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Model output discussion - 5th December 2016 - Into Winter we go

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2 minutes ago, northwestsnow said:

There is simply to much energy in the Atlantic and pretty much zero in the way of blocking highs to force enough energy south gooner, nothing i have seen in the NWP for the last numbet of days changes my opinion.The ecm this morning looks the most likely at 144 but again at the critical juncture the northern arm kicks in.Thats not an emotive reaction, thats just how it is.

I wouldn't disagree with that ...........................unfortunately

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7 minutes ago, northwestsnow said:

There is simply to much energy in the Atlantic and pretty much zero in the way of blocking highs to force enough energy south gooner, nothing i have seen in the NWP for the last numbet of days changes my opinion.The ecm this morning looks the most likely at 144 but again at the critical juncture the northern arm kicks in.Thats not an emotive reaction, thats just how it is.

I disagree there is zero way in blocking, models are now hinting a tad more strongly of some height rises coming down from the Arctic which may influence our weather down the line. As you say, the ECM in particular comes quite close to this but any subtle differences could lead to a totally different outcome.

Just how much heights comes from the Arctic is uncertain, the models have 'upped' the blocking slightly but still not enough to affect our weather but its something to keep an eye on because these situations can change very quickly and whilst it may look weak and meaningless, they can certainly have more effect on the weather than you might think.

Other encouraging thing for me is the models are not keen on shifting the PV from Western Russia so cold is never too far away. Just look at December 2014 and you just see how far away we were from significant cold when you look at those charts with a raging Atlantic jet, Russian high and barely any cold on our side of the Arctic. Things are better in this respect this year but you do need some luck and other things to go our way.

The heights from the Arctic could well downgrade but its one of those outlooks where cold weather may not be as far away as some might seem to think it is.

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2 hours ago, Summer Sun said:

ECM for winter

December

Temperature - Slightly above normal - precipitation well below average

SeasonalAnomalies_T2m_20161201_m1.pngSeasonalAnomalies_Rain_20161201_m1.png

January

Temperature - No strong signal perhaps marginally above average in parts of Scotland, NI and ROI - precipitation below average

SeasonalAnomalies_T2m_20161201_m2.pngSeasonalAnomalies_Rain_20161201_m2.png

February

Temperature - Marginally above average - precipitation above average for most

SeasonalAnomalies_T2m_20161201_m3.pngSeasonalAnomalies_Rain_20161201_m3.png

 

The odd thing about the rainfall anomaly is the deviation from mean is nearly always tiny. I mean if you take a location that gets 80 mm mean for December, to say that a 10% swing of 8 mm would mean it would be particularly wet, or feel wet is too much, also a swing the other way. Notice you never get noticeable swings, and maybe that is because they don't show any noticeable swing. Of course it also masks the frequency of the wet days or even hours, could be a couple of storms making up 30 mm, in real terms. For that reason, along with the temp anomaly's, these anomaly from mean have to be reviewed carefully indeed and are perhaps useful for flood agencies and other service providers.

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More posts moved into the model banter thread as they're not model output discussion. Please can we all just take 3 secs to consider where to post, it's not a lot to ask so that people can enjoy discussing the models and not have to wade through a mountain of off topic stuff.

 

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The Extended GEFS 6z shows plenty of support for anticyclonic activity with surface cold bringing frosts and freezing fog and there are also at least a few peachy very wintry runs with snow galore.:cold-emoji:

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Edited by Frosty.
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18 minutes ago, ArHu3 said:

It's here 

http://www.emc.ncep.noaa.gov/GEFS/mconf.php

changes at day 8 to even lower res. 

the eps change at day 10 to a lower res although I wonder if the recent update has changed that ?

Edited by bluearmy

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2 hours ago, MidnightSnow said:

Do you have these particular charts from a month ago? I'm just interested to know if there's been much change. Thanks

Somebody posted them and from memory there was some cold closer to the UK. I wonder when the run was made though, the monthly charts are from Nov28. Very bullish for a cold pre Xmas week but we know that changed on last thursday's run.

MonthlyAnomalies_T2m_20161128_w4.png

 

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I make 10 AO members here, with 6 negative and 4 positive by the end of the graph.

image.gif

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3 minutes ago, Paul_1978 said:

I make 10 AO members here, with 6 negative and 4 positive by the end of the graph.

image.gif

But if those AO indices are arithmetically derived from the model-generated synoptic forecasts (as I suspect they are) do they actually show us anything that said forecast-synoptics themselves do not? 

PS: I'm not trying to be sarcastic BTW.:) 

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Right then - here it comes...What'll it be? The first stellar run in what seems like ages? Or, more likely - teddy-at-the-ready!:D

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7 minutes ago, Glacier Point said:

12z data showing a shift in Equatorial low level westerly winds and convective anomalies much further east compared to 00z and 06z data. Be interesting to see what if any difference this makes to tonight's models.

Hello GP. Where do you get this information from? Do you have access to a broad overview of the data gathered? Not asking for you to post anything business sensitive, just curious as to broadly where this comes from.

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GFS 12z spinning up the low out west at t84. Reality or habit?

gfsnh-0-84.png?12

Worst of winds staying offshore, although Western Isles could be breezy.

gfs-14-102.png?12

Edited by Ravelin
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Just now, warrenb said:

I notice the GFS Para is back, what  is this ?

Hi, It's running ahead of an upgrade due in May 2017

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56 minutes ago, Glacier Point said:

12z data showing a shift in Equatorial low level westerly winds and convective anomalies much further east compared to 00z and 06z data. Be interesting to see what if any difference this makes to tonight's models.

Upper level winds still more easterly dominated but two out of three tropical forcing facets demonstrating an eastward trend [and therefore less likely to be destructively interfering on the downstream pattern].

What impacts could this cause for us in the UK?  what's your take on things regarding stratospheric warming? 

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12 minutes ago, warrenb said:

I notice the GFS Para is back, what  is this ?

It's updating now but be aware it's about 6 hours behind the op

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2 minutes ago, bobbydog said:

It's updating now but be aware it's about 6 hours behind the op

And therefore it will be the 06z run coming out !! (Just in case someone wants to compare and contrast)

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PV slightly weaker over NE Canada on this run at 144 (less purple), hard to see if this will help but the lows may track slightly differently when heading our direction and WAA may be a possibility.  The ENS that were of interest in the 06Z seemed to have slightly weaker PV in NE Canada early on.

Edited by Ali1977

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T156 looks a critical point to me on the GFS. If the flow swinging round the mother low in the Atlantic pushes more towards the north than to the east once on our side of the Atlantic, we could be in business. Knowing the GFS, it's not totally out of the question.

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