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Model Output Discussion - The Start Of Winter


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Guys & Gals.....

 

Many thanks for the responses....I appreciate them and how everyones viewpoint and take ont he outputs are interpretated individually... i am forever learning!!!!

 

keep up the fantatstic effort all....  it really makes this forum the best place to be for the likes of myself and other `wannabes` lol..

 

:clapping:  :clapping:

 

Marty, go to the Guides section as you will find lots of information on how to read charts and lots of other interesting articles, again if something is not clear then please ask.

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A few of you have asked today about rationale for the (tail-end of) UKMO latest 30-day outlook. There is, of course, a dedicated thread elsewhere for this but I'll just confirm that GloSea5 output rem

Thanks for this Barry   You are however wrong on both counts you suggest :   1) I have explained in extended detail, as much as I am able, the progress of the patterns thus far from autumn (see firs

Hopefully a timely interjection, but UKMO caution (again) that medium range NWP may not be adequately reflecting ultimate broadscale outcome. First tentative signs emerging, they suggest, of *possible

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Nothing like an Azores High for ruining your Christmas. 

 

There's still hope in the GFS though.

 

Should the jet stream move northwards, allowing the Azores High to build, it could well move north eastwards and give us a settled spell of weather.

Granted that there aren't many, if any solutions which bring this into play, but it's always a possibility. I don't know about you, but I'd take a cold, crisp & sunny Christmas over a rainy, Atlantic-driven Christmas any day of the week?

 

This being said, it's December 11th, Christmas day itself is two weeks away, and this is well beyond the reaches of high resolution, bringing it into the depths of FI. I think for now, attention should be drawn to the short term, especially as we have a frontal system bumping into some colder air tonight, in ADDITION to drawing colder air in with it. This will give many northern areas of the UK a snow event, for a short while at least.

 

I'd focus less on Christmas until it's within the 5-7 day range, where a general idea can be drawn as to what the weather may be like on that particular day.

Edited by Backtrack
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Agreed Nick, GFS P looks much more subject to a pattern change..Surely this is the better model isn't it?  Anyway, still no consistancy from the models.

Yes in terms of verification compared to the normal GFS but you can see its vastly different at the T192hrs timeframe compared to the 00hrs run but if you add this to the mornings ECM operational run then some signs that the PV might relent from Greenland.

 

I certainly wouldn't be booking the Mariachi band yet though because we need to see that lifting of low heights at T144hrs. Overall though I'm a bit more optimistic for the Christmas period , I'd rather we suffered the underwhelming output now and saw this change in time for Christmas, theres nothing worse than mild dross at that time.

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I wonder if the "interesting signs" are still showing within the METOs output today, they have been spot on not jumping on the occasional cold charts we have had in the last few weeks and stuck to their guns..These height rises over the pole and Greenland that are popping up might be something they are watching closely!!!

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Looking at the latest JMA week 2 upper anomaly it ties in very strongly with the current GEFS output: post-14819-0-81602900-1418295043_thumb.p

 

A flat Asian/Pacific jet, heights to the south, US and Russia and the UK under the influence of lower heights. For week 3-4 it looks like the influence from the NW and the south shifts (Azores) and the zonal flow may favour a more N/S split:

 

post-14819-0-55565500-1418295371_thumb.p

 

Certainly no clear sign in the NH for anything remotely like a NH blocking pattern setting up.

 

Looking at the CFS MJO and it returns to phase 5 in January after a hint of the Circle of Death: post-14819-0-04808400-1418295500_thumb.p

 

Composites: post-14819-0-59498700-1418295669_thumb.g

 

Though whether the MJO is still the main driver by then is debatable. I still get the impression that the trop is not looking helpful for a HLB in our region so we are relying on an SSW and for that to favour us. Although the CFS is consistent with Northern blocking Feb-March and also Jan now going that way, it rarely favours the UK. Again the US and Russia/Siberia looks like getting the bitter cold:

 

post-14819-0-54181900-1418296216_thumb.p

 

The strat experts are more knowledgeable as to if this is likely when the SSW occurs or is CFS misreading the signals? So a waiting game for 3-4 weeks in the hope the SSW does indeed develop. 

 

 

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Is this a sign of change in the extended NAO forecasts?. Yes, all but one is positive, however, there is a marked dive towards the end across the suite. I would take any model output showing a strong Azores High in FI with a large pinch of salt at the moment.

 

http://www.cpc.ncep.noaa.gov/products/precip/CWlink/pna/nao.sprd2.gif

 

 

Hopefully a potential cold spell beginning around New Year finally creeping into view.

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Just taking a look at the latest ensembles, very few members are going for a raging swerly jet and mild temps. Even out in FI. The majority of members are showing PM and LP to the north-ish. Think I even spotted the odd scandi HP appearing in one or two of them.  In a nutshell, I think it looks like the majority of the country is going to keep on getting normal winter weather with temps around average or slightly below. And with PM lows in the main feature/pattern, plenty of chances for snow the further north you go.

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I am very new to model watching and am trying to learn all the time but how can one be 75% certain for a whole 10 days..surely even the MO cant do this..

 

I am no expert, but zonal weather has a very high confidence level. 75% was building some uncertainty in due to the weather always has the prospect of surprising you. However I am nearer to 100% with regard to the upcoming 10 days. Obviously surface conditions are a very different matter as these are variable dependant on how flat the pattern is and where the jet sets up.

 

The mean for the 15-20th is an example:

 

  WSI_EuroEnergy

Mostly windy N Europe and wetter NW persisting next week in association with persistent marked low pressure. http://t.co/pMx3oMYhkS

11/12/2014 13:18

 

The PV is on the move from west to east and there is little chance of anything other than a strong negative height anomaly to the north. ECM and GFS 8-10 day anomaly very closely matched:

 

post-14819-0-68114600-1418305396_thumb.g

 

That is a very flat upstream flow. 

Edited by i'm dreaming of...
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where?

 

attachicon.gif1.gif attachicon.gif2.gif

 

attachicon.gif3.gif attachicon.gif4.gif

 

attachicon.gif5.gif :whistling:

sorry karl old chap, but theres nothing wintry next week on these runs except for the far north. in fact its looking like the mild weather you and most others dont like looks like being pretty dominant IF these charts varify... of course they may well change, but i believe these charts

 

attachicon.gif610day.03.gif attachicon.gif814day.03.gif

 

do support a gradual change from a north of west upper flow to a westerly with the flattend jet north of a strong azores high... and this is manifest in the current opperational runs.

And to be fair westerly flow can be cold.

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I am very new to model watching and am trying to learn all the time but how can one be 75% certain for a whole 10 days..surely even the MO cant do this..

hi James

I use the 500mb anomaly charts as the best 'guide' to the upper air pattern in the 6-15 day time frame. Correct, with some provisos, about 70-75% of the time for the upper air pattern. It is the upper air pattern which largely governs what occurs at the surface. Mind you trying to work out the bottom 500mb (approx 18,000 ft) is the tricky bit. Ignore the anomaly parts, shown as - or +ve on those charts, just look at what direction the contours (isobars if you like at 500mb) are showing for an idea where the weather is going to come from. Please feel free to pm me for a chat about these if you wish. Also take a look at the Net Wx Guides for more help.

As a favour can you pop your nearest town in your avatar please then we all know where you are reporting your own weather from?

thanks

Edited by johnholmes
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And to be fair westerly flow can be cold.

 

yes it can, but the current ecm (i chose this as its the best performing model ) would not suggest next weeks a cold westerly. its even suggesting the +10 (upper) isotherm over the southwest! briefly... thought two things... one i accept that the ecm might be over amplifying the uppers next week, and two, when frosty made that comment the charts might well have been showing alot more polar maritime incursions. i dont know, im guessing he was too busy to post charts to support his post. im as guilty of that as anyone but it does highlight the need to.

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Hi Mucka, can you help explain something for me please.

 

On those charts you posted above why is it that the Azores high never links with the Greenland high. Also how come the A.H just sits in that same location for weeks on end ?  

 

Is it something to do with earths internal magnetic differentials?

 

I once saw an amazing documentary on bbc with a very good , passionate , black lady presnter and in it she mentioned 6 very strong magnetic internal independent areas across the globe with Southern spain having one of these areas. Could it be that that stops the high moving very far afield, I.E retrogressing in to the central Atlantic  or North linking with Greenland high.

 

Your charts above clearly show everything shifting quite quickly accept the Azores high which only changes its shape not position.

 

Many Thanks.

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