Model Output Discussion 12z 20/04/13

[phil nw.]

I think we cant write off the next week after tomorrow for warmth , but F.I plus ens are still hinting at a solid warm up

Indeed and looking quite dry for a protracted period well into May too.

http://modeles.meteociel.fr/modeles/gens/graphe_ens3.php?x=263&ext=1&y=98&run=12&runpara=0

Only the odd showery day or two to supply any rain in the next 2 weeks by the looks of it.

The PV now on the wane as we would expect with high pressure starting to look likely around Europe and Scandinavia in early May.

http://modeles.meteociel.fr/modeles/gens/run/gens-21-1-240.png?12

A much different outlook to this time last year.

[Purga]

Very cool looking ECM tonight

That cold north sea is going to add to the cool feel although the days should be dry and mostly clear with warm temps in sheltered spots after chilly nights.

[ANYWEATHER]

Dramatic changes from summerlike temps to winterlike temps in the next 48hrs from the ecm....Pointless talking about further ahead from the weekend as T+72hrs is about as far as it goes! Certainly expect some severe weather though in this period  for some folks....!

[Gibby]

Good evening. Here is the report on the midday output from GFS, UKMO, GEM, NAVGEM and ECM for Tuesday April 23rd 2013.

All models show a westerly flow across the UK with a warm moist feed in the South and a fresh and showery feed in the far North. the dividing line over Northern Britain is represented by a frontal zone with outbreaks of rain. This situation remains in situ until late on Thursday when all models show a cold front moving SE across Southern areas followed by 36-48 hrs of sunshine and showers with some heavy showers with hail and thunder in places. On Sunday a drier and brighter spell develops as a ridge sinks South over Britain. With cold air from Friday all areas are at risk of frost overnight on Friday night and more especially on Saturday night.

GFS then shows Low pressure both moving slowly South from the North and North from the South early next week, a complex pattern which evolves into an unsettled and showery first half to the week with temperatures rising slowly with time. This more marked later in the week as Low pressure weakens and is replaced by developing High pressure over the UK with fine and sunny conditions for most as we enter the Bank Holiday weekend. The rest of the run looks broadly dry as High pressure migrates steadily towards Scandinavia with a fresh East wind developing over the South with low cloud and mist shrouding North sea Coasts making it's way all the way over to the West in the strength of the breeze at times, burning back somewhat through the daytime's. The NW would see the best of prolonged sunshine and warm temperatures for this part of the world whereas in the breezy misty South it could stay cold where low cloud lingers.

The GFS Ensembles show a colder snap over the weekend and start of next week before a slow recovery to average uppers occur later next week and beyond as High pressure rebuilds. Rainfall amounts will generally be small away from the heavy showery spell at the weekend and early next week.

The Jet Stream shows the flow continuing East or SE over the UK for the time being before the flow weakens as we move towards next weekend.

UKMO has Low pressure to the North and South on Monday with the UK sandwiched in between with some dry weather. Warm, humid weather is close by to the SE and with the colder air over the UK an area of heavy, thundery rain could hit the SE on Monday should the pattern develop as shown.

GEM too keeps the South of Britain in a 'Col' area between low pressure to the North and South and High pressure to the West and East. Some rain is likely in the North but the South is harder to call as is usual in 'Col' conditions showers can quickly breakout while at other times it can stay completely dry. Temperatures do look to be recovering somewhat in the South though as we move into next week.

NAVGEM looks broadly similar with the North looking most likely to see rain as we move into next week.

ECM tonight looks fairly poor for summer warmth as it looks like a general slack area of low pressure will cover the UK early next week and probably longer with light Northerly winds carrying some potent thunderstorms and heavy showers gently South across the nation each day. With generally chilly uppers in place and showers decaying at night frost is highly likely in places under clear overnight skies. Towards the end of the run pressure builds slowly with showers or storms becoming restricted to more Southern areas.

In Summary it's much as this morning with regard to the course of events beyond the weekend. It doesn't look particularly good in the short term but as the week progresses there are quite a few signs from all of the models and the ensembles that High pressure will want to build across or near to the UK settling things down but conditions at the surface will be determined by the position of the High cell and the source of airflow blowing across the UK. It's more runs needed I'm afraid tonight before we know for certain the longer term prognosis.

Edited April 23, 2013 by Gibby

[ANYWEATHER]

Indeed and looking quite dry for a protracted period well into May too.

http://modeles.meteociel.fr/modeles/gens/graphe_ens3.php?x=263&ext=1&y=98&run=12&runpara=0

Only the odd showery day or two to supply any rain in the next 2 weeks by the looks of it.

The PV now on the wane as we would expect with high pressure starting to look likely around Europe and Scandinavia in early May.

http://modeles.meteociel.fr/modeles/gens/run/gens-21-1-240.png?12

A much different outlook to this time last year.

TBH, some folks and not generally though will get a lot of precip in the days ahead with this set-up!

[weather_it_will]

It looks like a cool down is imminent.

The models do not seem to indicate any real warm up until end of first week in May, but even that is not guaranteed.

If previous years are to go by, April has been the best month for warmth and dry weather, so it's not looking good for the remainder of the year.

Edited April 23, 2013 by Deep Freeze

[SP1986]

The model output is fairly benign at the moment with little interest.

 

I thought I'd pull this chart out therefore... who is losing faith in the GFS?

 

[Frosty.]

I think there is lots to be optimistic about and something for everyone on the latest 12z runs. For a start, this coming weekend looks reasonable for most of the uk with a ridge bringing increasingly fine and sunny weather after a cold and showery start, saturday being the coolest day of the weekend as there will be more breeze and some showers to clear away but sunday is looking the better day with temps recovering somewhat after a cold and frosty start. As we go into next week, the weather is set to become more unsettled with a rather cold mixture of sunshine and heavy showers containing hail and thunder with sleet and snow to higher hills in the north, the southeast corner of england may be a little milder early next week for a time. From around midweek or soon after, the trough which brought the cold showery weather looks like filling and moving away to the northeast and pressure then rising across the uk with the showers risk fading with longer sunny spells and mainly dry conditions but with overnight slight frosts, as time goes on, the weather pattern becomes generally anticyclonic for all areas and probable above average sunshine totals and with the frost risk gradually diminishing but we have some unsettled and chilly weather to work our way through before we reach that fine may sunshine we are waiting for.

 

So, enjoy the warmth in the south tomorrow and thursday before the rain arrives from the north and then it looks like friday will become a colder day with sunshine and showers with a risk of hail and thunder and cold enough in scotland for wintry showers on hills.

 

 

[Carlrg]

Reached 21 degrees in London today. If i remember correctly someone's having sock stew for tea.

 

 

 

There's also a chance they will be having sock and chips tomorrow.

 

http://www.meteociel.fr/cartes_obs/comp_panel.php?mode=0&ech=18&size=2

[Mr Frost]

Reached 21 degrees in London today. If i remember correctly someone's having sock stew for tea.

There's also a chance they will be having sock and chips tomorrow.

http://www.meteociel.fr/cartes_obs/comp_panel.php?mode=0&ech=18&size=2

The highest temp in the UK today was 20.5 which equals 68.9 Fahrenheit.

Socks are staying in the drawer for now... :-D

Fed up of this weather IMBY, constant howling wind and showers on and off. Have not got above 14 degrees this year. Oh how I wish for a calm, sunny and warm day, tedious weather currently.

Edited April 23, 2013 by Mr Frost

[johnholmes]

The highest temp in the UK today was 20.5 which equals 68.9 Fahrenheit.

according to Wx Online these are the max values for today?

Stations: 188 Temp.

Hereford/Credenhill (76 m) 22.0 °C

London Heathrow Airport (25 m) 21.0 °C

Gravesend Broadness (3 m) 21.0 °C

London St James Park (5 m) 21.0 °C

Gatwick Airport (62 m) 21.0 °C

Charlwood (58 m) 21.0 °C

re the 20.5C that will be thrown to the odd number as is WMO practice so the rounded max will be 21C

Edited April 23, 2013 by johnholmes

[Mr Frost]

I had no idea that temps were rounded, you learn something new every day!

Heathrow hourly observations

Tabular (last six hours)Graphical (last 24 hours)

Date Time Weather Temp Wind Vis Pressure / trend

Dir Speed Gust

Tue

23

Apr 1500 18.9 °C W 11 mph 28 km 1020 hPa, Falling

1600 19.4 °C W 10 mph 26 km 1020 hPa, Falling

1700 20.2 °C W 11 mph 23 km 1020 hPa, Falling

1800 20.5 °C WSW 9 mph 25 km 1020 hPa, Falling

1900 19.8 °C W 10 mph 30 km 1020 hPa, Rising

2000 17.6 °C W 9 mph 30 km 1021 hPa, Rising

2100 16.6 °C W 7 mph 30 km 1022 hPa, Rising

Ah well... :-)

[Paul]

We're getting way off of the model output here, so perhaps the best spot to continue discussion about the temperatures today would be in today's weather discussion thread here:

http://forum.netweather.tv/topic/76441-tuesday-23rd-general-weather-chat/

[Purga]

Will the colossal cool down continue with the GFS 18z?

 

Looks pretty much the same so far.

Edited April 23, 2013 by Purga

[harryc]

Will the colossal cool down continue with the GFS 18z?

 

Looks pretty much the same so far.

OMG here we go!

[Purga]

-8 uppers getting very close to the north of Scotland

 

Just missed this time but -4s over much of the country

 

Cold uppers across the whole country for virtually all of the 18z run.

Edited April 23, 2013 by Purga

[mushymanrob]

think some are ramping up this coming cool down to suggest its something extra-ordinary. the first bite, thurs pm/fri takes temps back down to average (according to carole kirkwood on tv this morning), the second bite early next week reduces temps to below average.... big deal! nothing unusual there for mid spring... yes there might be a touch of frost overnight but by the time most of us get up itll be melted ( chart predictions of -6c are ridiculous) . cool fresh showery days in a warm sun is fine by me. it might not be bbq weather but so what?

[IDO]

Strong indications, at last, that the UK trough, from Friday onwards, is a transient feature, around five days, and looking a weak affair as well. Pressure rise from there, for seven days plus. The GEFS highlights this:

A slow return to average late April/early May uppers:

Last night's ECM ensembles also showing a more settled outlook (precip chart):

...not including the outlier op run. The ECM mean temps showing average output from D10-15:

The high looks like being close to the UK and meanders north'ish on some of the recent runs, so this needs to be clarified with further output. A good mix of Spring weather likely in the next two weeks.

[Frosty.]

There remains a strong signal for a very anticyclonic spell to evolve through early may and perhaps continue for at least a few weeks, just looking at the gfs 00z in FI shows high pressure not only over the uk, but also covering the atlantic and also scandinavia so it could be a long dry spell on the way. In the meantime, friday brings colder and showery weather to all areas with a big drop in temperature for southern england compared to the 20c today and tomorrow, perhaps even 21c but down to 10-11c on friday. The weekend becomes less showery as an atlantic ridge slides southeast so a lot of dry and sunny weather around but cool, especially on saturday once the residual showers have cleared, there will also be overnight frosts from friday night onwards but especially further north, into next week, it becomes colder and showery again, similar to friday with hail and thunder and the showers will be wintry on northern hills but from the middle of next week a nw-se split with pressure rising to the south and east so settling down here but low pressure beginning to affect nw britain with wind and rain returning, however, the unsettled weather in the northwest is likely to drift away towards iceland/greenland with an increasingly blocked and anticyclonic spell taking complete control of our weather from early may onwards.

[Frosty.]

I noticed the bbc map for friday shows no showers for the majority of the uk, just the residual rain clearing from the southeast but the gfs 00z precip maps show showers brewing up through the day, some becoming heavy and widespread through the afternoon and evening but then dying out overnight, less widespread showers on saturday and sunday looks fairly sunny and mainly dry across the southern half of the uk, especially the midlands and south but cloudier with a few showers across northern britain.

[Gibby]

A little late this morning but please remember you can always catch my analysis over on my website from just after 8am and 8pm each day if for any reason I'm too busy to post it across to here. Just go to the home page and select link to Model analysis. Although I'm in a quiter phase of work at the moment I envisage getting busy again with my craft business once summer kicks in, especially at the weekends so I might miss a few reports here now and then. Sorry.

Good morning everyone. Here is this morning's report on the midnight outputs from GFS, UKMO, GEM, NAVGEM and ECM for today Wednesday April 24th 2013.

All models show a slack Westerly flow over the UK with an undulating trough lying West to East over Central areas. To the South the air is warm and moist with hill fog and some sunny spells and to the North the air is colder and fresher with showers. Through the band itself cloud and rain will prevail for the next 24 hours when the models show the band accelerating SE across Southern areas leaving all areas in a cold and showery Northerly flow between High pressure to the West and low pressure to the East and later SE. Showers will be heavy over the weekend with hail and thunder in places and snow over Northern hills with frosts at night quite widespread. Sunday shows a ridge moving South over Britain killing many of the showers off and giving a reasonable day with sunny spells. Winds then freshen from the North in the North later Sunday leading us into next week's events.

GFS then shows a deep Low to the north carrying a cold front South on Monday with rain then showers for Monday and Tuesday. By midweek another ridge slips SE over the UK with a dry and bright day Wednesday. By Thursday a new Low to the NW clouds things up here with occasional rain while the South stays drier and becomes somewhat milder. FI today shows pressure building strongly near the UK and eventually over Scandinavia with dry weather extending to all with some good sunny spells though Southern and Eastern areas will be plagued by mist and cold low cloud filtering in from the North sea later, slow to clear in the daytime's.

The GFS Ensembles today show a lengthy chilly spell taking care of the first week with a steady rise in uppers later as winds settle more favourably from a warmer quarter. Although rainfall is scattered about throughout the run no huge amounts are shown anywhere with most of it falling in the form of showers meaning some see a lot and others see very little or nothing.

The Jet Stream shows the flow continuing across the UK for a few more days before a trough is set up taking the flow South to the West and North to the East of the UK into next week.

UKMO today shows Low pressure over Scandinavia, France and Spain with a chilly NNE flow over the UK. Despite a shallow ridge over the UK showers would be likely, some heavy through the daytime. In this setup frost would continue to be a risk overnight.

GEM today shows Low pressure never too far away from the UK next week settling down to the west of the UK by the end of the run. After a cold and showery start to next week things would slowly warm up somewhat as winds turn more to the SW with time and pressure recovers.

NAVGEM shows Low pressure to the South engaging with the cold flow around the Scandinavian low pressure maintaining a rather cold and showery theme across the UK while keeping High pressure out to the West. As well as some heavy daytime showers night times would be cold with frost a possibility.

ECM finally also keeps the UK rather cold and showery for much of next week as Low pressure continues to centre just to the East of the UK until the final days of the run when Low pressure slips across the North backing winds more towards the West. This would mean further showers in places but after the frost risk through the week this at least should be removed by the weekend with daytime temperatures recovering somewhat too, especially in the brighter South.

In Summary the weather next week looks like staying on the cold side with some heavy showers at times. There will be some days where many places stay dry and bright with few showers and some bright and warm feeling sunshine but where they occur hail and thunder is a distinct possibility with some snow on Northern hills and the continuing unwelcome risk of night frosts. With time there are signs of things warming up to some degree as high pressure begins to play a bigger role in our weather.

[Summer Sun]

-8 uppers getting very close to the north of Scotland

 

Just missed this time but -4s over much of the country

 

Cold uppers across the whole country for virtually all of the 18z run.

 

Purga uppers during the day at this time of year mean very little given how strong the sunshine is now day time temperatures for many will still get into double figures as this picture from Frosty shows. And when your in the sunshine it will feel very pleasant

 

http://forum.netweather.tv/index.php?app=core&module=attach&section=attach&attach_rel_module=post&attach_id=168909

 

Yes we're likely to have night time frosts but as I told you yesterday thats nothing unusual for this time of year its a pain for growers but its not as if its a rare thing as it isn't

 

Anyway back to the models and GFS has its continued hints of a pressure rise as we move towards the first full week of May again this morning http://www.null/ds/gfs.htm

Edited April 24, 2013 by Gavin.

[Harve]

think some are ramping up this coming cool down to suggest its something extra-ordinary. the first bite, thurs pm/fri takes temps back down to average (according to carole kirkwood on tv this morning), the second bite early next week reduces temps to below average.... big deal! nothing unusual there for mid spring... yes there might be a touch of frost overnight but by the time most of us get up itll be melted ( chart predictions of -6c are ridiculous) . cool fresh showery days in a warm sun is fine by me. it might not be bbq weather but so what?

Indeed. Northerlies are probably the most reliably sunny direction for the weather to come from, and any sunny spells at this time of year are going to be reasonably warm (even if they are interspersed by rogue wintery showers).

[Purga]

ECM carries on the chilly theme again this morning

 

Jump forward a few days

 

Cold uppers

 

 

 

And looking unsettled as well.

The ensemble mean looks cool and unsettled with frost likely

 

The GFS anticyclonic spell in FI looks rather isolated.

[Purga]

( chart predictions of -6c are ridiculous)

Really? This chart on 11th May in 1941 produced a record low nightime temp of -9.4C

 

It looks a lot less potentially cold than some we are seeing.

Edited April 24, 2013 by Purga