Model output discussion 8th Feb - Cold for now, but then what?

[Methuselah]

5 minutes ago, Seasonality said:

Indeed and apologies if I keep banging on about it but this has been an ongoing pattern, mild incursions get overestimated by the models and then truncated as they come into the nearer time frame. It happened during the January cold snap as well. Something @Bring Back1962-63 has been explaining much better than I can in his excellent updates and observations.

It could be said that that also applies to cold and interesting weather? Dull, drab sort of semi-coldness seems to always be the end result...

[Seasonality]

1 minute ago, Ed Stone said:

It could be said that that also applies to cold and interesting weather? Dull, drab sort of semi-coldness seems to always be the end result...

Good point, I freely admit I'm trying to put a positive spin on it to try to cheer up cold weather fans...  But very good point.

[Matthew.]

ECM says yes to the continued theme of the winter- mid-latitude blocking for next week. Cold minimums by night with plenty of frost.

[Frosty.]

Well, the cold has arrived, it feels like proper winter now with a very cold Ely breeze and scattered mainly light sleet and snow flurries / showers with frost early and late

A forecasters nightmare on saturday according to the Gfs 00z as an area of organised precipitation pushes in from the north sea, some of us will see a covering whilst others will see cold rain but it's a cold spell for all during the coming days.

Edited February 9, 2017 by Frosty.

[sparky1972]

3 minutes ago, Frosty. said:

Well, the cold has arrived, it feels like proper winter now with a very cold Ely breeze and scattered mainly light sleet and snow flurries / showers with frost early and late

A forecasters nightmare on saturday according to the Gfs 00z as an area of organised precipitation pushes in from the north sea, some of us will see a covering whilst others will see cold rain but it's a cold spell for all during the coming days.

morning all, already had our first brief sleety shower, although its forecast to be a dry chilly day, i guess thats what is going to make the next cpl of days more nowcasting than forecasting, here is hoping for short term upgrades regarding the ammount of snow that peeps might see.

[SMU]

Morning All-

Just a quick update from the other nights post- nothing much has really changed -

The second wave of warming is really coming into view now - very similar to the way the last one was modelled, initially progged to send the zonal mean into deep negative territory, the last 48 hours have seen the overall forecast to continue to run along the same timeline with a 'slight' moderation of the negativity of the zonal winds-

The mean (GFS) drops to + 2M/S on the 22nd- however as with the first warming assisted by the MJO the tropospheric response could well be more immediate -last time relating to the height anomalies - they had responded & built when the zonal wind had reached the +10M/S line (ave for mid Feb is ~ +23M/S)

The CFS again is very bullish about negative territory & whilst modelling wise it doesnt deliver 10HPA resolution particularly well - generally overall this winter in terms of its forecasts of 'shape' of zonal wind trending V actuals has been pretty good- so it could all be sematics as to whether we actually tick the 'final warming' box- its the steep decline towards zero M/S thats important & of course hopes of a slower / non existent PV recovery....

( CFS is in pink - GFS ens in Green )

As highlighted then the numbers look good & the magical 0M/S line may yet again be breached- however from a trop point of view the guide for me in terms of what we may well see develop @500MB is the 10M/S time line ( again assisted by the MJO ) - forecasts for this are 17/18 Feb so allowing for the slight lag of height anomalies building we would see the NH profiles to start to look on 17-19th- focussed on positive heights over greenland & in the atlantic with of course deeper troughing trying to filter into Scandi- a relative rarity this winter-that should put the UK in the frame still for getting cold late next weekend ( timed nicely for my 3 weeks off !!)

 -The ECM strat forecasts are mostly onboard with the forecast although im expecting lower zonal wind forecasts at day 10 when berlin updates today - yesterdays 10 day 100HPA forecast perfectly depicted the flow allignment highlighted above..

If we also review the last few days modelling ( without posting to many pics ) - the ECM in particular has been to progressive with the South easterly warm up, initially progged for Sunday- its now more Monday & we keep a continental influence for the whole week, so frosts by night however a higher diurnal range-

Snow over the weekend again looks more widespread than first modelled.. I guess somewhere at elevation in the UK will breach 10cms - Im expecting a dusting here - with peak availability over the UK being Friday 00z to sunday 12z before the slightly less cold uppers filter NE from Kent...

have a good day

S

 

 

Edited February 9, 2017 by Steve Murr

[Guest]

DAILY EUROPEAN TEMPERATURE AND PRESSURE CHECK No. 7  

MIXED NEWS - THE COLD POOL MOVES IN BUT THE REALLY DEEP COLD LOSES SOME OF ITS INTENSITY

In the build up to our cold spell, I feel that it will be useful to keep up-to-date with the current and trending temperature and pressure changes in Europe. I will try to produce these on a daily basis for the next few days around 0730 to 0800 (although I am away on a business trip from later today until Saturday – so no report on Friday and the next update will be on Saturday around 1300). We can see how the pattern is evolving and  monitor the extent and the severity of the cold.

Now, I shall pick up from my last “check” (on page 150 of the previous thread). This took us to February 8th.

European Surface Temperature Charts:

                  Current "live"                                  Feb 9th 0650                                  Feb 8th    1250                                 Feb 8th  0650                                    Feb 7th 1250

     

Note that it is important to allow for min/max temps when comparing the charts. The 0650s are usually close to the minimums and the 1250s are usually close to the maximums.

COMMENT:  Although the cold pool has continued to advance across Europe the area of deep cold has lost some of its intensity. As I said yesterday, the air flowing around the top of the HP to the north-east of Scandinavian and around the north-west Russian coast has been coming in off the warmer sea from the north. This has eroded some of the deep cold in that part of the pool. The remainder of the sub -20c temps (purple) is now more or less stationary. The sub -8c and sub -12c temps have edged further west and south-west. The better news is that the area of sub -4c temps has now spread across central Europe and the sub 0c temps now envelope western Europe and the UK (as near minimum temps but the maximums will be in the 1c to 5c range for most parts today). All this can be seen by comparing the two "0650" and the two "1250" charts. So, it will be cold or very cold for a few days (or longer - see final comments) but not quite as extreme as might have been expected several days ago.

GFS  0z February 9th T+6 European Charts: 

              2m Surface Temps                                      850 Temps                                          500 hPa Temps

                

COMMENT:   Compare today's charts (above) with yesterday's  (below).  Note the "overall" further expansion of the massive cold pool in terms of sub -4c and sub -8c surface temps (mid and dark blues) but less extensive sub -20c temps (purple). The area of sub  -24c temps (dark purple), sub -28c temps (pink) and sub -32c temps (light grey) in the north-east of the block is little changed. 

Scandinavia is colder with an expansion of sub -20c temps there. The sub -12c, -8c and -4c temps have progressed further westwards through Europe.

Similarly, the overall huge pool of 850s with sub -8c temps has expanded but the area of deeper cold has changed little with the pool of sub -20c 850s remaining in the north-east well away from Europe. The region of -12c temps is slightly smaller in the main pool. There is still the area of breakaway sub -12c temps which remains just to our north-east (the small sub -16c has gone). The area of sub -8c temps ahead of this has now extended across eastern UK and the -4c temps now cover almost all of the country.

GFS 0z February 8th T+6 European Charts: 

                2m Surface Temps                                      850 Temps                                         500 hPa Temps

                  

European Surface Pressure Charts:

                   Current "live”                                   Feb 9th 0650                                Feb 8th    1250                                  Feb 8th  0650                                   Feb 7th 1250  

      

   Current Met Office Fax: 0600 Feb 9th             GFS 0z February 9th T+6                      GFS 0z February 8th T+6   

                                                         

COMMENT:  If the news wasn't quite so good for the temperatures, it is better for the pressure. The Scandinavia HP continues to be more intense than the models were predicting. It reached a peak of 1057 mb at 2250 and for several hours last night at Drevsjo in central Norway. Although this has an altitude of 672 metres, Meteooceil do state that all their live and recorded figures shown are automatically adjusted to mean sea level readings (where they would have reduced all the readings by roughly 1.2 mb per 100 metres). A wider area there and up to northern Norway has seen pressure levels stabilise between 1050 and 1055 mb for much of the last 24 hours. Two more bits of better news. The central position of the HP has stabilised over central to northern Sweden and Norway. Rather further north than the models were predicting. The shape of the HP has been improving too. Yesterday, I was concerned by the strong south-eastwards ridging. This had meant that the deep cold pool had further to travel around it or might be blocked from its westward progression. Well this ridge is becoming less pronounced and is slowly edging westwards. Ideally we want a flatter southern flank to give a more direct easterly flow through Europe. The LPs to the south remain in a good position to prop up the HP. The central Mediterranean LP (just west of Italy) has remained more or less stationery, perhaps deepening very slightly. I mentioned that there were signs of another LP forming over the Black Sea and that has now happened. The position and shape of the LPs is also very important in determining the precise direction of the surface flow over the next few days. It looks fine for some time (in maintaining the easterly) but we need to see if a new trend starts to show up..

Overall, I must admit that it is disappointing to see the the really deep cold become a little less intense. It is difficult to be precise about how cold the UK will be over the next few days in terms of the marginal temps at the surface, the 850s and the dew points for snow, sleet or cold rain. There are likely to be colder patches and some snow, particularly away from the exposed coasts but all to play for. 

FINAL COMMENT:  Like the rest of you, I was disappointed to see that there is likely to be a delay in "phase 2" with the northerlies and Greenland HP perhaps not arriving until later in the month (assuming that the background signals still favour HLB at that time). This explains the change in the model output in the last 2 days. There have been some swings back and forth and phase 2 could still evolve more quickly. That Indian Ocean influence might not be so disruptive but we'll need to watch the updates from the likes of Tamara and GP on this. I still believe (perhaps too stubbornly) that the cold block is a massive one (less really deep cold is not too important - it's the extent of the surface cold that is vital) and will take a lot to shift. The Jet Stream is weak and meandering and the Atlantic remains extremely weak. If the PV lobe does transfer east towards Siberia, the wedge of lower heights is likely to push southwards over north-west Russia and northern Scandinavia. This would displace the HP somewhere to the south - the models currently favour the south-east but due south (perhaps right over us)  or more westwards to our north or north-west are also possibilities. Right now the HP is intense, stable and stationary. I feel there is a good chance that it will hang on in a similar position until much later next week. Then, as in January, we might narrow the gap between this cold spell and the one predicted to follow. I'm a little less bullish but not defeated!

NEXT UPDATE:  Saturday around 1300 - no report tomorrow (Friday) as I'm away on business.

EDIT: I will be more than happy if someone else wants to do an update tomorrow - at least with the liver pressure and temperature charts so that progress can be monitored while I'm away.

Edited February 9, 2017 by Guest
Correcting typos and to ensure that all the links and charts work properly.

[The Enforcer]

24 minutes ago, Frosty. said:

Well, the cold has arrived, it feels like proper winter now with a very cold Ely breeze and scattered mainly light sleet and snow flurries / showers with frost early and late

A forecasters nightmare on saturday according to the Gfs 00z as an area of organised precipitation pushes in from the north sea, some of us will see a covering whilst others will see cold rain but it's a cold spell for all during the coming days.

I don't get why those surface temperatures are so high for large swathes of the U.K. given the 850s and where the surface flow is coming from. They don't tally with the charts forecasting snow at the same time.

[Singularity]

Is this normality I see before me? GFS much more progressive from the west and ECM keen to explore amplified alternatives with lows sliding by to our south... yep, sure looks like it!

Starting to wonder if GFS' idea of racing an upper tropical wind signal across to the IO by early-mid next week (corresponding to a ridge through Europe) is isolated or perhaps ECM makes much less of it relative to the Pacific and to some extent stratospheric forcing.

[Summer Sun]

This morning the ECM ens shows the Op is slightly warmer than the mean between Tuesday and Friday-ish next week before coming to agreement around the 19th

[Gowon]

54 minutes ago, Ed Stone said:

It could be said that that also applies to cold and interesting weather? Dull, drab sort of semi-coldness seems to always be the end result...

True, we haven't had a noteworthy cold spell that includes snow with decent cold uppers, but we've had hard frosty nights at least.. 

[numbnutts(uk)]

i for one am not buying that band of rain thru the middle of that chart,dont see how it would be possible.

[East_England_Stormchaser91]

1 hour ago, Seasonality said:

Yes, and for two runs on the trot now by the ECM. More muted this morning but could be inter-run variance, 12z will be interesting watching. Not time to give up on winter possibilites yet.

Definitely not. It's still only February after all! If you think Spring is coming soon, you may have another thing coming. Can't count the amount of times when we have been well and truly into spring, only to be slapped in the face by a surprise cold snap, which has often been in the form of snow. April 2008 delivered some spectacular thundersnow here. Getting caught in it on my paper round made it quite unpleasant however! 

Snowfall is also more common in March here than December too. Still time yet. 

Now time to await the 06z! 

[Devonshire]

2 hours ago, winterof79 said:

Movement from the South

Umm - movement of what, from where, to where, with what possible effect?? (I realise yours isn't the only 1-liner in here this morning, but it is rather perplexing - this is the model discussion thread after all!)

[TEITS]

3 minutes ago, Devonshire said:

Umm - movement of what, from where, to where, with what possible effect?? (I realise yours isn't the only 1-liner in here this morning, but it is rather perplexing - this is the model discussion thread after all!)

I assume that is referring to the front moving up from the S. Only likely to bring rain anyway so nothing to get excited about.

 

[Frosty.]

53 minutes ago, numbnutts(uk) said:

i for one am not buying that band of rain thru the middle of that chart,dont see how it would be possible.

It will ultimately come down to nowcasting, saturday looks very interesting as some of us could see a fair dumping, especially with a bit of elevation.. even London & the SE generally could see some of the white fluffy stuff..good luck to all!

Edited February 9, 2017 by Frosty.

[weirpig]

Gfs  shows sleety snow mix  on this run as ever altitude will be the key   a few charts to illustrate

[SMU]

GFS 06z out to 144- watch the ridge coming NW out of portugal...

[warrenb]

Since the nadir of doom on Tuesday night, the models have slowly been slowing the rate of decline SE of the high pressure with each run, this meaning the wind stays in more a SE quadrant than a S'ly.

With the stagnation of the air, it also mean the UK produces it's own Cool Pool of air

Edited February 9, 2017 by warrenb

[mb018538]

Indeed - the very mild air has been tempered back now, so much so that colder air starts to edge back south again. Interesting little feature to the SW making much more of an impression on the 6z - even throwing some steady rainfall into the south of the country.

[Summer Sun]

Quite a change on the 06z..

06z

00z

Will have to wait for the ens to see what support this change has

Edited February 9, 2017 by Summer Sun

[gottolovethisweather]

Some corking good analyses in here from the usual suspects, so I need not add much more other than to say........... "Baby, it's cold outside" Temperatures are set to progressively fall by day and night over the next four to five days. Afterwards, you have to expect some milder and perhaps unsettled weather to attempt to penetrate our shores. However, I think it's quite likely that the last week of February will end on a bitter note as well. The trend of Easterlies in February has once again bore fruit, and with that, some snow is always likely, especially for parts due North and East and at elevation. Will I receive anything like a snow-fest in central Southern England, perhaps not but the local hills will almost certainly receive a dusting. Will you, my friends, acquire some magical white ice crystals as well? Watch the local forecasts and follow your local threads to find out whether the possibilities are there.

 

For fellow cold-loving fanatics, take care and have fun whilst the cold spell is in attendance. It cannot stay that way forever but the mildies might have a battle on their hands. I'd suggest we don't look beyond D5 in any great detail just yet.

Edited February 9, 2017 by gottolovethisweather

[Singularity]

 

Check out the change in the jet profile to our SW between the 00z and the 06z; a more concerted effort to jet it back into Europe.

 

GFS 06z (left) has essentially moved some way toward ECM 00z (right) with a drier theme and colder nights than with the GFS 00z, but will it now ease low pressure into Europe as per the ECM 00z? 

One thing it doesn't look to be doing is dividing up the mean trough to our west with the ridge as it extends NW - but retaining the lows on the southwest side of that ridge could still work out alright, though it places more dependence on the vortex dropping as close to our east as possible (less of a trigger low to dive on west flank of the vortex as per 00z ECM days 9-10).

 

Edit: I see Meteociel is well ahead of NW with the GFS upload (what's up with that Netweather?) and sure enough it does ease the LP east into Europe as per the ECM 00z! 

These are the kind of changes expected should the model be backtracking on its progressive upper wind signal with the MJO - hopefully that is indeed what's going on and this isn't just some kind of coincidence!

Edited February 9, 2017 by Singularity

[Frosty.]

6 minutes ago, Summer Sun said:

Quite a change on the 06z..

06z

00z

Will have to wait for the ens to see what support this change has

Fingers crossed the 6z is right, quite a flip back to cold!

Still in the game

Edited February 9, 2017 by Frosty.

[carinthian]

Weird pattern flow around the British Isles on this run between 144t-200t. Sure think the models are struggling with-in this period. Handling the low out west of Biscay is the problem and whether pressure rise to the North of the British Isles is again going to take hold. Probably best ignore this run until so more data becomes available in the reliable time frame. Sorry could not be more helpful but our team of fairly confident that the UK will remain in the below average temp range in the mid period (144t -240t )

 C