geordiekev

Yep, heights over Greenland for longer due to upstream changes, again. Think Nick mentioned both the NCEP & NOAA having low confidence in the US set up which ultimately has big changes to how the cold, firstly drawn West then back East over us will effect the shape of lows coming our way. UK forecasters nightmare

Believe me, I think I edited a post about 10 times due to the whole global sysyem being rotated 90⁰ & me currently viewing charts sideways to get a handle of where the current trop polar vortex is located. Still trying to get my head around the fact we would in Siberia from the current set up, poss. Apologies for posting the 90⁰ again & also for my atrocious Geography, as a maths guy who ended up in Swansea Uni for a decade due to thinking it was Midlands, any posts that mention Urals, Labrador etc and I'm gone. Swansea btw is beautiful if not v wet, though only during term time it seemed with gorgeous Summers. Had snow there once & it ground to a halt, as so unusual being a peninsula with a gazillion beaches

Take a look at the Greenland MSLP system plots first becsuse if the models can't hone in on that correctly in the next 48hrs, our N/S outcome is tail on the donkey territory

Everything is stalled, that's the issue, there's no normal West to East momentum. The amplified upstream pattern means the only variables in our part of the World is the cold being drawn West & then moving back East. If the systems in the u-bend are elongated we have a more of a horizontal flow & no SW forcing. Because the systems aren't being warmed as is the norm by the Atlantic, it's a cluster... Nerve racking but interesting

We are in a weird set up where the lows aren't spawned from USA but a result of cold being dragged West from our trop PV. The models really ain't a clue if it's a clean flow, disturbances or how much forcing from the rotated bizarre Canada fed Greeny block. As I've said before we're in now casting territory given the forecasting changes between 24h periods have huge inaccuracies

Because the models, as they get tweaked to make up for geographical accuracy shortfalls, havn't seen this pattern before. I think we saw similar modelled in December but it never came to fruition. If anyone can find the current outputs in the Archive good luck, bc in my 14 years model watching, I've never seen a USA set up as has just verified

Yep, like the drum I've been banging for a while, tilt your devices to understand the current situation, low pressure systems ARE NOT flowing accross USA and then the Atlantic. They are flowing West from the cold tPV to our North & then doing u-turns America is devoid of systems moving West to East, so throw the rule book out as the geographical tweaks programmers make are skewing outputs

Yep the flow of cold from the trop PV to our NEast being pulled out into the Atlantic & then doing a U-turn and heading back towards us, is something I doubt the programmers have had to deal with much. Disturbances in that flow back & forth have resulted in elongated systems earlier in the week, to more bowling ball of recent then both seperation and absorption of systems. A real head scratcher for forecasters

Yep, I think the geographical biases which are built into the models are struggling with the huge anomolies in areas they're not programmed to deal with, especially USA. See these few days as coming to the wire

Another one of those Sundays where the overnighters correct as the day goes on

Yep, the speed at which it washes away the Canada fed Greeny high seems a bit quicker. Seems odd that the cold flow, heading West that washes the high away, is so clean with no disturbances, which were shown previously & placed force on the systems on the Southern edge of the block, once they do eventually head East. Still think until the drivers of the Greeny block are in place, we will be non the wiser for our small island

As pointed out earlier by the anomolies there is nothing bog standard by the pattern the next 10 days. America systems are stagnant, highly amplified and high pressure very much in charge upstream. Add onto that the positioning of tPV. There's nothing bog standard about lows moving Westwards into Atlantic before doing a u-turn towards us, so would suggest SSW has had input. The fact I'm viewing the whole chart on it's side to get a sense of normality for my ASD, of where systems normally reside clearly suggests there's been significant effects by something. Again as the Canadian fed Greeny block is still positioning itself along with the E & W USA drivers, perhaps worth keeping towels dry a tad longer before using them as kleenex

GFS moving snow risks bit further North, retaining cold further North throughout. Is this another one of those weekends/days where the overnighters wobble for the day to improve? Seeing as the rotated Canadian fed block is yet to kick in the next 48/72hrs, defo not worth worrying yet

The latest GEFS MSLP anomolies confirming what a rare pattern we have coming up, so model geographical biases will struggle for a while. Of particular note is the USA wide Height anomolies, suggesting a stagnant, yet amplified, pattern. Of interest at the mid month point is a return of height anomolies in the Greeny & Scandi area. Sorry for looking so far ahead but the next few days up in the air on UK wide specifics, so giving them bit of a swerve and always try to avoid imby posts leading up to cold spells as at 777ft & 55⁰N keep my proper ramping to the regionals

Well the Greeny block is finally in place & about to rotate into a Canadian fed block, hence a reminder to view from US perspective. Looking at most animations, there's barely zero systems moving West to East over US. The change in the UKMO between t120 & t144 is I think the boundary of confidence. However, once the 2 US blocks do start drawing low pressure systems from their North there's still very little Eastwards momentum in the system, so the remaining heights over Greeny, out in FI if & when HP does form over UK, is defo my next watching brief for 2nd half March. Let's enjoy the 1st ½ for now

Once again big differences in models only hours apart in relation to what systems are spawned from the trop PV to our North & the difference their absence makes obvs large effect on cold drawn from the trop vortex for ourselves and N/S boundary. Anyone putting large confidence beyond 120h will need kleenex for the yolk me thinks 18z v 12z

We all know most outcomes won't make it to the final water jump but at least most of the ensembles are favouring a frozen jump in a only a few hours time, with Scotland already seeing the pink stuff today. The race was given the starting flag about 3 weeks ago & most have made it over the Foinaven fence, so all positive for most punters

As ever in these situations, peeps best waiting till the actual block sets up before taking beyond as gospel. Chill

Very plausible & another solution going forward. Those mentioning an Atlantic breakdown, I'm yet to see signs of any deep systems upstream & crossing America. Most of the systems are spawning from the trop vortex to our North, heading West initially by the Greeny block & then moving East, with forcing from both N/S elongating them. Due to this bizarre set up FI is 3/4 days & when the Canada fed Greeny Block does subside there's still not many deep systems traversing America & tPV still largely displaced still. Wouldn't rule anything in or out

And the purples heading further South too, which should aid further on

Again quite bizarre indeed how stagnant the system is, no energy heading W/E over USA, instead the Canadian fed Greeny block reversing the normal flow & squishing the lows being spawned from the tpv to our North & dragging them West, as the purples try & edge closer and closer. Brave call for any of the models predicting beyond a few days

Yes, is certainly my thinking if the tpv largely remains displaced. Very little energy traversing USA to return to business as usual

The charts were already posted suggesting 10+ days with precip spikes, clearly for differing areas and different models, so yes poor show for this forum

Just had to sign up to radar as Mother seems to think she saw snow 1hr ago & lives same village. Think the covid must be effecting her eye sight. However hope the accuweather snowcast predictions are true. 11hrs on Thursday