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Paul

Model output discussion - 7th January onwards

Paul

Please keep this thread solely to discussing the model output. The model banter thread is available for more loosely model related chat, ramps and moans.

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npsh500.png h850t850eu.png

Silly collection of lows out west aside, this is a decent effort from GFS. Perhaps optimistic in terms of how soon we get to this sort of point.

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5 minutes ago, frosty ground said:

234-778UK.GIF?08-12
Depends where you are, Darlington looks nippy

Where is this chart from, I can find the south of UK one on the GFS 0.25? Thanks

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1 minute ago, ICE COLD said:

This is what we want . Nothing marginal there Jeff 😂

BB844C51-A246-436D-B747-8787D906D6E5.png

192CFC25-E699-4159-90A6-63FB0C9E3786.png

Isn’t the high out West going to topple due to the lows near South Greenland?

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lows beginning to take that NW - SE track - a good starting point 👍

1500655961_tempresult_nsa9(1).thumb.gif.75bcd60a342b6b715c51de26ce28605c.gif

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3 minutes ago, Seasonality said:

This looks like a decent match to me. imageproxy.php?img=&key=d8af95ed7f22db9eimageproxy.php?img=&key=d8af95ed7f22db9e

gfs-0-384 (3).png

IMG_20190108_175735.jpg

A northerly from the artic to the equator 😂

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3 minutes ago, AppleUK 123 said:

Isn’t the high out West going to topple due to the lows near South Greenland?

Well we will never know because it won’t play out like that chart . All we’re looking at is trends that far out . At the min the trends are are friends. 

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11 minutes ago, frosty ground said:

234-778UK.GIF?08-12
Depends where you are, Darlington looks nippy

That chart is for 7 oclock in the morning though so bulk standard morning temps for January; in fact, positively balmy for down here.

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34 minutes ago, Ali1977 said:

This looks pretty cold, and FI is gonna be great I reckon

6EF60596-3158-45DB-BF6E-9D2B9CC9707D.png

This may sound daft but what would the wind direction and weather we’d get from that set up right there????

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-12 & -13 uppers on a straight northerly? One word sums that up for me which is 'unlikely'.

That said, the overall synoptics look perfectly feasible.

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2 minutes ago, Cuban Zebra said:

This may sound daft but what would the wind direction and weather we’d get from that set up right there????

It looks like a north westerly but could be wrong.

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1 minute ago, Cuban Zebra said:

This may sound daft but what would the wind direction and weather we’d get from that set up right there????

Initially rain to low levels, Wind starting from the W/NW then as the low slides accoss maybe winds from the North (ish) bringing in the proper cold air. 

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GFSp 12z has been censored to avoid mass hysteria (maybe 😋)

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Just now, Mucka said:

GFSp 12z has been censored to avoid mass hysteria (maybe 😋)

The GFS ens have a similar amount of v good charts by next weekend, similar on a cold scale to the 06z. Maybe more showing heights around Greenland.

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3 minutes ago, Jason M said:

-12 & -13 uppers on a straight northerly? One word sums that up for me which is 'unlikely'.

That said, the overall synoptics look perfectly feasible.

They have a bit of NE direction to them at first . 🙂

549A0A25-4163-4AFF-8E92-0A23D1698568.png

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Posted (edited)
1 hour ago, WhiteFox said:

Indeed. We are very lucky that they give us access to the Parallel run. Working in software, we use a parallel run as final testing for a new system to ensure that it operates in the same way as the existing system. Generally this is to ensure that no errors or unhandled exceptions occur during normal operational loads. 

Of course, in this case the output will be different because the underlying calculations are different; I would guess that they have a set of parameters by which they judge the veracity of the output and if it is outside certain bounds they would apply tweaks. But, as a rule, parallel runs are only performed when you are confident that you have your system ready for go live so it should be pretty close to the final operational system 

There were some interesting posts the other night stating that the GFS and parallel are currently experiencing difficulties and low verification stats. 

The argument was that the Federal shut down in the US means the models are running in auto mode with no intervention. 

The way automatic data is recorded has changed and due to the shut down the US models have not been adapted to this new system. So issues with initialisation data. This is compounded by the facts that the models need to be manually adjusted for known bias which isn’t happening right now  

Work has stopped on the GFS parallel. As Whitefox said the parallel is in a testing phase. This is where the model outputs are correlated against actual outcomes and the differences analysed (Root Mean Squared Error ‘RMSE’ for those of you who like regression models). The algorithms are then tweeked over the parallel period to reduce the RMSE and hence increase predictive accuracy. With the Fed shut down this is not happening. 

For those not hugely into stats RMSE is the standard deviation of the difference between forecast and actual outcome. Low indicating differences a small and a high RMSE indicating big dispersion between forecast and actual outcomes.

The upshot is a delay to the parallel taking the place of the existing model and lower verification stats for both GFS and parallel in the meantime.

This came from workers at the agency and there was a good article in the Washington Post 

https://www.google.co.uk/amp/s/www.washingtonpost.com/amphtml/weather/2019/01/07/national-weather-service-is-open-your-forecast-is-worse-because-shutdown/

Edited by Trom

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