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Model Output Discussion - heading into April


Paul

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Posted
  • Location: NR Worthing SE Coast
  • Location: NR Worthing SE Coast

We have had blizzards before at the end of April,so plenty of time ye.

 

Snow is more likely in April than November !

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Posted
  • Location: Cambridge, UK
  • Weather Preferences: Summer > Spring > Winter > Autumn :-)
  • Location: Cambridge, UK
38 minutes ago, SLEETY said:

We have had blizzards before at the end of April,so plenty of time ye.

 

Snow is more likely in April than November !

There is time. Like I said yesterday though,  850s were about -10 yesterday and it wasn’t even that cold. Maybe in modern times it’s harder than ever to get proper cold.

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Posted
  • Location: just south of Doncaster, Sth Yorks
  • Location: just south of Doncaster, Sth Yorks
2 hours ago, mushymanrob said:

Looking highly likely that a return to "normal" British weather after this quiet week.

Milder, even warm at times, but with the return to unsettled conditions with spells of rain. The usual NW/SE variation likely with the NW missing out on the best of the pleasant Springtime conditions.

 

test8.gif

814day.03.gif

Yes, agree with that summation mushy in the time scale shown

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Posted
  • Location: Beccles, Suffolk.
  • Weather Preferences: Thunder, snow, heat, sunshine...
  • Location: Beccles, Suffolk.

Well, for some time now, next weekend has looked like being rather pivotal, regarding the direction of travel. And, as this morning's GFS 06Z suggests, that is still very-much the case today:

h500slp.png    h850t850eu.png

And not a bad finale, either: SW-NE oriented jet; LP/tPV lobe/remnant safely out-of-harm's-way; and a warm Continent...What could possibly go wrong!:oldlaugh:

h500slp.png    h850t850eu.png

Edited by General Cluster
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Posted
  • Location: South Croydon
  • Location: South Croydon
15 hours ago, SLEETY said:

Everything looks dodgy after 96 hours if you ask me, ecm so different in its latter frames compared to 12 hours ago that's its laughable

you can see how the flight data issues are causing problems with the models. 

I notice you've been mentioning the lack of aircraft data in the data assimilation stage is affecting the accuracy of the NWP.

This looks fairly logical, but I didn't know how much of an impact it would have, or the amount of input data that comes from this source.  After a bit of hunting on the internet I found a study on the accuracy of the modelling (RMSE) when removing each source of input data (admittedly the focus is short run predictions).  Aircraft data is most significant for wind and temperature and the study finds it to be significant.  So my conclusion is that it must be a significant source of error in the modelling.

Sorry couldn't get the link to the study to work.  The title if you are interested is:

Observation System Experiments with the Hourly Updating Rapid Refresh Model Using GSI Hybrid Ensemble–Variational Data Assimilation

Edited by Trom
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Posted
  • Location: Longden, Shropshire
  • Location: Longden, Shropshire
1 hour ago, SLEETY said:

We have had blizzards before at the end of April,so plenty of time ye.

Yeah, in the good old days!  Not so sure about these days.

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Posted
  • Location: NR Worthing SE Coast
  • Location: NR Worthing SE Coast

Thats interesting the 06z icon wasn't so keen on blowing up that low South of greenland unlike the gfs blows it up and  we get quick switch in winds to warm direction. So maybe not a done deal yet. 

Straw clutching, i know! 

Then gfs tries another go at getting in a bitter Northerly later on. no consistency at all. 

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Posted
  • Location: South Oxfordshire
  • Location: South Oxfordshire
3 hours ago, SLEETY said:

Thats interesting the 06z icon wasn't so keen on blowing up that low South of greenland unlike the gfs blows it up and  we get quick switch in winds to warm direction. So maybe not a done deal yet. 

Straw clutching, i know! 

Then gfs tries another go at getting in a bitter Northerly later on. no consistency at all. 

After the last couple of days some warmth would be welcome to wet and cold, but I'm not sure the models have much of a clue beyond a couple of days out. Having said that I bet they all 100% agree with each other this evening - curse of the commentator! 

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Posted
  • Location: Hoyland,barnsley,south yorkshire(134m asl)
  • Weather Preferences: severe storms,snow wind and ice
  • Location: Hoyland,barnsley,south yorkshire(134m asl)

Anyone else having problems with meteociel?

i have cleared all cookies/cache etc but still to no avail.

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Posted
  • Location: Siston, Bristol 70m ASL
  • Location: Siston, Bristol 70m ASL
3 minutes ago, Allseasons-si said:

Anyone else having problems with meteociel?

i have cleared all cookies/cache etc but still to no avail.

Not working for me either

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Posted
  • Location: Hoyland,barnsley,south yorkshire(134m asl)
  • Weather Preferences: severe storms,snow wind and ice
  • Location: Hoyland,barnsley,south yorkshire(134m asl)
1 minute ago, TomW said:

Not working for me either

Glad to here it's not just me then.

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Posted
  • Location: Hoyland,barnsley,south yorkshire(134m asl)
  • Weather Preferences: severe storms,snow wind and ice
  • Location: Hoyland,barnsley,south yorkshire(134m asl)

Meteociel's back up and running,don't everyone jump at once because there is no northerly showing now

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Posted
  • Location: Hoyland,barnsley,south yorkshire(134m asl)
  • Weather Preferences: severe storms,snow wind and ice
  • Location: Hoyland,barnsley,south yorkshire(134m asl)
3 minutes ago, General Cluster said:

Still looking good for a warm-up::yahoo::clapping:

h500slp.png    h850t850eu.png

Looking good Pete,but what model is that?

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Posted
  • Location: Beccles, Suffolk.
  • Weather Preferences: Thunder, snow, heat, sunshine...
  • Location: Beccles, Suffolk.
3 minutes ago, Allseasons-si said:

Looking good Pete,but what model is that?

Silly me...GFS 12Z of course!:olddoh:

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Posted
  • Location: Hoyland,barnsley,south yorkshire(134m asl)
  • Weather Preferences: severe storms,snow wind and ice
  • Location: Hoyland,barnsley,south yorkshire(134m asl)
1 minute ago, General Cluster said:

Silly me...GFS 12Z of course!:olddoh:

I see that it comes out quicker on NW than on Meteociel.

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Posted
  • Location: NR Worthing SE Coast
  • Location: NR Worthing SE Coast

Hmm another Northerly that’s not going to properly get going,briefly effects Scotland  for 24 hours then back to the normal  looking charts.

 

 

Really feels almost Impossible to get long lasting cold into the UK.

 

Over and out....

 

 

Edited by SLEETY
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Posted
  • Location: Beccles, Suffolk.
  • Weather Preferences: Thunder, snow, heat, sunshine...
  • Location: Beccles, Suffolk.

So, here we are at T+384...and what a nice time to be (potentially) waving 'bye-bye' to the -5C isotherm!:clapping::clapping::yahoo:

h500slp.png    h850t850eu.png

Will ye no' come back again...?:oldgrin:

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Posted
  • Location: East Ham, London
  • Location: East Ham, London

Evening all

In truth, we knew the N'ly was finished when it became clear the zonal winds were heading back well above average after the warming. 

The resumed deceleration is all well and good but the base wind speed remains well above the normal so the Atlantic very much in charge and plenty of chance for some early warmth with the winter nightmare synoptics and a long fetch SW'ly.

GFS FI suggesting something more interesting heading toward mid month as the effect of the slowing zonal winds leads to a weakening and more amplified Atlantic with the jet heading a long way south.

Nothing unusual - it often happens late April we see the Atlantic amplify and a build of pressure to the NW allowing for a late and often potent N'ly in early to mid May as identified by Buchan.

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Posted
  • Location: Herne Bay Kent
  • Location: Herne Bay Kent
1 hour ago, Allseasons-si said:

Meteociel's back up and running,don't everyone jump at once because there is no northerly showing now

Of course not.. Anything you want you seldom get if its interesting or sought after.. Certainly weather wise.. Sad times indeed

Edited by Snowfish2
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Posted
  • Location: Bedfordshire
  • Weather Preferences: Seasonal
  • Location: Bedfordshire

Incredible that a small retrogressing low in Southern Greenland's vicinity can turn what appears to be a nailed on N'ly...

image.thumb.png.c4a90d4ae59439554ae45a49b226598c.png

...into this, just 24 hours later

image.thumb.png.743ee04e03859bdcd48c4b68fdc00225.png

If this was Dec, Jan or Feb (or even March) I'd be pretty annoyed. And then a (very) long fetch SW'ly another 48 hours on

image.thumb.png.cf974f8de4b1cd8fd7aa489ef44fd0c5.png

Unbelievable turn around Jeff

Coldies shouldn't despair too much, though, as there is another ghost cold chart to chase at 240 on the ECM!

Edited by LRD
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Posted
  • Location: Bedfordshire
  • Weather Preferences: Seasonal
  • Location: Bedfordshire

Easter Saturday according to GFS

image.thumb.png.37ca90f6b3f54cddfb7a22b1cca484aa.png

image.png.699cbb0b22abeb538c57298aff351f1a.png

I wouldn't normally post a single FI chart but this has been appearing a lot on GFS recently. Might be something, might be nothing at that range of course

 

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Posted
  • Location: Beccles, Suffolk.
  • Weather Preferences: Thunder, snow, heat, sunshine...
  • Location: Beccles, Suffolk.
27 minutes ago, Portsmouth Sun said:

I don’t understand why certain people on here cling to 10 day charts as gospel. Do you not understand the real world. In the reliable the south looks like warming up a treat. 

I'm nae sure many folks here take Day 10 charts as gospel, PS...But it is sometimes hard to explain all the wrist-slitting when things don't go according to plan. After all, the models don't make the weather!:oldlaugh:

And, as you say, the reliable time-frame looks okay for us Southern Softies!:oldgood:

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Posted
  • Location: Windermere 120m asl
  • Location: Windermere 120m asl
2 hours ago, stodge said:

Evening all

In truth, we knew the N'ly was finished when it became clear the zonal winds were heading back well above average after the warming. 

The resumed deceleration is all well and good but the base wind speed remains well above the normal so the Atlantic very much in charge and plenty of chance for some early warmth with the winter nightmare synoptics and a long fetch SW'ly.

GFS FI suggesting something more interesting heading toward mid month as the effect of the slowing zonal winds leads to a weakening and more amplified Atlantic with the jet heading a long way south.

Nothing unusual - it often happens late April we see the Atlantic amplify and a build of pressure to the NW allowing for a late and often potent N'ly in early to mid May as identified by Buchan.

Yes too much energy in the atlantic at present, a rejuvenated jet as we enter April aligning itself on typical SW-NE trajectory with heights nudging in from the SW, so a switch from cold and settled to mild and settled away from the far NW.

Further ahead, we could see a weakened atlantic with the jet looping again and heading southwards - all very normal as you say for mid April which is often the time of year when we see the death throes of the PV, and the atlantic entering its annual slumber - this is when we often see major switcharounds from cold to warm, northerlies to southerlies, easterlies to cyclonic spells, unusual synoptics, and when northern blocking has its greatest chance of getting a foothold.. so what is on offer for early April may well not sustain itself for very long.

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