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phil nw.

Model output discussion pm 13/01/2016

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A good ECM, but not quite as good as this mornings for keeping the cold spell going - hopefully someone can post the ECM ENS later to see how it lies within the spread. 

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Ukmo still out on a limb slightly, ecm falls back towards the gfs in building a high and flattening things back out towards a SW flow. Staying pretty cold right throughout though, some harsh frosts to come!

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Well, given that a rocketing AO is way out of line with general expectations, this run looks to be a poor guide for the polar field from +168. That's pretty irritating really as it means at least 12 hours until the next useful det. run... however the ensembles may yet prove interesting in that area.

For the UK though, high and dry is a decent bet I think, the cold hanging on at the surface perhaps right out until next weekend, with the real risk of a strong inversion developing with dense daytime fog that could be freezing.

Not convinced about how the Atlantic trough behaves after +96 though - that cold blob from the U.S. moves east incredibly fast and acts like rocket fuel for that trough. Even GFS wasn't that fast!

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think its wrong pv just explodes back to life.

I certainly feel and have seen weaker heights in Scandinavia take forever to go.

I think anything beyond 96 hrs is fi and although we don't get an easterly still cold and any snow that does fall will stick around so those who do get some will certainly be reminded its winter.

gefs looks pretty good through out the run so all is not lost I notice the gem been ditched lol and what about the French model

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12 minutes ago, feb1991blizzard said:

More runs needed but now it does look like the UKMO is the odd one out as posted above, the UKMO is the only one out the 3 that's likely to bring in a really potent frigid upper 850 profile from the E to N quadrant.

The Ukmo has led the way all week, there is nothing to suggest this is different.

The other models are playing catch up with the block. Expect corrections by the Gfs and Ecm on the 0z.

The ukmo has years of data on hlb around our shores, the other models gave a broader spectrum.

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5 minutes ago, nick sussex said:

The ECM I'd sum up as boring but very cold.

The UKMO very cold better chance of snow.

The GFS same as the ECM.

Regarding the ECM it does look a little flatter than this mornings run especially over the eastern USA. I would be surprised if the ECM ensemble spreads don't show some more interesting solutions.

The cold hangs on in the ECM till T216hrs but we're missing the snow to add to the very frosty conditions.

Nick, I know precipitation charts are dodgy at the best of times but agreed, even out to the end of next week looks basically bone dry across the whole country. (GFS charts). 

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1 minute ago, Lukesluckybunch said:

Looking at the ecm,could sombody please hazard a guess at each days temperatures at night.. Somthing like -2 to -5 each day or lower?

The minimum temperature charts have negative double figures somewhere most nights next week. Some very harsh frosts widely.

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I  can only imagine ecm being a bitterly cold run day and night but without the snowfall!!can anyone post the temp charts for day and night!!!bbc tweeted couple of hours ago how this could be the coldest spell since march 2013!!they even got a -15 on the uk map for the weekend!

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2 minutes ago, Nick L said:

The minimum temperature charts have negative double figures somewhere most nights next week. Some very harsh frosts widely.

Wel OK thanks,but surely 216 hours looks quite mild to me or am I totally wrong?

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Haven't seen these posted in a while. Quite rare to have extensive blue down the spine of the country.

2a0hput.png

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ECM not great for going beyond 7 days, I think the signs are there for a change / milder air to attack and try and take over again.  For me the HP either needs to hold firmer to out NE or if it retreats to retreat quickly with a chance to retrogress westwards into the Atlantic.  Halfway house will lock us into SW / W'ly pattern.  FWIW I don't see it holding out beyond middle of next week.  But a cold week ahead which is a January bonus

 

BFTP

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Just now, Lukesluckybunch said:

Wel OK thanks,but surely 216 hours looks quite mild to me or am I totally wrong?

Still chilly, generally 4-7c, coldest in the south. All pretty academic anyway with how temperamental the models past the start of next week!

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2 minutes ago, SaffW said:

Nick, I know precipitation charts are dodgy at the best of times but agreed, even out to the end of next week looks basically bone dry across the whole country. (GFS charts).

Yes frustratingly so! I shouldn't be picky because it will be very cold but it would have been nice for the UK to get some snow that's crunchy when you walk on it! Don't lose hope yet because regardless of the differences between the GFS/UKMO at least upstream they're much closer together at T120hrs with the amplitude and PV lobe position. The ECM is the odd one out for its swift push east of that and it lifts out the cold from the central USA much quicker.

Not saying that it won't verify but just that currently its the GFS/UKMO against it at T120hrs over the eastern USA.

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2 minutes ago, Nick L said:

Still chilly, generally 4-7c, coldest in the south. All pretty academic anyway with how temperamental the models past the start of next week!

I guess your right there,can't really look past monday/tuesday

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The big question presented tonight is can the Atlantic trough/low at 144 undercut like UKMO, or will the energy go over the top like ECM and GFS?

Both ECM and GFS send the energy north over the UK, this doesn't look like it will plough through the UK but it will mean that our high pressure will slowly become less cold, and it will remain dry.

UKMO on the other hand tends to send the energy under, allowing for more prolonged cold and the possibility of a frontal snow event from the south west.

Which outcome is more likely?

Well, with the UKMO of late, I'd put my money on the that model, at 144 and beyond the way the models are handling the oncoming Atlantic is questionable, as Steve Murr often points out, these synoptic setups often lend themselves to further trough disruption and more undercutting as we move into the more reliable time frames.

Will be interesting to see where we are in a few days time re Tuesday/Wednesday next week.,

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26 minutes ago, Singularity said:

Well, given that a rocketing AO is way out of line with general expectations, this run looks to be a poor guide for the polar field from +168. That's pretty irritating really as it means at least 12 hours until the next useful det. run... however the ensembles may yet prove interesting in that area.

For the UK though, high and dry is a decent bet I think, the cold hanging on at the surface perhaps right out until next weekend, with the real risk of a strong inversion developing with dense daytime fog that could be freezing.

Not convinced about how the Atlantic trough behaves after +96 though - that cold blob from the U.S. moves east incredibly fast and acts like rocket fuel for that trough. Even GFS wasn't that fast!

Yes differences beyond day 4 Singularity-again.

Looking at the 3 main runs at day 5

ECH1-120.GIF.thumb.png.2d3a10fa7cbd2b633gfsnh-0-120.thumb.png.f11d129eb8f40e877656969f9aba167_ukmo5.thumb.GIF.4f15091c20

the peak of the Atlantic ridging on all 3 and this seems the next key timeframe.The GFS/ECM then push through the ridge and leave us with that mid-latitude high.

UKMO the only model going with more jet energy going se off that Canadian trough which looks like sending low pressure underneath.This could at least help to situate any future UK heights further north(possible easterly if we are lucky)but of course that's speculation.

UKKMO a little out on it's own beyond day 4/5 can we continue to back it i wonder.

Edited by phil nw.
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1 hour ago, emotional rollercoaster said:

ECM1-192.thumb.gif.97014c931643fe24ce67d

retrogression into Scandinavia maybe

Hang on though. Where's that high going? Like you say, that could well progress eastwards and sit close to, or over Scandinavia. It's happened numerous times before, especially in summer. 

What could happen beyond week 2 is a spell of easterlies after a brief less cold interlude. 

Now that would salvage winter. From record breaking mild to a cold Jan & Feb. Interesting.  

Edited by Backtrack
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It's a brave call to not back the UKMO after the last few days.  Not saying it will be correct, but who'd be a forecaster brave enough to discount it? 

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The differences start as early as T96 hrs over the eastern USA.

The ECM fails to develop this shortwave, the UKMO and GFS both develop this to varying degrees:

ECH1-96.thumb.gif.c3446d83abef69177cb385UN96-21.thumb.gif.827085344fecf00c096df7gfsnh-0-96.thumb.png.b2e576fcda96cb6b365

 This is NCEP's view on this from the shorter term discussions.

THE GUIDANCE ALL
AGREES IN TAKING THE ENERGY SOUTHEAST THROUGH THE SOUTHERN PLAINS
ON SAT...WITH SOME AMPLIFICATION EXPECTED. THE AMPLIFICATION OF
THIS ENERGY SHOULD FOSTER SURFACE LOW PRESSURE DEVELOPMENT OVER
THE WESTERN GULF OF MEXICO ON SAT. THE 12Z NAM/12Z CMC AND 12Z
ECMWF ARE LESS-DEFINED WITH THE LOW PRESSURE DEVELOPMENT...VERSUS
THE 12Z GFS AND 12Z UKMET WHICH HAVE STRONGER LOW PRESSURE
DEVELOPMENT OVER THE WESTERN GULF COAST REGION. CONFIDENCE IS
HIGHLY LIMITED...AND WILL PREFER TO COMPROMISE TOWARD THE ENSEMBLE
MEANS LED BY THE GEFS MEAN AND ECENS MEAN WHICH AT LEAST HAVE A
LOW CENTER THAT TENDS TO SPLIT THE WEAKER AND STRONGER MODEL CAMPS.

This low travels ene and is over the se USA by T96hrs.

The amplification or lack of in the case of the ECM is important because we want the slower upstream solution to hold back low heights from spilling too far east into the Atlantic.

 

 

 

 

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Sorry to be a pedant but systems 'retrogress' against the usual W to E pattern 

so a high must move west to retrogress. 

Sorry to be anal

 

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The ecm 12z run looks very similar to the one a day or so ago with the core of heights well to the north of the UK which looks promising briefly only to drop over the UK and then to shift onto the near continent and somewhat a return to the Atlantic late in the run. A 'wiff' about it as per the failed easterly a fortnight ago where the troughing failed to undercut (or should I say died on its weeble) between 144-162z which would keep the cold locked in on this run too.

As mentioned this ecm run largely cold and dry but somewhat milder later with the high wanting to takes it's usual boring position.

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27 minutes ago, Backtrack said:

Hang on though. Where's that high going? Like you say, that could well retrogress eastwards and sit close to, or over Scandinavia. It's happened numerous times before, especially in summer. 

What could happen beyond week 2 is a spell of easterlies after a brief less cold interlude. 

Now that would salvage winter. From record breaking mild to a cold Jan & Feb. Interesting.  

 

3 minutes ago, bluearmy said:

Sorry to be a pedant but systems 'retrogress' against the usual W to E pattern 

so a high must move west to retrogress. 

Sorry to be anal

 

Correct.  Which means it is somewhat more likely than a retrogression.  Moving east is 'pro'gress, as in the more usual progression of weather systems.

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