Models, teleconnections and nowcasting

[knocker]

At 1800 UTC

[knocker]

The ext mean anomalies continue ti indicate a re-alignment of the tpv entailing a retrogression of the Atlantic trough. But no cross model agreement on the detail and thus some differences concerning the amount of influence from the resurging of the subtropical high will have over the UK

 

Edited February 7, 2020 by knocker

[Jordan S]

So as many know Sunday looking stormy as storm Ciara rapidly deepens as it approaches the uk. 

Gfs wind gusts.. 

Some very heavy rain moving across the country during sunday but the most rain is likely over parts of northwest England, Wales, parts of Scotland and Northern Ireland this may fall as snow on the hills in Scotland the weather front being very squally moving through all areas by Sunday evening. 

Winds very strong through Saturday night for many from a separate weather system this merges with storm Ciara, winds will strengthen further for many parts during sunday with gusts of wind likely atm to reach 55-70mph widely inland for England and Wales in particular but on hills and along the coasts in particular around 80mph is possible. 

Edited February 7, 2020 by jordan smith

[knocker]

Given the current situation regarding the grim flooding in many areas and the completely saturated ground in others, I would have thought the main priority at the moment is to keep an eye, or two, on the model outputs in the near time frame with this in mind.

And although there will be some rain in the next two or three days which will not help it's developments at the beginning of next week that need watching.

By midday Sunday a wave is developing on the trailing front in the Atlantic which is set to deepen quickly near the left exit of the jet as it tracks north east over the next 24 hours. But you will note that there is no consensus on the detail of this, by a long chalk, but hopefully this will be sorted quickly

But this could bring heavy rain and gales to many areas that don't need it

Edited February 20, 2020 by knocker

[knocker]

And moderate rain on the cold front as it tracks south east

[knocker]

The 0600 gfs. Hopefully the worst of the weather will be short lived and perhaps north of the worst effected areas

Edited February 20, 2020 by knocker

[knocker]

Quite an interesting Camborne midday sounding. The double structured cold fronts were not that long through and both appear to show on the sounding

Edited February 20, 2020 by knocker

[knocker]

Once the fronts mentioned above have moved away east, frequent squally wintry showers will ensue mainly in northern and western regions, but as can be seen another system is waiting in the wings and is tracking east. And by around 0200 Friday heavy rain from this will be effecting N. Ireland and NW Scotland and by morning much of Scotland and into N. England

The problem from this is that although the warm front quickly clears and the deep low tracks north east into Scandinavia, the trailing cold front and associated troughs become very slow moving against the high pressure to the south east  Thus rainfall may linger a while in some areas before fizzling out

The fronts are clear by saturday leaving a very wind day, particularly in the north with frequent squally wintry showers, snow on the higher ground, which may well coalesce courtesy of a trough embedded in the circultion

Edited February 20, 2020 by knocker

[knocker]

Over Sunday/Monday the frontal wve develops very rapidly as it tracks north east but it looks, according to the gfs anyway, that the triple point if it still exists will pass across southern Scotland and thus the heaviest rain passing north of the effected areas further south

Through midweek it's quite complex with two energy flows but Pm air from the next system to the north west dominates as a front tracks south east which co snow to quite low levels in the north

And wintry showers are the order of the Day on Thursday in the north

[knocker]

The ecm also takes Mondays low to the north but it all depends how active the cold front is as it tracks south east

As the low tracks north east this paves the way for Pm air to encroach the UK but the energy flows are quite complex around the tpv lobe and the amplifying subtropical zones and by t144 the low stalls near southern Norway veering the surface wind over the UK to NNW with a front approaching

And then more complications

Edited February 20, 2020 by knocker

[knocker]

Despite some subtle orientation shifts the tpv continues to be relatively compact and judging by the ext anomalies this evening, remains the dominate feature regarding the UK weather A strong westerly upper flow would presage a continuation of unsettled for the period.with temps varying around the average or a tad below. This of course does not rule out some wintry incursions as systems track east.

And the strat remains compact as well

 

[knocker]

Outlook - a tricky period of inclement weather over the next few days, particularly in the north

The North Atlantic 500mb and surface analysis for midnight. As can be seen the complex upper trough dominates which is reflated in the surface

Rain from the frontal system to the west is already effecting NW regions and this will move slowly south east through the day to reach the north Midlands and Wales by 1800 with further south remaining dry but pretty cloudy

The cold front and rain band will continue to track south overnight but it will become increasingly windy in the north with frequent heavy wintry showers under the influence of the deep low over Iceland

The front and rain clear the south coast Saturday morning leaving a very windy day, particularly in the north with plenty of wintry showers there of snow on the high ground. Could well be blizzard conditions in the north of Scotland A marked N/S temp contrast

Sunday is a tricky day with very much a N/S divide with one frontal system bringing strong winds with rain/snow over Scotland whilst in the south our old front has not gone very far and in fact has moved a tad north again as a wave forms on it away to the south west

And it is this wave that concentrates the mind over Monday as it tracks north east and deepness to be 975mb just west of the Hebrides by midday. bringing with more heavy rain, in particular over northern regions

The movement of this low has paved the way for the ingress of colder air generally and Tuesday will be a windy andd chilly day with showers and longer periods of rain which could be of snow over the higher ground in the north

 

[knocker]

The gfs has the tpv continuing to dominate proceedings thus the unsettled theme also continues through next week with showers, sunny intervals and some longer periods of rain with snow over northern hills. Temps generally a tad below average in the Pm air

Edited February 21, 2020 by knocker

[knocker]

The ecm is entirely different to the gfs next week. At t132 it is more amplified in the Atlantic/Europe arena

But the frontal wave in the western Atlantic then undergoes rapid cyclogenisis as it tracks north east with the associated fronts bringing heavy rain and strong winds to the UK. Not much point in looking further until the mid week detail gets sorted

Edited February 21, 2020 by knocker

[knocker]

Last night's EC weeklies up date is indicating the tpv becoming less influential on proceedings towards the end of the first week in March. So a quick glance at the output from the 7tth to the 21st

7-14

As can be seen the reorientation of the tpv. now centred over northern Canada, has facilitated amplification of the subtropical high resulting ina  more settled period of weather for the UK

14 - 21

No significant differences with again the southern half of the country being more favorable situated

Edited February 21, 2020 by knocker

[knocker]

This morning's fax updates has Monday's low deepening 27mb in 12 hours

[knocker]

When the cold front(s) wander back north as warm fronts

[knocker]

Mondays low will bring rain and strong winds to the country. Initially on the warm front and then the cold as the triple point crosses Scotland. Perhaps some snow on the high ground on the leading edge of the front

Over the next 24 hours the low tracks into southern Norway, the cold front clears the south coast, and the UK is in cooler north westerly Pm air with showers in western regions

And over the next 48 hours it again has the frontal wave undergoing rapid cyclogenisis as it tracks around the subtropical ridge

Edited February 21, 2020 by knocker

[knocker]

The tpv and the elongated and waving front(s) are the key players over the next few days

The North Atlantic 500mb and surface analysis for midnight

The patchy rain associated with the cold fronts tracking south down the country should clear this morning leaving a mostly cloudy day and quite mild. Different picture over Scotland and N. Ireland where it will be very windy with gales along with frequent wintry showers, which could fall as snow down to quite low levels and thus blizzard conditions. Note the marked temp contrast.

But as can be seen waves are forming on the fronts to the west and this brings moderate rain to areas of England and Wales that certainly don't need it at the moment through the latter part of this evening and overnight

The rain will slowly clear during Sunday morning but still windy with squally wintry showers over northern Scotland.

But note another wave is developing on the front away to the south west and this engages with the jet and deepens rapidly as it tracks north east to be near Scotland by midday Monday. There is still a little uncertainty on how this will develop as how it engages with the jet is critical so perhaps another look at this a bit later. At the moment it looks like bringing a fair bit of rain, perhaps some snow on the hills on the leading edge, and some strong winds

The low and fronts quickly clear and by Tuesday the country is well and truly in the grip of the upper trough and thus it continues windy with frequent wintry showers in the now much cooler air , courtesy of troughs tracking east in the circulation

A not dissimilar day on Wednesday

 

 

Edited February 22, 2020 by knocker

[knocker]

From here the gfs tracks yet another wave that has formed on the front north east to be 986mb N. Ireland by 0600 Thursday. Another leading edge scenario but generally rain with some snow o the high ground

Over the next five days a continuation of unsettled with very messy detail

[knocker]

Firstly little change regarding Monday's low with this morning's fax update.

And secondly some semblance of agreement between the ecm and gfs for the latter part of next week

[knocker]

There are no real signs that the tightly knit tpv is ready to release it's grip just yet

And the ext mean anomalies this morning tend to support this so continuing unsettled with temps a tad below average

 

[knocker]

The Monday low with the 06 ecm

[knocker]

The gfs making the developing frontal wave in the middle of next week a much more potent affair with some rapid cyclogenisis. More wind and rain if correct

Edited February 22, 2020 by knocker

[knocker]

The second half of the ecm run is dominated by the tpv so a continuation of unsettled and quite cool weather. But such is the domination the weakening jet is forced south and thus negating rapid cyclogenisis moving east and hopefully avoiding any major rainfall events