Model Output Discussions 12z 08/03/17

[Frosty.]

A strong recovery from the Ecm 12z in the later stages with high pressure building in. As for next week, it remains unsettled for a while and becomes colder with 522 dam thicknesses for a time, cold enough for wet snow on modest hills across the uk and even low levels having a wintry mix and night frosts would become another feature next week, especially when pressure rises later in the week with clearer skies and lighter winds and more in the way of sunshine so it would start to feel pleasant in the strengthening late march sunshine..hopefully high pressure will become established over the uk and continue well into April. Ideally migrating slightly further east with time and enabling warmer continental air to waft our way.

Edited March 15, 2017 by Frosty.

[Dancerwithwings]

Love March....18c to 19c recorded in parts of the UK today, but just in a few short days, next week will/maybe remind us that cold temps can bite back to 4c to 5c

If you like shocks to the system...GFS is showing next week a wind chill of -8 for parts of the UK... -6 for most 

Edited March 15, 2017 by Dancerwithwings

[Frosty.]

The GEFS 12z mean is indicating a quieter spell later this month with increasing Azores high influence bringing a pleasant spell of late march weather, especially further south.

Edited March 15, 2017 by Frosty.

[knocker]

For some time now the METO in their 30 day outlook has sneaked in weak signals for some blocking end of March/beginning of April. There has been some hints, of what I'm guessing maybe what they are looking at, from the EPS and to a lesser extent the GEFS and NOAA but all three are posing the possibility this evening to various degrees. It involves heights building to the north/north east with a weak trough/low pressure south towards the western Mediterranean. This leave much of the UK and France and Germany in a very slack and pretty static pressure area Of course it's quite on the cards they are not thinking along these lines at all and this is just waffle

 

[Frosty.]

30 minutes ago, Dancerwithwings said:

Love March....18c to 19c recorded in parts of the UK today, but just in a few short days, next week will/maybe remind us that cold temps can bite back to 4c to 5c

If you like shocks to the system...GFS is showing next week a wind chill of -8 for parts of the UK... -6 for most 

I love March too, the models are showing something for everyone during the next week or two from cold with wintry ppn next week with night frosts to warmth and sunshine (Gfs 12z low res)..nothing dull about the current output.

[Spikecollie]

5 minutes ago, Frosty. said:

I love March too, the models are showing something for everyone during the next week or two from cold with wintry ppn next week with night frosts to warmth and sunshine (Gfs 12z low res)..nothing dull about the current output.

Same for here in France...giboulées de mars en program, temps up and down and round about!

[Frosty.]

Tonight's Ecm 12z ensemble mean shows a rather colder spell next week and continuing unsettled / troughy with rain and showers, some heavy and thundery and cold enough for hill snow too but not a washout by any means as there would also be some dry and sunny spells around and night frosts where skies clear. Towards the end of next week shows signs of a gradual improvement as a ridge of high pressure builds in with generally drier and brighter conditions but still with an on going  risk of overnight frosts and probably some fog patches by then too. 

Edited March 15, 2017 by Frosty.

[knocker]

With low pressure in the area around Iceland and the Azores HP down to the south west the UK is the filling in the sandwich over the weekend with perturbations forming in the southern quadrant of the low and with weak fronts traversing the country bringing some showery rain  Quite a strong westerly wind will also feature until the main low tracks east to the Norwegian coast.

After that the next upper trough approaches from the north west, deconstructs to some extent by reinforcing the Iberian low, and spawning a large surface low pressure area in the Atlantic with a Little wave crossing Scotland midday Tuesday.

This heralds a few days of cooler quite unpleasant weather, as the main trough tracks slowly south east between the east European ridge and the Azores to the west accompanied by frequent wintry outbreaks as surface lows swan around the UK with the main depression ending over the Midlands 988mb by early Thursday.

During all of these shenanigans the surface flow veers northerly introducing a much cooler airstream with temps below average until the next surge north east from the Azores.

So taking this at face value next week is not looking too clever being very unsettled and quite cool.

Edited March 16, 2017 by knocker

[knocker]

The ecm does differ quite significantly with the handling of the upper trough next week. It does not have it dallying over the UK but transfers the main centre SW so that the surface low(s) are around Iberia. This doesn't mean the UK escapes completely and the middle of the week will still be showery and unsettled but it does allow the Azores to ridge NE sooner than the GFS scenario.

[Frosty.]

The Ecm 00z looks much nicer towards the end of the run with high pressure becoming firmly established.

[Frosty.]

Winter returns later next week according to the Gfs 00z..even cornwall gets some snow!

Edited March 16, 2017 by Frosty.

[Summer Sun]

Following the mean mid week looks to be the coolest part of the week after this the Op and control go on the colder side of the mean for around 5 or 6 days

[Summer Sun]

A quick look at the weekend and NMM joins Arpege by keeping the bulk of the rain in the west with some snow for high ground of Scotland and for a time the Pennines

NMM

Arpege

Edited March 16, 2017 by Summer Sun

[Frosty.]

There is good support for a late March cold snap from the GEFS 00z mean and a delayed / muted signal for high pressure to follow it. Later next week would become much colder with frosty nights, icy patches and some snow around, especially further north and on higher ground but wintry for the time of year.

Edited March 16, 2017 by Frosty.

[Sky Full]

On 9 March 2017 at 20:44, Sky Full said:

GFS 12z still trying to slow down the new growth in my garden by bringing on a cold snap in two weeks time.

  

Luckily the chances of this prediction verifying even close to this are probably less than 10% and ironically the very fact that the GFS says it could happen almost certainly rule it out completely, based on the disappointing degree of inaccuracy at this time scale shown during the last three months.  Can't be too harsh, though, as it's pretty much impossible to forecast the weather in this country beyond five days, isn't it?

Interestingly, 7 days after this post the GFS is still showing the same low pressure dominating on the 22 March, now only 7 days away, bringing cold conditions to all...

   

The ECM is now in broad agreement with this prediction:

   

If these conditions verify, it means that the GFS accurately predicted a change to colder conditions 14 days ahead!  In that case, I will have to apologise for my earlier scepticism...  

Only by the 26th March does the ECM see things settle down and bring warmer weather across the UK:

   

GFS not so quick to build the Azores high back across us, though:

   

Hopefully warmer and more benign conditions in place by the end of March but I can't help wondering how much this situation could change within 10 days.....   

[johnholmes]

SF

The link to UK Met Fax charts, scroll to the bottom and see the height being predicted on the 500 mb chart, not that different to GFS you show. They are certainly suggesting, on their model, colder upper air over the UK with 552 DM falling to about 536 DM for central southern England.

http://www.weathercharts.org/ukmomslp.htm#t120

Edited March 16, 2017 by johnholmes

[knocker]

Interesting development on the GFS 06 which is markedly different to the previous run. A shallow depression forms in mid Atlantic T102, courtesy the upper trough and tracks quickly north east to be western Ireland 999mb at T114. In the next 18 hours it deepens to 977mb and is over northern Scotland and if this materialized bringing some very inclement weather with it.

Edited March 16, 2017 by knocker

[Frosty.]

Everything but the kitchen sink next week on the Gfs 6z, rain, gales, snow, sleet, hail, thunder, frosts, ice and some dry weather with sunshine..not boring! 

Edited March 16, 2017 by Frosty.

[Frosty.]

Well, something that most of us hardly saw anything of during the winter..........snow looks like making an appearance next week, mainly across upland northern uk early / mid next week and then gradually further south as the colder, showery conditions dig further south..also a return of night frosts and icy patches before high pressure builds in with increasing amounts of dry and sunny weather but staying rather chilly with further frosty nights so a more wintry flavour compared to recently / currently.

The GEFS 6z mean shows the colder phase nationwide later next week with an atlantic ridge and trough to the east. 

Edited March 16, 2017 by Frosty.

[Summer Sun]

UKMO extended shows high pressure starting to build later next week - rather unsettled for France, Spain and Portugal

[mb018538]

Yep, nasty looking Iberian trough looks like forming, with high pressure closer to the UK. It could be a slow process though, and will take until the end of next week/next weekend for any pressure rise to become dominant. Until then, unsettled for most.



Looking very wet in the NW, with ppn totals over 100mm possible. The southeast looking pretty dry, with only a few splashes of rain in the next week or so. Your typical NW/SE split showing its hand once again.

[Frosty.]

The Ecm 00z ensemble mean looks increasingly blocked / anticyclonic towards day 10 and potentially well beyond but there is a lot of unsettled weather between now and then, most unsettled in the NW and later next week it does look colder with an increase in night frosts and wintry ppn, with snow mainly on hills and to lower levels in heavier showers, especially further north. As I said earlier, everything but the kitchen sink expected next week..quite a disturbed outlook but then becoming more settled as pressure rises from the end of next week.

[Eugene]

GFS 12Z showing a cold ENE'ly next weekend into the following week.

[The PIT]

A sudden cold snap in FI land and even better UKMO agrees with the the GFS at T144. Now we will have to see if the ECM goes along with the idea or changes it's mind from this morning. If it does then there's a fair chance that a cooler spell will come along. I'm saying cooler as I'm allowing for the normal downgrades to occur as it edges to reliable time frame of T96. At the moment it's looking quite potent.

[Summer Sun]

UKMO isn't as unsettled as GFS is - temps still likely to be down compared to late though it wouldn't feel too bad if we got some sunshine would all depend on what sort of setup we get