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Model Output Discussion; into 2015


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12z clusters are offering glimpses of a different story after mid-month with markedly more meridional pattern(s), but of course it's just not worth detailing all that stuff showing out post-15 Jan unt

Some very poor quality posts have been creeping into the discussion which really don't add anything to the thread apart from raising the ire of many who view this thread....Even a simpleton (in meteor

Nice tease from the ECM, no surprise looking at the strat charts, shame it can't happen though because apparently cold is not possible before Mid Jan!?!   Rule nothing out folks, as I posted yeste

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Correct me if I'm wrong, but although the charts show potential we are a long way off from seeing anything resembling a beasterly (The sort where most of the country will actually see some of the white stuff) It's ok having northerly or westerlies but when was the last time these delivered a decent snow event to the majority of the country's population that live in the south/ south east? At least with a decent easterly more of us and not just our region gets in on the act, and snowfalls and cold tend to have less marginality once the Continent cools out east- I still feel as though something is going to change to give us our wish- If we cant have any december snow for xmas my next fave time for a beasterly is between mid January to early feb just before the sun starts getting it's act together.

Here's hoping! :-)

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the scottish ski resorts should do well out of this setup. and if we are lucky there could be a small chance of a snowfall further south in between lows that is.it looks similar  to what we had in the first half of december

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Further signs of Arctic heights developing during the first week of January on the ECM op run in particular, a continuance of a recent theme, NH speaking. Yes, we will need our cards to fall right for another bout of cold or more appropriately snow-producing cold for sure, but I remain very optimistic. Down South the HP influence is the main player as we end 2014 as forecast many days ago. In time, it will even relax its' grip on these parts too, but we'll need to be patient. On the whole, the next five to seven days sees daytime Temps up to average at their very highest and overnight minimums as low as negative double-digits Celcius over the snow-fields in prone regions, Cairngorms etc. but not exclusively.

 

Off to watch the box.  :hi:

Edited by gottolovethisweather
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The ECM is exactly what I was alluding to earlier.

 

http://www.wetterzentrale.de/pics/Recm2401.gif

 

With the jet running SE a relatively weak area of HP is enough to potentially bring cold, snow. I shall have to check the archives later but im sure it was the winter of 2012/13 that often bought the snowfalls.

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Correct me if I'm wrong, but although the charts show potential we are a long way off from seeing anything resembling a beasterly (The sort where most of the country will actually see some of the white stuff) It's ok having northerly or westerlies but when was the last time these delivered a decent snow event to the majority of the country's population that live in the south/ south east? At least with a decent easterly more of us and not just our region gets in on the act, and snowfalls and cold tend to have less marginality once the Continent cools out east- I still feel as though something is going to change to give us our wish- If we cant have any december snow for xmas my next fave time for a beasterly is between mid January to early feb just before the sun starts getting it's act together.

Here's hoping! :-)

it depends on what floats your boat Kentspur.....IMHO, .the heaviest and most prolific snow events normally occur when the parameters are at their most marginal (eg T850's of -2C with dewpoints/wet bulbs just above OC and 500-1000hpa thicknesses of around 528-534....A pure easterly is normally a dry air mass which for snowfall requires anomolous SST's (for decent snow along east coastal districts) and/or low heights in the med basin to allow disturbances/troughs to run along easterly flow.........The sort of synoptic patterns to enable most of the country to receive a good snow event happens with an encroaching atlantic LP system bumps up against a cold pool that's been in place for 24 hour or more  (ie last night)

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The ECM is exactly what I was alluding to earlier.

 

http://www.wetterzentrale.de/pics/Recm2401.gif

 

With the jet running SE a relatively weak area of HP is enough to potentially bring cold, snow. I shall have to check the archives later but im sure it was the winter of 2012/13 that often bought the snowfalls.

Yes, I agree. We need to see that arctic high edge towards our side of the pole though. All too many times in winters past have I witnessed a strong arctic high that always seems to be on the wrong side of the pole. It often teases and sends a finger towards northern Greenland but this only serves to be a finger up to us as it retreats back again. It's for this reason that I hate depending on an arctic high as 9 times out of 10, it doesn't deliver true cold to our shores. What I want to see tonight is a clear downward trend in the ECM extended ensembles. This would be a positive sign.
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The ECM is exactly what I was alluding to earlier.

 

http://www.wetterzentrale.de/pics/Recm2401.gif

 

With the jet running SE a relatively weak area of HP is enough to potentially bring cold, snow. I shall have to check the archives later but im sure it was the winter of 2012/13 that often bought the snowfalls.

I think most of the UK did very well off of weak hp in Scandy during 12/13 winter.... so no real reason as to why that cant be the case again.. things are far from cut n dry at the moment as we move into 2015 things could easy go the way of the coldies.... they could of course go the other way too.. but im hoping they go similar to Jan and Feb 2013

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The ECM is exactly what I was alluding to earlier.

 

http://www.wetterzentrale.de/pics/Recm2401.gif

 

With the jet running SE a relatively weak area of HP is enough to potentially bring cold, snow. I shall have to check the archives later but im sure it was the winter of 2012/13 that often bought the snowfalls.

 

 

Think your right TEITS. It wasn't much of a 'block' but it was just enough to deflect the lows SE. That's probably what we need to hope for here in the near term. Much more fun if we could get 'the big one' in terms of a full beasterly as then the word 'marginal' doesn't enter the equation but beggars and all that.... :good:

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I think T168hrs is looking like perhaps a window of opportunity, much depends on whether we see the development of a favourable low upstream which could carve enough amplification ahead of it to help send more energy se.

 

With the background strat warming and drop in  strat zonal flow in the Arctic its one of those situations which could catch the models out.

 

NCEP mention a lot of uncertainty with northern/southern stream interaction over the USA at that time.

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Well after this week's events it's back to the hunt for cold, and as NS states above, there is a tiny window of possibility in 7/8 days time, unlikely but since there seems no other remote possibility of any serious cold reaching the UK (unless you live up a very high hill), might as well analyse it and keep an eye on it. 

 

It's to do with that blocking over the other side of the Arctic nudging ever nearer to our side. GFS/GFS(P)/ECM are quite similar on this at T192 - here's the ECM:

ECH1-192.GIF?27-0

The "tiny possibility" is that heights might somehow break through Greenland just a little bit more, encouraging more of the cold just above Iceland to head our way. It will be pretty cold coming from there:

ECH0-192.GIF?27-0

 

Doesn't look likely but stranger things have happened. One GFS ensemble member shows what this would look like:

 

gensnh-1-1-216.png

 

Well, at least it's something for coldies to look out for!

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The ECM is exactly what I was alluding to earlier.

 

http://www.wetterzentrale.de/pics/Recm2401.gif

 

With the jet running SE a relatively weak area of HP is enough to potentially bring cold, snow. I shall have to check the archives later but im sure it was the winter of 2012/13 that often bought the snowfalls.

HI TEITS,

 

Yes you are correct  - there were several undercutting scenarios producing significant snowfall without a big block e.g. 9th Jan 1020 mB

 

post-9179-0-14698600-1419709133_thumb.pn

 

and even more notably 23rd Jan 1015 mB

 

post-9179-0-55639400-1419708918_thumb.pn

 

The latter produced about 1 foot of snow here in Northampton.

 

Interestingly the NH pattern shows a big Alaskan ridge along with the PV over NE Canada as is expected in the next few couple of weeks  this year. Back then I remember a lot of discussion about whether these 'blocks' would resist  the rampant PV and promote trough disruption  - the naysayers were wrong again.

post-9179-0-62718200-1419709597_thumb.pn

Not saying this will happen again this year but is always a possibility which we should look out for to show up on the Ops and individual ensemble members (will not show on means)

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Could you explain what the black hole alert means or point me in the direction to read about it?

Thanks

 

The "black hole" on the chart in question shows a strong high pressure anomaly ridging towards the Arctic from Alaska.

 

The anomaly is so strong that it goes off the scale and therefore just shows as black.

 

 

Below is the anomaly chart in question and also the "normal" chart for the same time alongside.

 

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Having fully agreed with Crewe's post earlier I confess to being a little encouraged by tonight's ECM run. The run sort of makes sense given what is happening ( and projected to happen) in the stratosphere together with the other 'key drivers' outlined within Tamar's post and highlights the potential for some significant cold in North Western Europe from end of week 2 of January. still lots to fall into place beyond this frame and of course it could all go frustratingly wrong but it does highlight the fact that there are drivers working for us this winter. It will be interesting to see what the extended ECM ensembles have to show later. My gut feel is that we will get there eventually but it might need another attempt - perhaps 3rd/4th week of January. Once it does set in however I do think it will be long lasting.

 

I liked swilliam post above re January 2013 as it highlighted how shallow higher heights perfectly positioned to the North of the UK drove the advancing atlantic depressions to take a more southerly route than normal and provided a number of significant snow events for large swathes of the country including the south. Here in Dunstable we had two significant falls between the 18th-20th January. This set up was much more effective for UK wide snow than the huge Russian/Siberian high in place the previous year which brought significant cold and snow to much of Europe but the UK was very much on the western edge of the severe cold. 

 

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I am aware that I am doubting ECM again (was chastised for doing it this morning)  but a 1055hpa High over Alaska is quite rare, I thought 1050hpa were uncommon (more common in Siberia):

 

post-14819-0-97400500-1419712072_thumb.g

 

So I would be very wary of taking that seriously and looking at the height bias for D7 for the Alaskan Region you can see that even at that early stage it has massively over done heights on the last 5 12z runs:

 

post-14819-0-56940300-1419712321_thumb.p Mean: post-14819-0-33351500-1419712464_thumb.g 

 

Just something to take into account.

Edited by i'm dreaming of...
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Not sure where fi starts, but at 120h ecm and gfs look very similar for the uk with a mild looking south westerly raising temperatures a fair bit compared to now.

After that the POSSIBILITY of some pm shots, however like others on here my gut feeling is for milder weather to persist. 

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A quick question, the northern hemisphere seems to have less snow cover than normal,USA and eastern Europe especially. Am i right in thinking this winter is a very mild one (so far) for the NH???

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Some of you have already spotted the momentum but watching the direction of travel, I can't help but think we are drifting towards something very wintry for the second half of jan. Infact, it wouldn't surprise me if we saw at least one snow event during the first half of jan with the strong Atlantic jet interacting with ridges and driving a se flow ahead of disrupting frontal systems.

As far as the second half of jan is concerned, that Siberian chunk is desperate to get to Canada but the developing Arctic high will try and stop it. Getting very interested as to where it might be going.

 

Although still nothing of note within the GEFS in terms of anything cold, a trend today has been for a few of them to run the jet further south and lose the heights over Iberia. This won't do any harm at all for second half of Jan if it comes to pass. Before that, IMO we might struggle a bit for cold enough uppers to our east, but stranger things have happened.

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