Model Output Discussion - 16th Jan 12z onwards - Smile While You Post!

[Harsh Climate]

Latest GFS is a belter for snow on tuesday and wednesday!

 

ROUND 1 ~ Good 6 hours of snowfall for many

 

Swiftly followed by ROUND 2 ~  Another good 6 hours of snowfall for many

 

 

Cold overnight minima so snow shouldn't melt in between snowfalls

 

 

Only a guide but fun to look at, significant snow cover for many midlands north.

 

 

I think favoured areas a the moment are certainly northern ireland/scotland 85% risk,  northern england 75% risk,  north west england/midlands and wales 65% risk. But areas further south only 40% risk (lowering as you head further south.) Could be a double whammy for some!   

[Weathizard]

Slightly differences but the general theme by day 6-7 is the same. A more 'westerly' influence.

The strong section of vortex appears to be happy residing over Greenland, until we can have this 'removed' I personally think we'll struggle to get any significant cold.

[Pat Kennedy]

Looking at the GFS 18Z that Scandi high will have a huge say in the coming week.

[Mucka]

Looking at the GFS 18Z that Scandi high will have a huge say in the coming week.

 

Yes already the next low looks like it should slide but GFS trundles it NE with just a little disruption SE, surely it would not take much more of a correction of the high NW for it to slide?

 

Edited January 17, 2015 by Mucka

[SnOwFeSt]

Slightly differences but the general theme by day 6-7 is the same. A more 'westerly' influence.

The strong section of vortex appears to be happy residing over Greenland, until we can have this 'removed' I personally think we'll struggle to get any significant cold.

Not necessarily in my view. If the blocking in scandi is strong enough, a strongish vortex in Greenland can just provider us with slider after slider. Not as cold as a raging easterly no doubt, but could provide us with copious amounts of snow in favoured locations!

[Daniel*]

Rather astounded it's not more busy in here we have a week of possibilities - it seems once we enter the period of interest - the excitement dies down, and more discussion enters regionals, it should be the opposite really. The future is uncertain albeit it could be sweet for many up and down the country.

That would do us southerners nicely...cautiously optimistic.

[Freezing-Point]

Looking at the GFS 18Z that Scandi high will have a huge say in the coming week.

Let the battle commence.  In the NE corner we have the challenger 'Scandi High'.  In the SW corner, the reigning champion 'Azores High'.

[phil nw.]

Yes as other members have just posted the blocking to the ne more effective on this run which does reflect ens ht anomalies from the earlier 00z runs.

Too early to say if this is a trend towards an easterly but this will at least keep us in a cold upper trough feeding se from Greenland to Europe into week 2.

A  still below average pm flow for much of the time with chances of further slider lows which may eventually back the pattern further west.

[ukpaul]

Could anyone explain what is deficient in more southern areas to prevent snow falling at average elevations under the situation currently modeled for next Tues/Weds? Before the weekend, I was pointing out the mild sector on the 850's (which is still visible on current GFS and ECM charts), I was advised that this wouldn't be a problem. So what is the problem?

- 850's too high after all?

- dew points not low enough?

- lack of sufficient entrenched ground level cold air ahead of the front?

- precipitation not intense enough to generate adequate evaporative cooling?

- all of the above?

- none of the above - something else?

 

Depends what frame you are looking at - any one in particular?

 

Just checking, dew points climb too high at times and wet bulb freezing level also but these are at specific times and in specific areas.

Edited January 17, 2015 by ukpaul

[Met4Cast]

Perhaps.. just perhaps the Scandi high is becoming a trend and the models will start exerting more influence from it as the timeframe gets closer. Not a huge amount of support for this year but we've seen models in previous years under estimate the strength/Westerly extend of a Scandi block.

 

The coming couple of days will tell us more but we want to see further corrections West. As it stands we're in a better position than we were last night.

[Ali1977]

Hopefully some positives ref blocking to the NE, nothing really suggesting that from the professionals though so not sure hopes should be raised just yet

[legritter]

well ,its only early in the GFS run but good signs regards the high to our n /east ,we are still talking about 3 days untill the trough moves in from the west to affect us , come this time tomorrow things could look different in snowfall potential .A very fascinating and nail biting time for Model watching on the cards .ok it could be that the Atlantic does win out for a while but hopefully with cold into europe and perhaps our lovely azores booking a holiday further west we could get some dream synoptics we all crave for ,just look whats happened over the last week concerning the charts ,things could flip back in our favour tomorrow .And goodnight from me ,Fax charts update eagerly awaited gang .  

[John Cox]

Perhaps.. just perhaps the Scandi high is becoming a trend and the models will start exerting more influence from it as the timeframe gets closer. Not a huge amount of support for this year but we've seen models in previous years under estimate the strength/Westerly extend of a Scandi block.

 

The coming couple of days will tell us more but we want to see further corrections West. As it stands we're in a better position than we were last night.

Agreed. If we had the same amount of correction each day whilst the cold spell lasts then perhaps the Atlantic will not win out.

 

A lot to be optimist with tonights GFS charts

[Anti-Mild]

The trend for the Scandi High backing west is encouraging, but I'm trying so hard not to get excited as there have been too many 'encouraging signs' in the years gone by that have fizzled to not very much.

[The Enforcer]

Depends what frame you are looking at - any one in particular?

 

Just checking, dew points climb too high at times and wet bulb freezing level also but these are at specific times and in specific areas.

Well I'm just responding to general summaries like the one provided by Ian F, which don't refer to a specific timeframe or location.

[weather eater]

Westerly's a dead cert I was never sure and I'm even less so now, I keep using this word, evolution, in this sort of set-up small changes are having big impacts, let's just hope it's not a false dawn The runs over the next few days may make very interesting viewing.

[ukpaul]

Well I'm just responding to general summaries like the one provided by Ian F, which don't refer to a specific timeframe or location.

 

It's a more complex situation, on Wednesday for example there are times where snow looks possible at low elevations down south but others where it doesn't. Looking at the EURO4 would give you a clearer view but only from 48 hours before.

[Mucka]

Some quite big changes in GFS ensembles but too early to know if it is a new trend or just this run.

I will use p17 which is fairly typical to illustrate.

 

The low disrupts less put pushes through quickly on a more Southerly track pushing through SW England. This brings in SW winds ahead and a much larger warm sector meaning possibly only NE regions would see snow.

 

 

But on the plus side such an evolution would also likely bring in an Easterly at least for a time and provide better chances ahead for prolonged cold.

Unfortunately it downgrades Tuesdays snow chances and there are no cold uppers on the continent by the time the Easterly comes in but that could be modelled differently.

 

 

Note these changes are within the 5 day time-frame and quite a strong signal within this set of ensembles though not the majority outcome (but trending)

 

We may see some big changes again through tomorrow.

Edited January 17, 2015 by Mucka

[Jason M]

Well I'm just responding to general summaries like the one provided by Ian F, which don't refer to a specific timeframe or location.

Don't make the mistake of thinking there will be no snow down south. I suspect most will see a bit fall from the skies, just not what we would all hope for.

I'd be surprised if a little snow doesn't fall in most places at some point.

[Snowy L]

Could anyone explain what is deficient in more southern areas to prevent snow falling at average elevations under the situation currently modeled for next Tues/Weds? Before the weekend, I was pointing out the mild sector on the 850's (which is still visible on current GFS and ECM charts), I was advised that this wouldn't be a problem. So what is the problem?

- 850's too high after all?

- dew points not low enough?

- lack of sufficient entrenched ground level cold air ahead of the front?

- precipitation not intense enough to generate adequate evaporative cooling?

- all of the above?

- none of the above - something else?

 

Warm sector will get stronger the further south you go, so surface temps, 850s and dew points get more unfavourable the further south you go. These are negated a bit further east, but then this positive is cancelled out by the fact the ppn begins to fragment as it enters the southeast. Wednesday however there is some potential for snow in the southeast, but too far out to say at the moment.

Edited January 17, 2015 by Snowy L

[Met4Cast]

Some quite big changes in GFS ensembles but too early to know if it is a new trend or just this run.

I will use p17 which is fairly typical to illustrate.

 

The low disrupts less put pushes through quickly on a more Southerly track pushing through SW England. This brings in SW winds ahead and a much larger warm sector meaning possibly only NE regions would see snow.

 

 

But on the plus side such an evolution would also likely bring in an Easterly at least for a time and provide better chances ahead for prolonged cold.

Unfortunately it downgrades Tuesdays snow chances and there are no cold uppers on the continent by the time the Easterly comes in but that could be modelled differently.

 

 

Note these changes are within the 5 day time-frame and quite a strong signal within this set of ensembles though not the majority outcome (but trending)

 

We may see some big changes again through tomorrow.

 

As we've seen this past week, lows are likely to be modelled shallower closer to the timeframe - P17 there is definitely over-blowing the low

[Ali1977]

Some crazy looking GEFS, something is afoot.....maybe

Edited January 17, 2015 by Ali1977

[Mucka]

GFS short ensembles prolong the cold a bit again, that is 3 sets running.

 

 

On the 2m temps the warm up begins 23rd 12z and 22nd 00z but delayed again on 18z which will be largely as a consequence of the changes in how the slider is being modelled and bringing that Easterly for a little longer. If the 850's on the continent were very cold the changes would be more dramatic on the first chart.

 

Edited January 17, 2015 by Mucka

[john mac]

Some crazy looking GEFS, something is afoot.....maybe

[Mucka]

As we've seen this past week, lows are likely to be modelled shallower closer to the timeframe - P17 there is definitely over-blowing the low

 

Maybe but that doesn't fit with the trend in these ensembles going the other way as we are nearer the time does it?

We will have to wait until tomorrow to see if they have picked something up or it just a bit of a rogue set and it gets dropped.

Edited January 17, 2015 by Mucka