Short range model discussion - into 2018

[knocker]

33 minutes ago, lottiekent said:

Is it the long wiggly line of fronts extending east that is expected to bring this afternoon and evening's snow over the south?

There is snow currently in the south east from the front by the looks of it but later the snow will be from the developing wave on the front to the south of the UK

This and the showers are depicted brilliantly by the high res, MODIS at 1100 (courtesy the DSRS)

 

Edited March 17, 2018 by knocker

[knocker]

The cold pool ducks a little SW this evening and overnight, I wonder whether this is influencing the snow forecast for the south west?

[knocker]

Another stunning MODIS at 1300. Apparently this is a rare example of trapped 'Gravity Waves' moving westwards in the flow

 

[knocker]

The 1500 surface chart

Edited March 17, 2018 by knocker

[knocker]

The fax updates for 12 Sunday > 12 Monday

Sidney was busy a burying yesterday

[The Enforcer]

What intrigues me is the marked difference in how north of The Wash and Thames estuary convergence lines look on the radar. The former has produced lines of showers with bright echoes denoting heavier bursts. The latter is a single wider area extending as far west as the showers further north, but consists of mostly light snowfall with heavier elements almost exclusively east of London. This is very similar to the precipitation pattern that developed a few weeks ago. Is there a reason for this difference?

Edited March 17, 2018 by The Enforcer

[knocker]

I have no idea and suspect it would need to be looked at in greater detail but could it just be something simplistic such as different topography?

[The PIT]

19 minutes ago, The Enforcer said:

What intrigues me is the marked difference in how north of The Wash and Thames estuary convergence lines look on the radar. The former has produced lines of showers with bright echoes denoting heavier bursts. The latter is a single wider area extending as far west as the showers further north, but consists of mostly light snowfall with heavier elements almost exclusively east of London. This is very similar to the precipitation pattern that developed a few weeks ago. Is there a reason for this difference?

Well it's a bit like why does one heavy band of rain make it over the Pennines and another one doesn't.

[knocker]

https://earth.nullschool.net/#current/wind/isobaric/850hPa/overlay=temp/orthographic=-2.28,52.96,3000

[knocker]

Satellite at 2036 and 2100 surface chart. Temps widely down to -2-3C already

[knocker]

Today and overnight the UK will remain in the bitterly cold easterly regime with the continuation of frequent snow showers in many areas, albeit these will gradually die out later and overnight as another regime gets underway. But a more organized band of snow is already affecting the south as a frontal wave tracks up the Channel which by 1800 has the occlusion close to the south west. Thus the snow here will be more continuous and likely to last through the day and overnight in some areas. I will not attempt detail, even if I could, as this will be essentially a radar watch and well covered in the regionals. As mentioned a bitterly cold day with a severe wind chill.

By 1200 Monday the pattern change is well underway with the Azores ridging north to the the high cell which is now NW of Scotland and initiating the movement of the upper trough south over France. Less cold on Monday as the wind abates and backs and quite sunny with just isolated showers.

By Tuesday the ridge/high cell has become orientated SW/NE over the UK under pressure from the energy exiting the eastern seaboard portending another quite sunny dry day with the temp continuing to creep up, albeit still below average

By Wednesday the weather is becoming more unsettled, although the ridge is hanging on. with low pressure starting to dominate the Atlantic as a familiar pattern, of vortex lobe in the Hudson Bay area, trough in the south east US with a lot of east bound energy attacking the ridge gets underway. Temps still a little below average.

Thus by Thursday it is quite a messy picture to the west with the two energy flows tending to coalesce in mid Atlantic and depressions form in both flows and fronts and rain start to ingress the UK from the north west. By now temps will have returned to around average.

 

Edited March 18, 2018 by knocker

[knocker]

This morning's fax updates for 00, 12 Monday and 00 Tuesday

And satellite at 0445

[knocker]

The 0700 surface chart and the 06 earth wind map for 850mb. Interesting to note the clear area to the south west. there are clear skies here at the moment, whereas snow showers will have just copped north Cornwall

https://earth.nullschool.net/#current/wind/isobaric/850hPa/overlay=temp/orthographic=-2.97,52.60,3000

[The Enforcer]

14 hours ago, knocker said:

https://earth.nullschool.net/#current/wind/isobaric/850hPa/overlay=temp/orthographic=-2.28,52.96,3000

That might explain the aforementioned difference in the precipitation pattern - an upper warm front in the south east corner.

[knocker]

Satellite at 1030 and current state  of play

 

[knocker]

The midday geostationary and UK projection. (courtesy DSRS) The shallow low is in the western Channel

[knocker]

The 1300 surface chart. Quite knife edgy in Cornwall; with the temp at Culdrose +4C

 

[knocker]

Another high class MODIS at 1340 with the low in the western Channel and the occlusion running from the Channel through central France amongst other things

 

Edited March 18, 2018 by knocker

[Dancerwithwings]

Knocker......No chance of any sunshine today  

 

 

[knocker]

1 hour ago, Dancerwithwings said:

Knocker......No chance of any sunshine today  

 

 

 

Well not quite true Dww as it was a cracking morning with wall to wall sunshine. But it has gone downhill recently with the onset of slight snow, Quite knife edgy down here with the colder air winning out dropping the Culdrose temp from +4C to 0C in a couple of hours Anyway a quick look at what might evolve this evening and overnight but I wouldn't bet the house on it.

[John Badrick]

1 hour ago, Dancerwithwings said:

Knocker......No chance of any sunshine today  

 

 

We had a lovely day here in Bude north cornwall coast snowing early this morning with a good covering. Then the sun came out with blue skies for most of the day and the snow melted. Now we have heavy snow and back to a covering again.

[Dancerwithwings]

My apologies guys, I should of said ."No chance of any further sunshine today then" 

Knocker can I ask you your thoughts on your comment please...." what might evolve this evening and overnight but I wouldn't bet the house on it"..... as in ?

[knocker]

18 minutes ago, Dancerwithwings said:

My apologies guys, I should of said ."No chance of any further sunshine today then" 

Knocker can I ask you your thoughts on your comment please...." what might evolve this evening and overnight but I wouldn't bet the house on it"..... as in ?

Ah apologies as I wasn't hinting at any great insight merely emphasizing how tricky it is to forecast snowfall evolution with tricky synoptics. As it is I would be surprised if those charts are a long way out.

[knocker]

The fax charts fpr 12 tomorrow and 00 & 12 Tuesday showing the looped back occlusion clearing the Channel along with any lingering snow/rain and thereafter for the rest of the day and Tuesday a dry and more settled period with the odd shower in the east as a cold front battles against the ridge, Temps slowly improving and feeling warmer as the wind abates.

Edited March 18, 2018 by knocker

[knocker]

Satellite at 2015