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Model output discussion - 20th Feb onwards

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7 minutes ago, Polar Maritime said:

Plenty of snow showers being blown South from Friday into next week, On a cold Northerly flow..

a.pngb.pngc.png

A tatse of winter at last

18_156_preciptype.png?cb

Edited by Banbury

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1 hour ago, nick sussex said:

Looking at the models they don't show any fast response to the major SSW.

Sometimes we see a quick initial  response, others this takes time to propagate down. Its hard to imagine this won't have some effect:

ecmwfzm_u_f192.thumb.gif.fbfb4979a623e86

That's a big reversal and the strongest I've seen in terms of a major SSW.

 

image.thumb.jpg.4119ba21aa9a0282de7fd596The AO remains only slightly negative. 

We should soon be seeing a much more pronounced  -AO with WAA's feeding into the polar region.

Free to view models are just not factoring this in yet.

Which will then indicte to us at what heights the free to view models take their data from by comparing emergence of a more -AO on the Synoptics to the position of the downwelling SSW. 

A good insight to have regarding the working models we use. 

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Guest

Judah Cohen's weekly report has just been updated;  http://www.aer.com/science-research/climate-weather/arctic-oscillation. I have no time to do justice to this right now, so I'll be brief. Overall, it is a slight downgrade on last weeks' exciting predictions. Basically a slight delay to the last throws of the polar vortex until mid-March. The cold into Europe is also delayed and somewhat diluted. He agrees that the MJO will weaken steadily during the next week having entered phase 8. The AO going negative is also delayed but this and the major SSW will impact by mid-month.  He still expects northerlies or easterlies to dominate but more especially towards and after mid-March and into April.

Unfortunately, we were already almost too late and I fear that the 2 week delay in his prolonged cold spell predictions for Europe will be less extreme than he previously suggested. So "probably" more of the rather cold and marginal events. Sorry to sound a little deflated. I may provide a longer commentary on next week's report if it is more encouraging. In the meantime, we still have this week's coldish spell and possibly somewhat wintry at times.

EDIT: Whilst I was preparing this I see that bryan629 beat me to it (just like last week!). He views it more optimistically than I do. I really hope that he is right.

Edited by Guest

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10 minutes ago, fergieweather said:

Tonight's EC Monthly retains the colder than average, effectively northerly-dominated regime all the way through March. So, continuity with the last run.

Thanks for the update Ian. Do you mind me asking two questions, any news on what it does with the MJO and do you have any news on tonights ECM Upgraded operational run?

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2 hours ago, Nouska said:

The ECM 156 and 162 hour precipitation charts from Icelandic weather service.

ecm0125_nat_msl_t850_6urk_2016022912_156    ecm0125_nat_msl_t850_6urk_2016022912_162

 

Thanks for that.:)

 

The GFS 18z has a very similar scenario at that timeframe with ppn running into established cold air.

 

gfs-2-156.thumb.png.60dc9d60a4fd463408ac

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17 minutes ago, Banbury said:

16030706_2_2918.gif

If verified a covering of snow for quite a few

Yes indeed a belting for some!!

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54 minutes ago, fergieweather said:

Tonight's EC Monthly retains the colder than average, effectively northerly-dominated regime all the way through March. So, continuity with the last run.

I have to be honest Ian and just looking at the mean anomalies I find "northerly-dominated regime all the way through March" a little surprising.

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49 minutes ago, nick sussex said:

Thanks for the update Ian. Do you mind me asking two questions, any news on what it does with the MJO and do you have any news on tonights ECM Upgraded operational run?

Remains through phase 8 to d5; to 1 by d10 and round to 3 then 4 days 15-20.

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13 minutes ago, knocker said:

I have to be honest Ian and just looking at the mean anomalies I find "northerly-dominated regime all the way through March" a little surprising.

SFC flow charts remain from a N'ly quarter throughout, but with inevitably weakening signal by later March. Bear in mind it's not offering the day to day variance. 

Screenshot_2016-02-29-23-27-20-1.png

Edited by fergieweather
EDIT Weekly ENS mean anomaly showing 10m wind (arrows) by 27 March

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47 minutes ago, Bring Back1962-63 said:

Judah Cohen's weekly report has just been updated;  http://www.aer.com/science-research/climate-weather/arctic-oscillation. I have no time to do justice to this right now, so I'll be brief. Overall, it is a slight downgrade on last weeks' exciting predictions. Basically a slight delay to the last throws of the polar vortex until mid-March. The cold into Europe is also delayed and somewhat diluted. He agrees that the MJO will weaken steadily during the next week having entered phase 8. The AO going negative is also delayed but this and the major SSW will impact by mid-month.  He still expects northerlies or easterlies to dominate but more especially towards and after mid-March and into April.

Unfortunately, we were already almost too late and I fear that the 2 week delay in his prolonged cold spell predictions for Europe will be less extreme than he previously suggested. So "probably" more of the rather cold and marginal events. Sorry to sound a little deflated. I may provide a longer commentary on next week's report if it is more encouraging. In the meantime, we still have this week's coldish spell and possibly somewhat wintry at times.

EDIT: Whilst I was preparing this I see that bryan629 beat me to it (just like last week!). He views it more optimistically than I do. I really hope that he is right.

Sorry to beat you to it again ... i promise its not intentional :)

The reason why im optimistic of Cohens blog is he seems again very confident of  the cold pool sat currently eastern Siberia to retrogress westwards towards Europe..as the predicted AO is going to go "wildy" negative allegedly . So it sounds perfectly plausible for the cold pool to slide westwards around the -AO 

I am kind of inclined to agree it will modify as it goes to a degree, however, if this does occur and make inroads to Europe and across the sea to our shores... it will still have a decent bite to it :cold:

How much modification occurs will obviously depend on snow cover over eastern/ northern Europe but also to factor in convection with stronger solar energy and cold uppers departing Europe, Thats if he is correct of course.   as posts above are suggesting mostly a Northerly flow throughout March ...  . So long as it not a nusience value and brings the coldest winter month of spring with plenty of snow for everyone then im not complaining .

 

 

 

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1 hour ago, fergieweather said:

Tonight's EC Monthly retains the colder than average, effectively northerly-dominated regime all the way through March. So, continuity with the last run.

Hi Ian, I`m just wondering..... because the EC monthly effectively retains a Northerly dominated theme for March... could we be looking at a potential Omega block out west ? 

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NB: whilst UKMO recognise a greater chance v average of blocked conditions later March (due to SSW/MJO), they're not yet convinced re latest EC Monthly prognosis: suspicion is that EC's later output may be biased by lagged response to previous (and now less well defined) modelling of strong mid-Atlantic ridging further away in medium range. Signals are becoming more mixed by mid-month in latest other ensembles and thus weak mobility may yet come into play, but conversely it could all go down the blocked route...at least periodically. A tricky period, as UKMO note! Fascinating times.

Edited by fergieweather

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Roll up, roll up............place your bets.

gfs_ptype_slp_uk2_13.thumb.png.379b78097gfs_ptype_slp_uk2_14.thumb.png.8411fa0ea

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49 minutes ago, knocker said:

Roll up, roll up............place your bets.

gfs_ptype_slp_uk2_13.thumb.png.379b78097gfs_ptype_slp_uk2_14.thumb.png.8411fa0ea

Snow over Camborne!

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6 hours ago, Frost HoIIow said:

An extra blanket or two... and these may come in handy as well knocks :D

 

Blue-Crayon.jpeg

Fifty shades of blue no less.

But wait...what have we here? :shok:

gfs_t2maf_slp_eur2_51.thumb.png.900b63c9

Edited by knocker

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EC takes the Friday main snow threat further north across the Midlands. More eastward impetus rather than se for the occlusion.  Still looking at a messy wintry mix further south and probably some lying snow over the Cotswolds and chilterns. 

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2 hours ago, knocker said:

Roll up, roll up............place your bets.

gfs_ptype_slp_uk2_13.thumb.png.379b78097gfs_ptype_slp_uk2_14.thumb.png.8411fa0ea

Bank....

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1 hour ago, bluearmy said:

EC takes the Friday main snow threat further north across the Midlands. More eastward impetus rather than se for the occlusion.  Still looking at a messy wintry mix further south and probably some lying snow over the Cotswolds and chilterns. 

As does 0z GFS Op.  0z Arpege takes it even further north over northern England.

Very little 0z model guidance offering much over Southern England with regards to snowfall on Friday now.

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Just now, AWD said:

As does 0z GFS Op.  0z Arpege takes it even further north over northern England.

Very little 0z model guidance offering much over Southern England with regards to snowfall on Friday now.

Indeed some areas of the Southern Pennines could get pasted

160301_0000_78.png

160301_0000_78.png

Then topped up with showers from the East thereafter.

160301_0000_114.png

160301_0000_114.png

What you get you could keep too as it will not be over warm.

 

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Maybe one last hurrah on thur night into friday across the north, looks very borderline as you would expect at this stage of the season but certainly potential of places north mids/nw england esp with some altitude to see a covering i would think.

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I would be very wary of any snow accumulation maps the gfs churns out. We know the gfs tends to blow these out of all proportion. If the gfs had been anywhere close this winter my area would have seen at least 2 good snow events. Think apart from some wintry showers I can't really see anything apart from a dusting over many areas. Certainly no March 2013 event as Ian f has alluded too many times already. 

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