FetchCB

The simplest explanation is chaos theory https://en.m.wikipedia.org/wiki/Butterfly_effect I may be corrected here but atm it seems the models are more sensitive to the initial inputs than is normal Although the other thought could be that they are no more chaotic than usual is just the output has more of a focus and the desired outcomes more fragile. By that I mean people don't seem to react when the models flip from a North westerly to a southerly as much as they do from an Easterly to a southerly as the desire is for cold and snow

Nick is this due to the handling of the storm? Normally they prefer the EC in those cases

21 Jan

The weather will be the weather.... model runs do not determine the weather That as an aside given the proximity of really cold air to our east small changes that the models will not have resolved may result in as you say either chilly or something more interesting but that, given the extended outlook is likely to be the case throughout February not just tomorrow

Interestingly The Met mentioned in their Media output that a system of the West Coast of the US which is due to become a Nor'easter and firing up the Jet is the cause of the uncertainty

And of course between now and then the strength of the Easterly will wax and wane Also in true GFS fashion disappear only to appear later

Also slide 47. The comment comes from Climate Prediction Center. In addition to that the Space Weather Prediction Center also says it needs improvements in upper atmosphere Have to say though that the endorsements from the Stakeholders is hardly compelling even though they all say Implement

Familiar in what respect ,if you don't mind me asking?

Looking at the ensemble line (white) seems to suggest three episodes of slightly warmer 850's followed by colder 850's with each time the 850's getting colder than previously. Would seem to tie in with lows sliding NW/SE and is a scenario that has been seen before in the UK before the onset of a very cold period

dont the last two images show snow for south? Unless i'm missing something?

Its worth bearing in mind that this is/was due to go operational in two weeks time. If it had gone operational at the end of december there would be no GFS as it currently exists ie this would be the GFS and this place would have gone into meltdown )

I think since Mid December the warming of the strat was 10-15 days and then dependent on whether there was a quick response the trop would follow on afterwards. I think the far more knowledgeable on here have touted touted towards the end of Jan since then

It was due to go live on 24th Jan but whether ( no pun intended) the government shutdown affects that I'm not sure. What you are saying tho does make sense to me

It becomes a very complicated mess after a while and given the lack of resolution (at least compared to EC) I doubt the dynamics are being modelled correctly and probably being reflected in the fluctuating trop forecasts

Hasn't this been a recurring issue with the ECM since its update. I seem to recall comparisons to GFS dartboard lows? If so then it would support Steve Murrs suspicions that it may be being too progressive.

I think the issue is that a chart can show favourable conditions but cannot guarantee cold but if you goto this thread then you will probably find what your looking for and will help in your learning.

Probably being pedantic but the weather models do not predict anything let alone the most likely outcome , which seems to imply that the model has a choice. Current observations are loaded into a computer model and using proven scientific formulas and mathematics , present the results. The reason why they appear to be inaccurate over the longer term is called Chaos Theory. For this reason there is ensemble forecasting which attempts to even out the chaos theory but at the cost of resolution .ie the results will be less specific to a particular region. The ensemble forecasting allows forecasters to give broad forecasts and allow contingency planning which along with seasonal forecasting allow for preparedness.( these forecasts use the terms such as "likelyhood","possible" and "on average" which are compared to seasonal averages) The prediction (forecast?) comes from human intervention which will use his/her skill and experience to identify the most likely outcome. It is for this reason that they are professionals and do that for a living. The biggest problem is that "us" amateurs take what is often a somewhat vague analysis by the professionals or look at the computer generated outputs and allow our own internal bias for weather preferences to "cloud" our judgement and then hold that initial analysis as being wrong. As you have correctly pointed out the weather has the ability to make fools of anyone ,including the professionals ( October 1987 and BBQ summer are the most obvious examples) , especially if they predict anything with 100% certainty beyond the 5/6 day period but then again where would the fun be in this forum if everybody only stated what was 100% certain and not what was possible

Not sure if its mentioned this morning but isn't this the norm for GFS.....pick up Easterly at Day 10....drop it a few days later....then smell the coffee and return with the Easterly with 72-96h to go ? It is normally when the GFS reigns back the easterly that METO extended forecast mentions easterly and snow...and hey presto as if by magic.....

Its probably the opposite of storm surge with the water being pushed away from the shore Irma was an extreme example of this https://eu.usatoday.com/story/news/nation-now/2017/09/10/why-water-receding-tampa-bay-irma-approaches/651323001/

Almost a perfect eye

agreed 9mb in a little over an hour !!!

Just been watching Brett Adair who had gone down to Mexico City FL but has gone on to Port Joe which is further east as he said Mexico City had no elevation and no concrete structures and it wasn't safe....I fear for anyone that has stayed there

If the current rate of pressure drop continues it will be very close to a Cat 5 classification of <920 mb...whether this translates into wind is a different matter

it is only an estimation based on satellite images and all through the life of this storm the estimation has been ahead of the actual as if the storm is winding up from the top down.

Dvorak CI# 7.2 /Pressure 908.8mb / Vmax 146.0kt