johnholmes

Friday 15 Jan update using the upper air charts (500 MB chiefly) Taking ECMWF first and it has changed today from the last couple of days with both the upper and surface ridge shown as further NW than before. There is also in the last 2 days a signal for colder sir to advect west as the ridge conditions give way to a bit more cyclonic looking. 850 temperatures are brought down below -5 C in the last 2 charts. Is this a trend that will continue? Time will tell The NOAA charts for 6-10 especially have shifted the C of G of the ridge first east and now again more west. In the more westerly position the European trough is obviously further west thus allowing the possibility of colder upper air moving west. Currently the version yesterday showed the actual contour centre in the NW of the UK with the very high +ve anomaly (+390 DM) being just SW of Iceland. The UK is currently not in any deep cold air on the 6-10 or the 8-14, although this hint at temperatures falling somewhat at 500 MB. UK Met in the period 9-11 Jan ( their furthest public charts) show both the upper and surface ridge staying just north of northern Scotland. They have the European trough well east with a cut off upper low just south of the UK/nw France edging south over that period. So with all 3 outputs in the 6-10 day period seem to suggest no deep cold air but with upper and surface ridging being somewhere over or WNW of northern/western Scotland. This suggests a mainly dry spell with frost becoming more widespread but depending on cloud cover for its intensity. The upper pattern to me suggests little probability further out of any break down in the block. Obviously its actual position is going to vary slightly but remaining north rather than south. Models predicting further ahead do seem to suggest that deep cold is possibly 14-20 days away from today? Not my scene so that comment may be incorrect but I’ll leave that to others to firm up on. Climate Prediction Center - 6-10 Day 500mb Outlook WWW.CPC.NCEP.NOAA.GOV UK Met Office Fax Charts - UKMOMSLP Analysis and Prognosis WWW.WEATHERCHARTS.ORG UK Met Office . . Europe and North Atlantic MSLP analysis and prognosis charts

Hope any folk in he affected areas stay safe, even more you do not get flooded, that must be truly awful.

In the 'chase' for cold and snow,I do suspect this can be the case. But any prediction of ppn in any month that far ahead is often, say 2 out of 3 times, wrong for when/where/how much. That is often ignored in the hope for snow

Not according to the Extra skew-t for dover?

I love that comment, it is possible a fair number of other Net Wx coldies were also seeking help! Nothing, at upper level suggests anything is or will change from what I've been posting for several days. Quite why so many seem to be concentrating on T+240 or even 300h is beyond my understanding. The position of a surface high, with such solid evidence for where the upper ridge is likely to be has to be at least over the N'ern half of the UK or even further NW. Combined with the position of the Upper ridge and the subsequent development of the European trough over western Europe means that it will be cold with surface winds rather variable but probably, at least in the 4-6 day period from a NW-N'ly point and quite light. The amount of cloud is best followed by watching the Visual sat piccs over the UK area. Clear skies at night with relatively low daytime temperatures will slowly lead to overall dropping in daytime values. Turning to the S word then probably little chance other than the odd flurry in the above time frame. Beyond that then al look at the T-phi charts for your area will give some indication of any shower activity (unstable ascents). DO remember also to factor in the necessary additions to 'will it snow', 7-8 additional variables to IF the ascents show ppn is expected. Otherwise enjoy the colder weather and hopefully those of you badly affected by our recent 'monsoon' spell a chance for conditions to improve for you. Enjoy the count down and PLEASE be kind to each other. It could still go t--- up as 2006 demonstrated but that seems unlikely to me. I'll own up if it does and try and explain why! Original post: https://community.netweather.tv/topic/99706-model-output-discussion-into-2024/?do=findComment&comment=4993329

I love that comment, it is possible a fair number of other Net Wx coldies were also seeking help! Nothing, at upper level suggests anything is or will change from what I've been posting for several days. Quite why so many seem to be concentrating on T+240 or even 300h is beyond my understanding. The position of a surface high, with such solid evidence for where the upper ridge is likely to be has to be at least over the N'ern half of the UK or even further NW. Combined with the position of the Upper ridge and the subsequent development of the European trough over western Europe means that it will be cold with surface winds rather variable but probably, at least in the 4-6 day period from a NW-N'ly point and quite light. The amount of cloud is best followed by watching the Visual sat piccs over the UK area. Clear skies at night with relatively low daytime temperatures will slowly lead to overall dropping in daytime values. Turning to the S word then probably little chance other than the odd flurry in the above time frame. Beyond that then al look at the T-phi charts for your area will give some indication of any shower activity (unstable ascents). DO remember also to factor in the necessary additions to 'will it snow', 7-8 additional variables to IF the ascents show ppn is expected. Otherwise enjoy the colder weather and hopefully those of you badly affected by our recent 'monsoon' spell a chance for conditions to improve for you. Enjoy the count down and PLEASE be kind to each other. It could still go t--- up as 2006 demonstrated but that seems unlikely to me. I'll own up if it does and try and explain why!

My January total is 44.6 mm; so far had 36.4 mm, which is about 82% as a quick calculation

Re NOAA then nothing since last evening so my comments seem okay still. I say, seem, as the ECMWF output, see below, is a bit different at 500MB from NOAA by the 12th, with it showing a more S'ly position than NOAA. This obviously means that the surface high is further south than one would expect from NOAA. I still back NOAA over ECMWF but with just a slight doubt due to this. UK Met obviously do not go out that far with charts available to us. But the low coming off Greenland does show 'their' upper and surface ridges being pushed a bit further south over the coming weekend. Stick with the NOAA upper air charts for the 5-15 days from now is my advice. I may get egg on face but used to that! Climate Prediction Center - 8-14 Day 500mb Outlook WWW.CPC.NCEP.NOAA.GOV UK Met Office Fax Charts - UKMOMSLP Analysis and Prognosis WWW.WEATHERCHARTS.ORG UK Met Office . . Europe and North Atlantic MSLP analysis and prognosis charts

Dry, overcast, a low of 6.9 C, rainfall from midnight=0.2 mm; last evening 14.0 mm from 1800-2330

The 8-14 rarely shows as marked a response as the 6-10 does. But with both over the past week building the same pattern it would be most unusual if they turn out not to be what the 500 mb charts will actually show about 5-8 days from now and for 2 weeks or so. Don't ask me what happens after that but I would be surprised if the pattern is much altered for, stick my neck out, at least a 5-7 further days. Original post: https://community.netweather.tv/topic/99706-model-output-discussion-into-2024/?do=findComment&comment=4991275

The 8-14 rarely shows as marked a response as the 6-10 does. But with both over the past week building the same pattern it would be most unusual if they turn out not to be what the 500 mb charts will actually show about 5-8 days from now and for 2 weeks or so. Don't ask me what happens after that but I would be surprised if the pattern is much altered for, stick my neck out, at least a 5-7 further days.

Happy 2024 to everyone Not doing a full run down of the 500's but just posting the NOAA chart This has been consistent with this pattern for several days. The 6-10 is not often wrong and is more often right. Since Xmas day the intensity of the ridge and its position has developed steadily. The 8-14 keeps the pattern and about the same intensity of +ve heights in much the same area. It has gone pear shaped before but the probability is about 25%, at most. Even troughing over Europe is developed as the ridge develops. Will it snow and when-no idea, nor has anyone else. If you enjoy watching every GFS and other model churn out x times each day, fine but a better way if you do this. Is NOT to compare T+beyond 144 hours with the latest run, compare like with like, so 00 to 00, 12-12 etc. Until down to T+144, often keep doing it for another couple of runs. When that model shows consistency AND the other outputs continue to support that evolution, including sadly the much maligned teleconnections etc, then it is a high probability that that pattern will occur. Will it snow, just think back to summer and various models quite poor prediction of rainfall, both amount, and when and where. Not good quite often. To get snow you need about 8 additional parameters to be 'on board'. So try to be realistic PLEASE stop carping at one another it spoils the enjoyment for all of us. End of jh sermon, again Happy New Year, enjoy Net Wx.

Dry and cloudy after late evening and overnight rain, 1.8 mm since midnight, most fell before midnight8-9 mm I estimate without doing a full check hour by hour; current low is on 5.4 C

Rain started about 1 hour ago, otherwise a dry night, less wind than recently, a low of 3.8 C; this is the lowest since 14 th December; rainfall so far=0.8 mm

Dry with a mainly clear sky and a low of7.6 C, quite breezy and a gust to 27 mph overnight

Thursday 28 December 2023 Just over a week since I did an update on the anomaly charts. Nothing much changed for a few days but over the last 3 NOAA has changed now showing a fairly marked 500 mb ridge with a small +ve height anomaly . The anomaly first showed sw of the UK and has moved wnw over the past 72 hours. It has also created a very slight trough east of the UK. On the 8-14 chart the height anomaly is now shown at 150DM, a reasonable value with the contour ridging directed towards Iceland and Greenland. West of this is the usual trough over ne Canada with a ridge west of this north of Alaska. Not a classic set up for the UK/European areas but better than no signal for any meridional flow in this area. Turning to the ECMWF for a similar time scale to the 6-10 NOAA. It keeps the 500 flow in a general WNW flow with minor ripples running through it. Over Europe it does show a fairly flattish trough in day 1-2 but sharpens it somewhat by day 5 (7 Jan). The 850 MB temperature shows little sign of any colder air for the UK with the far north almost in the -5 C at times with most of the rest of the UK in the zero to -2 to -3C region. So a watching game to see if it will follow the NOAA and, indeed, if the NOAA charts intensify the ridge-trough set up for the UK and Europe region. Climate Prediction Center - 8-14 Day 500mb Outlook WWW.CPC.NCEP.NOAA.GOV Original post: https://community.netweather.tv/topic/99584-model-output-discussion-into-winter/?do=findComment&comment=4985886

Thursday 28 December 2023 Just over a week since I did an update on the anomaly charts. Nothing much changed for a few days but over the last 3 NOAA has changed now showing a fairly marked 500 mb ridge with a small +ve height anomaly . The anomaly first showed sw of the UK and has moved wnw over the past 72 hours. It has also created a very slight trough east of the UK. On the 8-14 chart the height anomaly is now shown at 150DM, a reasonable value with the contour ridging directed towards Iceland and Greenland. West of this is the usual trough over ne Canada with a ridge west of this north of Alaska. Not a classic set up for the UK/European areas but better than no signal for any meridional flow in this area. Turning to the ECMWF for a similar time scale to the 6-10 NOAA. It keeps the 500 flow in a general WNW flow with minor ripples running through it. Over Europe it does show a fairly flattish trough in day 1-2 but sharpens it somewhat by day 5 (7 Jan). The 850 MB temperature shows little sign of any colder air for the UK with the far north almost in the -5 C at times with most of the rest of the UK in the zero to -2 to -3C region. So a watching game to see if it will follow the NOAA and, indeed, if the NOAA charts intensify the ridge-trough set up for the UK and Europe region. Climate Prediction Center - 8-14 Day 500mb Outlook WWW.CPC.NCEP.NOAA.GOV

Slight rain at the moment after a windy night with a max of 51 mph, (never seen this high a gust in my sheltered back garden);; a low of 7.8 C; rainfall 0.8 mm since midnight

Well the NOAA 500 MB anomaly charts have now shown a similar pattern for the last two outputs, that is a 500 MB ridge building to the W/NW of the UK. Will do a run down tomorrow morning Original post: https://community.netweather.tv/topic/99584-model-output-discussion-into-winter/?do=findComment&comment=4985537

Well the NOAA 500 MB anomaly charts have now shown a similar pattern for the last two outputs, that is a 500 MB ridge building to the W/NW of the UK. Will do a run down tomorrow morning

Wet and breezy here with 13.4 mm since midnight

ditto here-13.4 mm since midnight

Dry and mostly sunny and a low of 4.9 C the lowest for 10 days, still 2 C above average. Lovely to see the sun.

Initially NIL model data; that began to arrive from, I think the early 1970's. I do remember in the mid 70's at Manchester Weather Centre, think it might have been 1975 Xmas. We were asked to predict temperatures to January 1st from 23 December!! Ha-ha. Anyway we managed to get hold of the medium range forecaster doing 3-5 days ahead with computer input and he suggested 'cold' most of the time, frosts most nights. It was pretty accurate. Done by a correct prediction of a jet streak west of Greenland apparently. How times change. By the time I retired in 1995 forecasts to 5-7 days were more or less routine. Interestingly when GP was using data some years ago Met UK refused to accept it. Now many of those ideas are routine for outlooks 10-30 days ahead. Happy Christmas all, off to start cooking my Christmas dinner

Happy Christmas to you all But the ECMWF shows little indication of any cold setting in this morning for the start of 2024?