Models, teleconnections and nowcasting

[knocker]

48 minutes ago, Dorsetbred said:

That last image with the two deep low to the north of Scotland looks really interesting. Suggesting they are that low in pressure, apart from the obvious windy spell, would you expect to see any knock on effect, because that creates a potential huge area of low pressure and so deep?

The problem appears to be initially the establishment of the major trough and them the baroclinic zone (breeding ground for cyclogenisis) in the southern quadrant develops these low pressures. And this continues according to the exm although this is subject to change as where get further out

[knocker]

There are some differences with the ext EPS from the GEFS earlier, namely involving the Aleutian ridge and the structure of the vortex lobes and trough extensions. This does allow a tad more influence from the subtropical high in the vicinity of the UK which possible indicates more of a N/S split in the likely more settled regime

[knocker]

Outlook - make the most of today's transient ridge as there is a lot going on to the west

The North Atlantic 500mb and surface analysis for midnight

Last night's rain has just about cleared and this morning dawns bright and clear for just about everywhere with a widespread frost.particularly in the north. This will remain the case through the day except in the north west which will become cloudy, followed by rain in the late afternoon and increasing wind, courtesy of a frontal system associated with the deep low that has tracked north east to Iceland

The first batch off rain will continue to track east through this evening to be followed later by the next area associated with the cold front which starts to track south east over Scotland Elsewhere a clear night but the wind is picking up

The cold front and belt of heavy rain continue to move slowly south east though Saturday and it will be very windy with gales along, and preceding the front, whilst to the south it will remain dry. Colder air will also be introduced in the wake of the front

The front and rain will clear the south east Sunday morning leaving a windy and showery day although a rogue little system does bring further rain to N. Ireland and Scotland. But to the west the huge Atlantic trough is getting into gear

And it gets into gear with a vengeance over Sunday night through Monday with a low undergoing rapid cyclogenisis and is 937mb south of Iceland by midday/ The associated cold front will bring heavy rain and strong winds through Monday

The rain will clear east Monday night but another system is deepening rapidly in the southern quadrant of the upper trough to the west as it tracks north east and this will bring further heavy rain and very strong wings on Tuesday

 

 

[knocker]

But the lows are moving very quickly and by Wednesday morning the low is over southern Norway as the next trough tracks down the west coast of Greenland to merge with the old one to the north. All of which results in a windy showery day on Wednesday before another low tracks east to bring more wind and on Thursday with snow on the high ground in the north.

But hopefully now a break in this very unsettled period is beckoning

[knocker]

And on that note the ext mean GEFS anomaly this morning has the Atlantic trough weakening and retrogressing which does allow the subtropical high to gain some traction which should bring more settled conditions to the southern half of the UK, albeit systems still tracking north east to continue changeable conditions in the north but not as wild as before

[knocker]

During the dynamic and unsettled period next week there is always going to be disagreement on detail at this range so just to settle at the moment on the ecm take on it

 

Edited January 10, 2020 by knocker

[knocker]

A quick glance at the EC weeklies update for the middle third of February

07 > 14

Still a suggestion of an Aleutian/Alaskan ridge with the tpv northern Canada with associated trough much regressed to the NW Atlantic This facilitates the subtropical high gaining some traction over the UK

14 > 21

The tpv trough extension a tad more influential and thus the subtropical high less so

 

[mountain shadow]

35 minutes ago, knocker said:

A quick glance at the EC weeklies update for the middle third of February

07 > 14

Still a suggestion of an Aleutian/Alaskan ridge with the tpv northern Canada with associated trough much regressed to the NW Atlantic This facilitates the subtropical high gaining some traction over the UK

14 > 21

The tpv trough extension a tad more influential and thus the subtropical high less so

 

Thanks Knocker.

Little encouragement for coldies there.

[knocker]

The salient points of the ext mean EPS anomaly

Alaskan ridge adjacent to the main tpv northern Russia with the weaker secondary lobe northern Canada

Thus the Atlantic trough has regressed west facilitating the subtropical high to gain traction to some extent in the vicinity of the UK, resulting in a more settled period but tending towards a N/S split

 

[Jordan S]

The Gfs and Gem as well as other models still mostly in agreement this morning with the low for tuesday. 

Atm It's looking like a very potent low which will be deepening as it crosses the uk. 

Edited January 10, 2020 by jordan smith

[knocker]

Midday Tuesday with the 06 gfs

[Methuselah]

I not sure whether it's just me or not (it's certainly possible!) but there does seem to be a higher-than-usual amount of guff being expounded, in the Mod thread, just now...? 

Or am I simply suffering from 'I-know-I-said-it-was-going-to-snow-but-it-hasn't' syndrome too!

[knocker]

Rain from the warm fronts is already effecting N. Ireland and western Scotland and this wlll clear to the east this evening before another heavy band associated with the cold front will start ti track slowly south east after midnight but not clearing western Scotland courtesy of other fronts following The winds in the north will start to pick up shortly effecting much of the northern half of the UK by morning but will abate quite quickly behind the main cold frontfront.

Edited January 10, 2020 by knocker

[knocker]

The position of the deep low and cold front on Monday

and then the rapid frontal development over night

 

[knocker]

No surprises with the ext GEFS mean anomaly this evening with the Alaskan ridge adjacent to the the twin tpv lobes with the main lobe over northern Russia and thus some regression of the atlantic trough, allowing the subtropical high to gain some traction over the UK. Thus tending more settled in the southern half of the UK

[knocker]

The pattern change that is currently being indicated starts getting underway around t168 when the tpv lobe over northern canada begins to weaken and thus the atlantic trough retreats west. This allows the subtropical high room to maneuver in the vicinity of the UK leading to a quieter and drier period, with the exception perhaps being the north west. We are truly blessed

Sidney was contemplating Spring this morning

[knocker]

NOAA in the same ball park

[Jordan S]

Likely to be a narrow line of very heavy rain developing within tomorrow's frontal system as it moves slowly southeastwards across the country during tomorrow afternoon for more Northern areas and into the evening and overnight through England and Wales possibly a delay in the clearance of the rain for more southern counties as the frontal system possibly develops a wave along it, this all accompanied ofcourse by very strong winds in the north with gusts like I mentioned this morning of close to 60mph in places pennines will likely see higher gusts then widely 30-40mph for England and Wales perhaps higher over the higher parts of North Wales upto 50-60mph here through tomorrow afternoon and night although a chance of a little higher than 40mph for England in that narrow band of the heaviest rainfall this should clear to the east of the UK by mid morning Sunday with wintry showers for parts of Scotland and also an area of heavy showery rain likely moving into Wales during Sunday morning then possibly through central parts by the middle of the day, elsewhere drier with sunny spells but breezy. 

Arpege..

With Mondays deep storm system set to move northeast to the west of Scotland the frontal system from that also likely to develop a narrow band of very heavy rain with much higher gusts associated with this with more general outbreaks of rain around it very windy everywhere with gales in places and Some heavy snow likely for higher parts of Scotland particularly the mountains with this frontal system.. this all pushes eastwards clearing most Eastern areas after midnight, although it may take longer to clear for the far southeast into Tuesday morning..  Wintry showers effecting Scotland particularly western parts of Scotland after the clearance as colder air moves in this may fall to some lower levels too. 

Arpege..

Gem..

Tuesday afternoon and possibly into Wednesday morning looking likely to be stormy for England and Wales with more heavy rain but will cover this tomorrow. 

Edited January 10, 2020 by jordan smith

[knocker]

The North Atlantic 500mb and surface analysis for midnight

Heavy rain associated with the cold front, currently effecting western Scotland and N. Ireland will move slowly south east during the day preceded by strong and very gusty winds. Further south remaining dry, albeit breezy, with a bit more cloud than yesterday. Noticeable colder air in the wake of the front

The belt of rain will continue to move south east overnight but slowing down a tad as a wave develops on the cold front and some heavy showers will effect western regions, courtesy of troughs tracking east in the westerly flow, and these could be of snow o the high ground.

The rain will eventually clear the southeast on Sunday leaving a day of sunshine and shwers, which will be mainly concentrated in the north west

But away to the south west at the base of the upper trough a low pressure system is undergoing rapid cyclogenisis near the left exit of the jet and by midday Monday is 942mb west of Ireland. The occlusion associated with this will sweep east across the country on Monday with very strong winds and heavy rain

The front and rain quickly clear to the east over Monday night but you will note a wave forming on the trailing front away to the south west and this will track north east and deepen to cross the country on Tuesday bringing more rain and strong winds. The rain could be of snow over the high ground preceding the front with the marked temp contrast

The low quickly clears to the east leaving a breezy, showery and cooler day on weds but we are not out of the woods just yet as another low is developing to the west

[knocker]

From this point things start getting a bit messy with the first murmurings of the transition previously mentioned

 

Edited January 11, 2020 by knocker

[knocker]

The ext GEFS mean anomaly continues the transition that sees the north Canadian vortex become the secondary lobe, and thus the regression of the Atlantic trough, allowing the subtropical high to gain more traction over the UK. Indicating a more settled spell of weather apart possible for the north west

[knocker]

Heavy rain but wind easing behind the front

Edited January 11, 2020 by knocker

[knocker]

The ecm in transition

[knocker]

The transition of the ext EPS mean anomaly much along the lines of the GEFS so I'll skip the waffle

[Jordan S]

The centre of the pretty intense storm system for Monday moves fairly close to the west of Scotland and Northern Ireland on Monday afternoon with the strongest winds moving into Western and northwestern Scotland later Monday very strong winds everywhere else particularly in association like I said yesterday with the narrow band of very heavy rain expected to develop within the weather front associated with this storm. 

Wind gusts..

Here's the jetstream forecast for the same time frame..

Edited January 11, 2020 by jordan smith