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

[knocker]

No significant change in the anomalies this evening from last evening and they are all on the same page.

In the 5-10 range the vortex over Franz Joseph land.trough eastern Pacific and western Atlantic with a ridge situated in eastern N.America (some intense WAA), Thus a fairly weak jet tracking SE out of N. America and then NE around the Azores ridge situated to the SW of the UK before settling on a upper flow from the WNW over the UK. This has all the indications on a N/S split as systems track around the HP with the south remaining dry. Just how the detail of this split materializes depends on the det runs interpretation of colder/warmer air phasing but certainly the percentage play remains a fairly quiet period interspersed with the odd unsettled foray from the Atlantic with temps significantly up on this weekend.

Still some significant changes as we proceed. Upstream a lobe of the vortex N. Canada, retrogression of the N, American ridge to GOA. With the main arm of the vortex now over NE Europe and the positive anomalies weakening to the SW of the UK a more zonal westerly flow ensues with perhaps a period of more unsettled weather with the temps possibly varying around the average

 

Edited February 12, 2017 by knocker

[Weather Observer]

As posters above have said, we now turn our attention to what is possible at the fag end of winter. I looked back at the synoptics of a few blocked winters like 1963/4 and 1975/6 and noted that the tendency for heights to reset themselves in places that did not support cold and snow was a strong one. And because these changes are so slow in themselves it can be frustrating. Like watching a GFS high in FI which follows us  around like a mosquito. However, even in these unfavourably blocked winters their is usually a decent cold shot or two.

So while I cannot say whether the last train has left the station, I wouldn't throw away the ticket yet. And when the synoptics are right, then March can deliver proper winter. Take the example below. 10cm of snow on the south coast, which for 2 days did not melt at all in brilliant March sunshine and was still lying in the shade a week later. If only!

[comet]

58 minutes ago, Paceyboy said:

Perhaps coldies should take a break and maybe view the models again Friday morning, seeing as we shall most likely be in a period of milder weather for at least 4 or 5 days (also projection-wise)

Positives to be had by saving on heating bills, I wont complain. 10-12c in the day looking likely in south UK midweek onwards.

Wouldn't it be amazing to have an early March potent easterly with sub -10c uppers and low thickenesses, the power of the sun, the contrast between North Sea SST and a deep cold pool aloft. It would be fanstastic to see some proper convection.

Its not over until mid March for me personally.

 

Stratosphere gph profile charts look very tasty by months end, so wouldn't rule anything off the table. Would agree though once we get into March you need  the coldest uppers and cloud cover to support lowland laying snow cover or deep surface cold similar to what we saw in late March 2013 which came from a Easterly. 

[Chris.]

Azores high looks a lot less powerful in tonights 18Z run and the atlantic taking advantage of it and creeping in further east.

12Z

 

18z

Edited February 12, 2017 by carsey

[Cheshire Freeze]

Oh hang on, what's this...

GFS has started to pick up on that ridge moving out of Canada which can be traced back to day 8. It's enough on this run to initiate something of interest.

[feb1991blizzard]

Good agreement on the displacement SSW / Near SSW happening between ECM anf GFS now. hello cool showery spring with wintry PPN!

http://www.instantweathermaps.com/GFS-php/showmap-strat.php?run=2017021300&var=HGT&lev=30mb&hour=228

[knocker]

The GEFs continues it's upstream transition to a GOA ridge and a vortex lobe N. Canada leading downstream to a zonal Atlantic with faint ridging to the SW and S. As of last evening some indications of a Scandinavian trough late in the day which may, repeat may, be reflected in some Pm incursions.

Meanwhile back at the ranch not a great deal to report with the transition of the high pressure  from the east to the south west and south and the westerly flow promoting Atlantic incursions around the ridge. Ergo mainly dry in the south with temps around average or above.

As an aside this morning's 100mb chart at T360 is not adverse to the vortex/trough influencing the UK.

Edited February 13, 2017 by knocker

[knocker]

Varying a little in detail but the ecm essentially singing from the same hymn sheet as the gfs.

[jvenge]

1 hour ago, knocker said:

The GEFs continues it's upstream transition to a GOA ridge and a vortex lobe N. Canada leading downstream to a zonal Atlantic with faint ridging to the SW and S. As of last evening some indications of a Scandinavian trough late in the day which may, repeat may, be reflected in some Pm incursions.

Meanwhile back at the ranch not a great deal to report with the transition of the high pressure  from the east to the south west and south and the westerly flow promoting Atlantic incursions around the ridge. Ergo mainly dry in the south with temps around average or above.

As an aside this morning's 100mb chart at T360 is not adverse to the vortex/trough influencing the UK.

Beautiful, Knocker. I'm looking forward to an early Spring. 

GEFS mean anomaly is also going for mild mild mild. I may be seeing 14 degrees in a few weeks, which would be spectacular.

One can't help but feel that if a turn around in model output is coming, it will manifest if the 6-8 day range, rather than looking into the depths of FI. It would be a little too simple to be able to countdown Spring from 15 days out :-)

[Summer Sun]

Although the Op is very much on the cold side of the mean in FI it does have some support

The ECM ens keeps delaying anything colder (below zero) 1st it was around the 20th now it's towards months end

[Summer Sun]

At D7 this morning UKMO, ECM and GFS all show high pressure nearby it's just where it will sit as to whether we get westerlies or a northwesterly 

[Summer Sun]

GFS 06z turns thing very mild this time next week

[Frosty.]

Looking at the models, I think that's pretty much it as far as a cold spell is concerned for the rest of February. It looks like a generally unsettled and much milder outlook with just short-lived colder incursions, mainly across the north and some brief quieter interludes with fog and frost, chiefly in the s / se.

[Seasonality]

6 hours ago, jvenge said:

Beautiful, Knocker. I'm looking forward to an early Spring. 

GEFS mean anomaly is also going for mild mild mild. I may be seeing 14 degrees in a few weeks, which would be spectacular.

One can't help but feel that if a turn around in model output is coming, it will manifest if the 6-8 day range, rather than looking into the depths of FI. It would be a little too simple to be able to countdown Spring from 15 days out :-)

Europe deserves a warm up now. However I note a reappearance of scatter and cooler runs appearing in the ensembles for the last third of the month that wasn't there of late.

 

[Frosty.]

8 minutes ago, Seasonality said:

Europe deserves a warm up now..

And the uk deserves a proper cold spell! however, it looks like the models are taking us towards a much milder and generally unsettled pattern.

 

[jvenge]

6 minutes ago, Frosty. said:

And the uk deserves a proper cold spell! however, it looks like the models are taking us towards a much milder and generally unsettled pattern.

 

Difficult to get it Frosty at this time of year now. Backend of February to early March you need something more special as opposed to January. Not saying it can't happen, but the chances aren't good.

19 minutes ago, Seasonality said:

Europe deserves a warm up now. However I note a reappearance of scatter and cooler runs appearing in the ensembles for the last third of the month that wasn't there of late.

 

I'd love an early Spring, but I'm doubtful :-) Some corkers in the GEFS though, but I'm skeptical when they are as far out as they are. I'll believe it nearer T144.

[Nick F]

2 hours ago, Frosty. said:

Looking at the models, I think that's pretty much it as far as a cold spell is concerned for the rest of February. It looks like a generally unsettled and much milder outlook with just short-lived colder incursions, mainly across the north and some brief quieter interludes with fog and frost, chiefly in the s / se.

 

19 hours ago, KyleHenry said:

Yes I can definitely agree with that. The next window of opportunity evolves in 12 days time. Approximately 25th Feb. 

There is typically a lag time of around 10 days for an MJO-induced Rossby Wave to reach high latitudes (Hoskins, B. J., and D. J. Karoly, 1981: The steady-state linear response of a spherical atmosphere to thermal and orographic forcing. J. Atmos. Sci., 38, 1175–1196) - phases 8 more favourable than 7 for UK so like you say around the 25th, but not because of the subsequent return to phase 7 shown on the GEFS, but from the current phase movement through 8 and 1. The GFS forecast for it move back into phase 7 around the 24th may not have an impact until into early March.

For example, MJO went into phase 7 on the 9th Feb, 10 days on from then we can compare the phase 7 composite for amplitude >1 with the forecast GEFS z500 mean for the 19th Feb, not too dissimilar upstream other then the lower heights downstream over Scandi

Feb MJO composite for phase 8 with amplitude >1 (below),

10 days from current phase movement into 8, takes us to around the 25th,  IMO movement from 8 into 1 more favourable than 7 into 8, but obviously MJO propagation in 8/1 and the resultant increased amplification of Rossby waves into higher latitudes does not automatically = blocked/cold/snow for us unfortunately, as more mesoscale changes in the atmosphere can ruin prospects.

However, we do also have the wave number 1 warming helping to displace the sPV over toward NW Russia / northern Scandi after its current return to northern Greenland / N Pole area. This appears to have the immediate response of increasing the 500mb zonal flow over far N Atlantic into Scandi, but with time height rises / amplification transferring east over N America under a stratospheric high developing and moving east towards Greenland may allow height rises over N Atlantic and perhaps into Greenland to end the month.

Of course, I could be completely wrong, the atmospheric patterns don't always follow the historic composites of oscillations and/or there is disconnect between the trop and the strat. But I think there is some positive indications from both the MJO movements and next sPV displacement to give tentative signs of winter returning at the end of this month and into early March. Not ideal, as snow tends not hang around as long as Dec-Jan, but don't be fooled by the warm up and early Spring feel over the next 10 days or so.

Edited February 13, 2017 by Nick F

[mb018538]

Not much to add in the 12z runs....generally mild and mobile. Drier further south and east. Frost limited, temps a bit above average.

[Summer Sun]

The updated ECM weeklies overnight for the next 4 weeks show above average temperatures with precipitation starting to increase during late Feb and early March

[mcweather]

I see the GFS 12z operational has now even robbed us of the eye candy that was appearing post 300hrs. Let us hope that Nick F is right in his well thought out and composed post.

[nick sussex]

The ECM improves in terms of some potential towards day 9 and 10 and the GFS moves in the other direction. I think the issue still remains the reluctance of the outputs to remove a chunk of the PV over ne Canada. Theres no chance of ridging north whilst that remains there. If more amplitude does appear upstream then the troughing to the east from day 8 to 10 is well placed. It still overall looks a bit messy and complicated, the Azores high is trapped in and can't escape nw because of that shortwave energy off the ne USA. I still wouldn't rule out some cold towards the end of February , theres certainly a good source of that to the ne and any more amplitude upstream could deliver that south into the UK.

[knocker]

Still pretty good agreement with the anomalies this evening.

Still the main lobe of the vortex around Franz Joseph area but signs of it becoming more complex with another lobe around N. Canada. Still the trough in the western Pacific and western Atlantic with the ridge in N. America producing some very positive anomalous temps.Thus a continuation of the upper flow swinging out of North America setting up a zonal westerly pattern that swings around the ridging in the eastern Atlantic. Ergo little change to the previous general analysis of the southern half of the UK remaining predominate;y dry as systems tend to impact the north west. The detail as usual to be sorted by the det. runs. Temps around average or slightly above.

The 10-15 period continues the readjustment of the vortex with a stronger N. Canada/Greenland lobe. the retrogression of the N. American ridge to the GOA and thus a more definitive zonal flow with the decline of the ridge in the eastern Atlantic. The GEFS is bowing a little to a trough over the UK and mid Atlantic ridge. All this would tend to suggest a generally more unsttled picture for the UK with temps still around average or above.

 

Edited February 13, 2017 by knocker

[Stozzy]

Nice looking charts in the reliable timeframe . Mainly dry , rain at times in the north and west , mild . Roll on summer 

[feb1991blizzard]

2 minutes ago, Stozzy said:

Nice looking charts in the reliable timeframe . Mainly dry , rain at times in the north and west , mild . Roll on summer 

If you consider that a nice looking chart then you must love UK's default weather, wet (but not tropical amounts)  and generally the average uk winter bordering spring / autumn temps.

[Stozzy]

20 minutes ago, feb1991blizzard said:

If you consider that a nice looking chart then you must love UK's default weather, wet (but not tropical amounts)  and generally the average uk winter bordering spring / autumn temps.

Hence with the emoji . Sorry there was a bit of sycasm , it couldn't be any worse really