12z Model Comparisons

[Thundery wintry showers]

12Z Model Comparisons: Tuesday 14th March 2006.

T+96 (to Saturday 18th March)

GFS: 1040mb Greenland High and light easterlies over Britain, northerlies moving into Scotland. 1000mb low over NE Scandinavia.

UKMO: Extremely similar to the GFS, low over NE Scandinavia a bit less deep at 1005mb.

ECMWF: Again as GFS and UKMO, this time with 1000mb low over NE Scandinavia.

NOGAPS: 1055mb Greenland High, easterlies over Britain, 990mb Scandinavian Low, the same setup as on the other three models with northerlies moving into Scotland.

JMA: 1040mb Greenland High, slack 1010mb lows over N Scandinavia, easterlies over Britain, northerlies moving into Scotland.

GEM: 1040mb Greenland High, 1000mb low over N Scandinavia, easterlies but changing to a northerly over Scotland and N England.

Complete agreement that a northerly regime will start to push south at T+96.

T+120 (to Sunday 19th March)

GFS: 1040mb Greenland High, 1030mb Icelandic High, 995mb low over E Scandinavia and NE winds over Britain.

UKMO: 1035mb Greenland High, 985mb low over E Scandinavia, easterlies over Britain and the main influx of northerlies to the east of Britain.

ECMWF: 1040mb Greenland High, 995mb Baltic Low and north-easterly winds sweeping across the British Isles.

NOGAPS: Entire Grid Undefined.

JMA: 1040mb Greenland High, 990mb low over Cent Scandinavia, with slack north-easterly winds over Britain, as opposed to the potent, cold showery north-easterlies shown by GFS and ECMWF.

GEM: As JMA but with 990mb low over East Scandinavia. Slack NE winds over Britain.

ECMWF and GFS go for a very potent looking north-easterly, UKMO keeps us in easterlies, JMA and GEM go for a slack and relatively mild north-easterly.

T+144 (to Monday 20th March)

GFS: 1045mb Greenland High, 990mb low over E Scandinavia with 1000mb trough over W Norway. Northerly winds over Britain.

UKMO: 1040mb Greenland High, 985mb low over E Scandinavia, northerlies over Britain.

ECMWF: 1035mb Greenland High, 990mb low over E Scandinavia with 1000mb trough over W Norway. Northerly winds over Britain.

NOGAPS: 985mb low over France, 1005mb trough over W Norway, 1055mb Greenland High and strong north-easterlies for Britain.

JMA: 1045mb Greenland High, slack N/NE winds over Britain, 980mb low over SE Scandinavia.

GEM: 1055mb Greenland High, 990mb low over E Scandinavia, northerlies for Britain.

Northerlies look to be the outlook at T+144 although NOGAPS goes for a north-easterly, and JMA shows the northerlies only just reaching England.

[Thundery wintry showers]

12Z Model Comparisons: Wednesday 15th March 2006.

T+96 (to Sunday 19h March)

GFS: 1040mb Greenland High, 990mb low over E Scandinavia, light easterlies for Britain.

UKMO: 1045mb Greenland High, 985mb low NE Scandinavia, light NE winds for Britain, not especially cold.

ECMWF: 990mb low over NE Scandinavia, 1040mb Greenland High and light north-easterlies for Britain.

NOGAPS: 1050mb Greenland High, 995mb lows over N Scandinavia and the North Sea, NNE winds for Britain, and quite cold and potent looking.

JMA: 990mb low over NE Scandinavia, 1050mb Greenland High, NE winds for Britain but not looking especially cold.

GEM: 1045mb Greenland High, 995mb Scandinavian Low, light easterly winds over Britain swinging around to the north in Scotland.

Complete agreement on a Greenland High and Scandinavian Low, but disagreement on the precise wind direction over Britain. Indications are that the cold Arctic air won't have reached us by Sunday.

T+120 (to Monday 20th March)

GFS: 1050mb Greenland high, 985mb low over E Scandinavia, cold northerlies over Britain.

UKMO: 1045mb Greenland High, 985mb low over E Scandinavia and also a 995mb low just off Denmark, with cold NE winds over Britain.

ECMWF: 1040mb Greenland High, 990mb low over NE Scandinavia with a low also over the Baltic regions, cold NE winds over Britain.

NOGAPS: 1055mb Greenland High, 990mb low over SE Scandinavia, northerlies over Britain.

JMA: 1055mb Greenland High, 990mb low over E Scandinavia, northerlies over Britain.

GEM: 1045mb Greenland High, 985mb low over NE Scandinavia, but northerlies still only penetrating into Scotland, just a moderately chilly NE flow for most.

All models bar GEM expect Arctic air to be upon us by Monday, with UKMO and ECMWF going for a north-easterly, others going for a northerly. Sunshine and snow showers the likely outcome.

T+144 (to Tuesday 21st March)

GFS: 1050mb Greenland High, 990mb low over Cent. Scandinavia but also 1000mb trough in northern North Sea, more northerlies for Britain.

UKMO: 1055mb Greenland High, 990mb low over SE Scandinavia with 1005mb trough over W Scandinavia, NNW winds over Britain.

ECMWF: 1055mb Greenland High, 990mb low over Russia, northerlies over Britain.

NOGAPS: 1055mb Greenland High, 995mb low generally over N Scandinavia, impressively cold northerlies over Britain.

JMA: 1055mb Greenland High, 990mb low over E Scandinavia, NNW winds over Britain. Similar to UKMO.

GEM: 1050mb Greenland High, 985mb low over NE Scandinavia, 1005mb low over W Scandinavia and NNW winds for Britain.

Outlook is for a cold Arctic dominated regime and with pressure shown as reaching 1050-1055mb over Greenland, signs that the northerly could be every bit as potent and long-lasting as the one at the beginning of March. UKMO, JMA and GEM finish with NNW winds and probably limited shower activity; other models suggest something more potent.

[Thundery wintry showers]

12Z Model Comparisons: Thursday 16th March 2006.

T+96 (to Monday 20th March)

GFS: 1055mb Greenland High, 990mb low over E Scandinavia, light easterlies for most of Britain but northerly in NE Scotland.

UKMO: 1050mb Greenland High, 980mb low E Scandinavia, light NNE winds over Britain.

ECMWF: 1050mb Greenland High, 990mb low NE Scandinavia, easterlies over most of Britain but northerly in NE Scotland.

NOGAPS: 1050mb Greenland High, 985mb low E Scandinavia, light NNE winds over Britain.

JMA: 1060mb Greenland high, 985mb low NE Scandinavia, light easterlies over Britain.

GEM: Unavailable

All models seem to be agreed that an Arctic blast is waiting in the wings.

T+120 (to Tuesday 21st March)

GFS: 1050mb Greenland high, 990mb low over Scandinavia, 1015mb weak high over Britain, cold with almost no wind, just light westerlies for N Scotland.

UKMO: 1045mb Greenland High, 985mb low over NE Scandinavia and also a 1005mb low over W Scandinavia. Moderate northerlies over Britain.

ECMWF: 995mb low over NE Scandinavia, 1050mb Greenland High, light easterlies over Britain.

NOGAPS: 1050mb Greenland High, 985mb low NE Scandinavia, 995mb trough W Scandinavia, and moderate NNW winds over Britain.

JMA: 990mb low up over N Scandinavia, 1060mb Greenland High, 1010mb low off W Scotland, 1020mb high over eastern Britain.

GEM: Unavailable

Some disagreement on the models on whether we will get a northerly coming straight in, or a weak high developing over the country.

T+144 (to Wednesday 22nd March)

GFS: 1055mb Greenland High, 1000mb low over southern Norway, 1015mb high to the east of Britain and light southerlies over Britain.

UKMO: 1045mb Greenland High, 1000mb low over SW Norway, north-westerlies over Britain.

ECMWF: 1050mb Greenland High, 1010mb low off N Scotland, 1015mb high right over Britain.

NOGAPS: 1045mb Greenland High, 995mb low over S Norway, north-westerlies over Britain.

JMA: 1055mb Greenland High, 980mb low over SW Norway with viciously tight isobars there, north-westerlies over Britain.

GEM: Unavailable

The disagreement continues- a clear split, GFS/ECM vs. UKMO, NOGAPS and JMA.

[Thundery wintry showers]

12Z Model Comparisons: Friday 17th March 2006.

T+96 (to Tuesday 21st March)

GFS: 1050mb Greenland High, 985mb low over NE Scandinavia, light easterlies over Britain.

UKMO: 1050mb Greenland High, 980mb low NE Scandinavia, light easterlies over Britain.

ECMWF: 1045mb Greenland High, 985mb low NE Scandinavia, 1010mb trough W Scandinavia, light easterlies over Britain.

NOGAPS: 1055mb Greenland High, 980mb low NE Scandinavia with 1005mb trough over W Scandinavia, light easterlies in England & Wales and northerlies in Scotland.

JMA: 1060mb Greenland high, 985mb low NE Scandinavia, 1005mb trough over W Scandinavia, light easterlies over Britain.

GEM: Unavailable. What on Earth happened to the 12Z GEM runs?

Apart from NOGAPS, all models go for light easterlies.

T+120 (to Wednesday 22nd March)

GFS: 1050mb Greenland high, 990mb low over N Scandinavia, 1010-1015mb high over Britain.

UKMO: 1045mb Greenland High, 985mb low over N Scandinavia, 1020mb high over Britain.

ECMWF: 1045mb Greenland High, 990mb low NE Scandinavia, 1020mb high over Britain.

NOGAPS: Entire Grid Undefined.

JMA: 1065mb high over Greenland, 990mb low over NE Scandinavia, 1020mb high over Britain.

GEM: Unavailable

GFS goes for a weaker high over us than the other models.

T+144 (to Thursday 23rd March)

GFS: 1050mb Greenland high, 990mb low NE Scandinavia, weak 1015mb high to the east of Britain, 985mb Low at around 47N, -20W. ESE winds picking up.

UKMO: 1045mb Greenland High, 995mb low N Scandinavia, weak 1020mb high to SE of Britain, 985mb low at around 48N, -25W, with little wind over Britain.

ECMWF: 1040mb Greenland High, 1020mb high to east of Britain, 990mb low NE Scandinavia, 990mb low around 50N, -22W, with southerlies over Britain.

NOGAPS: 1055mb Greenland High, 1000mb low over NW Scotland, 1010mb high SE England, south-westerlies of cold origin over Britain.

JMA: 1060mb Greenland High, 995mb low NE Scandinavia, 985mb low around 45N, -28W, and southerlies over Britain.

GEM: Unavailable

Strong disagreement among the models. This is, from a model comparisons point of view, what I want to see- then we can get a proper spread of marks!

[reef]

Thanks again for that Ian. :lol:

One thing that seems quite interesting out of the comparisons is how poorly the Greenland high is predicted. On some days theres a 15-20hPa difference in pressure between models at only T+120, thats a pretty big difference and could explain the chopping and changing of the models (especially lately).

[Thundery wintry showers]

Yes- there has been a lot of variation in the Greenland High lately. I seem to notice that NOGAPS and JMA are probably more guilty of overdoing Greenland Highs than the GFS within the reliable timeframe, so those two may well start dropping marks in the model comparisons results thread.

12Z Model Comparisons: Saturday 18th March 2006.

T+96 (to Wednesday 22nd March)

GFS: 1050mb Greenland High, 990mb low over NE Scandinavia, weak 1015mb high over Britain.

UKMO: 1050mb Greenland High, 990mb low NE Scandinavia, weak 1020mb high over Britain.

ECMWF: 1045mb Greenland High, 985mb low NE Scandinavia, 1010mb slack pressure over Britain, evidence of a shallow low over northern Scotland and shallow 1015mb high just off the Lincolnshire coast.

NOGAPS: 1060mb Greenland High, 990mb low NE Scandinavia, 1015mb high over Ireland and cold northerlies for England, Wales and Scotland.

JMA: 1055mb Greenland High, 990mb low NE Scandinavia, 1020mb high over Britain but 1010mb low off NW Scotland.

GEM: Something seems to be up with their 12Z runs!

The models seem to be generally agreed on a weak high situated over Britain, but NOGAPS goes for northerlies, and ECMWF has the high rather weaker than the other models.

T+120 (to Thursday 23rd March)

GFS: 1050mb Greenland high, 995mb low SW of Iceland, 970mb low at around 48N, -25W, with retreating 1020mb high to the east of Britain and south-easterly winds over Britain.

UKMO: 1045mb Greenland High, 1000mb low stuck over Scandinavia, 970mb low at around 50N, -25W, with retreating 1025mb high to east of Britain and southerly winds over Britain.

ECMWF: 990mb low over NE Scandinavia, 1040mb Greenland High, deep 985mb low around 50N, -20W, with south-easterlies over Britain. Pressure very uniform to the north and east of Britain.

NOGAPS: Strong 1055mb Greenland High and 990mb NE Scandinavia low, 975mb low at around 50N, -20W, and 1015mb high retreating to east of Britain with southerlies over Britain.

JMA: 1055mb high over Greenland, 990mb low over NE Scandinavia, 1010mb trough in North Sea, 980mb low at around 49N, -22W, with north-westerlies over the northeast of Britain, and south-easterlies over the SW.

GEM: Unavailable

The models all agree on our high being pushed away eastwards but the specifics vary. I wouldn't be backing the JMA's trough in the North Sea.

T+144 (to Friday 24th March)

GFS: 1040mb Greenland high, 975mb low at around 52N, -20W, strong ESE winds over Britain.

UKMO: 1035mb Greenland High, 980mb low around 55N, -20W, southerlies over Britain and mild air sweeping in.

ECMWF: 985mb low over SW Britain dominating the picture, with strong easterlies for Scotland and N England, light southerlies further south. Looking mild in the south. Still 1045mb Greenland High.

NOGAPS: 1045mb Greenland High, 980mb low at around 50N, -25W, south-easterlies over Britain.

JMA: 1045mb Greenland High, 980mb low just off SW England, SE winds over Britain.

GEM: Unavailable

Further disagreement between the models, but a breakdown to mild conditions in the south is quite possible by Friday, looking at the ECMWF and UKMO in particular.

[Thundery wintry showers]

12Z Model Comparisons: Sunday 19th March 2006.

T+96 (to Thursday 23rd March)

GFS: 1050mb Greenland High, 980mb low at around 48N, -20W, a weak 1000mb trough over Britain and easterly winds for Scotland.

UKMO: 1045mb Greenland High, 1015mb High just to the east of Britain, 980mb low at around 48N, -22W and southerlies over Britain. Not particularly mild southerlies (polar front still to the south)

ECMWF: 1050mb Greenland High, 1015mb high to the east, very little wind over britain, 980mb low at around 46N, -20W.

NOGAPS: 1050mb Greenland High, 1015mb high to the east, 980mb low at around 46N, -20W, and southerlies over Britain. Cold.

JMA: 1055mb Greenland High, 1020mb high east of Britain, 980mb low at around 48N, -20W, southerlies over Britain. Cold.

GEM: It's back! 1045mb Greenland High, strong 990mb low N Scandinavia, 1015mb high over south-eastern Britain, 980mb low at around 46N, -25W, and light southerlies (cold) developing over Britain.

GFS and ECMWF are out on their own; other models say southerlies but not particularly warm ones.

T+120 (to Friday 24th March)

GFS: 1040mb Greenland high, 990mb low just west of Scandinavia, 985mb low in the English Channel, strong easterly winds for Britain.

UKMO: 1035mb Greenland High, 985mb lows to the SW of Britain, low pressure in charge and strong easterly winds.

ECMWF: 1040mb Greenland High, 995mb low still over N Scandinavia, 995mb low in the English Channel and strong easterlies over Britain.

NOGAPS: 1050mb Greenland High, low just off SW Britain, strong easterlies over Britain.

JMA: 985mb low just to the west of SW England, with 1050mb Greenland High, southerlies over Britain and milder air pushing north.

GEM: 1030mb Greenland High, 975mb low at around 50N, -25W, and strong south-easterlies over Britain turning southerly in the south.

Strong agreement on some kind of mild/cold frontal battleground. The UKMO and ECMWF have backtracked from their mild outlook yesterday.

T+144 (to Saturday 25th March)

GFS: 1035mb Greenland High, 990-995mb lows over Scandinavia, and light easterlies in southern Britain, northerlies elsewhere.

UKMO: 1030mb Greenland High, 995mb low just off East Anglia, easterlies over the north, milder westerlies in the far south.

ECMWF: 1000mb low around the Alps, 1025mb high off western Scotland, cold north-easterly winds over Britain. No pronounced Greenland High but pressure still at 1030-1040mb in the area.

NOGAPS: 1045mb Greenland High, 990mb low over Denmark, northerlies over Britain.

JMA: 995mb low to the east of East Anglia, easterlies for N Scotland, westerlies S England, little wind and low pressure elsewhere. 1040mb Greenland High.

GEM: 980mb low off western Britain, mild SW winds sweeping in and no evidence of a Greenland High any more.

The models are clearly undecided as to whether the mild air or the cold air will win, or whether we will instead end up with a prolonged battleground.

[Thundery wintry showers]

12Z Model Comparisons: Monday 20th March 2006.

T+96 (to Friday 24th March)

GFS: 985mb low off SW England, 1050mb Greenland high, strong easterlies over Britain.

UKMO: 985mb low over W Ireland, 1045mb Greenland high, strong south-easterlies over Britain.

ECMWF: 1040mb High over Greenland, low at 985mb off SW England, strong easterlies over Britain.

NOGAPS: 1045mb Greenland High, 985mb low off SW England, strong easterlies over Britain.

JMA: 1050mb Greenland High, 990mb low off SW England, strong easterlies over Britain.

GEM: 1040mb Greenland High, 975mb low a fair way west of SW England, easterlies in the north, SSW winds for the south.

GFS and ECMWF are out on their own; other models say southerlies but not particularly warm ones.

T+120 (to Saturday 25th March)

GFS: 1040mb Greenland High, 995mb low over SE England, strong easterlies over the rest of Britain.

UKMO: 1040mb Greenland High, weak 1010mb trough over central England, anchored to deep 970mb low in the Atlantic. Easterlies in the north, SW winds in southern England.

ECMWF: 1000mb Baltic Low, 1045mb Greenland High, 1005mb troughs over Scandinavia and light easterlies over Britain with a northerly source. How it gets here from the T+96 evolution, I have no idea.

NOGAPS: The grid is undefined.

JMA: 1005mb Baltic Low, 1020mb High to the north, and easterlies over Britain.

GEM: 990mb low off east Scotland, W winds in southern Britain, N winds in the north.

The disagreement continues. I think this is going to be a very good period for comparing accuracy of the models with some varied marks.

T+144 (to Saturday 25th March)

GFS: 1035mb Greenland High, weak 1000mb trough over central England linked to deep 975mb low in Atlantic. Easterlies in the north, mild showery looking SW winds for the south.

UKMO: 975mb low in the Atlantic, with SW winds sweeping northwards across Britain.

ECMWF: 1030mb high to the north of Britain, deep 975mb low in the Atlantic, SE winds over Britain.

NOGAPS: 995mb Baltic low, 985mb Atlantic low, easterlies in the SW but northerlies penetrating elsewhere.

JMA: 975mb Atlantic low, SE winds over Britain, high pressure just to the NE at 1025mb.

GEM: 980mb low just south of Britain, strong easterly winds.

With anything from biting northerlies and snow showers, to frontal battlegrounds, to high pressure, to mild showery SSW winds being forecast at the three timeframes, it's anyone's guess as to the final outcome. One thing is for certain, it will be interesting doing the results in 4-6 days' time.

[Thundery wintry showers]

12Z Model Comparisons: Tuesday 21st March 2006.

T+96 (to Saturday 25th March)

GFS: 975mb low to the W of Britain, 1040mb Greenland High, mild, bright and showery SSW flow over Britain.

UKMO: 990mb low over W Scotland, showery south-westerlies over Britain, looking mild.

ECMWF: 990mb mid-Atlantic low, 1000mb trough over N Britain, mild, showery looking SSW flow over Britain.

NOGAPS: 990mb Scandinavian Low, 975mb low in Atlantic, light westerlies over Britain.

JMA: 1045mb Greenland high, 975mb low in Atlantic, 1005mb trough over Britain. Mild, sunshine-and-showers type SSW winds spreading north over Britain.

GEM: Not again- there's no 12Z!

Apart from the NOGAPS, the evolution suggests that mild will "win out" with south to south-westerly winds and probably a mix of sun and showers, transferring northwards during the day.

T+120 (to Sunday 26th March)

GFS: 975mb low S of Iceland, secondary 985mb low over N Ireland, southerlies over Britain. Looks cloudy wet and windy.

UKMO: 980mb low W of Britain, 990mb low NW of Britain, SW winds over Britain.

ECMWF: 995mb low over central Britain, with lows at 985mb to the west, easterly winds pushing back into Scotland, still that mild showery SSW flow for southern areas.

NOGAPS: 975mb low in the Atlantic and SW winds over Britain, again probably of a showery nature.

JMA: Two 975mb lows in the Atlantic, SSW winds over Britain.

GEM: No 12Z.

Most models, with the exception of ECMWF, go for continued south to south-westerly winds, probably with sun and showers, though secondary depressions are shown on the GFS.

T+144 (to Monday 27th March)

GFS: An incredibly complicated picture. Lows at 975mb SW of Iceland, 1000mb to the north of Britain and over Scandinavia, and strong 990mb low to the SW of Britain. Westerly winds over Britain, switching to southerly in the south.

UKMO: 990mb lows to the west, S or SW winds over Britain.

ECMWF: Weak 1000mb low over Britain. ESE winds in Scotland, low-index further south.

NOGAPS: 980mb low to the NW with 990mb low also to the north. WSW winds, probably with sun and showers.

JMA: 980mb low in the Atlantic, 995mb low north of Scotland, SW winds, probably sun and showers.

GEM: No 12Z available.

Spring warmth, sun, and showers, together with winds from a south-westerly quarter, looks to be the outlook from the models tonight, although ECMWF disagrees, keeping the cold air in Scotland, while GFS goes for an extremely messy picture.

[Thundery wintry showers]

12Z Model Comparisons: Wednesday 22nd March 2006.

T+96 (to Sunday 26th March)

GFS: 990mb low over central and northern Britain, light winds in these regions. Westerly winds in the south.

UKMO: 995mb low over S Scandinavia, 985/990mb lows in the Atlantic, light winds over Britain but a SSW airflow just to the SW.

ECMWF: Elongated 990-995mb low out into the Atlantic extending to W Scotland. Light winds in Scotland, SW winds over England/Wales.

NOGAPS: 980mb southerly tracking low in Atlantic, 995mb low just west of Britain, SSW winds.

JMA: 985mb lows in Atlantic, 1000mb trough over southern Scotland, with SW winds further south.

GEM: 1030mb Greenland High still at large, 980mb low to the west, cold ESE winds over Britain, but SSW winds in the extreme south.

Apart from GEM, the consensus is that it will be mild with south-westerly winds.

T+120 (to Monday 27th March)

GFS: 985mb low off SW England, 990mb low off the coast of NE England, and low-index pattern over England & Wales but north-easterlies in Scotland.

UKMO: 985mb low in Atlantic, 995mb low off the coast of NE England. Easterlies in Scotland, SW winds over England & Wales.

ECMWF: Still that elongated low over and to the west of Britain. Easterlies for N Scotland, westerlies over S England, low centred at 980mb in the mid Atlantic.

NOGAPS: Undefined.

JMA: Dominated by 980mb low just off western Ireland, and southerlies over Britain.

GEM: 980mb low in mid Atlantic, ESE winds over Britain.

The GEM keeps the cold air locked in, and a few other models have the mild air not quite extending into northern Scotland. Sunshine and showers and mild looks to be the outlook for England and Wales though.

T+144 (to Tuesday 28th March)

GFS: Lows at 985mb over Scandinavia and 1005mb in the mid Atlantic. Northerly winds over Britain.

UKMO: Floppy 995mb low over England & Wales, easterlies in Scotland.

ECMWF: 985mb low over Ireland, easterlies in Scotland, westerlies in S England.

NOGAPS: 985mb low off W Ireland, floppy 990mb low over Britain, easterlies in N Scotland, westerlies in S England.

JMA: 985mb low off W Scotland, low pressure over Britain, easterlies in N Scotland but SW winds elsewhere.

GEM: 985mb low off W Ireland, 995mb floppy low over Britain, easterlies for N Scotland, westerlies for S England.

This is far from the conclusive "mild mild mild" outlook that prevailed among the models yesterday!

[Thundery wintry showers]

12Z Model Comparisons: Thursday 23rd March 2006.

T+96 (to Monday 27th March)

GFS: Low at 980mb just to the NW of Britain, strong west-south-westerly winds over Britain with sunshine and blustery showers indicated.

UKMO: 990mb low over central Britain with 985mb low just W of Ireland. Unsettled, westerlies in England and Wales, easterlies in northern Scotland, probably fairly mild.

ECMWF: 985mb lows over N and S Ireland, southerlies over Scotland, England and Wales. Probably wet/windy.

NOGAPS: Grid undefined.

JMA: 985mb low to the SW of Britain, 990mb low over S Scotland, SW winds for England and Wales but easterlies for the far N of Scotland. Probably mild.

GEM: Low at 980mb to the west, 1000mb trough over southern England, ESE winds further north.

Mild and windy weather is indicated on all models except GEM, which goes for cold and windy.

T+120 (to Tuesday 28th March)

GFS: Low at 984mb just SE of Iceland with a ridge over to Scotland. Wet windy westerlies, with a colder NW flow moving into western areas.

UKMO: 995mb Scandinavian Low, 1005mb trough over SW England, northerlies filtering into Scotland and northern England.

ECMWF: 990mb lows to the NW and NE, slack winds over N Scotland, westerlies elsewhere.

NOGAPS: Undefined.

JMA: 990mb low just to the east, 995mb low to the west, northerlies for Britain but not yet of an especially cold source, around the periphery of the low.

GEM: 990mb low just to our west, SE winds in Scotland, southerlies over England and Wales with the milder air making it northwards.

Tremendous confusion as to the outlook.

T+144 (to Wednesday 29th March)

GFS: 1005mb low over Scotland, WNW winds elsewhere, moderately cold.

UKMO: A weak high at around 1015-1020mb over Britain, sandwiched between northerlies and southerlies. High at 1025mb over Spain.

ECMWF: 990mb low over Scotland, westerlies over England and Wales.

NOGAPS: 1000mb low in SE England, north-easterlies elsewhere. 1020mb high ridge in the mid Atlantic.

JMA: 1000mb low over S Ireland, little wind in the south, easterlies in the north.

GEM: 1000-1005mb lows to the south, the main 1000mb centre just off SW England, with easterlies over Britain.

If a forecast is to be produced from this range of model outputs- it's anyone's guess!

[Thundery wintry showers]

12Z Model Comparisons: Friday 24th March 2006.

T+96 (to Tuesday 28th March)

GFS: 990mb lows to the N and E of Britain and also a secondary low off SW Ireland, 985mb centre east of Iceland, showery westerlies over Britain.

UKMO: 980mb low to the north of Britain, with 990mb low off E Scotland. Cold northerlies transferring south into northern England, westerlies in southern England.

ECMWF: Large 990mb low over Scotland, and 995mb low west of Ireland. Westerlies over the southern half of Britain.

NOGAPS: 990mb low over NE Britain, 995mb low quite a way out to the W of southern Britain. North-westerly winds.

JMA: 990mb low over northern Britain, 995mb secondary low quite a way out to the W of southern Britain. Westerly winds over the south.

GEM: 990mb low over southern England and slack pressure gradient over the whole British Isles.

The UKMO seems to be out on its own with the cold northerlies, although all models are suggesting that temperatures will be no milder than average for the time of year. Unsettled weather is certainly on the cards and a secondary low is consistently shown on all models (bar UKMO and GEM)

T+120 (to Wednesday 29th March)

GFS: One 995mb low over Scandinavia, one just south of Iceland, moderate showery north-westerlies over Britain.

UKMO: Big 980mb low to the north of Britain, 990mb low approaching the west of Ireland. Southerlies, and a band of wind and rain moving east.

ECMWF: 995mb elongated low extending from Scandinavia to south of Iceland with 990mb centre just south of Iceland. Showery westerlies over Britain.

NOGAPS: Undefined.

JMA: 1000mb trough over southern Britain, 990mb Scandinavian Low, slack pressure gradient except over N Scotland with cold northerlies spilling in- a setup conducive to snow in Shetland.

GEM: 990mb low south of Iceland, with weak 995mb elongation into Scotland, showery westerlies.

A showery outlook with average temperatures, except for JMA (northerlies for N Scotland) and UKMO (southerlies and rain)

T+144 (to Thursday 30th March)

GFS: 995mb Scandinavian Low, 1000mb low over southern Britain, generally slack pressure gradient but northerlies and possible snow for N Scotland.

UKMO: 995mb low over NE Britain, with 990mb low to the north, WSW winds in the south, but a cold northerly feed just to the north-west of the British Isles.

ECMWF: 990mb lows to the west of Britain, southerlies, rain moving east.

NOGAPS: 1000mb low in SE England, north-easterlies elsewhere. 1020mb high ridge in the mid Atlantic.

JMA: 995mb Scandinavian Low, 1005mb trough over southern England, easterlies over England & Wales but northerlies in Scotland. Temperatures low enough for snow showers to occur in the north.

GEM: 985mb low off NW Scotland, 995mb low off W Ireland. South-westerly winds and average to fairly mild temperatures.

A lot of confusion still among the models, with anything from mild southerlies and rain to cold north/east winds and snow showers in the north.

[Thundery wintry showers]

Model Comparisons for T+144, T+120 and T+96 on 25 March 2006.

T+96 (to Wednesday 29th March)

GFS: Large 980mb Icelandic Low, 995mb Scandinavian Low, 1000mb low extending towards SW England. Light westerlies over Britain.

UKMO: 990mb low to the north, 995mb low extending to S Ireland, westerlies in Scotland but veering southerly elsewhere as rain spreads from the SW.

ECMWF: 990mb low to the north, WNW winds over Britain. Low at 1000mb not far off SW England.

NOGAPS: 1000mb low off East Anglia, 985mb low S of Iceland, westerlies over Britain.

JMA: 995mb low to the north, 990mb secondary low off W Ireland, with a low-index pattern, southerlies in the W, westerlies in the far N.

GEM: 985mb low off W Scotland and showery westerlies for Britain.

Westerlies are the main theme although the next low looks to be moving in from the Atlantic.

T+120 (to Thursday 30th March)

GFS: 995mb low in the North Sea, 990mb low to the west of Ireland, 980mb Icelandic Low, very little wind over Britain but probably a lot of rain.

UKMO: Low at 990mb off N Scotland and weak 995mb lows over northern England, with very little wind over Britain but probably a lot of rain.

ECMWF: 990mb low off W Britain with southerlies over Britain and rain sweeping NE.

NOGAPS: Two 985mb lows, one over SW England and one south of Iceland. ESE winds over Britain, though not cold ones.

JMA: 980mb low off NW Scotland with strong winds around it, westerlies over Britain.

GEM: 985mb low off W Scotland, secondary 990mb low in the Atlantic, SW winds over Britain.

GFS and UKMO are in good agreement with each other, otherwise a fair spread of outcomes.

T+144 (to Friday 31st March)

GFS: Complex 990/995mb lows to the west, the nearest being a 990mb low off W Scotland. Southerlies over Britain, and rain moving east.

UKMO: 990mb low to the north, 995mb low over Cent. England, with little wind, but probably a lot of rain.

ECMWF: 980mb Icelandic Low extending into N Scotland, westerlies over Britain.

NOGAPS: 995mb lows over Denmark and to the west of W Scotland. A ridge of high pressure over the E, winds turning from W to the SW.

JMA: 975mb Icelandic Low with strong winds around it, 1000mb low in North Sea, westerlies over Britain.

GEM: 995mb low covering the British Isles, easterlies in the far N of Scotland, westerlies in the far S of Britain. 990mb low centre to the west of Britain.

Unsettled with near or rather above average temperatures looks to be the outlook, that's as much as can be pinned down at this stage.

[Thundery wintry showers]

Model Comparisons for T+144, T+120 and T+96 on 26 March 2006.

T+96 (to Thursday 30th March)

GFS: 975mb low off NW Scotland, secondary 995mb low over S Ireland. WSW winds over Britain, some cold air wrapped in over Scotland. 990mb low out in the North Sea.

UKMO: 985mb low off NW Scotland, 995mb low over W Scandinavia, 995mb low west of SW England, westerlies over Britain.

ECMWF: 985mb low off NW Scotland, 995mb low centred over NW England, a generally southerly flow.

NOGAPS: Undefined.

JMA: 985mb low off NW Scotland, with 995mb extension over to Ireland. Southerlies over Britain.

GEM: 990mb low west of Scotland, WSW winds over Britain.

It seems that there is divergence even at T+96!

T+120 (to Friday 31st March)

GFS: 985mb low over N Scotland, 1000mb secondary low over SW England. Westerlies over Britain, strong in central and northern areas, looking showery.

UKMO: 990mb lows over Scotland, 1005mb secondary low off SW England. Showery looking westerlies over Britain, as GFS.

ECMWF: 990mb low off W Scotland, 1000mb Baltic Low, south-westerlies over Britain. Shallow 1000mb low also over Scotland.

NOGAPS: 985mb low to the west, 990mb extension into Scotland with light winds in Scotland, westerlies over England & Wales.

JMA: 985mb low off NW Scotland, 995mb low S of Scandinavia, 1000mb low off SW England. Westerlies over Britain.

GEM: 985mb Icelandic Low, 1000mb low off SE England, light winds over Britain, westerly in the south.

More agreement at T+120 on a westerly flow.

T+144 (to Saturday 1st April)

GFS: 995mb low in the North Sea, 1000mb low over NW Scotland, NNW winds over Britain.

UKMO: 995mb low off N Scotland, 1010mb low off SW England, westerlies over Britain.

ECMWF: 990mb low off NW Scotland, WSW winds over Britain, 1000mb extension of low into Scotland.

NOGAPS: 995mb low in North Sea, 985mb low to the west of Ireland, W winds in far S of England, E winds in N Scotland, and light winds elsewhere. Cold arctic air not far north of Scotland.

JMA: 985mb low off NW Scotland, westerlies over Britain. 995mb secondary low on the east coast of Scotland.

GEM: 985mb low off NW Scotland, 1000mb low over E Scotland, westerlies.

The GFS seems to be out on its own with those cold NNW winds.

[Thundery wintry showers]

Model Comparisons for T+144, T+120 and T+96 on 27 March 2006.

T+96 (to Friday 31st March)

GFS: 975mb low to the W of Britain, 990mb low over N Scotland, westerlies over Britain, with SW winds pushing east into western areas.

UKMO: 990mb to the W of Britain, 995mb low over N Scotland and also Scandinavia, westerlies over Britain, with SW winds pushing east into western areas.

ECMWF: 990mb low to the W of Scotland (further north than on the other models), 995mb low to the north, westerly winds over Britain, still SW winds pushing into western areas.

NOGAPS: 985mb low to the W, with 990/995mb lows over Scotland and Scandinavia, light winds over Scotland, westerlies for England and Wales.

JMA: 980mb low to the west of Britain, 1000mb low over Scotland, SW winds over Britain.

GEM: 990mb lows to the W and E, slack pressure gradient over Britain with little wind.

Apart from GEM, which hasn't fared particularly well lately, the models are in good agreement.

T+120 (to Saturday 1st April)

GFS: 985mb low over N Ireland, light southerlies for Scotland, very strong WSW winds for England and Wales.

UKMO: 990mb low centred over NW Scotland, with strong westerly winds for Britain.

ECMWF: 995mb lows in the north Sea and to the west of Scotland, with light winds for Scotland, and moderate WSW winds for England & Wales.

NOGAPS: 990mb low covering Scotland, moderate westerlies over England and Wales.

JMA: 985mb low centred to the west of Scotland. Moderate south-westerlies over Britain.

GEM: 1000mb low over Ireland, light winds for southern Britain, northerlies pushing into Scotland and N England.

People looking out for April Fool's Day snowfalls might want to back the GEM, but it's very much out on its own, with a warm and unsettled outlook suggested by all other models.

T+144 (to Sunday 2nd April)

GFS: 995mb low generally to the N and NE, WNW winds over Britain, notable 1020mb high moving up into central France.

UKMO: 995mb low to the north of Britain, slack westerlies over Britain.

ECMWF: 1000mb low over Scandinavia, slack westerlies in the south, northerlies for Scotland.

NOGAPS: 995mb low over NE Scotland, with a cyclonic north-westerly regime over Britain and strong winds.

JMA: 990mb low off NW Scotland, with moderate westerlies over Britain.

GEM: 995mb lows over and to the west of Scandinavia, slack northerlies over Britain.

A surprising amount of agreement on the models that it will turn showery with lighter winds, and probably colder.

[Thundery wintry showers]

Model Comparisons for T+144, T+120 and T+96 on 29 March 2006.

T+96 (to Sunday 2nd April)

GFS: 1005mb low over central Britain, 1000mb Scandinavian Low, westerlies in the south, northerlies for Scotland.

UKMO: 1000mb low off NE Scotland, westerlies for most, but northerlies pushing into Scotland.

ECMWF: 1000mb low over NE Britain, westerlies in the south, northerlies in the NW.

NOGAPS: Undefined.

JMA: 995mb low centred over S Scotland, strong westerlies over England and Wales.

GEM: 995mb low off E Scotland, W/NW winds in the south, northerlies elsewhere.

T+120 (to Monday 3rd April)

GFS: 1000mb low centred over SE Scandinavia, 1030mb high south of Iceland, northerlies for Britain.

UKMO: 1005mb Scandinavian Low, 1025mb Icelandic High, 1020mb Euro High just off S England, westerlies over Britain except for the northern half of Scotland (northerlies).

ECMWF: 1005mb Scandinavian Low, north-westerlies for Britain, certainly cold enough for snow in Scotland. 1025mb highs to the W and SW.

NOGAPS: Only shows yesterday's output.

JMA: 1025mb high SW of Iceland, 1020mb Euro High, 1010mb Scandinavian Low. Westerlies in the extreme south, but light northerlies elsewhere.

GEM: 1025mb Icelandic High, 1000mb low off W Scandinavia, NW winds over Britain.

It looks like getting colder with winds from a north-westerly quarter.

T+144 (to Tuesday 4th April)

GFS: 1030mb high off W Scotland, with light northerlies around its periphery over Britain.

UKMO: 1005mb Scandinavian Low, 1015mb trough in North Sea, 1025mb Icelandic High, with easterlies in the extreme south on northern periphery of a low over Spain, northerlies elsewhere.

ECMWF: 1005mb Scandinavian Low, 1030mb high SW of Iceland, cold northerlies over Britain with high likelihood of snow showers.

NOGAPS: Has hit the self-destruct button. No run today.

JMA: Easterly winds on the northern flank of a 995mb low to the west of Spain. 1030mb high off NW Scotland centred over Iceland.

GEM: 1005mb Scandinavian Low, 1025mb high to the NW, easterlies for the extreme south on northern flank of 1005mb low over W France, northerlies elsewhere.

It certainly isn't unrealistic to be thinking about sunshine and snow showers at this stage, but there is uncertainty as can be seen from the variation in outputs.

[Thundery wintry showers]

Model Comparisons for T+144, T+120 and T+96 on 30 March 2006.

T+96 (to Monday 3rd April)

GFS: 1000mb Scandinavian Low, 1010mb low nudging towards SW England, 1030mb high centred over Greenland. Southerlies for southern England, northerlies for Scotland.

UKMO: 1005mb Scandinavian Low, 1025mb high to the W and S, north-westerly winds. Maybe cold enough for snow in the north.

ECMWF: 1000mb Scandinavian Low, 1030mb high to the W, NW winds in the south, northerlies in the north.

NOGAPS: Undefined.

JMA: 1005mb Scandinavian Low, 1025mb high to the W and NW, and 1040mb centre over Greenland. Northerly winds with snow showers a real possibility.

GEM: 1000mb Baltic Low, 1000mb low to the N of Scotland, 1025mb High to the W/NW of Britain. NW winds. Snow likely in Scotland.

The GFS is out on its own trying to introduce milder air from the south. All other models go for a cold showery looking N/NW flow.

T+120 (to Tuesday 4th April)

GFS: Easterlies connected to deep 995mb low west of Spain, 1025mb high off NW Scotland. 1000mb low, E Scandinavia.

UKMO: 1005mb Scandinavian Low, 1025mb high ridging into western Britain, light northerlies.

ECMWF: 1000mb Scandinavian Low, 1030mb high to the west, northerlies and probably snow showers.

NOGAPS: Gone AWOL.

JMA: 1000mb Scandinavian Low, 1025mb high to the NW, easterlies in the far S, northerlies elsewhere.

GEM: 1000mb low to the north, 1000mb Scandinavian Low, 1025mb high ridging up from the Azores. Northerly winds.

GFS out on its own again! Trying to play catch-up with the Euro models?

T+144 (to Wednesday 5th April)

GFS: 1000mb low over France, 1015mb high covering N Scotland, and east to north-east winds over Britain.

UKMO: 1005mb Scandinavian Low, 1025mb high to the NW, northerlies, temperatures easily low enough to support snow showers.

ECMWF: 1005mb Scandinavian Low, 1030mb high to the W as a ridge from the Azores, northerlies.

NOGAPS: Only 00Z available.

JMA: 1005mb Scandinavian Low, 1025mb high to the NW. NE winds in the south, northerlies in the north. Snow showers likely.

GEM: 990mb Icelandic Low, 1000mb Scandinavian Low, 1025mb Azores High. A classic "toppler" with anticyclonic northerlies changing to north-westerlies.

It remains realistic to be contemplating the chance of sunshine and snow showers- more so than yesterday, though the GFS begs to differ on its 12Z run.

[Thundery wintry showers]

Model Comparisons for T+144, T+120 and T+96 on 31 March 2006.

T+96 (to Tuesday 4th April)

GFS: 1005mb Scandinavian Low, 1030mb high to the W, anticyclonic northerlies over Britain of cold origin.

UKMO: 1005mb Scandinavian Low, 1030mb high to the W, 1020mb trough off N Scotland, anticyclonic north-westerly winds of cold origin.

ECMWF: 1005mb Scandinavian Low, 1030mb high to the W, anticyclonic northerlies of cold origin.

NOGAPS: 1000mb Scandinavian Low, 1030mb high way out to the W, strong northerlies from the Arctic.

JMA: 1005mb Scandinavian Low, 1025mb high to the W and NW, northerly winds straight from the Arctic.

GEM: 1005mb Scandinavian Low, 1025mb high ridging into the mid Atlantic from the Azores. Easterlies in the south on the northern flank of 1000mb Spanish low, northerlies elsewhere.

NOGAPS and JMA go for quite potent northerlies, GFS, UKMO and ECMWF go for anticyclonic northerlies, GEM a bit out on its own with the easterlies for southern Britain.

T+120 (to Wednesday 5th April)

GFS: 1005mb lows to the N and over Scandinavia. 1015mb trough over Scotland, slack anticyclonic NW winds in the south.

UKMO: 1005mb Scandinavian Low, 1030mb high to the W, anticyclonic northerlies with a toppler indicated, less cold air with NW winds to the W of Scotland.

ECMWF: 1000mb low to the north, with less cold north-westerlies toppling around the top of the 1030mb high to the west and bringing rain to the north.

NOGAPS: Undefined.

JMA: 1005mb Scandinavian Low, 1025mb high to the W, a north-easterly flow covering Britain, strong northerlies for N Scotland.

GEM: 1005mb Scandinavian Low, 1025mb high to the W with 1015mb "toppling" ridge to the NW. North-easterlies over Britain.

This time it's JMA and GEM vs UKMO and ECMWF, with GFS opting for an alternative scenario.

T+144 (to Thursday 6th April)

GFS: 990mb Icelandic Low, 1030mb high to the west with 1020mb toppling ridge over Britain, very light northerlies except for N Scotland (westerlies)

UKMO: 990mb Icelandic Low, 1025mb high to the SW, WNW winds over Britain, a classic "toppler" situation.

ECMWF: 985mb lows to the N of Scotland, 1030mb high well away to the SW, westerlies over Britain but cold NW'lys pushing towards north-western Britain.

NOGAPS: 1005mb low to the east, 1015mb highs to the west and light NNE winds over Britain.

JMA: 985mb low west of Iceland, 1000mb low off SE England, 1010mb trough to the east of Scotland. NNE winds, but signs of toppling to the NW from 1025mb high to the W with 1015mb ridge to western Scotland.

GEM: 980mb low W of Iceland, 1020mb high to the SW, 1000mb low to the SE, very slack northerlies.

Good agreement on a toppler situation, which was initially picked up by yesterday's GEM and to a lesser extent the ECMWF.

[Thundery wintry showers]

Once I have gone and come back from Amsterdam this weekend, I won't be doing the model comparisons any more, because they are too much work.

(see date and time posted)

[johnholmes]

I was afraid this would happen Ian. It is a big task for every day. Sad that its happened but unless we can get the whole forecast team to be involved and each be responsible for one day a week, then it seems like its the finish.

Thanks for giving it a go anyway.

regards

John

[The PIT]

Pity as I was enjoying them.

[Paul]

A clue for you all - check the small blue print at the bottom of Ian's post!!!!!

[J10]

GGGGGRRRRRRRRRR at Ian

But also a relief

[johnholmes]

very good, although I cannot remember seeing it when I posted but then I do have a pair of very old eyes!

[J10]

Model Comparisons for T+144, T+120 and T+96 on 3 April 2006.

T+96 (to Friday 7th April)

GFS: 985mb Low to the North of Scotland centred to the West of Southern Norway, 1045mb Greenland High, and High Pressure to the West of the UK. Slack High over Europe. W/SW winds from a Northern origin

UKMO: 1035MB Greenland high, 990mb Low Pressure centred about 200 mils North of Scotland, W/SW winds, form a Northerly origin for the North, but from a SE direction on the South.

ECMWF: Greenland High and Mid Atlantic ridge, 990mb Low pressure to the North of Scotland, giving W/NW winds over the UK.

NOGAPS: 1025 mb Mid Atlantic High, no High Pressure over Greenland, 985mb centred to the North off Scotland by 100 miles, giving W/SW winds from a northerly direction for northern UK, W/SW winds from the continent in the S

JMA: 1045mb Greenland High, 1025mb Mid Atlantic Ridge, 990mb low pressure centred 100 miles off the north coast of Scotland, giving W/SW winds of a Northerly origin to all of the UK, slack conditions over the continent.

GEM: 1035mb Greenland High, 1020mb Mid Atlantic High, with a 980mb Low Pressure 300 miles to the North of Scotland, giving W/SW winds over the UK form a northerly direction

General Agreement on a low pressure to the North, but NOGAPS and UKMO go for winds from the continent in the South

T+120 (to Saturday 8th April)

GFS: 990mb Low to the North of Scotland, slacker than the +96 chart, Greenland High 1040mb, Mid Atlantic High 1030mb and becoming stronger. Slack high over Europe, W/NW winds.

UKMO: 1035 mb Greenland High, 990mb Low Pressure to the West of Norway, but the UK in a col with low pressure 1005mb trying to push up from the SW, winds light and variable

ECMWF: The 990mb low pressure to the North pushes to the East of Scotland and gives W/NW winds over the whole UK, 1030mb Mid Atlantic High.

NOGAPS: Mid Atlantic High 1025mb, no pressure rise over Greenland, Low Pressure well to the SW of the UK 995mb, and the Low Pressure 995 to the Wet of Norway, leaving the UK in a col, with light variable winds,

JMA: 1040mb Greenland High, 1030 Mid Atlantic High, 980mb Low Pressure centred to the wet of SW Norway giving W/NW winds over the whole of the UK

GEM: 1030mb Greenland High, with a 1020mb Mid Atlantic ridge, a 990mb low pressure centred just to the North of Scotland, giving W/SW winds again from a N direction

UKMO and NOGAPS go for the Northern Low Pressure to push away, leaving a col over us, the others maintain the Northern Low Pressure controlling our weather.

T+144 (to Sunday 9th April)

GFS: Twin centred Low Pressure 995 E of Scotland and 200 miles further North, much slacker again than the T+120, High Pressure over Greenland and Mid Atlantic, both weakening to 1025mb. n/nw WINDS

UKMO: The low-pressure 1000mb pushes NE to Southern UK, allowing a NE flow to push in on its back edge. Mid Atlantic High 1025mb, Greenland Ridge 1025mb, Low Pressure 995 to the west of Central Norway

ECMWF: 1030mb Mid Atlantic High, the Low pressure 985 is to the East of Scotland, but gives N/NW winds over the UK

NOGAPS: Mid Atlantic High 1025mb, the Low off Norway pushing away to the North (1000mb) centred off the coast of Northern Norway, the low to the SE still centred 300-400 miles to the SW but bringing NE winds to Northern parts of the UK, E winds to the South.

JMA: 1030mb Greenland High, 1025 mb Mid Atlantic high not joined, twin centred low pressure 1000mb, to the East and NNE East of Scotland, giving a cold northerly flow over the UK.

GEM: 1025mb Greenland high, with a slack 990mb low pressure to the north of Scotland giving w/nw winds over the UK

UKMO and NOGAPS show the low pressure to the SW pushing in, giving NE winds on the back edge. GFS and GEM have the weakening low pressure to the North giving W/NW winds, the JMA is on its own with a bitter northerly over the UK. The ECM is a mix of JMA and GFS/GEM.