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DAILY EXPRESS BREAKING HEADLINE!!!!!! "GIANT NINJA DISC SNOW ARMAGEDDON SLICES THROUGH ENGLANDSHIRE WORLD NEXT WEEK!!!!"

If you go on Meteociel and use the UK GFS charts you can find soil temperatures from there. Charts are "temperature du sol" example below

The term used for snow melting conditions is "sublimation". In perfect conditions for snow melt the sun would be out and a gentle to moderate breeze. It takes a lot of energy to turn ice(snow) into water vapour, about 7 times the amount of energy needed to boil water! The energy needed to sublimate the snow from your driveways, gardens etc mainly comes from the sun. Windy days are also an aid in sublimation as this helps remove the water molecules once they leave the snow and enter the atmosphere. Low humidity is also a snow melter. The conditions we are about to see country wide, will not aid sublimation. There will be lots of low cloud and the wind will be bitting cold, once the high res models start predicting snow amounts for certain locations at 24-36 hours out you can bet the snow that falls will stay for the remainder of next week Imo. Tayside, Fife, Lothians and borders all in for a tanking next week if this mornings 6z is anything to go by.

at 60 N it looks like 3 changes, all part of the same overall reversal however, that 0 line is the reversal point. Some chaos going on up there right now thats for sure. Interestingly 83/84 had a similar pattern. However not as strong a reversal or as prolonged. But for the month of the SSW and pattern similarity thats the closest match I can find. I think it is a matter of heat flux waves and intensity causing the quick changes in wind speed / direction. Winter 83/84 was equally topsy turvy, a very mild Dec, followed by a cold and in the north exceptionally snowy Jan under a polar maritime airmass, followed by an average Feb with some snow. Snapped from the "forgotten winters of the 1980's" in this forum

@CreweCold looking at these plots from 2009 then 2010 you can see on the zonal mean temp time series average seasonal temps in 2010 don't really seem to be effected by the 2009 warming, similarly the 2011 chart looks the same you can check it here http://www.cpc.ncep.noaa.gov/products/stratosphere/strat-trop/ I've added the 2017 chart and the start of 2018 so far, for comparison. Of course these are mean charts and certain areas / places will experience colder / warmer months that others.

Nice visualisation

Great 12z runs from GFS and UKMO, starting to reflect what has been / still is a record breaking SSW event. Some of these charts are going to have to have the max / min parameters re drawn to list just a few below My personal favourite.... thats an all time record breaker right there for that height and latitude OOOFFFTTT

Thanks, I was reading a bit more this morning and thats the assumption I came to also. That is one confused looking chart also! @Quicksilver1989 that global temperature trend chart from 1900 - 2012 is in Fahrenheit, so then showing -17 deg C drop on the blob you point out over a century? Must be Celsius I assume?

From what I have read polar vortex intensification, growth of polar winds and temperature anomolies happens at a much slower rate than the break up of the vortex during a SSW. The slow growth is related to lower wave activity in to the Stratosphere during the early stages of vortex intensification and is characterised by slow cooling of the vortex via thermal relaxation. Ive seen a few posts suggesting the polar vortex will now not return due to the time of year, seasonal change etc however this is not necessarily the case as the charts below will show. Re-intensification is much more likely during La Nina years than El Nino. Currently clinging on to La Nina state. As you can see from the next chart Vortex intensification does occur through into mid march but only on very few occasions. A link to the full study. https://www.google.co.uk/url?sa=t&rct=j&q=&esrc=s&source=web&cd=4&cad=rja&uact=8&ved=0ahUKEwilxubVgKDZAhVIDcAKHUUkBucQFghAMAM&url=https%3A%2F%2Fatmos.washington.edu%2F~dennis%2FLimpasuvanetalJGR2005.pdf&usg=AOvVaw1Dv6L_6aRC-CV0YIoFXQNb Hope this helps

I figured from earlier Fyrirstaoa means "obstacle" what does Hryggur mean?

Thats either telling me that the downwelling is strong enough to counter any GFS MJO predicted phase 7 mid level amplitude input or the MJO is moving into 8 / 1 COD (most other models) , would have no effect regardless? Or am I picking this up all wrong?

From ECMWF website I give you these charts for MSLP + 168 +192 +216 +240 a wee explanation what the colours represent below. Basically this the deeper the purple the lower the confidence. A flavour of the 500mb height charts also + 216. +240 These are not charts I am overly familiar with, and they may look this way for confidence level at longer range a lot, or maybe they don't.....

@tight isobar the problem I am seeing with the GFS is that its kinda on its own in regard the MJO GFS vs the rest

The more I look at this SSW situation the more I am drawn back to the 1999 warming. (I have mentioned this in here previous) A lot of the Trop drivers at the time were the same / similair compared to any other year. The time of year and the SSW type were Split and early / mid Feb. La Nina and E QBO. MJO in same phases with similar amplitude. Eddy heat flux at most height levels and 60N Zonal mean wind reversal similar. 1999 Eddy heat flux at 10hpa / 50hpa then 150 hpa 2018. 1999 wind at 60N at 10hpa / 50hpa then 150 hpa. 2018 1999 - To me shows it took 2 hits over the winter to make the split happen, two wind reversal events over that winter both due to limited heat flux events. 2018 - we are having one whooping heat flux event causing the split, does this cause a different trop response to the one in 1999? I hope so because that wasn't great from a cold / snow perspective. Take your pick from any of the February and March BBC weather forecast on youtube to see for yourself. Anyway here is a GIF of the 1999 split from the Patrick Matanaeu site. very similar in nature, split vortex takes similar paths and note the vortex lobe over Asia make its way back towards the Canadian vortex, similair to what we are seeing this time. Of course there are plenty of other trop conditions at the starting point that will be different from what happened in 1999 given the chaotic nature of the atmosphere and all the variables there are, I am not saying its game over for cold / snow. Purely an observation based on past events. the chaos......

MJO Composites for March. Phase 2 then phase 3. From left to right = 500mb all amplitudes of MJO, 500mb amplitudes >1, surface temp anomaly all amplitudes, surface temp anomaly amplitudes > 1 Phase 2 Phase 3

Mean sea level pressure (colours) with 10mb strat winds overlaid. To me there appears to be a lot of stratosphere / troposphere coupling from that image

Could this be the start of the ECM / GFS battle between backround signals starting to show? GFS keeping the MJO in phase 7 for some time, La nina forcing showing its hand GFS vs ECM GFS VS ECM GFS essentially showing the MJO tropical convection unable to make its way into stage 8 as the La Nina signal is still in charge. This is good as it allows the NAO to head negative and lock in the colder air due to mass of energy heading into the polar flows and the AZ high NOT weakening but positioning itself correctly. ECM appears to be backing off the La Nina signal somewhat with most ensembles heading towards a more Neutral state. That allows the weakened MJO to progress towards 8 & 1 and unlitmately its death. Of course the SSW modelling is a whole new ball game added into the mix and although we can see what the GFS is predicting in terms of this, no such access for the ECM variant (that I can find). What would be magic for the end of this winter would be for the MJO to follow the GFS path and then in time with the next uptick in GWO to further enhance the SSW trop response hopefully locking in pattern of cold. GFS ECM +240

Model output minus ICON (keep getting processing error when uploading for some reason) and CPTEC (utter garbage) from meteociel. I snapped the +144 output from Monday. + 144 for 2 reasons, first because it gives us the max UKMO range and second because + 144 from Monday is wind reversal day = official start of SSW. First the ECM From Monday From today Both for Sunday at 13:00. Not a million miles away, misread the pacific ridge angle slightly but main vortex elongation and break away low pressure system shown. AZ high not as regressed as shown from Monday, Downstream similarities good. Next the GFS From Monday From today Both for Sunday at 13:00 HMMM make your own mind up, not great from GFS if you ask me. The UKMO Really good from UKMO IMO, overall pattern almost nailed from back on Monday JMA Similar to GFS, probably worse, decent effort any smaller vortex evolution. Heights downstream up into Svalbard similar. GEM Great effort from GEM! Often overlooked but in my top 3 NAVGEM just below mid table, a kind of Stoke city type effort CMA bit over progreessive in many ways but overall ok. There you have it, starting conditions are set for the SSW. EDIT:- I should have waited until Saturdays 18z run to do this but its the weekend folks

And Strat guru, Amy Butlers reply. Then our own Start Guru's reply incase folks haven't seen them.

Where is @tight isobar? I need a model output riddle to decipher before I head for the sack! Great model watching today, that GFS control pub run looks smashing! Just a thought before I head off, the GFS has the MJO stalling in phase 7 at decent amplitude, the ECM MJO see's a drop in to phase 8 and fading out fast. Do we want the GFS - MJO outcome or the ECM outcome, one gives more extra tropical forcing for HLB than the other for a longer term. Add the SSW effects to the mix and I know which one I prefer.

@Optimus Prime has a point take Feb 1999 SSW for example. Pick out the Feb 1999 SSW from the chart and notice The ENSO states...La Nina. Also an East QBO. Both same as now. Next MJO phase 7..... .....as we are now. Dramatic wind reversal similar to what we are about to see and is forecast obviously. Net result... not a great looking snow anomaly map for the uk. Just trying to keep things in perspective. Note the saving grace for snow lovers might be that this SSW happened 10 days later than the one we are about to see. May just be about enough of winter left to see a difference. Fingers crossed. Edit...ok Steve Murr's post after this trumps mine in more ways than one, epic post. In that this 1999 split was a wave 1 split and we are about to see a wave 2 split so be interesting to see how it plays out.

January 2009....... Feb 2018........ nice similarity in wind reversal intensity. SSW + 30 days snow anomaly plot Thanks for the link @lorenzo

Stratosphere just got some extra heat thanks to Falcon heavy, well worth a watch incredible stuff

Tonight various 12z model output operational runs again at +144 (approx 48 hours post vortex split) JMA run not out yet but will edit post when its available. I've included the Jetstream this time also. All models attempting to show a progressive elongation of the main portion of vortex, The Azores High still prominent and not as obvious in Westward retreat or strength reduction compared to 24 hours previous. Also Maybe a start to that SE tilt to the jet stream that Nick Sussex mentions earlier. ICON has the most prominent Pacific ridge on this run the rest retreating towards more zonal outlook from 24 hours earlier. Overall I think today the model outlook shows typical uk wintery interchangeable conditions throughout. (this is not sitting on the fence but just how I see it) However, if a quick trop response is on the cards then we may see that change in the outlook over the next few days to an even colder and promising non typical (nowadays) wintery outlook. ECM UKMO GFS GEM NAVGEM CMA CPTEC ICON GFS GFS