Model Output Discussion - 05/01/2016 18z onwards

[karlos1983]

Definite back track from the 18z. Might even get up for the 00z. 

I won't be humouring the GFS and watching its fl fiasco, I'm happy enough out to 144

Southwesterlies holding back 

Edited January 9, 2016 by karlos1983

[johnholmes]

These are my daily comments after looking fairly closely at the anomaly charts I use, links as usual below

SAT and changes between ec-gfs, ec back to trough-ridge-trough and flow over uk=n of w but gfs not=much as chart above=about s of w! (chart not shown in this post)

 

Noaa 6-10 and 8-14 show no marked change from charts above=suggests cold spell lasting into 19 January at least. Latter part looks dominated by upper ridge which presumably will have a surface high somewhere beneath it.

 

ec-gfs not in agreement, and although they led the way (ec especially) in predicting the pattern change, I am more inclined to believe noaa than the other two.

 

http://www.cpc.noaa.gov/products/predictions/610day/500mb.php

http://mp1.met.psu.edu/~fxg1/ECMWF_0z/hgtcomp.html

Edited January 9, 2016 by johnholmes

[Nouska]

I like charts that give a lot of detail....

flow and theta E 

 

[TomDav]

Just now, Greenland1080 said:

Tom are those charts in HD?

Its 0.25 degree spatial resolution

[Eskimo]

Will there be snow? Here's what to look out for if you are a beginner 

Precipitation Chart - Fair bit of precipitation around on Thursday morning, some of it snowy, even down to south.

Upper air temperatures - Ideally in this situation upper air temperatures need to be around -5C, which is the safe foundation for snow in the UK. Here you can see that the majority of the UK is under -4/-6. 

Dew Points - Dew points ideally need to be at freezing, as you can see, dew points are below freezing behind the front and just above freezing ahead. 

2m air temperatures - 2m air temperatures is the air that you feel, and here you can see that the north Midlands northward have the best chance, the south looks a little too warm for any falling snow currently. 

Thicknesses - Thicknesses ideally need to be 'blue' to make it easier to read. As you can see, it's looking quite marginal quite a few people here.

Based on the values above, I think it's going to be marginal the further south and east you are, however at the moment obviously high ground looks very much favourable for snow next week or anyone above 100m from the North midlands northwards.

Before anyone says, "snow can still fall at these particular values as well, not just them"...of course it does happen, but this post was just for those who want to know what it can take to get snow falling. 

[Ice Day]

So, the upgrades I were hoping for after last nights 18z have continued, tonights GFS is backtracking towards the ECM.  

Uppers at 174 are another small improvement vs the 12z.  If we can keep the upgrades coming we could have a very interesting week or two ahead!!!!

Edited January 9, 2016 by Ice Day

[P-M]

2 minutes ago, PerfectStorm said:

Will there be snow? Here's what to look out for if you are a beginner 

Precipitation Chart - Fair bit of precipitation around on Thursday morning, some of it snowy, even down to south.

Upper air temperatures - Ideally in this situation upper air temperatures need to be around -5C, which is the safe foundation for snow in the UK. Here you can see that the majority of the UK is under -4/-6. 

Dew Points - Dew points ideally need to be at freezing, as you can see, dew points are below freezing behind the front and just above freezing ahead. 

2m air temperatures - 2m air temperatures is the air that you feel, and here you can see that the north Midlands northward have the best chance, the south looks a little too warm for any falling snow currently. 

Thicknesses - Thicknesses ideally need to be 'blue' to make it easier to read. As you can see, it's looking quite marginal quite a few people here.

Based on the values above, I think it's going to be marginal the further south and east you are, however at the moment obviously high ground looks very much favourable for snow next week or anyone above 100m from the North midlands northwards.

Before anyone says, "snow can still fall at these particular values as well, not just them"...of course it does happen, but this post was just for those who want to know what it can take to get snow falling. 

 

Thanks for this - informative and easy to understand for newbies. 

[johnholmes]

a nice post for new folk, the only other parameter I would add is your height above sea level, that can be significant in marginal conditions.

[Spurry]

The GFS 18z keeps the cold over the country as far out as 180hrs which is a lot longer than the 12z,I try to keep optimistic but the 18z is not known as the pub run for nothing , just hope the 00z verifies ,then we can all relax a bit. 

[bobbydog]

troughing into the Med- 

scandi high coming........?

 

[Mapantz]

You can add in these three charts when looking for snow as well.

 

The Wet bulb takes humidity and temperature in to account.
0 degree isotherm can help to look for snow falling at certain levels, if other key ingredients come together.
ThetaE can also help in looking for snow to levels down to sea level.
 

[johnholmes]

I think the first idea was to keep it as simple as possible. There are about 8 paramaters if anyone wants to check all those that affect will it be snow or rain, see the Guides for that.

[Ice Day]

Large parts of North and Central Europe are still extremely cold at 210hrs (just for fun).

I would love to know Old Met Man's view on the output at the moment, his posts have been a little rare recently!?

[gottolovethisweather]

15 minutes ago, PerfectStorm said:

Will there be snow? Here's what to look out for if you are a beginner 

Precipitation Chart - Fair bit of precipitation around on Thursday morning, some of it snowy, even down to south.

Upper air temperatures - Ideally in this situation upper air temperatures need to be around -5C, which is the safe foundation for snow in the UK. Here you can see that the majority of the UK is under -4/-6. 

Dew Points - Dew points ideally need to be at freezing, as you can see, dew points are below freezing behind the front and just above freezing ahead. 

2m air temperatures - 2m air temperatures is the air that you feel, and here you can see that the north Midlands northward have the best chance, the south looks a little too warm for any falling snow currently. 

Thicknesses - Thicknesses ideally need to be 'blue' to make it easier to read. As you can see, it's looking quite marginal quite a few people here.

Based on the values above, I think it's going to be marginal the further south and east you are, however at the moment obviously high ground looks very much favourable for snow next week or anyone above 100m from the North midlands northwards.

Before anyone says, "snow can still fall at these particular values as well, not just them"...of course it does happen, but this post was just for those who want to know what it can take to get snow falling. 

Worth pinning this post IMO, check with Paul if okay to do so, will no doubt help many folk out. 

[nick sussex]

At least the GFS 18hrs run hasn't deflated the mood. It will be hard going though to get to an easterly off its evolution because theres too much energy spilling east but at least in the earlier timeframe its less progressive.

The high moving in could produce some sharp frosts especially where theres snow cover.

After a rather dramatic week things do look on an upward trend for cold, lets hope this continues tomorrow morning.

[snowangel32]

Gfs pub run back tracks and keeps cold locked in longer just small changes makes a huge difference.

pub run 

Compared to the 12z 

[Eskimo]

I'll do the same post when the hi-res NMM comes into focus as well. Mainly for observational purposes though 

Edited January 9, 2016 by PerfectStorm

[Man With Beard]

ECM op fairly faithful to the main cluster on the ens for London

Most significant cluster remains cold afterwards

[gottolovethisweather]

14 minutes ago, johnholmes said:

I think the first idea was to keep it as simple as possible. There are about 8 paramaters if anyone wants to check all those that affect will it be snow or rain, see the Guides for that.

Amazing to think that the science of Meteorology could be so complex, er. not really as the more we attempt to take in, the more the weather as part of Mother Nature will treat us as fools. Now time for all these snow charts to start trickling into t24 to t48 hour timeframes. Thanks JH as ever. 

Edited January 9, 2016 by gottolovethisweather

[gottolovethisweather]

10 minutes ago, Mapantz said:

You can add in these three charts when looking for snow as well.

 

The Wet bulb takes humidity and temperature in to account.
0 degree isotherm can help to look for snow falling at certain levels, if other key ingredients come together.
ThetaE can also help in looking for snow to levels down to sea level.
 

Another to pin somewhere? Nice one Mapantz.

[Nouska]

The most important thing to consider for snowfall charts is that they are only of much value at short lead times - ie a waste of time calculating all the parameters at five days out.

The ECM predicted snow falling at 132 hours for example...

we'll see where the snow actually falls on the day.

[gottolovethisweather]

14 minutes ago, nick sussex said:

At least the GFS 18hrs run hasn't deflated the mood. It will be hard going though to get to an easterly off its evolution because theres too much energy spilling east but at least in the earlier timeframe its less progressive.

The high moving in could produce some sharp frosts especially where theres snow cover.

After a rather dramatic week things do look on an upward trend for cold, lets hope this continues tomorrow morning.

Was it your shortwave which I saw riding over the top of the mid Atlantic ridge heading towards Iceland Nick, as that would indicate a different Jetstream profile at D6/D7 which is to be expected I guess. This now being one which favours prolonging the cold. What I'm looking at is on the chart on this post by Karlos. 

Edited January 9, 2016 by gottolovethisweather

[phil nw.]

46 minutes ago, Nouska said:

Is this perhaps a response to the fact that the GEFS spend the fifteen day forecast period in an amplified state in MJO phase 8.

Looks very like the phase 8 January composite for our part of the world.

It may be Nouska but a similar path is being shown on the ECM mean at day 10

Yes it's a mean chart but the weakening polar heights and the reformation of the Greenland /Canadian vortex is apparent on that.

I admit that it was not what i anticipated from the ECM especially after the morning suite.Hopefully this changes and maybe someone with access to later ECM output can say this is a blip.

In any event we still look like seeing around a week of cold with snow possibiliies whatever happens beyond and for that i guess we would all be happy enough.

[weirpig]

17 minutes ago, Spurry said:

The GFS 18z keeps the cold over the country as far out as 180hrs which is a lot longer than the 12z,I try to keep optimistic but the 18z is not known as the pub run for nothing , just hope the 00z verifies ,then we can all relax a bit. 

What!  is was only a few runs that the gfs 18z was picking a new trend for less cold conditions and a lot of people were saying it was the new gospel 

 

[carinthian]

Well how would you like to make a forecast on that fax Chart ? Certainly the 528 dam line is well in place. The short wave looks now well documented between Iceland and Ireland. Follow the core jet winds at 850mb level will probably take you though the Irish Sea. Embedded will be a warmer sector, probably 52 degrees south, with the coldest sector over Scotland and a under cut later into Ireland and a rush of deeper  cold air quickly into the Southeast. Just my view, but a snow potential for many on Wednesday night into Thursday. A great period of model and forecast watching.

 C

Edited January 9, 2016 by carinthian