Model Output Discussion 04/01/19 11:45 >>>>· Page 25

doctormog
Advanced Member

09 January 2019 18:52:07

I think that's a very optimistic outlook with the Azores High so close,

ECM rolling out, strongly zonal at T216.

Originally Posted by: Shropshire

Day 9? Someone was telling me emphatically yesterday that it is not worth looking beyond day 8 (or is that only when it shows cold).

Aberdeen

Current conditions (personal WS)

Rob K
Advanced Member

09 January 2019 18:52:20

#602

In some ways it reminds me of some of the 80's winters - cold enough for some snow almost anywhere at times but the south always at risk of rain and milder weather whilst the North stays more consistently cold.

Originally Posted by: Hippydave

Exactly echoing my thoughts from earlier. Not so much Scandi high/blast from the east territory, more messy cold low pressure systems with a wintry mix just about anywhere.

Not sure I would really call the ECM "strongly zonal", Ian - a very buckled jet there.

Yateley, NE Hampshire, 73m asl

"But who wants to be foretold the weather? It is bad enough when it comes, without our having the misery of knowing about it beforehand." — Jerome K. Jerome

Shropshire
Advanced Member

09 January 2019 19:14:18

#603

Exactly echoing my thoughts from earlier. Not so much Scandi high/blast from the east territory, more messy cold low pressure systems with a wintry mix just about anywhere.

Not sure I would really call the ECM "strongly zonal", Ian - a very buckled jet there.

Originally Posted by: Rob K

Its a +ve NAO at T240 which admittedly only takes us to Jan 19th. But I'm not going to get excited about that sort of chart.

From December 27th 2020, zonality will be banned from mixing with the UK. We appreciate that this may come as a shock to younger people and old Uncle Barty. This ban will last for a minimum of ten days.

jhall
Advanced Member

09 January 2019 19:15:05

#604

IBM Introducing the World’s Highest-Resolution Global Weather Forecasting Model

"IBM announced today that they will be introducing the world’s highest-resolution global weather forecasting model later in 2019--the IBM Global High-Resolution Atmospheric Forecasting System (GRAF). The model will be the first hourly-updating weather model that is able to predict something as small as a thunderstorm virtually anywhere on the planet.

The current top global forecasting models, the European (ECMWF) model and the U.S. GFS model, subdivide the global atmosphere into grid boxes that average 9 kilometers and 13 kilometers on a side, respectively, then solve the mathematical equations of atmospheric flow to generate a forecast for each of those grid cells. The new GRAF model employs a variable-resolution grid, resembling a honeycomb, that can be configured with higher resolution over areas of particular interest (Figure 1). Over land areas, the GRAF grid elements will have average resolutions of 3 km, which is about 3 - 4 times greater than the European and GFS models"

https://www.wunderground.com/cat6/IBM-Introducing-Worlds-Highest-Resolution-Global-Weather-Forecasting-Model

Originally Posted by: Gavin D

Very interesting. However:

"Initially, the highest-resolution version of the GRAF model will run at least 12 hours into the future; a lower-resolution version now being tested extends out as far as 120 hours." So it's not going to be a replacement for the GFS or ECMWF.

Cranleigh, Surrey

Whether Idle
Advanced Member

09 January 2019 19:16:59

#605

This is how I think the situation will play out - a much stronger Azores High throwing slices of relative mildness our way, certainly affecting all but the north eastern quadrant, keeping the cool NWly flow balanced and close to average.

This is pert 14 from the 12GEFS suite:

Dover, 5m asl. Half a mile from the south coast.

some faraway beach
Advanced Member

09 January 2019 19:18:11

#606

Haven't looked into it but it will be related to resolution. When talking about resolution there is a lot of confusion because it can apply to two different things:

1) The vertical and horizontal resolution the computer resolves at

2) The data sets output by the model. For example, NCEP provide 0.25 deg, 0.5 deg and 1 deg data sets from the same GFS run. The lower resolution sets are smaller, so are cheaper and quicker to download. For example, I believe MC plot the 1 deg GFS data set as standard. On TWO I run the 0.25 out to 96, 0.5 from 96 to 180 and 1 from 183 to 384.

Both points are applicable to the GEFS too.

Therefore the issue you raise is almost certainly related to resolution.

Originally Posted by: Brian Gaze

That makes sense. You can start with the same overall data, but if the grid size differs, then so will the values used. For instance, if the temp for London comes from one small grid, covering inner London alone, it will differ from the temp derived from a bigger grid, on the control run, which might cover the whole of the Greater London area.

2 miles west of Taunton, 32 m asl, where "milder air moving in from the west" becomes SNOWMAGEDDON.

Well, two or three times a decade it does, anyway.

Gandalf The White
Advanced Member

09 January 2019 19:24:13

#607

I think that's a very optimistic outlook with the Azores High so close,

ECM rolling out, strongly zonal at T216.

Originally Posted by: Shropshire

I know you can interpret a synoptic chart so I question why you've posted this clearly erroneous comment.

Firstly the Azores high isn't close - it's actually over the Azores from T+168

Secondly if you think the pattern at T+216 is 'strongly zonal' then you must have a particularly idiosyncratic definition of zonal that nobody else shares.

Location: South Cambridgeshire

130 metres ASL

52.0N 0.1E

Brian Gaze
Administration Topic Starter

09 January 2019 19:24:54

#608

ECM 240 overhead looks poor for cold. I'd expect it to be one of the mildest runs in the ENS (which I've not sneakily had a peek at).

https://www.theweatheroutlook.com/twodata/ecmwf.aspx?run=12&charthour=240&chartname=mslp500_arc&chartregion=nh&charttag=NH%20500hPa%20GPDM

Brian Gaze

Berkhamsted

TWO Buzz - get the latest news and views

"I'm not socialist, I know that. I don't believe in sharing my money." - Gary Numan

Ally Pally Snowman
Advanced Member

09 January 2019 19:29:37

#609

ECM 240 overhead looks poor for cold. I'd expect it to be one of the mildest runs in the ENS (which I've not sneakily had a peek at).

https://www.theweatheroutlook.com/twodata/ecmwf.aspx?run=12&charthour=240&chartname=mslp500_arc&chartregion=nh&charttag=NH%20500hPa%20GPDM

Originally Posted by: Brian Gaze

It's actually a pretty cold chart -5c to -7c 850s over the UK . And looks similar to the GFS which went on to be Snowmegeddon.

Bishop's Stortford 85m ASL.

pdiddy
Advanced Member

09 January 2019 19:30:40

#610

ECM 240 overhead looks poor for cold. I'd expect it to be one of the mildest runs in the ENS (which I've not sneakily had a peek at).

https://www.theweatheroutlook.com/twodata/ecmwf.aspx?run=12&charthour=240&chartname=mslp500_arc&chartregion=nh&charttag=NH%20500hPa%20GPDM

Originally Posted by: Brian Gaze

I was expecting the wedge of heights to the North of UK to be bigger/more impactful after the 216...

Whether Idle
Advanced Member

09 January 2019 19:34:43

#611

I was expecting the wedge of heights to the North of UK to be bigger/more impactful after the 216...

Originally Posted by: pdiddy

That'll be the influence of the Azores High then...

Dover, 5m asl. Half a mile from the south coast.

Gandalf The White
Advanced Member

09 January 2019 19:35:15

#612

ECM 240 overhead looks poor for cold. I'd expect it to be one of the mildest runs in the ENS (which I've not sneakily had a peek at).

https://www.theweatheroutlook.com/twodata/ecmwf.aspx?run=12&charthour=240&chartname=mslp500_arc&chartregion=nh&charttag=NH%20500hPa%20GPDM

Originally Posted by: Brian Gaze

The T+240 chart gives 500-1,000 hPa thickness values of around 525 dam for London down to 520 for the North of Scotland. I'd have thought they were pretty impressive for a west to north-westerly flow?

Edited by user 09 January 2019 19:36:32 | Reason: Not specified

Location: South Cambridgeshire

130 metres ASL

52.0N 0.1E

Rob K
Advanced Member

09 January 2019 19:42:03

#613

The T+240 chart gives 500-1,000 hPa thickness values of around 525 dam for London down to 520 for the North of Scotland. I'd have thought they were pretty impressive for a west to north-westerly flow?

Originally Posted by: Gandalf The White

Quite cold upper air but it’s amazing how much modification you can get at the surface by the time the air has reached the SE corner - you could probably add about 12-14C to the 850s for the max temps in London in a westerly regime.

Edited by user 09 January 2019 19:54:50 | Reason: Not specified

Yateley, NE Hampshire, 73m asl

"But who wants to be foretold the weather? It is bad enough when it comes, without our having the misery of knowing about it beforehand." — Jerome K. Jerome

Gandalf The White
Advanced Member

09 January 2019 19:45:24

#614

Quite cold upper air but it’s amazingly how much modification you can get at the surface by the time the air has reached the SE corner - you could probably add about 12-14C to the 850s for the max temps in London in a westerly regime.

Originally Posted by: Rob K

Yes, around 6-8c at the surface would not be unusual in that set-up but I'd expect a wintry mix in any heavier showers outside London and with some elevation.

Location: South Cambridgeshire

130 metres ASL

52.0N 0.1E

pdiddy
Advanced Member

09 January 2019 19:52:27

#615

That'll be the influence of the Azores High then...

Originally Posted by: Whether Idle

the very same Azores high on the GFS at the same period...

doctormog
Advanced Member

09 January 2019 19:55:16

#616

http://www.wetterzentrale.de/maps/GFSPARAUK12_120_2.png

Hopefully, as has been the case, the rest of the run will show a number of cold incursions hitting the country on the same timescale as previous runs.

Aberdeen

Current conditions (personal WS)

Bugglesgate
Advanced Member

09 January 2019 19:55:49

#617

Yes, around 6-8c at the surface would not be unusual in that set-up but I'd expect a wintry mix in any heavier showers outside London and with some elevation.

Originally Posted by: Gandalf The White

Reminds me of dubious sweets my Gran used to feed us :-

https://www.oldestsweetshop.co.uk/winter-mixture

Chris (It,its)

Between Newbury and Basingstoke

"When they are giving you their all, some stagger and fall, after all it's not easy banging your heart against some mad buggers wall"

Arcus
Advanced Member

09 January 2019 20:09:48

#618

the very same Azores high on the GFS at the same period...

Originally Posted by: pdiddy

Indeed, it does make me laugh when people talk about "we need to get rid of the Azores High to get cold" when what they mean is the Azores High ridging into Europe.

Also remember in the longer term that in a situation with a slowing Jet as the SSW downwell displacement takes place then the "boulder/river" scenario comes into play in terms of how the Jet affects/is affected by the synoptics.

Edited by user 09 January 2019 20:21:11 | Reason: Not specified

Ben,

Nr. Easingwold, North Yorkshire

30m asl

Tim A
Advanced Member

09 January 2019 20:19:22

#619

Quite cold upper air but it’s amazing how much modification you can get at the surface by the time the air has reached the SE corner - you could probably add about 12-14C to the 850s for the max temps in London in a westerly regime.

Originally Posted by: Rob K

Not sure -5c to -6c 850 temps are cold enough for much in the way of snow away from the highest ground in PM air when pressure is 1015mb +. The 850hpa layer is much higher than if MSLP was 990mb .

Tim

NW Leeds

187m asl

My PWS

Gavin D
Advanced Member

09 January 2019 20:26:19

#620

Checking in on NASA's seasonal forecast model, which last month showed dramatic February cold in northern Europe - the latest forecast is less pronounced. North America looks like classic strong El Niño despite a very weak Niño SST anomaly in the model! 🤔 pic.twitter.com/K5pz9Sn8jq
— WorldClimateService (@WorldClimateSvc) January 9, 2019

Gandalf The White
Advanced Member

09 January 2019 20:44:53

#621

Not sure -5c to -6c 850 temps are cold enough for much in the way of snow away from the highest ground in PM air when pressure is 1015mb +. The 850hpa layer is much higher than if MSLP was 990mb .

Originally Posted by: Tim A

Thickness value (500-1,000 hPa) of around 525 dam for London suggest wintriness is possible. Certainly not values for guaranteed snow, I agree, away from elevation.

Location: South Cambridgeshire

130 metres ASL

52.0N 0.1E