Model Output Discussion

[Guest North Sea Snow Convection]

Cant disagree there ,but there are some subtle changes in the models this morning and Met website also alludes to some of these changes with wintry showers forecast for the north and east this indicates a trough of low pressure sliding south east and introducing easterly winds or southeasterly ,with high pressure once again building over scandinavia and russia.

Temperatures over scandinavia and russia are set to plummet almost reaching record values in Arkhangel with nearly -40 forecast and this intensely cold dense air is slowly pushing west and south west with the high pressure ridging towards us.

Although i cant see the BEEB sticking their necks out just bet , a big pattern change could well be on the cards as i cant see this low hanging on much longer than next week ,before this biterly cold air simply barges it out of the way and although i try to to be as objective as i can i think there are some straws to clutch for cold lovers here lets see if the models or at least the UkMO can continue the theme 60% or even 70 % chance at the moment of this very cold air returning !!!!

I agree with what you say and have been suggesting recently that this may be the eventual outcome after this frustrating low pressure complex decides to get a life!

There are signs that the phasing of the upper trough with the lows developing on the suppressed jet stream do want to take a track rather further south of the UK, but at face value anyway on most of the models, pressure remains stubbornly low still to the north of this with the main arctic continental push still brushing the NE of Scotland and areas to the north of this.

Still a reasonable chance that this trend southwards will continue with pressure rising ever further southwards in the wake of these lows - but if it is to happen, it is unfortunately being a very drawn out process.

[KTtom]

06z is showing a big snow event for northern England for Monday

Some nice porn to look at at the end of the run also :lol:

http://www.wetterzentrale.de/pics/Rtavn3841.png

Edited February 16, 2010 by KTtom

[Schmac]

Good morning all!

I am from (roughly speaking) the same area as jethro and would also be very interested in hearing the opinions of some of the more learned model watchers on what we in the Somerset / Wiltshire area could expect over the next few days / weekend.

A bit of light patchy rain here this morning with temps around 4°c.

Very new to all this "model watching" stuff!... Trying to learn though! Very impressed with how some of you guys (and gals!) manage to get so much info from them!

I used to live up your way TEITS (in Huntingdon)... Looks like I missed a good Winter!

Keep up the good work all... Fascinating reading!

[TEITS]

Certainly plenty of potential in these charts.

During the weekend anyone N of the M4 looks to have upper temps around -7C.

http://www.wetterzentrale.de/pics/Rmgfs992.gif

Now this proves a nightmare to forecast at this range because disturbances will develop around the centre of the LP. However trying to work out where this will be at this range will prove problematic!

[Guest North Sea Snow Convection]

Looks like a trend is developing with the GFS Just like the 18z

Roll on March!

[cooling climate]

Again another run and another shift south and east. It could well be that what we are

looking at on the models for the end of the week could all be a good couple of hundred

miles further south and east.

This would mean colder still than what the models are currently showing.

The synoptics in deep FI are realistic imo but at a earlier time frame and it could very

well be a case of cold over the UK with snow where any precipitation falls to becoming

very cold (bitterly cold) with snow for many.

Again just to repeat what I said the other day I think the end of February and at least

the first week of March to be the coldest and most wintry for many, many years (much

colder than 2005/6 and 1995/6).

[karyo]

Again just to repeat what I said the other day I think the end of February and at least

the first week of March to be the coldest and most wintry for many, many years (much

colder than 2005/6 and 1995/6).

I really hope you're right! So far, the extended De Bilt ensembles don't look good!

http://www.knmi.nl/exp/pluim/vijftiendaagse/Data/15DAAGSE_06260_NWT.png

Karyo

[TEITS]

Again just to repeat what I said the other day I think the end of February and at least

the first week of March to be the coldest and most wintry for many, many years (much

colder than 2005/6 and 1995/6).

Certainly hope so and based on your predictions and Tamara, who I have massive respect for, you could be right yet again.

The E,ly at +384 really is perfect synoptically. Worth some members saving the chart because when it comes to an E,ly via blocking to our E the positioning and orientation of the HP is perfect. Im not saying this will happen but it will be handy to keep that chart for future reference, even for next winter.

[full_frontal_occlusion]

...I think the end of February and at least

the first week of March to be the coldest and most wintry for many, many years (much

colder than 2005/6 and 1995/6).

and

Looks like a trend is developing with the GFS Just like the 18z

With all the teleconnections favouring continued cold into March (even if tempered by seasonal factors), it does begin to look as if the downward propagation of the MMW is beginning to affect model evolution towards a NE'ly blast.

Looking forward to the verification.

ffO.

[Guest North Sea Snow Convection]

and

With all the teleconnections favouring continued cold into March (even if tempered by seasonal factors), it does begin to look as if the downward propagation of the MMW is beginning to affect model evolution towards a NE'ly blast.

Looking forward to the verification.

ffO.

Yes - there are provisional signs that it might be. I wouldn't expect the ensembles to pick up on this just yet, so there is no cause for concern that these don't look overly cold just yet. I'm speaking of both ECM and GFS here.

As we know, these can and do change at a switch! As climate change has pointed out, a very gradual correction further south of the low pressure areas is occuring in line with the often over northwards positioning, and exaggerated energy extent of these by the models beyond the 4/5 day period which has been a persistent error throughout this winter.

Edited February 16, 2010 by North Sea Snow Convection

[Frosty.]

Again just to repeat what I said the other day I think the end of February and at least

the first week of March to be the coldest and most wintry for many, many years (much

colder than 2005/6 and 1995/6).

It's a pity JH would disagree with that as he doesn't see any deep cold reaching the uk unless he has subsequently had a change of mind on that score, with JH on board so to speak, would add more weight to your predictions plus as karyo said, the extended De Bilt ensembles are not so good!

Having said all that, the models so far today have a more wintry flavour but again it's the far north which would appear to be the coldest and snowiest area of the uk during the next week.

[Guest North Sea Snow Convection]

It's a pity JH would disagree with that as he doesn't see any deep cold reaching the uk unless he has subsequently had a change of mind on that score, with JH on board so to speak, would add more weight to your predictions plus as karyo said, the extended De Bilt ensembles are not so good!

Having said all that, the models so far today have a more wintry flavour but again it's the far north which would appear to be the coldest and snowiest area of the uk during the next week.

It's a plausible prediction though. At the very least to see some -10 850 uppers and below arrive in the UK, even at the end of Feb. Even Feb 2005 cold spell achieved this at times and the NH is much colder now than it was then.

The analysis as outlined in the stratosphere thread does give support to such an eventuality. There are further negative zonal winds in the pipeline to re distribute the energy pattern across the NH once more and the emergence of high pressure in the Svalbard/Iceland region is quite feasible with time. The ensembles, at least imo, have not been a very reliable tool this winter and were next to useless a couple of weeks ago changing almost completely one way and back again from one day to another.

[Nick B]

I really hope you're right! So far, the extended De Bilt ensembles don't look good! http://www.knmi.nl/e...E_06260_NWT.png Karyo

Scatter begins in earnest from Saturday on that chart. FI should begin at least then. Up to that point it's staying cold and could well get colder..

Edited February 16, 2010 by Nick B

[johnholmes]

hi Frosty

I'm not sure just what the early March period is likely to bring to be honest.

Ignoring, just for the moment, what the GFS output shows this morning-remember its oscillated between a less cold scenario, almost into mild, in some of it FI ideas in the past few days. Then looking at the main 'players' so to speak and they are, at least at first glance, not all suggesting a similar outcome.

The 30mb temperature (my brief look in the Stratosphere indications and by no means a definitive one; best read those posts by ch and GP and others for that), and its still way above normal, or was last evening.

The AO and NAO are well below zero with the PNA now showing indications of becoming above the zero line.

Turning to the 500mb anomaly charts and NOAA, along with ECMWF and GFS versions, all suggest a similar pattern. That is a very long track along the Atlantic having originated way north at 500mb. There is almost no sign of any blocking returning to an area which would favour a significantly colder spell. The upper air pattern seems, if not locked, then very reluctant to change, both in the actual charts and in the predictions of 10-14 days ahead-taking us almost to the end of February.

At some point that wavelength must change but its probably going to be towards the end of the first week in March before we can realistically expect that.

Further out with the links and ENSO, as I posted yesterday from the IRI site, shows El Nino persisting, the MJO shows little sign of changing overmuch, (so no major cold signal there), and happenings around the tropics don't especially suggest any major cold following as a result of events there.

Like I often say or said, in my lrf thread, these are simply forecasts though and can and do go wrong. yet again I have to mention the events last February-everything supported a cold continuation-it did not happen.

Summing up, I would say that the occasional ideas in FI from GFS for much milder temperatures are 70-30% against it happening, other than for some extreme south and SW areas at times. For the rest of the UK then this cold but not deep cold seems the most likely, even when this particular low eventually dies a death. The overall signals to me over the next 10-14 days are for Pm air rather than Am air. Beyond that time period, and assuming the upper wave length well upwind of us does change in the time scale I've suggested, then about a 50-50% chance of a markedly colder spell but at 50-50 its as likely for the wave length to settle in such a way as we get a milder spell.

Not a direct answer but the best I can give at the moment.

ps

just to add that the NOAA 5 and 6 day model checks for the northern hemisphere show all 3 main models about even in accuracy.

So for the shorter term, 5-6 days, nothing to choose between them currently.

Edited February 16, 2010 by johnholmes

[TEITS]

Latest +24 fax chart.

http://www.meteociel.fr/ukmo/fax/fax24s.gif

Still very uncertain when/where this will turn to snow and how many hrs of snowfall are likely. The Met O suggesting 3-6cm of snowfall and in my opinion Leicestershire, Lincs look in prime position.

[johnholmes]

The NAE an GFS at 06z have differing ideas on where the snow will fall. Looking at the 'rainfall' charts and NAE make more of the amount falling and move it further NW earlier than GFS does.

Its going to be down to radar watching I suspect come tomorrow. Keep an eye on the various parameters, especially zero isotherm, dewpoint, and 850mb temps along with the 1000-850mb thickness.

[Backtrack]

FI indeed, but what are people's thoughts on Monday's snow fest?

Looking at the GFS, some places could be in for a good 6 inches of snow.

Edited February 16, 2010 by Backtrack

[Wilks]

Looks like a trend is developing with the GFS Just like the 18z

Roll on March!

That is exactly the sort of chart I want to see now for that timescale! As with past experience on the models by the time that date is here it will be a complete opposite and we'll be in some nice milder weather!

[492]

Drier air has filtered north from central France overnight and dewpoints over northern France are now quite low. As the low to the northwest slips southwards the wind should gradually back and draw this low dewpoint air towards the south coast and turn the rain to sleet or snow.

[R.P. McMurphy]

As the models stand there is certainly a good snow event showing for next Monday even though it's well out in FI. I also thunk some members need to have a reality check and stop getting excited about charts from MARCH!!! Have you learnt nothing yet?!? xD

[Guest North Sea Snow Convection]

As the models stand there is certainly a good snow event showing for next Monday even though it's well out in FI. I also thunk some members need to have a reality check and stop getting excited about charts from MARCH!!! Have you learnt nothing yet?!? xD

It might be as well not to take the (tongue in cheek) intentions of posting a GFS t384 chart too much at face value just as much as you rightly say that members shouldn't get carried away by such a chart itself

[kold weather]

Some very interesting trends this morning, the key is the western low now barely develops which means only the briefest of SW flows before the LP's come rolling into the south of England, this means a much bigger snow threat.

So this morning anywhere from the Midlands northwsrds would be in for a possible very snowy 7-10 days, I still am very happy with my call of a snow threat, but saying that the 06z shows exactly how most of the country can stay in the cold air...

So all in all, small changes, big upgrades!

Finally, watch out for early March, I think looking at the teleconnections and the global signal once this west based -ve NAO runs out of steam with a southerly jet we could well see another reload of the -ve NAO, whilst the GFS may well be extreme I don't think its a shock that its showinhg hints of a another cold thrust, though I think there may well be something of a southerly before we get a big reload...

Edited February 16, 2010 by kold weather

[Ben_Cambs]

Some very interesting trends this morning, the key is the western low now barely develops which means only the briefest of SW flows before the LP's come rolling into the south of England, this means a much bigger snow threat.

So this morning anywhere from the Midlands northwsrds would be in for a possible very snowy 7-10 days, I still am very happy with my call of a snow threat, but saying that the 06z shows exactly how most of the country can stay in the cold air...

So all in all, small changes, big upgrades!

Finally, watch out for early March, I think looking at the teleconnections and the global signal once this west based -ve NAO runs out of steam with a southerly jet we could well see another reload of the -ve NAO, whilst the GFS may well be extreme I don't think its a shock that its showinhg hints of a another cold thrust, though I think there may well be something of a southerly before we get a big reload...

Good post there, I should think at times the snow risk extends to most of the country, and this set up will be excellent for the Scottish Ski Resorts for sure. The latest AO and NAO forecasts do go for a rise towards towards the end of Feb, but still -ve before a possible reload of -ve which would send it deep into negative terrority.

http://www.cpc.noaa....a/nao.sprd2.gif

http://www.cpc.noaa....ex/ao.sprd2.gif

Personally IMO it will be a cold start to spring due to the latest teleconnections, probably not within the boundary of very cold weather but I dont know what other members think

Edited February 16, 2010 by Snowman0697

[Duane S.]

Well, some rather pleasant FI scenarios getting throw up by the models now! However, I'm more interested in the short-medium term changes in the models, shifting the LP's coming in off the Atlantic on a more Southerly track. An increasing recurring theme I think from now on.

[Backtrack]

Given the uncertain track of Lows, it is likely to disappear on the next GFS run.

Would be surprised if there was any settling snow at low levels, it's typical of their hyperbole with warnings. The front is a weakening feature.

Very much agree John, I don't think the pattern can shift to bring very cold air across us, and more likely is the breaking thru of LP from the SW to cause a slight pressure raise over Europe.

Thank's Ian - Here's hoping the low follows the same path as it was when that run was made. Convection is looking likely now in these showers now too - Exciting stuff.