8-14 not dissimilar but the Scandinavian HP less intense with a broader area of weakish negative hts SW of the UK Still no sign of any amplification upstream with a very zonal flow across the Pacific and North America. With the same caveat as above this would leave the UK in a cooler, drier, easterly airstream

 

At first glance the 1534 is not in agreement at D10 with the surface HP much further to the east and a ridge from the SW over the UK with  LP just to the west/ n. west. This will tend the winds more to the SW and below average temps after T156.

 

Charts courtesy WxBell

 

EDIT

Just noticed this from the GFS ops. I'm not being serious of course but it's worth quick glance before discarding.

post-12275-0-91260600-1416203402_thumb.g

post-12275-0-55400300-1416203410_thumb.g

post-12275-0-54228500-1416203419_thumb.p

post-12275-0-06852700-1416206577_thumb.p

post-12275-0-21788200-1416206594_thumb.p

Edited by knocker
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Models at day 6

GFS

gfs-0-144.png?0

Recycling Euro/Scandi ridge sums it up really, winds generally south to south easterly but never particularly cold beyond this point.

 

Parallel

gfs-0-144.png?0

Some brief wet and windy weather for the northern half of the UK before the Azore high ridges north east to return anticyclonic conditions to the UK. Low resolution is similar to the GFS with persistent heights to our east but never really a particularly cold draw.

 

UKMO

UW144-21.GIF?17-05

Pretty unsettled weekend for most of the UK with fronts pushing from west to east. The Azores high would probably build back in but serious doubts about how north it will get. Yesterday Ian Ferguson still mentioned a more mixed south/south west westerly pattern dominating in the mid-term, this operatinal would potentially support such a claim.

 

GEM

gem-0-144.png?00

Strong south/south easterly with the ridge shown on all the other outputs well and truly squashed back to the Azores. The result is a continuing battle of Atlantic trough vs Euro/Scandi ridge but with nothing significant pushing through. It predicts an unseasonally mild Sunday with temperatures in the mid/high teens in the south. This isn't supported by the other models for various reasons as shown above. 

 

A lot of variations even at 5 or 6 days out really. So not a lot of confidence. I do have concerns that there is an increasing amount of more progressive runs coming in now and not just from the usual suspects.

GFS mean

gens-21-1-240.png?0

The high is more Euro based than over Scandinavia at this time.

Still time for change, but in my view, the output is moving slightly away from the proper east/south easterly option in the mid-term.

 

ECM at day 6

ECM1-144.GIF?17-12

Edited by Captain shortwave
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This is the closest thing to the cooling trend apart from other models showing atlantic war machine starts up.

 

ecm500.192.png

 

ecm500.216.png

 

ecm500.240.png

At least it be frosty by night at this setup.

Edited by pip22
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This is the closest thing to the cooling trend apart from other models showing atlantic war machine starts up.

 

ecm500.192.png

 

ecm500.216.png

 

ecm500.240.png

At least it be frosty by night at this setup.

If we can compare that to 36 years ago to the day, there are some similarities...

Rrea00119781128.gif

So perhaps it's a case of there being some potential but acknowledging we must bide our time

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Poor runs this morning. There has been a big change in the ensembles as well with much more Atlantic influence being shown. The block is still there but most of the runs are now showing it as a MLB and that is essentially a mild weather set up for Western Europe with winds always being from a southern quadrant. Bad news for the SW if true as well as this will equal big rainfall totals if it comes to pass.

As Steve said above, will be interesting to see where we are tonight. Also ECM ensembles will be interesting later on.

Jason

Easy to forget we're still in mid November!

Edited by Jason M
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Morning - not the best of overnight runs, pretty disapointing really. Thats the ups & downs of looking past 144 for accuracy -

I will revisit the 12s - see where we are then.

what ive noticed steve is the 12zs seem to be bring the heights and amplification back into play but as soon as the 00zs come out next day then everything falla flat again and we start the process all over again!!we just not getting anywhere with this and also ecm was way further west with the pattern over europe over the past few days and now has gone east again! !! The ecm had such a strong area of high pressure across scandinavia and well into the uk just 24 hours ago for the end of this week but seems to have pushed slightly East like always!!
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As the METO have been saying all along I'm afraid, nothing cold in the outlook on any models this morning. I'm still hoping a possible change happens mid dec as Snowbalz eluded too some days ago( possible) Looking at this set up I'm not quite sure where any cold will arrive from however. The high pressure to the East now looks like getting barged out the way next week.

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Well it once again looks like Atlantic is going to win out for the back end of month. Bringing further rain and winds. Feeling cool under a polar maritime flow though. Just feel like we're once again chasing the cold just like last year. Hopefully we see a change around mid dec but I'm not holding much hope.

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CAA

The advection name tag has just been specifically assigned to 'that date' in november 2010 -

Yes its a concern - updates to come in 6 hours!

We were right to be concerned. ECM now agrees with the others.
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what ive noticed steve is the 12zs seem to be bring the heights and amplification back into play but as soon as the 00zs come out next day then everything falla flat again and we start the process all over again!!we just not getting anywhere with this and also ecm was way further west with the pattern over europe over the past few days and now has gone east again! !! The ecm had such a strong area of high pressure across scandinavia and well into the uk just 24 hours ago for the end of this week but seems to have pushed slightly East like always!!

 

 

Hi. Thats why some of us try and warn you about the ECM D9-10 charts. We have been there and have the bloody T-Shirt to prove it. Unless ECM has support, forget it at that time range. And when the mean supports it, it doesn't mean there is good support, it usually means the whole suite is skewed, as last year's winter is a testament to.

 

Anyway GEM and GFS continue yesterday's more robust Atlantic, and ECM joins them at D9-10. Not saying they have got this right between them yet and usually 3 united runs would give good verification. 

 

Yesterday an Azores wedge at around D7 on the ECM managed to push NE towards Iceland: post-14819-0-01233700-1416210017_thumb.g

 

This wedge was the catalyst for the D10 Scandi high. This morning the phasing of the lower heights to the NW does not allow that wedge to escape:

 

post-14819-0-41473900-1416210136_thumb.g

 

However some of the GEFS do get that wedge through at that time scale, but unlike ECM the vast majority don't go on and over amplify the HP. So the interaction from last night has cluster support on the GEFS but the ECM bias of over amplifying that wedge of HP only has a background signal in the GEFS. Although the ECM outcome is feasible, we have to treat it as doubtful due to its bias. 

 

As for the GEFS, they have now gone to the SW to NE jet as we enter D8. From Friday for 3-5 days the GEFS remain in favour of the uppers plume:

 

post-14819-0-68424400-1416210784_thumb.g

 

So a swing towards the repeating pattern continues from yesterday but still low confidence and more runs needed to get clarity.

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what ive noticed steve is the 12zs seem to be bring the heights and amplification back into play but as soon as the 00zs come out next day then everything falla flat again and we start the process all over again!!we just not getting anywhere with this and also ecm was way further west with the pattern over europe over the past few days and now has gone east again! !! The ecm had such a strong area of high pressure across scandinavia and well into the uk just 24 hours ago for the end of this week but seems to have pushed slightly East like always!!

Yes, and the Meto had no doubt whatsoever about this in their extended forecasts. A big early season win for them and it now looks much less hopeful for a cold spell in the first half of Dec.

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Morning - not the best of overnight runs, pretty disapointing really. Thats the ups & downs of looking past 144 for accuracy -

I will revisit the 12s - see where we are then.

theres no doubt steve very big swings from last night seriously feel this is going to drag on into december main feature being middle ground, cant see a zonal train setting up no time soon and cant see beasterly but i can see cooler surface temps with frost and fog.

 

thats ok suits me let the action commence because this is ideal for future developements.

 

ECM1-240.GIF?17-12

if we could get this between the azores and scandi block se into europe it would be game on..... but tbh i was expecting a turn around hopefully tonights runs will revert back but got a feeling that the party poppers are going to have to wait a while longer yet.

 

but hey no zonal and more seasonal is still a step in the right direction.

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I know I keep banging on about this but tonight's ECM 12z is a perfect opportunity to test this out. If you go from 144 to 168, you will see pressure rise suddenly up towards the Iceland/east Greenland area. None of the other 12z runs go with this. Lets see if it verifies over the next few days.

just going back to my post last night - see above. The ECM run this morning goes a long way to proving my point about it's over amplification issues. And this was at T144 to T168.
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