scotland Scotland - Regional Discussion - 23/12/13 >>>

[Ravelin]

Well it got to the stage i had to take desperate measures to get my snow fix....by going to the cinema to watch Disney's Frozen with the wife and 2 of the kids. If only I had the power to create snow and ice like the queen in the film! Film was OK, certainly not the worst kids film I've had to sit through.

Temperature now up to 5.1/4.3C and pressure dropping as the next system moves in.

Edited January 5, 2014 by Ravelin

[lorenzo]

Make up for the kids film by watching Lone Survivor .. 

[Buriedundersnow]

cracking new charts from ECM might be due to all the storms but will help greatly when we see some snow

 

[skyeblue]

Lashing doon here but what's new,WILD !,!,

[Buriedundersnow]

anyone else seeing hints from the models of a 2010?

 

 

2010

 

 

forget the overall hemisphere profile look at the atlantic with two ridges and a cut off low to the south of Greenland and ECM even looking to line up some lows similar over the US.

 

remember then we saw heights try to build northeast first.

[lorenzo]

Couple of decent squall lines zooming through or LEWPs if you want to get all technical.

 

At last the models are serving up something of a cliffhanger versus the endless output of Atlantic jetstream conveyor belt of huge thermal gradient, 200mph peak jet, rapid cyclogenesis / bombogenesis..

 

ECM / JMA / GEM 

 

..and of course the model that is impervious to blocking and either doesn't see it or just wants to crank the jet through it we have the

 

GFS.

 

UKMO at 144 compared to the GFS really shows how far east GFS pushes things through..

 

It's had bad press for this eastward bias and tonight is a good example, the only kind thing I can say is that it is doing better than last winter and that the ECM has had moments this season where it's really been seeing things that aren't there, especially with respect to how much it amplifies things.

 

An old adage that the GFS 18z follows the ECM 12z will surely be tested later, esp. with the marked differences. Looking forward to the ensembles now that we have a puzzle to solve.

 

 

[aggy]

Some intense rain there torrential last time I seen rain that heavy was in Thailand

[Buriedundersnow]

updated NCEP 500mb charts and only thing to say is AMAZING!!!!!!!!!!!

 

 

6-10 day yesterdays- todays

 

 

 

 

8-14 day   yesterday-todays

 

 

[Buriedundersnow]

ECM mean anomalies charts agree with the NCEP

 

NCEP 6-10 day chart and ECM we will call day 8 right in the middle

 

[Buriedundersnow]

ECM mean anomalies charts agree with the NCEP

 

NCEP 6-10 day chart and ECM we will call day 8 right in the middle

 

[Buriedundersnow]

ECM 500 anomalies charts agree with NCEP

 

6-10 day NCEP and in the middle day 8 of ECM mean anomalies

 

 

8-14 day NCEP and day 10 ECM mean anomalies

 

Edited January 5, 2014 by Buriedundersnow

[lorenzo]

Extended discussion link is here BUS, usually the 6-10 and 8-14 have analogs for CONUS and commentary, at the weekend they down tools.

 http://www.hpc.ncep.noaa.gov/discussions/hpcdiscussions.php?disc=pmdepd

 

I like this sentence

 

THE 5/00Z GFS OFFERED AN EXTRA SHORTWAVE

 

No S.h.i.t. sherlock - not like it !! LOL !

 

Link for CPC discussion is here http://www.cpc.ncep.noaa.gov/products/predictions/610day/fxus06.html

 

Model guidance including analogs here - http://www.cpc.ncep.noaa.gov/products/predictions/short_range/tools/model_guidance.php?dayin=11

 

eg http://www.cpc.ncep.noaa.gov/products/predictions/short_range/tools/model_guidance.php?dayin=11

 

dates bottom right

 

 

I know that you like a visit to the archives. Top left figure is the correlation coefficient. Simply put how much now looks like this selection of dates 1.00 being the best.

 

Enjoy !

 

 

 

Edited January 5, 2014 by lorenzo

[blitzen]

Rain finally reached here now and it's very heavy.   Sure I heard Thomas S on bbcnews 24 at 4.30pm mention that it would be the east coast that would get windy tonight from Aberdeenshire, down through Fife and the borders. Is that right?  Dead calm here at the moment.

Edited January 5, 2014 by Blitzen

[Buriedundersnow]

cheers for the links LORENZO.

 

i have been trying to find they discussion things but that site has so many things on it i tend to get a bit lost but saved to favourites now so thanks.

 

i already had the links to the analogues i hadn't notice the correlation thing at the top.

[snowy owl]

Really windy here now, rain was battering the window earlier.

[lorenzo]

No worries John has studied the CPC anomalies for a good few years so I would advise to download any PDF he places up on them , he usually puts them in the tech thread. e.g http://forum.netweather.tv/topic/76236-in-depth-model-discussion-and-summaries/page-8#entry2882162

 

Another link I liked was J Weaver for the GEFS reforecast product, it re-analyses the GEFS and then strips out wayward variables, bear in mind this is GEFS and if like tonight we see evidence that the suite is too progressive then this may be too. However, an interesting other output to play around with.

 

http://www.esrl.noaa.gov/psd/forecasts/reforecast2/probabilities/index.html

 

[Buriedundersnow]

cheers i'll take some time looking through them and see where i can get.

 

I'm quite impressed with the ECM mean 500 charts remember these charts at day 10 first piece of energy dropping into Europe then trough to our west now at 0hr and 24hr.

 

[Buriedundersnow]

wheres CATCH gone?

[LomondSnowstorm]

Looks like we're heading for another GFS/ECM squaring off. In this instance it's not quite as massively dependent on Greenland heights but rather a Euro-Scandi transition (most likely, although it also requires that upstream amplification for sufficient WAA to 'pump' the high up).

Taking the GEM 12Z op as an example of roughly what we're looking for, we can take the starting point as +48 when the initial mid Atlantic ridge is carved out by that massive US coldwave, the leading edge of which is causing some pretty chilly temperatures at the Packers game I'm watching at the moment. As I said a few days earlier, this was quite crucial to future developments, and although the ridge in itself doesn't bring in any cold it does initiate the change in the pattern. The fact that the GFS was quite clearly wrong on this feature (something which its own modellers suspected a few days ago) should perhaps give an indication as to which way the next dilemma is likely to head:

Anyway, roll it on three days later and, while the lows have made it pretty close to fully phasing, there are lighter blues appearing between Greenland and Svalbard, with signs of a split jet north of the UK and a cross polar flow:

The 'BUS Siberian Express' would require more WAA, with the trough really digging in further south just off the eastern seaboard and stalling, something like this:

Of course, with the jet significantly stronger such a setup is very difficult to achieve straight away, which is why we'll need a few bites of the cherry to get there.

Anyway, the main difference between the above and the GFS is that the GFS spills the Atlantic troughing further east, shunting the polar flow and subsequently the increased heights further northeast:

With the GEM's slightly more significant blocking the trough stalls in the Atlantic and disrupts southwards, once again becoming sharp and vertical and giving another dose of WAA:

The next stage, and the one that's been a bit harder to achieve on the modelling (other than the ECM ens which is a bit better for this) is a euro trough - we need some kind of trigger low, either a flat southerly jet from the west or a shortwave dropping in from the northeast, to extend the easterly flow our way and the further west the heights setup the easier it is for the cold to make it.

The GEM get very close to perfection with this but the disrupting low comes in a bit too far east, and by the end we're on the very edge of the cold pool:

Because we aren't quite taking the direct route there are still a good number of obstacles to overcome, including shortwaves in the wrong place (i.e. East Greenland or where we'd like our blocking to set up), shortwaves not forming in the right place (i.e. just to our south/southwest), the PV heading back east into Greenland and shunting the whole pattern further east or even a northeastwards ridging of the Azores. Almost all of these combined scuppered a seemingly stuck on easterly in December 2012, and in this instance any one could scupper this particular attempt at an easterly. However, as long as we get to some kind of blocking setup, even some sort of UK high, there will likely be further opportunities down the road, particularly if we can get a block which is far enough north to deflect the jet southwards. In summary, we're slowly but surely making progress, and while it may be another day or two before we see some proper FI stonkers those kinds of outcomes are certainly in the mix at the moment.

The GFS almost always flattens the pattern more than any other model and even in instances where it comes closest it usually has to make some kind of adjustment upstream in the process. The modelling consensus appears to be broadly with the more amplified outcome and the GFS does appear at least to be making moves towards the modelling consensus run by run.

In summary, trending very definitely less windy, quite probably drier and likely colder, with the depth, timing and longevity of any major cold spell still up for grabs. Maybe a 30% chance of hitting the beasterly jackpot within 10 days (increasing to 50+% if you include setups which give a shortlived chance of snowfall based on either a battleground setup or a weakish southeasterly) with the longer term potential looking very interesting as well, accounting for the usual shroud of zonal FI fog which often lingers over the models, particularly the GFS.

 

The MT is pretty fun at the moment, with the usual GFS fan club coming out to play(as Nick pointed out those guys are few and far between across the pond where the ECM is considered as something close to the gold standard of medium range modelling) along with the mildies, uber pessimistic coldies, overly optimistic coldies and even a few people who actually look at the models before posting 

[Cheggers]

Morning all, back to the grind stone as they say, and as usual it is wet and dark.

[Ravelin]

A grey, damp feeling start to the week, matching the general mood of the first day back at work after the festive break. Temperature at 8am was 5.1C, which is slightly better than the 7.1C it was just before midnight last night (although it did hit a low of 3.7C sometime during the night). There's a bit of a breeze but nothing noteworthy compared to recently (at some point over the Xmas period the wind, in conjunction with some un-noticed weakening of the metal through rubbing against a concrete fence post, managed to snap one of the steel poles outside our office that we have antenna mounted to).

 

It's going to be a long slog work wise until the summer holidays in July with little to look forward to, especially before April. We could really do with some of the colder looking charts to come to our rescue and provide some interest for the latter part of Jan and into Feb.

[mardatha]

Is like the Wreck of the Hesperus here - howling whistling wind, battering hammering rain. I give up. Wonder if there's any empty cooncil hooses in Alaska..?

[over_the_rainbow]

Damp and dark here, but not windy. I'm missing the sun! Hoping it will visit Perth maybe on Wednesday! 

[Zenarcher]

Heavy showers here all morning with some thunder around 11am too.

[DR(S)NO]

Seems to be very mild today...already breached 10c earlier.

Huge clap of thunder and lightning around 11am.

Quite gusty winds...presuming they are likely to increase in magnitude.

Updated SEPA warnings this morning moves the likelyhood of more damaging flooding along the towns seafront ..from flood alert to flood warning......along with quite a few other locations.

Edited January 6, 2014 by DR(S)NO