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Model output discussion 25th Jan - The final third of winter beckons..


Paul

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Posted
  • Location: North East Cotswolds, 232m, 761feet ASL
  • Location: North East Cotswolds, 232m, 761feet ASL
8 minutes ago, DJ RY said:

BBC weather for the month ahead says wet & windy weather for much of the upcoming month.

Well looking at the models, it looks like an unsettled 7 days or so to come but thereafter, there are hints of the jet stream easing off again somewhat. I'm not sure which chart they use and as I'm still learning about the weather patterns and how to read and understand various models etc then we'll just have to wait and see if they're correct or not.....

METO still say signs of a prolonged cold period but low confidence, any set up will be low confidence beyond day 16 and I imagine neither of the mentioned want to have a guess and create Express like headlines in case they fail.  Certainly no cold spell set in stone, just a window of opportunity at the minute.

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Posted
  • Location: st albans
  • Location: st albans
12 minutes ago, DJ RY said:

BBC weather for the month ahead says wet & windy weather for much of the upcoming month.

Well looking at the models, it looks like an unsettled 7 days or so to come but thereafter, there are hints of the jet stream easing off again somewhat. I'm not sure which chart they use and as I'm still learning about the weather patterns and how to read and understand various models etc then we'll just have to wait and see if they're correct or not.....

Just read it (and last Mondays). both seem to be well written and an accurate portrayal of what the models are showing

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Posted
  • Location: Chisinau, Moldova.
  • Location: Chisinau, Moldova.
41 minutes ago, Ali1977 said:

I'm wondering why it's so quiet in here, can't post picture but what a great set of ENS with several Stella setups.  I understand it isn't full support but some of these bring some really cold air with great looking prolonged blocked setups.

P20 is pretty severe cold, especially in the south in the wind - day time wind chill would be below -10c with plenty of snow.  If only this became reality.

Because any potential benefit is 10 or so days a way, at the best case, and people have seen that too many times this winter ;-)

FI seems to be beyond t144 at the moment. Probably best not to get too caught up in individual model runs and look at the daily trends as a whole. 

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Posted
  • Location: st albans
  • Location: st albans

the reason for a lack of interest is that the upcoming scenario consists of

a) strengthening heights right across the east of the NH

b) strengthening northern arm jet (fed from a displaced chunk of slowly dissipating Canadian vortex s of Greenland)

the envelope is huge and until we see some consistency on where the jet will end up and where the ridging also, its hard to be optimistic for coldies.

you could be looking at balmy southerlies or frigid easterlies. if it were a few weeks earlier than those southerlies would probably still deliver surface cold but mid feb is less likely without an easterly tilt to the flow)

i'm encouraged to see something worth watching/chasing but I am far from thinking that we will see proper snowfall next month

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Posted
  • Location: Kirkburton, Huddersfield - 162.5mtrs asl.
  • Weather Preferences: Winter synoptics.Hot summers.
  • Location: Kirkburton, Huddersfield - 162.5mtrs asl.

There is an ever growing signal in the GEFS to eventually have a trigger low undercutting. Make no mistake February can deliver the goods.......stronger sun and lengthening days do not cut it with me when looking at these charts. The winter thus far has got to have been good with regards to frosts etc in the Southern areas and the longer range holds much promise. A period of the Atlantic trying to push through the meridian is nothing to get fraught about as it is not exactly pushing through to Siberia.

gens_panel_dtu8.png

gens_panel_zbc5.png

Not a bad bias corrected mean

gensbcnh-21-1-288.png

Edited by winterof79
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Posted
  • Location: Eastbourne and Larnaca,Cyprus .
  • Location: Eastbourne and Larnaca,Cyprus .

Its looking like a bit of a frustrating stalemate at the moment. The PV over Canada is doing us no favours, and this continually feeds low pressure which is unable completely detach from low heights over Greenland.

We need the main PV lobe to edge nw and need and some amplification to slow the upstream pattern, this would give a better chance of energy disrupting se near the UK.

So regardless of how good high pressure might look to the ne its changes upstream we need to see. It might be that this will take several attempts if the high to the ne holds on.

We need all the help we can get with the MJO, the normal forecasts are out a bit later , the MacRitchie one shows continued progress towards the favourable colder phases with an increase in amplitude today so hopefully this is replicated in those later.

 

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Posted
  • Location: Eastbourne and Larnaca,Cyprus .
  • Location: Eastbourne and Larnaca,Cyprus .
1 minute ago, Dennis said:

also MJO is on good stage

65.gif

That looks better than yesterdays forecast, the phase 5 composite looks quite close to both the ECM/GFS outputs which could suggest we're seeing the MJO impacting more on the NH pattern. NCEP update their overview later so hopefully that sticks to last weeks suggestions that we'll be seeing less interference on the MJO.

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Posted
  • Location: Surrey and SW France.
  • Location: Surrey and SW France.
Just now, nick sussex said:

That looks better than yesterdays forecast, the phase 5 composite looks quite close to both the ECM/GFS outputs which could suggest we're seeing the MJO impacting more on the NH pattern. NCEP update their overview later so hopefully that sticks to last weeks suggestions that we'll be seeing less interference on the MJO.

It's interesting to note that the last two major SSWs coincided with that MJO phasing in a high amplitude.

Jan '09  rmm_200901.pngJan '13 rmm_201301.png

There's maybe something in the theory you were reading about in that paper - difficult to identify the chicken or the egg as the jump coincides with SSW commencement on 6th January 2013 but MJO leads well ahead of SSW date  24th January 2009.

http://ds.data.jma.go.jp/gmd/tcc/tcc/products/clisys/mjo/monitor.html

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Posted
  • Location: Bexhill-on-Sea, East Sussex
  • Weather Preferences: Winter Snow, extreme weather, mainly sunny mild summers though.
  • Location: Bexhill-on-Sea, East Sussex

looking good:)

gfsnh-0-162.png

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Posted
  • Location: Kirkburton, Huddersfield - 162.5mtrs asl.
  • Weather Preferences: Winter synoptics.Hot summers.
  • Location: Kirkburton, Huddersfield - 162.5mtrs asl.
26 minutes ago, Steve Murr said:

Afternoon All-

So this is it for Winter- from differing perspectives this could be another roll of the dice for cold ( namely the SE ) or for most the last roll of the dice-

We have a window of about 4-6 weeks left where things can be very wintry, however the earlier the better really as post week 3 we do start to see the sun getting higher & daytime potential temperatures creeping up-

Again, depending on your location in the UK for the most part this has been a borefest of a winter - I would actually put it on a par with some historic winters for blocking - 47, 63 etc - sadly for us the block has more or less been to far SE, so for places in Eastern / SE europe like Turkey etc this has probably been their version of our 63 -

The 500 anomaly plot so far says it all

IMG_2173.PNG

So other that brief continental influences the winter so far has been a non starter, which includes the scottish Ski industry where coverage of snow has been pretty sparse...

The dice then, in the shape of the SSW is about to be rolled in the next 10 - 12 days-

We have a SSW forecast by the GFS & the ECM is virtually there - bottoming out the zonal mean at exactly 0M/S ( The GFS mean is negative -4 M/S )

GFS V ECM

IMG_2171.PNGIMG_2172.PNG

The key landing zone date is Feb 1st as that is the date we go negative - 

In terms of propergation the standard 10HPA reversal to seeing the core 500MB charts seeing a direct change is usually around 10 days - however sometimes ( & something Im going to look into detail this summer ) is the NH blocking pattern responds quicker to the warming - aided by high MJO activity & higher amplitude phases - so what I would expect to see is a major block forming pacific side - then another block forming Around scandinavia - Perhaps further west..  The models are picking up on plumes of The WAA moving North towards the pole at day 6-8 & are trying to resolve what that means for the formation of the upper high-

The GFS 100HPA charts at day 8 go for a split of the vortex with High pressure developing in the location mentioned above-

IMG_2169.PNG

its not a full on split up to 10HPA as the vortex looks to recover post warming-

So we are now getting the outlines emerging of a block towards Scandi & a lobe of PV dropping south into Russia-

With this pattern things tend to retrograde west in cycles, so cycle 1 this week ( 144-168 ) deep cold may well start to filter into Eastern Europe from that lobe, cycle 2 may well force it west into central europe ( maybe even the UK ) - a third cycle may be a bullseye -

essentially what 1 cycle is - is a sharp pulse of WAA moving North / North east with a cut off low dropping south on the Eastern flank , High pressure builds over the top allowing the mean flow around the high to create Easterlies underneath- Because this then ruptures the jet again further west you get another pulse of WAA & another cut off low, the secondary developing high then merges with the first High pressure forcing the cold further west & you get a long draw easterly underneath-

What has failed in recent years is on cycle 2 or 3 the jet has been to strong to get vertical WAA so the cut off low sinks SE instead of South ( or even East into the block ) & we miss the boat -

So ***IF*** something is going to develop from the East delivering snow to the UK, look for 2 or 3 cycles of 'shunting' cold west for it to happen.

Earmarked dates - Feb 6-8 cycle 1, Feb 9-12 cycle 2 ( circa 240-312 in the models ) cycle 3 if needed 13-16th..,

fingers crossed

S

I presume you mean a little like this set up for the blocking

archivesnh-1991-1-25-0-0.png

Then a bit of WAA like this

archives-1991-1-28-0-1.png

And then a advection west of colder air like this......Cycle 1

archives-1991-1-31-0-0.png

and Cycle 2

archivesnh-1991-2-4-0-0.png

Leading to BULLSEYE

archives-1991-2-8-0-0.png

Easy peasy.

 

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Posted
  • Location: Bexhill-on-Sea, East Sussex
  • Weather Preferences: Winter Snow, extreme weather, mainly sunny mild summers though.
  • Location: Bexhill-on-Sea, East Sussex

Look at all that cold over Scandi getting ready to pounce! 

gfsnh-1-174.png

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Posted
  • Location: Wirral, Merseyside
  • Weather Preferences: Snow & Thunderstorms
  • Location: Wirral, Merseyside
1 minute ago, snowray said:

looking good:)

gfsnh-0-162.png

Look at the uppers marching west!!

gfsnh-1-162.pnggfsnh-1-180.png

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Posted
  • Location: Bexhill-on-Sea, East Sussex
  • Weather Preferences: Winter Snow, extreme weather, mainly sunny mild summers though.
  • Location: Bexhill-on-Sea, East Sussex
3 minutes ago, Day 10 said:

Look at the uppers marching west!!

gfsnh-1-162.pnggfsnh-1-180.png

Indeed, a much better run, lets see if that lovely cold can make it over to us, if this run fails, well, mmmm....:rolleyes:

 

Edit, let the battle commence! 

gfsnh-0-198.png

Edited by snowray
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Posted
  • Location: Manchester
  • Weather Preferences: Sunny and warm in the Summer, cold and snowy in the winter, simples!
  • Location: Manchester

Given how poorly GFS models (underdoes) trough disruption at such ranges this is a very good chart.

gfsnh-0-186.png?12

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Posted
  • Location: Kirkburton, Huddersfield - 162.5mtrs asl.
  • Weather Preferences: Winter synoptics.Hot summers.
  • Location: Kirkburton, Huddersfield - 162.5mtrs asl.

Better from the 12Z the block beating its chest

gfs-0-198.png?6 06Z

gfs-0-192.png?1212z

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Posted
  • Location: Manchester
  • Weather Preferences: Sunny and warm in the Summer, cold and snowy in the winter, simples!
  • Location: Manchester

GEM improved as well, finding some undercut 162

gemnh-0-162.png?12

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Posted
  • Location: Wirral, Merseyside
  • Weather Preferences: Snow & Thunderstorms
  • Location: Wirral, Merseyside

If the easterly floodgates could be unlocked it would be BITTER!!! :cold:

gfsnh-1-198.png

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