Model Output Discussion

[Cecil Hogmanay Melchett]

ECM now has the Atlantic in by the weekend,probably sunday but we now have model consenus on that trough directly affecting our weather as get to the weekend.Im going to make the most of the next 4 or 5 days as i have a feeling a sustained unsettled spell is on the way,granted it is FI but we are looking at the jet heading south or directly across the uk in the not to distant future.

Wed thur fri and posibly saturdy for the se looking fantastic though.

:lol:

[SP1986]

If the jet heads straight across the UK you can expect a humid, mild feel to the days (around 15-16C) and mild night with copious amounts of rain and very little in the way of sunshine, except between fronts.

If however the jet heads south then we can expect a chilly dry feel to things (around 11-12C and cool but not chilly night, perhaps 8-9C), and a showery outlook.

[Cecil Hogmanay Melchett]

If the jet heads straight across the UK you can expect a humid, mild feel to the days (around 15-16C) and mild night with copious amounts of rain and very little in the way of sunshine, except between fronts.

If however the jet heads south then we can expect a chilly dry feel to things (around 11-12C and cool but not chilly night, perhaps 8-9C), and a showery outlook.

Yep a worrying trend towards unsettled as we go through the weekend ste,definite signs of a poor outlook mid term

with a trough sat over or directly next to the uk.

yuk.

:lol:

[SP1986]

Yep a worrying trend towards unsettled as we go through the weekend ste,definite signs of a poor outlook mid term

with a trough sat over or directly next to the uk.

yuk.

:lol:

I would rather have 15-16C with a humid feel to things and copious amounts of rain, rather than temperatures nearly 10C below average to be fair.

[Wilxy]

More settled spell by the end of tomorrow but a breakdown from the west looks likely by next week as the charts continue to predict this!:lol:

[Thundery wintry showers]

If the jet heads straight across the UK you can expect a humid, mild feel to the days (around 15-16C) and mild night with copious amounts of rain and very little in the way of sunshine, except between fronts.

If however the jet heads south then we can expect a chilly dry feel to things (around 11-12C and cool but not chilly night, perhaps 8-9C), and a showery outlook.

I think a lot depends on the specifics. If the jet heads straight across the UK but is only weak, the result can often be bright, showery and thundery due to relatively infrequent frontal systems. A stronger jet usually means more frontal systems and more cloud, suppressed maxima and copious rain.

A jet to the south of the UK often doesn't mean a showery outlook at this time of year- north-easterly regimes tend to be cool, dull in the east and sunny in the west, because the relevant airmasses no longer become unstable as they pass over the North Sea. A cold showery type with a southerly tracking jet would generally have a Scandinavian Low in the mix, feeding in northerly and north-westerly winds, taking air in from moister and less stable air sources.

Meanwhile I think Weather09 is right about the scenarios for next week. A slackening low over the UK is usually more conducive to heavy showers and thunderstorms with sunshine in between than a brisk westerly with low pressure to the N and NW. The latter scenario often sees large amounts of cloud spilling in from the west, and only light-moderate showers- comparitive atmospheric stability and strong winds reducing the length of time a parcel of air passes over the landmass being two factors.

[mushymanrob]

very true TEITS

quite why we have negative posts about FI when after Tuesday, most of us, will have Wed-Sat with plenty of sunshine,

i post negetive comments about fo john because fi is showing not so pleasant weather! everybodies aware the fi might change, im guessing that many of us arelooking for a decent settled warm spell, this weeks to be upgraded or extended. so looking to fi although unreliable, gives hope... or not!

[BlueHedgehog074]

For tommorrow, looks as though it could be a wet start to Summer for places as a band of rain sweeps in from the West accompanied by light to moderate Southerly winds: http://www.netweathe...9b63378e1afa192 (GFS UK wind speed/dir streams map)

Eastern areas likely to miss out on the rain during the early morning while the precipitation spreads further Eastwards. The GFS, Met Office Outlook and BBC's Precipitation Map generally agree to drier and brighter conditions spreadin' in from the West as the rain clears Eastwards by the evening with higher pressure extending Eastwards:

http://www.netweathe...9b63378e1afa192 (GFS Height 500hpa + SLP map) and http://news.bbc.co.u.../forecast/10209

With humidity looking high for places (according to GFS Uk Humidity), I think the rain should maintain most of its intensity as it moves Eastwards and could be heavy in places. Some of the Western hills could see in excess of 30mm in places: http://www.netweathe...9b63378e1afa192 (GFS UK Precipitation with grid values)

So an overall wet day to come with drier periods, but certainly becoming drier and brighter thereafter as high pressure becomes established over the U.K.

Will be a bit of a question to see how long this dry spell lasts depending on ECMWF's, GFS's and Met Office's future updates.

Edited May 31, 2010 by Rainbow Snow

[rmc1987]

I would rather have 15-16C with a humid feel to things and copious amounts of rain, rather than temperatures nearly 10C below average to be fair.

There's a choice is there?

LOL this is a rather interesting chart......

http://www.wetterzentrale.de/pics/MT8_London_ens.png

[SP1986]

There's a choice is there?

LOL this is a rather interesting chart......

http://www.wetterzentrale.de/pics/MT8_London_ens.png

There's always a choice, preferences. However yes weather will do what it decides to do.

The ensembles generally hover around average so it's not so bad, and there is much agreement even way out.

[Thundery wintry showers]

i post negetive comments about fo john because fi is showing not so pleasant weather! everybodies aware the fi might change, im guessing that many of us arelooking for a decent settled warm spell, this weeks to be upgraded or extended. so looking to fi although unreliable, gives hope... or not!

I haven't really noticed any notably negative posts of yours recently. But regarding hopes of settled warm spells, perhaps some could do with lowering their standards a little. It would genuinely seem from some posts that high pressure there or thereabouts until T+240 is considered a success and anything less a disaster, and when standards are set that high, "disaster" is going to apply in 99 cases out of 100.

Since the weather is something we can't control a bit of "glass half full" wouldn't go amiss- as far as the next week goes it's more like "60-80% full" from a settled warm weather perspective.

[conor123]

There's a choice is there?

LOL this is a rather interesting chart......

http://www.wetterzentrale.de/pics/MT8_London_ens.png

I'll take the hot outlier and run with it!

ECM and UKMO have both moved in the direction of GFS now.

JMA is probably the best this evening though not a very reliable chart..

[TonyH]

I haven't really noticed any notably negative posts of yours recently. But regarding hopes of settled warm spells, perhaps some could do with lowering their standards a little. It would genuinely seem from some posts that high pressure there or thereabouts until T+240 is considered a success and anything less a disaster, and when standards are set that high, "disaster" is going to apply in 99 cases out of 100.

Since the weather is something we can't control a bit of "glass half full" wouldn't go amiss- as far as the next week goes it's more like "60-80% full" from a settled warm weather perspective.

Quite, even unsettled spells often contain nice days to the extent that they can be 'settled' unsettled spells with areas missing much of the showers and being rather warm in the sunshine!

[MP-R]

I haven't really noticed any notably negative posts of yours recently. But regarding hopes of settled warm spells, perhaps some could do with lowering their standards a little. It would genuinely seem from some posts that high pressure there or thereabouts until T+240 is considered a success and anything less a disaster, and when standards are set that high, "disaster" is going to apply in 99 cases out of 100.

Since the weather is something we can't control a bit of "glass half full" wouldn't go amiss- as far as the next week goes it's more like "60-80% full" from a settled warm weather perspective.

Perhaps I speak for myself or maybe not but looking back I've made quite a few negative comments about the weather since March - mainly because the weather has been the wrong way around for me personally - settled weather in spring and then taking a turn in summer.

However, just a subtle difference in the nature of an Atlantic trough would make all the difference between a pleasurable and a disastrous month. A nice slack low pressure system feeding in thundery showers with sunny or brighter intervals would be far more summery than leaden skies, moderate or drizzly rain and unseasonal winds.

[The Northern Ramper]

Exactly

Summer in the uk for me is a nice few days followed by a breakdown with thunderstorms, then another nice few days.

[SP1986]

Myself I have nothing to be particularly negative about, either way 25C and sunshine and high humidity, or low humidity, or even 15-17C, rain and high humidity suits me either way, I dont particularly mind.

What I dont particularly like is 14-16C with low humidity, as it tends to feel particularly chilly in those scenarios.

[Kentish Kiwi]

Perhaps I speak for myself or maybe not but looking back I've made quite a few negative comments about the weather since March - mainly because the weather has been the wrong way around for me personally - settled weather in spring and then taking a turn in summer.

However, just a subtle difference in the nature of an Atlantic trough would make all the difference between a pleasurable and a disastrous month. A nice slack low pressure system feeding in thundery showers with sunny or brighter intervals would be far more summery than leaden skies, moderate or drizzly rain and unseasonal winds.

From what I can see the ECM looks rather nice in that regard, (more so than the GFS which seems more like the latter) with a slack low pressure feeding southerlies into the East, although the west would as always fair worst in such a situation. Out into FI and +240 also looks like a nice evolution, with a slack southerly flow, instability and relatively low pressure.

UKMO looks the best of the main three at +144 in my opinion, Atlantic beginning to make inroads into the West but high pressure still firmly in charge, with the low probably only helping to add moisture and warmth to the set-up at that stage. If such an evolution were to occur, it would seem likely that the east held onto the sunshine and warmth past even monday before a breakdown (if the low continued to track eastwards).

GFS definitely seems the most bullish about how quickly it brings in the low pressure and associated breakdown. From previous experience isn't this often the case? With the GFS over-estimating the extent and strength of lows and often, come the time in question, the low pressure has been pushed back and weakened?

Edited May 31, 2010 by Kentish Kiwi

[William of Walworth]

Just posted in the Summer thread about it, but The Weather Outlook's latest update (31st) to its online seasonal forecast is suggesting a second half of June dominated in the South by warmer, more settled weather. Is this not a wild card outlier though from what most other extended forecasts are suggesting?

[SP1986]

Nothing to do with the integrity of FI but I find it interesting how in FI the 850hPa temperatures seem to reeact to daylight, from 192 hours onwards you find the +5C 850hPa line going retracting at night and moving back over at day. Is this is error or is the GFS picking up on the fact that upper air temperatures reacts to diurnal changes.

It surprises me, I've always though temperatures at that level were steady with no diurnal changes - its something Ive noticed on ensemble suites as well.

Does anyone know?

As for the 18z, I can live with it - not bad, even in FI but as we know, FI should be treated with extreme caution (you have to say that each time now if you want to keep your integrity it seems)

[reef]

Nothing to do with the integrity of FI but I find it interesting how in FI the 850hPa temperatures seem to reeact to daylight, from 192 hours onwards you find the +5C 850hPa line going retracting at night and moving back over at day. Is this is error or is the GFS picking up on the fact that upper air temperatures reacts to diurnal changes.

It surprises me, I've always though temperatures at that level were steady with no diurnal changes - its something Ive noticed on ensemble suites as well.

Does anyone know?

As for the 18z, I can live with it - not bad, even in FI but as we know, FI should be treated with extreme caution (you have to say that each time now if you want to keep your integrity it seems)

Its certainly possible and occurs most often at this time of year when the sun is strongest. Bear in mind lots of things in the atmosphere absorb energy from the sun, be it clouds, dust and even the air. This is magnified hugely if you look in areas with very hot temperatures. Take a look at India 12z and 00z and how the +25C and +30C isotherms shrink and grow depending on the time of day.

http://www.wetterzentrale.de/pics/Rsasavn182.png

http://www.wetterzentrale.de/pics/Rsasavn302.png

The effects in the UK are much less due to it being cooler in the first place and the sun being much weaker, not to mention theres far more mixing of air. It usually always occurs when its sunny but in the case you mention its noticeable merely because of the temperatures hovering around that 5C 850hPa mark. Look over Greenland and you see the same happening at this time of the year with temperatures falling away at night.

[Stormyking]

Its certainly possible and occurs most often at this time of year when the sun is strongest. Bear in mind lots of things in the atmosphere absorb energy from the sun, be it clouds, dust and even the air. This is magnified hugely if you look in areas with very hot temperatures. Take a look at India 12z and 00z and how the +25C and +30C isotherms shrink and grow depending on the time of day.

http://www.wetterzen.../Rsasavn182.png

http://www.wetterzen.../Rsasavn302.png

The effects in the UK are much less due to it being cooler in the first place and the sun being much weaker, not to mention theres far more mixing of air. It usually always occurs when its sunny but in the case you mention its noticeable merely because of the temperatures hovering around that 5C 850hPa mark. Look over Greenland and you see the same happening at this time of the year with temperatures falling away at night.

I have noticed this too with isotherms, thanks for the information on this as I too was wondering why it was doing this .

Anyway 18z not bad really, not cold and not too hot, it has very nice comfortable looking temperatures.

I also reckon its quite mixed with atlantic infulencing and some decent warm weather with high pressure tyring to build in far FI but that will change probably.

Looks like thundery potential is decreasing as we get closer to the weekend

[rmc1987]

So a pleasant few days after today's wet weather. Then we will see a change from Sunday to more unsettled conditions as Low Pressure moves in and that LP looks like it'll sit right over us.

[Frosty.]

Today is the last poor day until sunday according to the GFS 00z, high pressure will settle the weather down for 3 or 4 days, longest in eastern areas and temps will rise into the mid to high 70's F between wed/sat, maybe 80f+ in southeast england BUT during the weekend it looks like low pressure will push in from the west and I would expect some thundery rain and showers by sunday at the latest and then continuing unsettled and cyclonic with potentially thundery showers into the first half of next week but a nice albeit short spell of summer weather to enjoy from tomorrow through to the weekend.

[MR EXTREMES]

Today is the last poor day until sunday according to the GFS 00z, high pressure will settle the weather down for 3 or 4 days, longest in eastern areas and temps will rise into the mid to high 70's F between wed/sat, maybe 80f+ in southeast england BUT during the weekend it looks like low pressure will push in from the west and I would expect some thundery rain and showers by sunday at the latest and then continuing unsettled and cyclonic with potentially thundery showers into the first half of next week but a nice albeit short spell of summer weather to enjoy from tomorrow through to the weekend.

awsome summer then thundery weather = more summer weather.

[conor123]

http://www.wetterzentrale.de/pics/Rtavn1264.png

Ahh, yes please!

The ECM is going against the GFS again this morning showing the warm air never really leaving the UK and trying to push back in from the east next week thanks to a slack low out in the atlantic.

The GEM also goes for something similar.