Gerry

Top post informative and succinct as ever, lets just hope this thread doesn't deteriorate into "whens it going to snow" . Mods I posted a link to this thread in the mod. discus. thread can replies in here be monitored and moved/ deleted to keep this valuable knowledge resource intact.

Ooops yes objective not subjective am sure Steve knew what I meant, still back to the models....

Nick mighty fast fingers... doesn't help that I am watching match of the day as well as working and keeping an eye on the n. hemisphere who said men couldn't multi task

No problem good to see you being subjective amongst all the flan flinging personally cant be bothered posting any more, one hell of an omega block to end the 18z just about sums up the gfs output at the moment, anyway heres the link www.weathercast.co.uk/latest-model-forecasts/gfs-ncep.html regards Gerry

Steve these? these?

Sorry that was me I renewed my subscription and then it broke Well the oz has brought forward the frontal snow event to saturday night when we still have -10 850's in place so any talk of marginality based on tis ot put is nonse of course its only one run. Convective showers for next 2 days seems the order of the day plenty of instability although pressure is a little too high for the North sea snow machine to really start firing

Sounds all very familliar I decided to take 6 weeks off work to enjoy the days you never get back I need a holiday and a spell in the Betty Ford to get over it. That is a vey good question we have one whole inch here in Ashford its a good job I wnt panic buying today for essentials and bought a generator. Despite being an avid model and weather nut I take the view now that i will wait until it starts snowing before I get remotely excited, from an imby perspective this does not compare to winters of old.

I've given up going to bed having been kept up for the past 6 weeks I've forgotton what sleep is he's a little darling until the sun goes down then he turns into the

pleasure although all my knowledge is gained from the learned members of this forum, am awaiting my sons 3.am feed

A true polar low is sourced from within ice free waters of the polar region the main criteria for their formation is temperatures at or below -40c at the 500hpa level, using the 12z ecm 500hpa plots for the north sea for 3.oo am today we can clearly see that this feature has formed on the boundary of the small finger of -40c ( marked in red). In addition to the 500hpa criteria we also need temps of below -10-12 at the 850 hpa layer the same time frame plot clearly identifies tha this criteria is also met as the temp at 850 hpa is progeed to be in the region of -12 So essentially you could argue that its meets true polar low criteria however I very much doubt it will generate the massive amount of energy associated with these features, it is indeed however worth watching and will no doubt result in quite significant convective snow fall where it makes landfall it will however run out of steam pretty quickly as the upper air profile does not support continued development. You will note that the ecm pics this feature up on the precip charts and it can clearly be seen on the msl pressure charts as a 1002mb shortwave. Hope this helps essentioally it is a short wave that has formed in the easterly flow but it is adopting thE PL characteristics due the the steep temperature gradient caused by the warm seas and very unstable upper air mass.

UKMO following GFS at 144 growing consensus for a scandi high and long fetch easterly?

Agree, the amount of blocking in the later stages is quite remarkable and would return a CT well below zero ties in with stewarts thoughts for the latter stages of Jan, we d have a very stickly moment/hurdle to get over through later in the week with the high sinking, given the back ground drivers it would be just our luck to either get the high bang over us or to end up on the wrong side of the block. Still plenty of old school weather between now and then, will be very interesting to see how the infrastructure holds up. My parents were at the Oracle the night Reading and Basingstoke ground to a halt they even closed the M20 here in Ashford for 1.5 inches of lying snow yesterday. Dont know if anyone has caught the BBC news 24 forecast talking of cold snap lasting 2 weeks read into that what you will but I can never recall the BBC ever stating such a thing.

Its broadly the same evolution as last evenings ecm although this variance would see the cold pool mixed out very quickly due to the source of the easterly not having a deep pool of cold air, would be nice if this is a trend only time will tell

At short range all the model precip charts are fairly consistent i.e 24hrs but beyond that they are pretty much next to useless witrh regard to volume beyond this timeframe they are merely indicative of probable location of rain/snow fall. Using Dublin as an example with the current and progged set up at 24hrs both ecm and gfs are broadly the same 24hrs by 72hrs again the distribution is simillar however greater variance is evident in intensity with the GFs widely recognised as overplating convection and the ecm always underplaying By 144 we have reached a different synoptic set up so both distribution volume are not comparable. The best model for short range precip is probably the WNM or Meto. I will say that if last nights 1wz ecm verifies Dublin will do well from convective showers

Here you go Jim -40 uppers at 500hpa covering CET zone on 12z ecm from 120-168 accompanied by 850's of -10 to -14 accompanying precip charts are seriously underplaying the convective potential.