Model output discussion - after the beast, what next?

[sebastiaan1973]

10 hours ago, John Michael How said:

Out of interest what does the high pressure look like? The pink or blue areas?I'm travelling to Mauritius on Friday in the vast pink section- hoping their unusually wet summer has come to an end! Abnormally warm SSTs have meant an even warmer than average late summer there?????‍♂️

Hi John, pink is high pressure. Have a nice stay at Mauritius. This MJO-composite would apply after 10 april. 

[Derecho]

1 hour ago, Summer Sun said:

Delighted to say the 7-day temp trend ditches the blues for the north as virtually all of the UK trends slightly above average (the north joins in around midweek)

Isn't that like saying you are delighted you lost a football game 4-0 because its one better then losing 5-0 in the last game?

Aren't those charts just comparing day 7 temperature to day 1? You would expect it to show red during April is that is the case.

FWIW  I want spring warmth now but I don't want to see any more rain, we have had enough of it in recent weeks. If we can't get a decent spell of warmth then I'd rather see some cold dry weather instead because it would still feel nice during the day.

Edited March 29, 2018 by Quicksilver1989

[Nick F]

Bit of a headache for forecasters trying to get some consistency from the models with the boundary between cold and mild air which ripples north and south over the Easter Weekend, but particularly into early next week, thanks to differences in the angle of approach of the low arriving to the SW by Monday, but as to be expected that far out .

00z EC has a snow event roughly M4/London northwards on Monday, 00z GFS further north with the snowline across N England and southern Scotland. These snow charts for Monday noon

EC GFS

Monday perhaps the last chance saloon for snow across England and Wales - as the recent general theme from ENS guidance and ops as we head into the first 7 days or so of April - is for the trop PV currently over Svalbard and Nern Russia to move back across Greenland and eventually into northern Canada, which means a SWly flow for us and much of western Europe.

 

Edited March 29, 2018 by Nick F

[cobby]

Missed the models for a couple of days so not seen these temps coming

[Nick L]

12 hours ago, Tim Bland said:

ECM has snow M4 North on Monday 

 

Those nonsense snow depth charts surfacing again...

[Nick F]

8 minutes ago, Nick L said:

Those nonsense snow depth charts surfacing again...

Yep, there's a big difference to conditions conducive to snow falling from the sky and it actually settling and those snow depth charts look outlandish - given it will likely be too warm to settle on the ground away from high ground, certaintly to those depths, not sure how they come to those amounts!

Besides, Monday's potential snowfall will be leading edge and turning back to rain for most, so even more reason to be sceptical of those depths!

Edited March 29, 2018 by Nick F

[Fozfoster]

https://www.netweather.tv/weather-forecasts/uk/10-day

looking cold here for Easter 

[Nick L]

4 minutes ago, Nick F said:

Yep, there's a big difference to conditions conducive to snow falling from the sky and it actually settling and those snow depth charts look outlandish - given it will likely be too warm to settle on the ground away from high ground, certaintly to those depths, not sure how they come to those amounts!

Besides, Monday's potential snowfall will be leading edge and turning back to rain for most, so even more reason to be sceptical of those depths!

I think those charts are not snow depths, but falling wintry precip. The chances of accumulating snow on low ground through the Midlands on Monday is very small, the timing would be wrong for it. Accumulating snow in the day time in April is extremely difficult.

[Summer Sun]

Nice to see high pressure starting to build over mainland Europe allowing the UK to get in a milder flow of air

[Milhouse]

Yes SS. It Certainly stirred some interest from me when i saw the 6z roll out. Says a lot about the past month when im getting excited by what is still a fairly unsettled outlook. But those temps would definately get those spring plants flowering. 

[stodge]

Morning all

Still uncertainty over the coming weekend yesterday but some clearer signs of the cold easing into the second week of April. Plenty of uncertainty as none of this has yet reached hi-res and the struggle between the colder and warmer air masses allied to the vagaries of the jet stream have made the transition from winter to spring even more problematic this year.

Looking ahead to Sunday April 8th and let's see if the transition to something more "normal" is becoming clearer:

Starting with ECM 00Z at T+240:

A deepening and quite broad LP area is approaching from the west with strengthening winds and frontal rain crossing the British isles followed by what looks like quite a cool unstable showery flow. HP is ridging weakly from the Azores into central Europe and a SW'ly flow covers the British Isles which may be returning PM air in origin.

GEM 00Z at T+240:

Similar to ECM. The LP has stalled to the west of the British Isles and filled slightly in situ but has now drawn in a cool SW'ly of returning PM air. Rain or showers for many with the driest weather for southern and eastern parts.

GFS 00Z OP at T+240:

A variation on the same theme. LP to the NW of Scotland and a slack W'ly flow over the British isles. The driest and brightest weather for southern and eastern parts while the north and west are likely to see more in the way of rain and showers. Further into FI the LP drifts north and HP builds in from the south west and moves east bringing in a warm SE'ly airflow and kick starting spring.

GFS 06Z OP at T+234:

Different orientation to the LP providing more widespread unsettled conditions with rain or showers for many and some quite strong winds in western areas. Once again, FI builds heights strongly from the SW leading to an MLB over the British Isles but is that a hint of retrogression at the very end of FI ?

GFS 06Z Control at T+240:

An Arctic NW'ly is fading away to the east as HP builds up from the SW. Further into FI a strong MLB builds over southern Scandinavia until our friend retrogression gets involved and the HP begins to displace NW through northern Britain toward Greenland.

GEFS 06Z at T+240:

http://www.meteociel.fr/cartes_obs/gens_panel.php?modele=0&mode=1&ech=240

The Mean puts the LP slightly further north and elongated to the north of the British isles. Some Members have weak HP in charge and others put the LP to the south or east. It's a messy picture but while the generalities are clear the all-important specifics are to be resolved. Moving further into FI and a very strong signal for northernblocking emerging with HP to the north of the British Isles. It's possible the orientation will allow a warm SE'ly flow to develop but the GEFS favours a more E'ly hint which wouldn't be very cold by this time. It's a strong signal so worth noting.

In conclusion, whatever happens over the coming weekend, a sense that the "cold" regime will fade by the end of next week as Atlantic LP on a more northerly-oriented jet stream, move in. GFS then points strongly toward a general rise in pressure from the SW translating into an MLB over or just to the east of the British isles but that in turn becoming subsumed into northern blocking from Greenland. A spell of fine weather perhaps and possibly warm conditions but a strong signal for something cooler as we approach mid month.

In the medium term colder air fades and a brief period of Atlantic domination with frontal cloud and rain followed by sharp showers (as often happens in April) before the pressure rises and the weather settles.

 

[MattTarrant]

1 hour ago, Nick L said:

I think those charts are not snow depths, but falling wintry precip. The chances of accumulating snow on low ground through the Midlands on Monday is very small, the timing would be wrong for it. Accumulating snow in the day time in April is extremely difficult.

Given sufficient intensity I would assume snow will settle, just devoid of any significant impacts to major travel routes. Considerably transient though with sub surface temperatures too high.  

Edited March 29, 2018 by MattTarrant

[Frosty.]

The last 2 Gfs runs have ended on a high, literally..hope it does become warmer and more settled towards / during mid april with high pressure taking centre stage for a change!..also worth noting the latest MO update ties in with what the Gfs 00z / 6z show!?????smiley face

Edited March 29, 2018 by Frosty.

[Cheese Rice]

Looking at the ECM precipitation maps you can see snow is possible as far south as Bath 

 

 

As it pushes northwards it'll turn to rain on the southern extent, though looking at the ECM its looking 80/20 snow to rain so not bad. 

The boundary line between cold air runs across the central spine of Northern England, these areas likely to see snow throughout more especially to higher ground.

 

 

Timing is poor dependant on your location, southern areas look to get the snowfall at around early morning, perfect timing, could well be waking up to a covering of snow. Northern areas the snow pushes in during the afternoon.

What can't be underestimated is that unlike the last easterly ground temps will be cooler as we have had a consecutive run of cold nights, especially in the North.

From an IMBY perspective Leeds Bradford Airport meto forecast shows a few days of 0.c night temps, and three days of falling snow, so I'm not worried about ground temps.

 

 

Edited March 29, 2018 by Cheese Rice

[Frosty.]

My search for longer term warmer / settled weather continues with the GEFS 6z..here is my cherry-pick!

Edited March 29, 2018 by Frosty.

[Tim Bland]

5 hours ago, Nick L said:

I think those charts are not snow depths, but falling wintry precip. The chances of accumulating snow on low ground through the Midlands on Monday is very small, the timing would be wrong for it. Accumulating snow in the day time in April is extremely difficult.

Agree ...they show falling snow and assume it all accumulates which obviously it won’t. Met office see enough of a risk of accumulation to issue a warning though.

[Summer Sun]

12z ICON gets the milder air further north quicker than the 06z on Monday morning

12z

06z

[Summer Sun]

12z ICON shows temps getting closer to where they should be for most after Monday maybe even a bit above average in places at times. So warmer rain rather than cold rain

[Eskimo]

GEM best for snow so far. Heavy snowfall for the Midlands and Northern England. Although tad confused as it's a Tuesday event here. 

Edited March 29, 2018 by PerfectStorm

[Summer Sun]

UKMO 12z also coming on board now with the milder air slowly moving north from Monday Scotland though always remains close to the colder air

Today 12z (t144 850's not available at the time of posting)

Yesterday 12z

 

 

Edited March 29, 2018 by Summer Sun

[Man With Beard]

Cold digging a long way south of Sunday. Should mean at very least a snow to rain event from Birmingham north on Monday, maybe even down to the M4 on the UKMO.

   

ECM clusters still keen to put us on a warmer trajectory by D10, and possibility of settled weather by mid-month with lots of positive height anomalies nearby at D15 (if block is south of east, expect warm - if block is north of east, cool but not probably not cold)

  

[feb1991blizzard]

After Mondays bedlam the GFS then proceeds with a N'ly.

[Summer Sun]

20 minutes ago, feb1991blizzard said:

After Mondays bedlam the GFS then proceeds with a N'ly.

And then quickly replaces a northerly with high pressure milder air slowly but surely returning from the west

Around next weekend seems to be the potential turning point for a more settled spell of weather to develop as indicated again today from the met office

 

Edited March 29, 2018 by Summer Sun

[Midlander]

3 minutes ago, Summer Sun said:

And then quickly replaces a northerly with high pressure with milder air slowly but surely returning from the west

 

You seem to have a mild bias, not objective. You only really comment when the model indicates mildER weather.

Edited March 29, 2018 by AppleUK 123

[Summer Sun]

Just now, AppleUK 123 said:

You seem to have a mild bias, not objective. You only really comment when the model indicated mildER weather.

Nah you must have missed my posts in winter which had plenty of chat relating to cold weather