Model Output Discussion 12z 03/04/13

[Cheshire Freeze]

Yes it does look like the GFS has made a step towards the ECM on the 18z.

The 18z GFS paints an interesting picture for next weekend.

On the face of it there would appear to be the suggestion of some elevated plume like storms. Though being so early in the season I'm sceptical over how likely this is (GFS would suggest it's a low probability but a possibility nontheless).

Then the cold front passage and the risk of some very strong winds

That's a bank 100x over for me.

Edited April 7, 2013 by CreweCold

[Panayiotis]

The 18z GFS paints an interesting picture for next weekend.

On the face of it there would appear to be the suggestion of some elevated plume like storms

Then the cold front passage and the risk of some very strong winds

That's a bank 100x over for me.

It is very interesting especially for the SE where I would expect most if any thunderstorms would develop. Edited April 7, 2013 by Panayiotis

[Cheshire Freeze]

It is very interesting especially for the SE where I would expect most if any thunderstorms would develop.

I would expect some fairly 'active' CF activity in that set up with, as you say, perhaps some elevated storms in the SE as the nose of humid air gets impeded by the CF to the W. Any surface based imports would be swiftly killed off by the lower than average SST profile.

Edited April 7, 2013 by CreweCold

[summer blizzard]

Another beauty of an FI..

[Jezzer]

Another beauty of an FI..

Now that would be nice!

[Frosty.]

The Gfs 00z brings an early taste of summer later in FI, spanish plume type conditions with temps hitting 24-25c in the midlands but much cooler and wetter further north and west. We have a lot of unsettled weather between now and then though with low pressure(s) sweeping across the uk with gales at times, next weekend could be very windy but also much milder, the mild air sweeping north across scotland by sunday so the very cold spring will be last to depart northern scotland. Beyond the weekend it remains wet and windy at times but mild and then later next week we see high pressure building from the south with more settled and warmer weather extending northwards but nw britain probably remaining unsettled with temps closer to average.

Edited April 8, 2013 by Frosty039

[mushymanrob]

after a quite miserable week ahead with wind, cloud and rain at times, there are continuing hints of something significantly warmer for a day or two next sunday. the general theme the ecm and gfs suggests is that beyond this week there will be a more mobile regime, changable, westerly, but with an option quite close for something much warmer to develop. of course this is in fi, but its a plausable evolution . both the gfs and ecm show that this might happen in some form, although they differ in timing and evolution. hopefully they are onto something and that might become apparent in a few days, but for now, its fi eye candy.

[Summer Sun]

So this morning we still have GFS back tracking to NAVGEM with a very deep depression crossing to the west of Ireland with heavy rain and strong winds from many

And UKMO delivers some warm southerly winds for a time during the early hours before the low moves through

Edited April 8, 2013 by Gavin.

[Kentspur]

Our area was the snowless zone all winter so hopefully we will go some way to makin up for this by recording the highest warm spell temperatures as we often do:-)

[Summer Sun]

So just as GFS drops the idea of something warm and settled ECM jumps on board by send the low further west the further east you are the better chance you'd have of seeing something warmer and sunnier

By Monday its only NW Scotland which misses out but even here temperatures will be higher than of late

ECM ends with a much better pattern than of late

All this would bring a rapid thaw of the remaining snow on high ground

Edited April 8, 2013 by Gavin.

[Frosty.]

The Ecm 00z shows very mild air sweeping north across the uk by next sunday, it could even be classified as warm in central and eastern areas for a few days before a very brief cooler blip spreads east but with another pulse of much milder/warmer air waiting in the wings to push northeast beyond T+240. This means the very cold spring which will continue across scotland all this week, will be blown away by sunday with a rapid thaw setting in for the scottish mountains by sun/mon and then through next week, so 1 more week of excellent skiing conditions but then the big thaw with the increased dangers that brings.

Edited April 8, 2013 by Frosty039

[Gibby]

Hi everyone. A new working week an what doe the models hold in store for us over the coming couple of weeks. Here is my view of the 00zs from GFS, UKMO, GEM, NAVGEM and ECM for today Monday April 8th 2013.

All models are fairly agreed on the pattern of events through this week as Low pressure weakens and moves East over the South of England or the English Channel in the coming 4-5 days. there influence for the North will be limited with the South seeing the majority of the rain from these though even here much of the rain will be light, especially in the first few days. it will stay rather cold and any precipitation be it in the form of showers or the more general rain in the South could well fall as sleet or snow still on Northern hills. By the end of the week a quieter spell of weather looks likely as the Low exits East and brings a slack NW flow over Friday and possibly Saturday with pressure rising strongly from the South.

GFS is rather different to this general theory holding Low pressure close to the South of the UK through Friday and Saturday with further rain at times with a strong and blustery Southerly flow developing over the weekend as a very deep depression winds itself up in the eastern Atlantic. This swings NE to the NW of Scotland with heavy rain and strong winds for all as troughs swing West to East in the flow. FI then sets up a SW flow for several days with rain at times in temperatures close to average before pressure builds later next week from the South, settling the weather down and drawing up some very warm air from Southern Europe towards the end of FI with the faintest hint of the first thundery disturbance of the season drifting slowly north across France in the final frame.

The GFS Ensembles show the continuing slow rise in uppers through this week eventually to levels somewhat above the long term mean. There is some rain shown through the transitional period over the next week or so before rainfall becomes less common. The very warm weather depicted by the operational at the very end of the run is not supported by any other member so can be largely discounted unfortunately.

The Jet Stream shows a continuing trend to move it gradually further and further north towards a more typical position for Spring as it lifts NE towards Scotland through next week bringing the South at least on the warmer side of the flow. It does take quite a while though with this week seeing very little evidence of change at the surface anywhere.

UKMO has next weekend with a developing strong SE flow over the UK. It will probably feel rather chilly out in the wind and though a lot of dry and bright weather is possible in the East troughs would be knocking on the door of the West with rain edging slowly East later.

GEM has the axis of the depression to the West rather differently sending strong to gale SW winds and rain across the UK at the start of next week which continues for the rest of the run as further troughs follow in the maintained strong SW flow.

NAVGEM today is broadly similar to GEM in bringing a strong SW flow to start next week before pressure builds from the south midweek with warmer and less unsettled conditions edging slowly North.into Southern England midweek though in the time scale conditions would remain largely windy and cloudy for most.

ECM today shows the deep Low at the end of the weekend further to the West in the Atlantic and subsequently meaning less of the UK is seriously affected by it with the north and west seeing the eventual brunt of wind and rain as it passes to the NW. Further to the South and East pressure is building over the near Continent and this should eventually send warmer and more settled weather into these areas at least later in the week.

In Summary today a pattern is beginning to form. This week will stay largely on the chilly side with some rain at times especially in the South with some snow still over Northern hills. By the weekend a change to a milder if rather strong Southerly flow looks likely as a deep depression winds up to the west of the UK. This pumps up High pressure over the near continent sending much milder conditions into the UK from the South as we move through next week. The extent and longevity of this warmer weather will depend on how the Atlantic behaves and it's interaction with it but it does look at long last as though the weather may get out of the rut of Southward locating depressions and Jet Stream to positions more akin to the time of year we are now in. So if that transpires conditions should develop much more April like next week.

[NorthNorfolkWeather]

The evolution post 144 seems to be the most important aspect this morning

at 144 we have UK showing the eastern side of the country basking in real warmth

whereas the ECM has a deeper low, in about the same spot

GFS has a dartboard low just off Ireland

Post that time going out to t192 the GFS and ECM have diverged enormously,

GFS has the low totally in charge with small secondary lows running south of it over the UK, giving what could be high rainfall totals over the south of the country

ECM has the low tracking much further North with a warm southerly flow over all of the country with a potentially thundery breakdown from the south

[West is Best]

Message for John H as I can't PM you.

Hi John,

Hope all is well with you. It's that time of year again when my running friends start looking nervously at the weather. I'm wondering if once again you could possibly do us a dedicated forecast for the London marathon? The event starts at 9am on Sunday 21st April.

Ideal conditions are 11C, dry but cloudy! Things to look out for are the amount of sunshine, which at this time of year can make a huge difference because running in the sun negates a lot of the official shade temps, wind direction and strength (best case is easterly, worst is a strong westerly for the final miles), and rain. Actually rain's not that horrendous providing it's not lashing down.

If you're able to do a forecast and keep it updated, with all due caveats, it would go down fantastically with runners all over the country and would be very appreciated.

All best,

WIB

Edited April 8, 2013 by West is Best

[Frosty.]

The Gfs 06z shows a wild weekend ahead with gale to severe gale force SWly winds due to a vigorous depression centred to the west of ireland, at least that depression will sweep mild air to all parts of the uk by sunday and it also looks warm for southern, central and eastern areas with temps reaching 18-19c 65f in places with a lot of sunshine on sunday but duller with some rain for northern and western areas, by early next week the 6z shows cooler atlantic air pushing across the uk. shunting the warm air away to the east but temps will become around average which is around 12-13c so it will still feel mild but it remains unsettled with wet and windy spells well into next week, then we see a change, the same change which occured on the gfs 00z with high pressure pushing north into the south of the uk with increasingly warm and summery fine conditions with temps well into the 70's f, some areas reaching 24-25c, such as the midlands and a general 21-22c elsewhere across southern britain but rather cooler and more average for northern uk, the hope is that the anticyclonic spell will then extend further north to bring a nationwide warm and fine spell eventually.

[Methuselah]

Sorry I can't resist it. 510 dam about to reach N Scotland 1 week before May begins......Oh behave yourself GFS!

That'll sure have the gutter press excited!

Overall though, it's hard to call the model outlook anything other than an improvement?

[Milhouse]

My impression looking at the big 3 is we are about to enter a breezy, mild and showery period from Saturday onwards with low pressure taking a noticeably different track to what weve been used to i.e sw-ne rather than w-e or nw-se in some cases. It seems to be the generally higher pressure over Europe that will help in producing the tilt in the jet stream. The renewed injection of high pressure northwards at the weekend should serve to reinforce this block. It does look rather unsettled at times though with the GFS showing the chance of some lively squally showers and brisk mild w-sw winds. ECM more settled.and becoming warm from 144h onwards.

[johnholmes]

Message for John H as I can't PM you.

Hi John,

Hope all is well with you. It's that time of year again when my running friends start looking nervously at the weather. I'm wondering if once again you could possibly do us a dedicated forecast for the London marathon? The event starts at 9am on Sunday 21st April.

Ideal conditions are 11C, dry but cloudy! Things to look out for are the amount of sunshine, which at this time of year can make a huge difference because running in the sun negates a lot of the official shade temps, wind direction and strength (best case is easterly, worst is a strong westerly for the final miles), and rain. Actually rain's not that horrendous providing it's not lashing down.

If you're able to do a forecast and keep it updated, with all due caveats, it would go down fantastically with runners all over the country and would be very appreciated.

All best,

WIB

Been away for 3 days so will clear my pm box.

Too early to even make any guess let alone forecast but will do something by this weekend on a provisional basis. If I forget please remind me.

[Milhouse]

By the middle of the week low pressure out in the Atlantic will start to usher in some slightly milder air initially to southwestern parts. So before the proper warm up comes at the weekend southern parts should see temperatures approaching average vaules. One more day of brisk raw easterlies to come tomorrow for northern England and Scotland before winds fall lighter but continue to come from a slight east direction. Then its all change on Saturday and much milder air swamps the UK.

Edited April 8, 2013 by Milhouse

[ANYWEATHER]

By the middle of the week low pressure out in the Atlantic will start to usher in some slightly milder air initially to southwestern parts. So before the proper warm up comes at the weekend southern parts should see temperatures approaching average vaules. One more day of brisk raw easterlies to come tomorrow for northern England and Scotland before winds fall lighter but continue to come from a slight east direction. Then its all change on Saturday and much milder air swamps the UK.

Unfortunately though we will have to endure cloud wind and rain, so the milder weather will not be fully realised by many!

[-uksnow-]

Huge discrepencies between UKMO + GFS at T96

UKMO:

Has us in a slack N/NE'rly flow, perhaps some storms about? Also has two separate lows, one to the NE of scotland and one straddling in the mid atlantic

GFS:

Much deeper (965mb) low in the atlantic (now why doesnt that suprise me?) with low pressure hitting the UK and disrupting, followed by heights building over Europe by 120 with a southerly flow

pumping up some warmer uppers

lets see if UKMO agrees...somehow i think it wont, not by 120 at least..

[Summer Sun]

GFS is keeping the low slightly further west on this run wet and windy in Ireland and western England warmer and more settled for eastern England

[-uksnow-]

UKMO not quite as fast to build heights over Europe and clear the low to the NE, but its not half bad.

[Summer Sun]

UKMO continues to promote southerly winds

GFS at the same time

[Zenarcher]

That deep low in the Atlantic is slightly further West on the GFS 12z run compared to the 06z thanks to high pressure pushing in over the UK and budging the low further West.

Here's the difference between the two runs,

Edited April 8, 2013 by weathermaster