Model Output Discussion - New Year and Beyond

[mountain shadow]

6 minutes ago, RainAllNight said:

I've recently found a site with charts that illustrate quite nicely how April and May are the months with the most frequent Northerly and Easterly winds.

https://weatherspark.com/y/45062/Average-Weather-in-London-United-Kingdom-Year-Round#Sections-Wind

The site says its data comes from NASA's MERRA-2 Modern-Era Retrospective Analysis.

It surprises me that westerly winds are favoured as much in July and August as they are in December and January. Why might this be?

I would say it's very simply because the jet stream moves from West to East.

[nick sussex]

The GFS 06 hrs run so far even flatter than the 00hrs run .

The glancing blow of colder uppers modelled further east and once the models latch onto this trend with a rampant PV they rarely backtrack .

 

[feb1991blizzard]

4 minutes ago, nick sussex said:

The GFS 06 hrs run so far even flatter than the 00hrs run .

The glancing blow of colder uppers modelled further east and once the models latch onto this trend with a rampant PV they rarely backtrack .

 

I've accepted it a long while ago, i am just hoping for the pacific / scandi ridge to verify to help trigger a late season SSW.

[Ali1977]

Plenty of cold air on tap in we ended up with this set up. Can the Russian high build and link with the Arctic heights I wonder !! 

Edited January 25, 2023 by Ali1977

[andymusic]

a slight interest for coldies again on the gfs 6z run with a cold pm shot on 6th Feb - a little into la la land to have any confidence in it as yet

[sub zero]

The start vortex is on the ropes after a string of warmings on the latest gfs op run and ends up like this at 384..                       I've always thought that the trop vortex doesn't really follow the strat following a warming, but when looking at the charts it seems it does in this case ..

With the lack of excitement, I'm guessing there has to be a displacement or a split for us to benefit from a cold point of view, but in this case we have neither, just a shrinkage..

But with the strat vortex in scraps after the warming bombardments, is it no help to us at all to bring in the cold...?

 

[bluearmy]

Well hemispherically we are now seeing a response in the trop from events in the strat. It should be noted for next time that the size of the n pacific ridge into the pole was not seen on the nwp until we got close to the reversal - however, with the Canadian vortex and overall pattern we will not see any beneficial coldie consequences for nw Europe away from the possibility that we get another cool/cold zonal set up in week 2 which could dig into Europe somewhat.   If the reversal was sizeable around 60N then we could have seen some blocking establishing around 60/65N which might have been of note 
 

[Purga]

Cor.. thanks Canada !

Edited January 25, 2023 by Purga

[kold weather]

GFS 06z Fi is for the bin I suspect, it's once again developing once in a generation low down to 916mbs. Other models are nowhere near that ballpark at 240hrs and so beyond that is meaningless on the 06z.

[winterof79]

Cold zonality for Northern Britain certainly not mild

 

 

 

Edited January 25, 2023 by winterof79

[nick sussex]

18 minutes ago, Purga said:

Cor.. thanks Canada !

I’ve never seen sub -10 850s off a wnw flow . Regardless of how cold the air is being pushed out of ne Canada .

Ignore this nonsense from the GFS, it has a known bias for overdoing the depth of cold with anything from the west round to north .

The only time it might get close is in continental flows .

[Polar Maritime]

Similar to yesterday's 6z at the same time stamp - which is a long way out into the run..

Yesterday:

Today:

 

 

[Nick F]

Trouble is the GFS, and other models too, won't really pick up well if at all shortwaves and resultant secondary lows that develop to the south or southwest of the main parent low in the cold Pm flow at range, which often hold back the deep cold it shows trying to reach us from the northwest past day 10. These secondary lows forming over the NW Atlantic usually, where there is a steep thermal gradient / sharp baroclinic zone. The straight isobars with uninterrupted flow all the way from Labrador Bay to NW Europe rarely come off like it depicts on the 06z for a time.

Looking at the 00z EPS days 11-15 - can clearly see where our flow is likely to come (below) from in early Feb, first 9-10 days anyway, coldest in the west closer to the cold Pm source:

Edited January 25, 2023 by Nick F

[cold snap]

3 hours ago, mushymanrob said:

Thanks.. but i am wrong.. either because the anomalies failed to pick up on an emerging pattern, or i simply didnt interpret them correctly.

But it's very rare you're wrong 

[Rain All Night]

14 minutes ago, Nick F said:

The straight isobars with uninterrupted flow all the way from Labrador Bay to NW Europe rarely come off like it depicts on the 06z for a time.

Unfortunately it did come off once, so the seed of hope and expectation has forever been planted!! 

[Nick F]

10 minutes ago, RainAllNight said:

Unfortunately it did come off once, so the seed of hope and expectation has forever been planted!! 

A rare beast Jan 1984, we often wheel the month that year out most winters when we have a cold Pm flow forecast as an example of what *could* happen, but most end up disappointed. Other than the big snow events in the 1980s, I do actually remember Jan 1984 bringing some wet snow and slush even to Kent and thought is strange at the time it coming from the west, even though I was only 8 years old. I fully don't expect a repeat in early February.

[Chesil View]

47 minutes ago, RainAllNight said:

Unfortunately it did come off once, so the seed of hope and expectation has forever been planted!! 

Remember it well Rainallnight. Even had some in Bournemouth from that. Was working out in the North Dorset Hills and saw a few coverings round that time.

Once the seeds been planted eh?

 

[Rain All Night]

Just now, Chesil View said:

Remember it well Rainallnight. Even had some in Bournemouth from that. Was working out in the North Dorset Hills and saw a few coverings round that time.

Once the seeds been planted eh?

 

I'm rather envious, as speaking of seeds, I was busy being an ovum at the time!

[Nick F]

Cold front sweeping south on the noon fax chart seems a contradiction in name looking at surface temperature obs this afternoon, which show colder temps ahead of the front across S England & milder air to the north.

However, the cold front separates colder air aloft, as can be seen at 850 hPa level, moving down from the north:

 

[Methuselah]

4 hours ago, mushymanrob said:

Thanks.. but i am wrong.. either because the anomalies failed to pick up on an emerging pattern, or i simply didnt interpret them correctly.

Those must be the most honest three words I've seen in 20-years, mushy... And, no, I'm absolutely NOT being sarcy. If I knew what the weather was going to do, I'd be a millionaire by now!

[Dangerous55019]

Hello everyone. 

Its been a couple of weeks since I last did this, so lets have a look at what the CFS V2 is forecasting for the next four week for us........


Week 1 - 25th to the 31st January: The UK appears to be sat under a rather large ridge of high pressure that stretches way out into the North Atlantic... This would give us light winds, plus if the anticyclonic gloom dissipates, the risk of more frost and fog... Other than that... Not a lot else to say really.

Week 2 - 1st to the 7th February: That massive ridge of high pressure appears to have sunk further south towards Spain and Portugal, with a trough of low pressure now starting to build up from North Eastern Canada, Greenland, and Iceland and slowly stretching its way towards us here in the UK. Looking at this chart, I would say that we'd be in a westerly and zonal airflow. Pretty average for the time of year really.

Week 3 - 8th to the 14th February: For us here in the UK, it looks like a rinse and repeat of week two... But... But, but, but... That ridge of high pressure over the Atlantic appears now to be linking up with a Scandinavian/Siberian High and encircling the pole!! Could this pump cold(er) air into the trough of low pressure? Its too far out to tell, and this is a low res model... But I'd say one to keep a weather eye on. 

Week 4 - 15th to the 21st February: Very similar to week 3 but with slightly weaker looking anomalies. Plus with the orientation of the high over mainland Europe, and the fact that it appears to be covering England and Wales, I'm gonna say that this could put us in a mild and westerly airflow.


Will it play out like this or not? Only time will tell. Hopefully this will help some of the more experienced members on here piece the puzzle together. But remember... The weather will do, whatever it wants to and there's nothing we can do about it, but watch.  

[nick sussex]

The GFS now trying to perform a miracle against the PV which sharpens up and tries to develop a ridge to the ne .

[feb1991blizzard]

hallo, hallo, ere we go.

[Johnp]

Oi Oi Saveloy, what’s going on here?

[Mike Poole]

Well I have to say, you’d offer very long odds on getting a draw of WAA like this with the current setup!  GFS T264:

There are outliers, and then there are outliers!