Short range model discussion - into 2018

[knocker]

As mentioned earlier later tomorrow there could well be snow showers in the south east in the unstable north easterly wind. A couple of forecast soundings

[johnholmes]

pretty dry above 6000 ft though?

[knocker]

1 minute ago, johnholmes said:

pretty dry above 6000 ft though?

Yes that's true. Perhaps I should change that to snow flurries? I'm assuming that air would start off very dry and only pick up so much moisture off the North Sea?

[Whether Idle]

8 minutes ago, knocker said:

As mentioned earlier later tomorrow there could well be snow showers in the south east in the unstable north easterly wind. A couple of forecast soundings

Knocker, most models are playing this down.  What makes you suggest that the showers will be anything more than shallow affairs?

[knocker]

11 minutes ago, Whether Idle said:

Knocker, most models are playing this down.  What makes you suggest that the showers will be anything more than shallow affairs?

If I gave that impression I apologize, I wasn't intending to suggest otherwise but in any case I certainly wouldn't want to be definitive about this at the moment

Edited February 3, 2018 by knocker

[Whether Idle]

8 minutes ago, knocker said:

If I gave that impression I apologize, I wasn't intending to suggest otherwise but in any case I certainly wouldn't want to be definitive about this at the moment

Thanks for clarifying.  I see shallow showers of rain, sleet and graupel, with the odd snow flurry Monday as the colder air digs in and removes the moisture.

Edited February 3, 2018 by Whether Idle

[knocker]

Further to earlier. Tomorrow looking to be a clear dry day for most after a frosty start with temps generally in the 4-5C range and still showers likely in the south east with an occlusion paying close attention. They could be of rain, sleet or snow.

Clear overnight and a widespread moderate frost Monday morning and another clear chilly day with temps in the 4-5c range but away to the NW the cold front is approaching N. Ireland and north west Scotland.

It over the next 24 hours it continues to track south east and by 12 Tuesday it is orientated the Borders/Wales/Cornwall and it has occluded and subsequently lost much oomph a so the probability is patchy rain/sleet/snow as it edges further south east.

 

The ecm 3-7 850mb anomaly and contours

 

 

Edited February 3, 2018 by knocker

[knocker]

Given the very interesting times I trust it's not out of order to keep an evening check on the NOAA, GEFS and EPS anomalies.

No huge change from last evening except possible the vortex trough extending a tad more south east towards the UK. Thus although we still have the strong westerly upper flow the diverging flow in the eastern Atlantic may just be slightly further east with perhaps the northern arm of the flow across the UK which could allow systems to do the same. Anyhow the detail of this to be sorted by the det runs.

So essentially a continuation of unsettled weather and possibly quite windy at times with temps still below average

Edited February 3, 2018 by knocker

[knocker]

Today after a frosty start in many places it will be bright and quite sunny, particularly in the west, albeit rather cold with max temps in the 4-5C range. It will though become increasingly windy in the south during the day with a brisk north east wind which will lead to some showery activity in the south east, some of which will be of snow. in the unstable air.

These will continue overnight which being clear with light winds will lead to a quite hard frost generally. This is the general picture for the rest of Monday with temps struggling to reach 4C but the showers in the south east will die out as the wind abates.

By 00 Tuesday the cold front that can be seen to the north west on the above fax has occluded and is lying western Scotland Ireland. During the day it will track south east and slowly lose it's identity but as the preceding air is much colder now the precipitation may well fall as patchy sleet and snow, particularly in the north At this stage, as can be seen, all of the warmer air has been squeezed out and the nearest WAA is on the western flank of the ridge

.

By 12 Wednesday the fronts associated with this have tracked east, suppressing the ridge, driven by the energy leaving the eastern seaboard and are approaching western Ireland.

So now we are back to familiar scenario of the fronts occluding and becoming weaker as the reach the UK

Edited February 4, 2018 by knocker

[knocker]

The latest fax charts for Tuesday

[knocker]

Both the ecm and gfs have the UK pretty dry over the next ten days

[knocker]

[chrisbell-nottheweatherman]

5 hours ago, knocker said:

The latest fax charts for Tuesday

Am I interpreting these correctly, Malcolm?  I ask as it appears to me that the occlusion is transitioning from a surface feature to an upper-level one, which I presume will have an influence on precipitation.

[knocker]

8 minutes ago, chrisbell-nottheweatherman said:

Am I interpreting these correctly, Malcolm?  I ask as it appears to me that the occlusion is transitioning from a surface feature to an upper-level one, which I presume will have an influence on precipitation.

Really just an indication that the occlusion is weakening as it crosses the country and the airmass differences are disappearing. So yes you could put it like that Chris and precipitation will cease

[chrisbell-nottheweatherman]

3 minutes ago, knocker said:

Really just an indication that the occlusion is weakening as it crosses the country and the airmass differences are disappearing. So yes you could put it like that Chris and precipitation will cease

Cheers.

[ghoneym]

Latest Meteogroup updates from midnight +24 then + 48

  

[knocker]

The high res. Modis at 1300 and the 12 geostationary showing the wodge of cloud to the west associated with the warm front . And on that subject some nice WAA running north through Iceland to the Arctic. Sat images courtesy off Dundee Satellite Receiving Station.

[knocker]

In the near time frame nothing much different to this morning's assessment.

A cold clear night tonight with the showers continuing in the SE and a widespread frost in the morning. Another clear sunny day tomorrow with the showers in the SE dieing away but with the next frontal system gearing up to th north west.

The front tracks south east overnight and through Tuesday, after another moderate frost, but by now it has occluded and lost much of it's oomph so patchy rain sleet and snow before it fades away.

Overnight and into Wednesday the ridge reasserts itself before the next front arrives from the north west for a repeat performance but the upper trough to our east has become more positively aligned which impacts on the orientation of the front as little waves form on it which slows down it's progress south east across the UK

 

Edited February 4, 2018 by knocker

[knocker]

The ecm 2-6 temp anomaly and contours and the GEFS 10 day rainfall showing most places very dry apart from western Scotland which is not a total surprise as it is is the front line as the fronts track south east and are at their most active.

[knocker]

The anomalies this  evening are showing no significant changes from last night.

An active Canadian vortex with associated trough orientated south east towards the UK. A strong westerly upper flow across the US and exiting the eastern seaboard with the Azores high pressure suppressed south. But again in the eastern Atlantic the upper flow abates and diverges with the southern arm turning sharply south east under the influence of the positively orientated trough to the south of the UK and the northern arm NE slightly later under the influence of the east European high pressure ridging into the eastern Arctic. Ergo systems tracking east will slow and tend to swing south east in the vicinity of the UK. As the UK is at the coal face the det runs will need to sort the detail of this, Thus the percentage play is remaining unsettled but nothing drastic with temps below average, albeit the air to the east is not as cold and the PM does get modified.

[knocker]

Today after a frosty start in many places it will be dry, sunny, and quite cold with temps in the 4-5C range, The exception being the SE and East Anglia where wintry showers, many of snow, may well continue. By evening cloud and rain on the occlusion will have reached N. Ireland and western Scotland.

The front will continue to track south east overnight and through Wednesday increasingly turning to snow in the north and Midlands and sleet and snow further west and the showers dieing out in the south east. Frequent wintry showers behind the front, initially in the north west but spreading further south to western areas as the front progresses.

some scattered rain and snow showers in some areas overnight and in the early hours of Wednesday but after after a clear night quite a moderate frost in many areas. But by early afternoon cloud and rain/snow has reached N. Ireland and western Scotland from the next front.

The front makes quite slow progress through Wednesday and Thursday as the upper trough becomes positively aligned south of the UK and yet again it will be marginal bringing patchy rain/sleet/snow in most areas but more especially the NW/W.

So in a nut shell continuing cold and dry apart from western Scotland and NW England

 

Edited February 5, 2018 by knocker

[knocker]

The ecm 500mb GP anomaly and the 850mb temps contours

[knocker]

The front to the west at 06 and the WAA into the Arctic

[chrisbell-nottheweatherman]

8 minutes ago, knocker said:

The front to the west at 06 and the WAA into the Arctic

I haven't been following the main MOD thread in order to get a long-term view of what the models suggest in terms of the vortex much of recent (this thread is much more civilised), but I'd have thought that WAA  in the Atlantic must be having a disruptive effect.  What also strikes me about the temperature anonalies is the depth of cold air in the North Atlantic south of Greenland.  Could a NW'erly be colder than a NE'erly at present, I wonder?

Edited February 5, 2018 by chrisbell-nottheweatherman
Modified to avoid confusion or inadvertent misrepresentation.

[knocker]

40 minutes ago, chrisbell-nottheweatherman said:

I haven't been following the main MOD thread in order to get a long-term view of what the models suggest in terms of the vortex much of recent (this thread is much more civilised), but I'd have thought that WAA  in the Atlantic must be having a disruptive effect.  What also strikes me about the temperature anonalies is the depth of cold air in the North Atlantic south of Greenland.  Could a NW'erly be colder than a NE'erly at present, I wonder?

Quite likely although of course it does get modified on it's travels And you would expect the thread to be more civilized with a Cornish gentleman strolling the corridors.

Edited February 5, 2018 by knocker