Short range model discussion - into 2018

[Methuselah]

Och well...Isn't it strange, that the first folks to accuse the professionals of 'not being able to forecast past 3 days' are also the first folks to write-off the entire winter (or summer) just because one or two model-runs don't go according to plan? 

[damianslaw]

I don't believe any of the models have the track and intensity of the projected low forecast to zip through the UK somewhere right - won't know until it arrives. They are perhaps overdoing its intensity and I suspect it may track further south and be a shallower feature when it does arrive. We shall see. Just a feeling but I think the models will correct again tomorrow, today being an unusual one - a major about turn of events, perhaps reacting too quickly. We often end up somewhere in the middle ground scenario when see such a flip with a feature still to arrive for 72 hrs or so.

[johnholmes]

1 hour ago, knocker said:

According to the latest fax for 1200 Wednesday the MET is putting the central pressure 986mb.

 

A rule of thumb prior to the days of computer models was that the surface low would move in the general direction of the warm sector isobars. Not totally true as the deepening caused the low to turn to the left to some extent.

[knocker]

The front and rain that has been tracking south east overnight will clear the SE during the day leaving clearer, colder conditions in it's wake as the wind veers.WNW. But this will be accompanied by much stronger winds, with perhaps gales in places along western coasts and frequent showers in the same areas, mainly of rain but turning to snow in the north. Worth noting the jet winging across the Atlantic as it reaches around 200kts.

Overnight tonight and through Tuesday the colder air becomes more established across the UK with a continuation of the very strong WNW winds, reaching gales force in places, and frequent squally showers with the snow showers moving further south with lying snow reaching lower levels in the north.

By midnight Wednesday the strong winds over the UK have veered more to the north west as the main players the upper trough and the Azores high pressure realign a tad whilst at the same time the eastern seaboard low has appeared on the scene north east of Newfoundland 1001mb. Over the next 24 hours  it tracks rapidly ENE on the very strong jet and deepens very rapidly to be 965mb over western Scotland by midnight Thursday. This potentially could bring a fair amount of snow in the Scottish mountains and, more to the point, gales with winds gusting in the 75kt region across N. Ireland and northern England as the low tracks quickly into the North Sea. I say potentially because any alteration the the track and intensity in the interim could still change the detail

In the wake of the low the UK is back in a cold, showery north westerly airstream as the the Azores begins some transitory ridging in mid Atlantic but that's for another time.

 

Edited January 15, 2018 by knocker

[knocker]

The ecm not in agreement still with the gfs vis the handling of the low. More or less the same position Thursday midnight but the center is around 10mb higher and it doesn't clear into the North Sea quite so quickly and perhaps a tad further south thus the swathe of stronger winds, after initially affecting N. Ireland. may well be NW over NW England and Wales gusting in the 65kt region during the early hours of Thursday. But the detail of this will probably not be settled until late in the day.

[ghoneym]

The PDF was a bit scewed this morning but just starting to see the low modeled on the second chart, following John's rule above I would say track will be through northern Scotland at its center? 

[Man With Beard]

As Knocker mentions, the ECM has dropped the intensity of the storm - perhaps 75mph for Welsh and NW coasts, 60-65mph generally inland for England/Wales. 

GFSkeeps it stronger - generally 65-75mph inland for all parts except N Scotland but a deeper area centred close to Cumbria/Northumberland at 80-85mph and maybe 90-95mph on coasts/hills there.

All a tiny bit further south than yesterday evening.

[knocker]

Exeter have multiple fronts waiting to clear and in the meantime moderate rain here with wind gusting 40mph

Edited January 15, 2018 by knocker

[Man With Beard]

Latest GFS joins ECM in having a slightly weaker storm for Thursday morning and slightly south. Scotland largely clear of the wind now, but snowy instead. Most of England/Wales 60-75mph winds for inland areas, 75-85mph through Lancashire-Yorkshire (esp. on coasts/hills)

  

[knocker]

A glance at a forecast skew-t for 12 on Tuesday for NW Scotland gives an indication of the old airmass with the Tropopause down to 400mb.

[knocker]

Whoops-should of course read cold airmass.

[knocker]

The midday analysis And showery out west according to the midday HR Modis

Edited January 15, 2018 by knocker

[knocker]

The track with the 12 Ikon

Strongest winds The NW, Wales and the Midlands with perhaps a fair bit of snow southern Scotland

Edited January 15, 2018 by knocker

[knocker]

Some tricky wave conditions around the south west, N.Ireland and western Scotland coasts in the strong north westerly over the next couple of days and then the North Sea.

Edited January 15, 2018 by knocker

[Man With Beard]

The ARGEPE is known to overdo wind speeds but the chart below emphasises the problem with this storm, which is that inland areas seem to be almost at as much risk as coastal ones - 80-90mph winds through the northern cities on this one.

[Mark Neal.]

In the short term eyes to the W/NW. For many western areas winds turn that way and increasingly cold. Looks like NW England, Wales/Scotland/N Ireland and even central areas see troughs in showery airflow. Euro4 reflecting this well its 12z run has just updated.

    

 

Edited January 15, 2018 by Mark N

[knocker]

At 1800 Wednesday the ecm has the open wave 988mb just west of N.Ireland. At 00 over the north Irish Sea and at 0600 Thursday 980mb east of Hull.The strong winds would be south of that track, particularly over Wales and the west Midlands perhaps gusting in the 60kt range with also a fair amount of rain

[cowdog]

7 minutes ago, knocker said:

At 1800 Wednesday the ecm has the open wave 988mb just west of N.Ireland. At 00 over the north Irish Sea and at 0600 Thursday 980mb east of Hull.The strong winds would be south of that track, particularly over Wales and the west Midlands perhaps gusting in the 60kt range with also a fair amount of rain

Its gone quiet quickly from being a serious worry to being just another storm. The shift on the latest ECM is similar to the 12Z GFS, its a remarkable change for the models for an event that is less than 3 days away!

[knocker]

9 minutes ago, cowdog said:

Its gone quiet quickly from being a serious worry to being just another storm. The shift on the latest ECM is similar to the 12Z GFS, its a remarkable change for the models for an event that is less than 3 days away!

To put this in perspective this is the low at 2100 this evening. In my book the models aren't doing a bad job if they get it pretty near in 48 hours with a 200kt jet winging across the Atlantic. There will probably still be some more adjustments

 

[knocker]

[Man With Beard]

The ECM downgrades Thursday's (or is it Wednesday's?) storm further, with gusts 50-70mph for the Midlands / Wales / South, so a fairly average Atlantic storm.

However, the ECM ensembles still pack a punch, with over 50% now seeing the storm hitting IOM / Lancashire at between 90 and 100mph in gusts, and even higher than 100mph for the N Wales coast on some. The idea of the storm primarily hitting S Scotland has been reduced significantly when compared with last night.

It may be that the higher definition of the op run is putting it ahead of its ensembles now, or it may be that it is touch and go if the low will interact with the jet or, rather, where it will interact.

[Hotspur62]

Well Louise Lear on bbc news at 10.40 showed quite a snowy picture tomorrow for Nw England and most of Scotland and looking at the graphics the Low for Weds night/Thurs seemed quite a long way North compared to evening models although she did mention there could be significant snow but that looked over Scotland only,She did say it is one to watch though as exact track not set in stone.Thereafter looks chilly and sunny for weekend with scattered wintry showers on coastal areas.Be Interesting to see where we are this time tomorrow as over last 24hrs the Low has tracked quite a bit Southwards and wouldnt be surprised if this trend continues.Fascinating Model watching atm

[knocker]

Today and tonight can be generally summed up fairly briefly. A complex area of low pressure is situated to the NW/N and the UK is in a strong WNW/NW airstream with gales in many places along western coasts. (Currently gusting around 50mph here).

This cold unstable air will initiate frequent squally wintry showers down the western side of the UK (Spreading a little inland) of just about everything. Snow, hail, rain, thunder, but particularly prevalent in Scotland, N. Ireland and NW England where the snow showers will be more frequent and lying snow may well accrue.

Tomorrow brings a slight lull, relatively speaking, before our wave depression gets in on the act and brings some wet and stormy weather Wednesday night  into Thursday. I think it worth while just following the storm as indicated this morning by the gfs just to show how tricky it is to nail down the precise track and intensity, even over short time scales. And probably worth mentioning this still is not nailed down. So at 0300 this morning it is just developing off the eastern seaboard and at 00 is still a shallow feature north east of Newfoundland.

In the next 24 hours it nips across the Atlantic on a very strong ENE jet (in the 100kts region at 500mb) to be in the north Irish Sea 982mb by 00 Thursday. As it then quickly crosses the north of England into the north sea it will generate some very strong winds south of it's track, gusts in the region of 60-65kts accompanied by rain which may well be of snow along the northern edge in southern and central Scotland.

But as mentioned this is still not set in stone and the latest fax (It was 1800 yesterday) has it 8mb deeper. The low quickly tracks into eastern Europe and the UK is back in a cold, unstable, NW regime by 00 Friday.

Edited January 16, 2018 by knocker

[Spikey M]

A definite downgrade in the severity of the storm, which my conservatory roof is happy to hear. It’s coming in as a NWly as well, rather than a straight up Wly or even SWly as some feared, although it may still flatten out.

In unrelated matters, why is someone (some people?) seemingly confused by everything Knocker - who is doing a great job in here - is posting?

[knocker]

The ecm has the low a little further SW in the Irish Sea and not quite as deep at 988mb at 00 Thursday. By 0600 just east of Hull 986mb and certainly not so enclosed and active as the gfs. Gusts south of this in the 45-55kt range. So still major differences all round which is not a major surprise and this probably will not pinned down until later.