Day_9

January 16

Hands up who remembers this time last week…… it was all “in the bag”…… until it wasn’t

January 14

The ensembles show my earlier point almost every time. Good clustering (consensus) up to 5, sometimes 6 days. After that anyones guess.

in this latest case I would say after the cold spell, the signal is for seasonally average with the possibility of milder or colder outbreaks ahead…..

January 14

The fact that the wheels come off so quickly is just more reason to not to pin your hopes on anything that a model shows as a possibility- particularly beyond a 4/5 day timeframe.

the global atmosphere is a chaotic system with so many variables that it is impossible to give anything other than broad outlines of possibilities.

Because severe cold and snow is so rare for a small Atlantic island, any hint of that as a potential outcome gets people understandably very excited….. and the fall from that elation is long and painful.

Many years of lurking on here tell me that the number of times snowmageddon forecast out at 240 actually verifies is probably in single percentage points.

January 11

10 minutes ago, Ice Day said:

Absolute scenes at 138

In all seriousness, this is quite some upgrade from the GFS

Coming into the reliable now, that SW feature has been consistently modelled on enough runs across all models that it is a viable option on the table - although, at the drop of a hat it could all disappear…….

but that would have been in previous years. Synoptically this year feels like extremely different, i mean we’ve got a totally shredded Atlantic , cross polar flow, an enormous pool Of bitterly cold air just about to smother us, and what is the vortex doing? “LOLZ”.

so we could witness some memorable events especially given what has been a consistent signal since the autumn. Forget inter run variables, look at trends in the way of up or downgrades to help determine the most likely outcome in terms of longevity or severity.

precipitation events that so many crave still a fair way off so ignore snowfall charts (although they are entertaining !!)

January 8

1 hour ago, Chesil View said:

Let it snow and frosty ground make very good points,when looking at some of our biggest snow events. You often actually need those milder( but still cold uppers) to bring the snow fall.

I hark back to it often but the great South west blizzard of Feb 1978 came with uppers around minus 2 and produced drifts over 20 feet deep.

I got photos of me helping my old man dig his Hilman Imp out of the snow - don’t know why we even tried, the wall of snow from our drive onto the road was almost level with the roof of the house

January 7

If severe cold and the sort of snow many on here crave come off, we will have 24-36 hrs warning max.

January 7

Just go back to page 1-3 in this current thread……. Day 10 charts always look tantalising but they usually always flatter to deceive

January 7

43 minutes ago, Mike Poole said:

Lovely run from the ICON, but it looked different to recent output to me, here’s an animation, we pick up the story at T90, watch the UK high:

It actually sinks, and the height rise into Greenland is exclusively from the WAA from Canada.

That lovely angry little low out South West could absolutely blast the SW IF it ends up colliding next Sunday. Still 7 out, get it at 5 and we’re increasing probabilities

January 7

Mega lolz

January 6

1 hour ago, Battleground Snow said:

That arctic high could push the entire vortex south here

Special synoptics

Would be a once in a lifetime if it happened, but it’s one run amongst many every day and it’s 11 days out….. they do rather prod the imagination. This sort of chart would very quickly become misery for millions once the initial novelty was out of the way.

January 6

Is @tight isobar ok???

January 6

6z vs 12z gfs ensembles (for Cardiff):

12 looks cleaner/more confident but still a massive amount of scatter and look at the way some of the members just plummet which will clearly never happen that quickly, hence the air of cautions when getting excited about single members and single runs.

Either way, a thankful period of dry for all those currently affected by floods, the last thing they need now is subzero.

January 5

Just now, Ali1977 said:

Day 9 GEM worth a booooom

Day 9.

it isn’t worth a sausage, let alone a boom. Let’s come back here on the 14th January and see, looking at individual runs and foaming at the mouth about them is the quickest route to madness

January 5

1 hour ago, Nick F said:

Didn't this happen in December 2022? Big Greeny block modelled initially with bitter NE'ly flow and everyone got excited, then it vanished into thin air and we got the Atlantic in instead. But still too early to be worrying about this possibility. But there is a risk the block drifts too far west or weakens to the NW.

Yes, it literally disappeared after a single run and everything went mild and wet for the rest of the winter. This place was beyond desperate. But it’s because those events are so relatively rare that folk pin all hopes on anything that shows it - however far out. It’s crazy when most know we’ve only got reasonable assurance up to 4/5 days out.

January 4

There is a massive difference between a single run (or even a single pert in a single run) showing narnia- like charts and actual verification - especially at 2 weeks out.

If it can go wrong, then it probably will. It doesn’t take much for 3 days worth of bubbles to burst.

we are thankfully going colder and more importantly, drier. It has done nothing but rain since June. i want to be able to get out in the fresh air. It has been a thoroughly depressing period. I don’t necessarily want to be penned in by ice days either. A bit of snow would be lovely for the kids for a week or so but the actual chances ???? Maybe we are overdue a big one, but an awful lot has to come together for it to happen.

enjoy the charts, there are some absolute amazing synoptics at the moment.

January 4

2 hours ago, Met4Cast said:

This chart could be plucked straight out of the archives from 1962/1963.

That is fantasy island. Yes we are probably well overdue a significant cold spell but the likelihood of this verifying is low surely at that timeframe?

January 3

Where is @tight isobar when you need him?!!

January 2

We’ve got agreement up to day 5ish. Everything after that is up for grabs. The trend is colder = good (if that’s what you like). We all know what a naughty pop up shortwave can do…. Remember last year? so let’s just enjoy a bit of dry, crisp weather, we’ve had nothing but wet since June. Then a bit of snow for the kids would be nice for a week or two…..

January 1

44 minutes ago, Scott Ingham said:

The consistency around the 15th of this month for true Greenland Heights is now something to behold and it is THIS period that can deliver significant and substantial cold and snow! Is this the 5th time I’ve mentioned this today?

It’s in fantasy island. Surely, have we learned nothing?

December 28, 2023

18 minutes ago, Polaris said:

Whilst a 16 day mean chart may seem insane.
So does a D10 model run chase that we’ve been in since beginning of December.

Rewind 14 days from now and we were in a Christmas blizzard. Reality was one of the mildest Christmas’s on record.
Away from the highlands and northern Scotland (groundbreaking that)

I’d go with John’s chart as is a higher probability!

Actually, precipitation and wind were bang on.

December 18, 2023

Tbf we get more white easters than xmas’

December 3, 2023

I asked chat GTP to do something on the next 2 weeks. Here is the result:

Certainly! Let's delve deeper into the GFS (Global Forecast System) and ECMWF (European Centre for Medium-Range Weather Forecasts) models for a more nuanced analysis of the UK weather over the next two weeks.

**GFS Model:**
1. **Temperature Insights:**
- GFS indicates a gradual cooling trend, particularly in northern and inland regions.
- Watch for potential temperature fluctuations, especially in areas prone to cold air advection.

2. **Precipitation Patterns:**
- GFS suggests scattered rain showers along coastal areas, with the possibility of inland regions experiencing a mix of rain and snow.
- Keep an eye on short-term precipitation spikes, and note any rapid changes in the forecast.

3. **Wind Dynamics:**
- GFS predicts variable wind directions with increasing speeds, especially in western and northern parts of the UK.
- Wind chill effects may play a role in perceived temperatures; be prepared for these variations.

**ECMWF Model:**
1. **Temperature Trends:**
- ECMWF aligns with GFS on the cooling trend, highlighting the potential for colder conditions in the coming days.
- Pay attention to temperature anomalies to gauge the severity of the cooling trend.

2. **Precipitation Analysis:**
- ECMWF emphasizes the likelihood of precipitation, with indications of both rain and snow in various regions.
- Look out for any discrepancies between GFS and ECMWF precipitation forecasts for better accuracy.

3. **Pressure Systems:**
- Both models hint at the dominance of high-pressure systems initially, contributing to stable conditions.
- ECMWF, however, suggests a quicker transition to a low-pressure system, possibly influencing weather patterns sooner than GFS predicts.

**Conclusion:**
Combining insights from both GFS and ECMWF models, we anticipate a cooling trend with the potential for precipitation and variable wind patterns. Keep a close eye on temperature anomalies and pressure system dynamics for a more comprehensive understanding of the evolving weather scenario.

Original post: https://community.netweather.tv/topic/99584-model-output-discussion-into-winter/?do=findComment&comment=4969225

December 3, 2023