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Model output discussion - proper cold spell inbound?


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Evening All  Ice Cold hope your still with us .... So the much touted SSW is coming into view & here’s my thoughts + timelines of when / where to expect it... We have seen lots of p

Well it's probably fair to say that I've been rather quiet on these forums for the last few years really, especially since 2013. After 15 years of internet weather watching, and more importantly,

Well - ho hum - let's have a sit rep. My eyes are hanging out on stalks.  The pacific first - engine of the climate system. How is our AAM looking in the face of the current high amplitude MJO?

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4 minutes ago, bobbydog said:

might as well call this the north-west thread..... :D:p

We all know it’s the south east model thread really ??

Models not looking to great in the short term, chance of a dusting for Scotland and parts of northern England Mon/Tues anything further out is just guesswork.

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27 minutes ago, Jason M said:

It seems to me that people see what they want to see and get upset when others have a different view.

FWIW I think this week looks underwhelming and I say that as someone living in the SE. That said, others (Frosty for one) clearly see something different. As always, time will tell.

Meanwhile looking into the longer term the GFS suite is poor tbh but I do note a stronger signal in the GEM ensembles for something mid month from the east. Yes, I know its GEM but I have to say the GEM ensemble suites have by and large wanted nothing to do with the phantom easterlies being shown this year. They were also first to pick up on recent height rises to our south after the last cold blip so maybe an early trendsetter. From memory (and I may be wrong) I think the GEM ensemble suite runs at higher resolution than the GEFS albeit clearly its a lesser model. 

Spot on Jason.

This is the day 15 GEM ensemble mean 500Mb anomaly.

gem-ens_z500a_nhem_61.png

Very promising...

Edited by mulzy
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7 minutes ago, Day 10 said:

I was just backing up the point that the Northwest isn't as great for snow as some people think it is. That is the first post I think I have ever made in here about the Northwest! I always go into the regionals for that.

mate i know. i was only joking hence the smilies :D

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Great looking Ecm 12z ensemble mean through the week ahead with cold / very cold weather dominating bringing widespread frosts, some severe frosts, especially over any snow fields and there will be snow in places along with icy patches..a real taste of winter coming up..further ahead generally cold zonality with further wintry weather at times..a lot better than what we've seen in the last few weeks or so..in my opinion!:cold::)

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ECMAVGEU12_240_2.png

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An interesting time - I'm not very clued up on the MJO/AAM mechanisms, but I'm noting some are saying the projected progression is not being backed by what the models are showing i.e we should be entering a sustained period when northerly/easterly airstreams will take hold; the reason why we aren't seeing this may well as some have said be down to the more dominant forcing taking place in the stratosphere; which as some are stating when on a major warming trajectory tends to result in the PV having a last hurrah and then it implodes, so perhaps it is this factor which is being programmed through the models - a return to a westerly flow, but a cold one thanks to all the frigid air bottled up over arctic canada, before we see those burgeoning heights shown by some of the models today building out from siberia very quickly and once the strat is hit by the warm injection, bang goes the PV, up shoots the azores high to Greenland and its all eyes to the NE.

Sticking to the reliable, its a case of taking each day as it comes, hard to pinpoint where any wintry precipitation will affect where and for how long.

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Whilst nothing exceptionally cold is being shown in the models, its great to see the mean barely getting above -5c on the 850hpa temp ensembles (North Yorkshire) all the way out to 384hrs.

Hopefully all members will see something wintry as we head into an interesting looking month for coldies.

graphe_ens3.php?x=292&ext=1&y=1&run=12&r

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Current outlook painted by the models is still on for one of the coldest weather we've had this season (so far..). NE'lys picking up in less than 24 hours time for the most of the UK. Temperatures on a positive downwards trend into next week. Snow showers likely Sunday to Monday in Parts of EA and the SE, could give a few cm's.

Tuesday and Wednesday looking to be the colder of the days as surface cold conditions start to develop. A weakening front from the Atlantic moves SE across the country during Tuesday and into Wednesday, bringing a renewed surge of cold air, this time from the NW (not the first time this winter and again remarkably cold 850's from this direction).

Post Thursday things become tricky. Another front moving SE will bring some Precipitation into the NW. This front makes more advancement into the UK compared to Tuesdays, with a temporary rise in temperatures likely. Whether this will be rain or snow, is still open to doubt. It may not even make it at all.

Come the weekend, which is was into FI imo, a renewed cold NW airstream is likely as things stand. Both GFS and EC are going down this route now.

What a winter this has been and we are only in February... 

 

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1 hour ago, Day 10 said:

I know, sorry mate. The whole North/South crap just annoys me, people from both let the whole thread down. I always post with the whole of the UK in mind but starting to lose the will to post in here.

Don't stop posting mate, your input is much welcomed so don't let the bug*ers grind you down. It would just be better if everyone just ignored the flame type posts....these posters thrive on a reaction so just ignore them and they'll eventually go somewhere else.

Anyway, looking at the ECM and note that from 96 until pretty much the end of the run that it's above the mean, not by much mind, but every little helps and all that.

Diagramme ECMWF/CEP

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9 minutes ago, Ice Day said:

Don't stop posting mate, your input is much welcomed so don't let the bug*ers grind you down. It would just be better if everyone just ignored the flame type posts....these posters thrive on a reaction so just ignore them and they'll eventually go somewhere else.

Anyway, looking at the ECM and note that from 96 until pretty much the end of the run that it's above the mean, not by much mind, but every little helps and all that.

Diagramme ECMWF/CEP

Yes, and importantly the members at the colder side don’t go above -7/-8 ish to the end. 

What stands out to me even more is the divergence starts at D2(ish). So wiggle room remains! That’s pretty early by ecm standards!

Edited by karlos1983
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18 minutes ago, Ice Day said:

Don't stop posting mate, your input is much welcomed so don't let the bug*ers grind you down. It would just be better if everyone just ignored the flame type posts....these posters thrive on a reaction so just ignore them and they'll eventually go somewhere else.

Anyway, looking at the ECM and note that from 96 until pretty much the end of the run that it's above the mean, not by much mind, but every little helps and all that.

Diagramme ECMWF/CEP

So plenty of members mixing out the cold much more before it gets to us next Thursday 

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4 minutes ago, karlos1983 said:

Yes, and importantly the members at the colder side don’t go above -7/-8 ish to the end. 

What stands out to me even more is the divergence starts at D2(ish). So wiggle room remains! 

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Scatter-highlights uncertainty!.

Also the operational divergance!.

Block formation being underestimated,  although a zonal pattern looks incoming (for a lim-period)..and frontal push against the cold 'in place screams precip-transition, of the wintery type.

Also AGAIN is the inflow of an easterly type...that indeed has a reverse mobile link..in regards to snow potential; and nowcast forecast for eastern/south eastern parts....

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13 minutes ago, BlakeyWeather said:

Whilst nothing exceptionally cold is being shown in the models, its great to see the mean barely getting above -5c on the 850hpa temp ensembles (North Yorkshire) all the way out to 384hrs.

Hopefully all members will see something wintry as we head into an interesting looking month for coldies.

graphe_ens3.php?x=292&ext=1&y=1&run=12&r

What I find interesting about that chart is the spread at +192. The op is one of the mildest. One or two go close to minus 10. Having looked at weather charts since the 60’s, I feel this winter has a few cold surprises in the tank.?

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Just now, tight isobar said:

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Scatter-highlights uncertainty!.

Also the operational divergance!.

Block formation being underestimated,  although a zonal pattern looks incoming (for a lim-period)..and frontal push against the cold 'in place screams precip-transition, of the wintery type.

Also AGAIN is the inflow of an easterly type...that indeed has a reverse mobile link..in regards to snow potential; and nowcast forecast for eastern/south eastern parts....

Edit;..

18z will be a reasonble insight-to 24/48 hr..predict..with regards to snow potential- and values of ground settlement..

Its almost nowcast time!!!!

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3 minutes ago, shaky said:

Waiting for your icon update lol!!look forward to them to be fair!

LOL, the ICON isn’t my friend anymore, it was the first model that went Pete Tong on us yesterday! Only because it was the first to roll out, but mud sticks :nonono:

I’m still not entirely convinced this coming week is nailed yet. I guess we should firm up soon. Perhaps the ICON can totally redeem itself! 

I do think +144 is intersting though on the ECM, not sure if I’m looking forward to it or dreading looking tomorrow. Anyway plenty to keep us all interested atm, it’s going to get a tad toasty up top soon.

getting closer...

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What bugs me is now much less in the way of cold air ECM (left) has heading down toward the UK at just 3 days range compared to GFS (right): 
 ecmt850.072.pngh850t850eu.png
Even at this short range the flow over the Azores High is flatter. This being at a time when it should be as amplified as possible... but even so, going against ECM at 3 days' range is not something one can ever do with much confidence.

The impact on the speed of the frontal boundary and how much it mixes out is astronomical. The size of the milder (okay, less cold - but with temps up to 8*C on SW coasts!) wedge on the ECM is, relative to GFS and what we could be playing for, absolutely tragic.

 ecmt850.096.pngh850t850eu.png

That this large difference occurs at such short range tells me that tomorrow should be the decider with respect to what's reasonably possible Thu-Fri. No amount of secondary low formation is going to be able to overcome a preceding evolution akin to the 12z ECM (except, of course, over the likes of France...). Hopefully the fact that the UKMO 12z resembled the GFS will turn out to be meaningful.

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Well after this hit and run easterly, with a high pressure cell flying over Scandinavia before being sucked into the Russian high, I'm struggling to see much to be positive about in the EC ensembles (apart from the generally below average picture) - not a single ensemble run today, from the ECM, has managed to deliver maximum daily temperatures of -5 for de Bilt - you'd imagine if there was a serious chance of an easterly, then at least one run would manage it in a 15 day period.

 

 tempresult_dor4.gif

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4 minutes ago, Steve Murr said:

Where’s the Hummm smiley...

IKON through 84 18z V 90 12z

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ECM was the first model to split the Atlantic energy @144 - can the IKON continue that process — better @84

How the heck is it even possible to change that much at 84 hours!!its crazy!!lets see what mr gfs brings!!hoepfully something similar!

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