johnholmes

Very unusual occurrence waiting for a bus around 10 am this morning. Complete blue sky, not a cloud in sight, and a couple of dozen snowflakes floating down. Made me think back to the first couple years in the Met Office at RAF Worksop, that happened, rain not snow, in brisk westerlies as shower clouds cleared but the ppn appeared to fall from a blue sky

At dawn, clear sky other than shallow cu on eastern horizon, white frost with a low of -6.3 C, the lowest for at least 3 years, not yet had chance to check how far back. Found it=Feb 11 th 2012 with -8.4 C

Dry with patchy Ci and Contrails but 7/8 blue, coldest night this winter and back to 15 March 2023; -3.1 C

Not sure why anyone is saying it was not predicted, UK Met Fax has shown it for several days, forecasts also suggested it tracking east rather than its current south of east. The area predicted for snow has, as it often does , varied between central Scotland and north Midlands!

Dry and cloudy, frosty, low after midnight=-1.7 C but -2.2 C before

A cloudless and pretty cold day, Max 2.7 with a Td of -06C and breeze of 10+ mph=feels like -6/-7 C

Monday 15 Jan From last Thursday The fact that NOAA charts show a westerly by the end of the 6-10 day period coupled with this being shown on the 8-14 (this is the third consecutive such chart,) does suggest to me a more unsettled and rather cold westerly with lows eventually succeeding in moving less cold air, perhaps only temporarily in the 10-14 day period. Little to add, the possible snow event for this area looks to have ‘gone’. That for the far south seems less likely. The less cold air on all 3 charts I use looks set to arrive by Saturday. At the moment not looking all that mild but no sign of any cold for a couple of weeks from Saturday for the UK. Have to say not sure what to make of the pattern in the very far west of the NOAA charts ! 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 Original post: https://community.netweather.tv/topic/99760-model-output-discussion-colder-but-how-cold-and-for-how-long/?do=findComment&comment=5012819

Monday 15 Jan From last Thursday The fact that NOAA charts show a westerly by the end of the 6-10 day period coupled with this being shown on the 8-14 (this is the third consecutive such chart,) does suggest to me a more unsettled and rather cold westerly with lows eventually succeeding in moving less cold air, perhaps only temporarily in the 10-14 day period. Little to add, the possible snow event for this area looks to have ‘gone’. That for the far south seems less likely. The less cold air on all 3 charts I use looks set to arrive by Saturday. At the moment not looking all that mild but no sign of any cold for a couple of weeks from Saturday for the UK. Have to say not sure what to make of the pattern in the very far west of the NOAA charts ! 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

A clear cold blue sky morning with an air frost giving a low of -1.3 C; this is the lowest since 6/12/23

Dry and fairly cloudy with a temperature currently of 2.3 C; it dropped to 0.1 C with ground frost 0300-0400

Not got time to post the full set of charts I use but they are along similar lines to yesterday. So deepish cold to start next week before the upper flow on NOAA and ECMWF turns more westerly cutting off the deep cold. Also borne out by UK met at 144h. Just where snow will fall and settle still seems uncertain but the low shown on Met Fx charts is the system that is the cause so watch how UK Met deal with it over the next 3-4 days and their forecasts/warnings for where snow is most likely. Certainly looks to become less cold/milder into next weekend I feel. ps obviously coastal areas from Monday into perhaps Wednesday are likely to see coastal snow showers, with a small risk of these being more extensive on any troughs that form, little advance warning of these, say 6-12 hours at most. Original post: https://community.netweather.tv/topic/99760-model-output-discussion-colder-but-how-cold-and-for-how-long/?do=findComment&comment=5010067

Not got time to post the full set of charts I use but they are along similar lines to yesterday. So deepish cold to start next week before the upper flow on NOAA and ECMWF turns more westerly cutting off the deep cold. Also borne out by UK met at 144h. Just where snow will fall and settle still seems uncertain but the low shown on Met Fx charts is the system that is the cause so watch how UK Met deal with it over the next 3-4 days and their forecasts/warnings for where snow is most likely. Certainly looks to become less cold/milder into next weekend I feel. ps obviously coastal areas from Monday into perhaps Wednesday are likely to see coastal snow showers, with a small risk of these being more extensive on any troughs that form, little advance warning of these, say 6-12 hours at most.

Almost totally clear sky for a change, white ground frost with a low of 0.6 C

Cloudy with 0.2 mm since midnight, current low is 4.6 C; seeing the sun will be a plus whenever that happens!

Thursday same charts The NOAA chart now shows all contours into UK are from a westerly point but also still from a cold source, (NW Canada/Alaska) and about 528 DM maybe just above.The upper trough has moved west, from between Iceland and nw Scotland to be nearer Iceland. There is little indication of any troughing into Europe for the third chart in succession. ECMWF just looking at the -5 C 850 MB line, (period 17-21 Jan) starts S Wales to the Thames and ends up over the northern tip of Scotland, with a general WNW 500 MB flow from the initial N’ly Finally the T+144 to 168h Met O upper air and surface charts, (15-17 Jan) show the upper ttrough extending to some extent into southern Europe but not as sharp as the issue I showed on Tuesday a N’ly on the first day changing to a deepish surface feature with a SW;ly flow for all but the far north of Scotland by the end (17 th=Wednesday) So what can we suggest for the surface weather in the 6-10 day and then the 8-14 period some of these charts cover? Deepish cold to start by the end of this weekend over pretty much all of the UK. Dry for most but mini troughs are quite possible in the N’ly (they do often feature in these flows), a few snow showers around coasts early next week, enhanced over any area affected by a trough. There is a probability of the low shown on the Met O T+144 of spreading some snow into areas, say Midlands south possibly turning to rain in the SW. How far north this gets is difficult to suggest and best to wait to see how the synoptic models deal with it, by Sunday this should be getting clearer! The fact that NOAA charts show a westerly by the end of the 6-10 day period coupled with this being shown on the 8-14 (this is the third consecutive such chart,) does suggest to me a more unsettled and rather cold westerly with lows eventually succeeding in moving less cold air, perhaps only temporarily in the 10-14 day period. Beyond that, not for these charts Climate Prediction Center - 6-10 Day 500mb Outlook WWW.CPC.NCEP.NOAA.GOV Original post: https://community.netweather.tv/topic/99760-model-output-discussion-colder-but-how-cold-and-for-how-long/?do=findComment&comment=5006868

Thursday same charts The NOAA chart now shows all contours into UK are from a westerly point but also still from a cold source, (NW Canada/Alaska) and about 528 DM maybe just above.The upper trough has moved west, from between Iceland and nw Scotland to be nearer Iceland. There is little indication of any troughing into Europe for the third chart in succession. ECMWF just looking at the -5 C 850 MB line, (period 17-21 Jan) starts S Wales to the Thames and ends up over the northern tip of Scotland, with a general WNW 500 MB flow from the initial N’ly Finally the T+144 to 168h Met O upper air and surface charts, (15-17 Jan) show the upper ttrough extending to some extent into southern Europe but not as sharp as the issue I showed on Tuesday a N’ly on the first day changing to a deepish surface feature with a SW;ly flow for all but the far north of Scotland by the end (17 th=Wednesday) So what can we suggest for the surface weather in the 6-10 day and then the 8-14 period some of these charts cover? Deepish cold to start by the end of this weekend over pretty much all of the UK. Dry for most but mini troughs are quite possible in the N’ly (they do often feature in these flows), a few snow showers around coasts early next week, enhanced over any area affected by a trough. There is a probability of the low shown on the Met O T+144 of spreading some snow into areas, say Midlands south possibly turning to rain in the SW. How far north this gets is difficult to suggest and best to wait to see how the synoptic models deal with it, by Sunday this should be getting clearer! The fact that NOAA charts show a westerly by the end of the 6-10 day period coupled with this being shown on the 8-14 (this is the third consecutive such chart,) does suggest to me a more unsettled and rather cold westerly with lows eventually succeeding in moving less cold air, perhaps only temporarily in the 10-14 day period. Beyond that, not for these charts Climate Prediction Center - 6-10 Day 500mb Outlook WWW.CPC.NCEP.NOAA.GOV

Max balloon data is 00Z and 12Z Original post: https://community.netweather.tv/topic/99760-model-output-discussion-colder-but-how-cold-and-for-how-long/?do=findComment&comment=5005196

Found this about weather balloons; certainly in my time world-wide ascents main times were 00 and 12Z for all data including balloons. Currently, the global radiosonde network includes about 900 upper-air stations, and about two-thirds make observations twice daily (at 0000 and 1200 UTC). The network is predominantly land-based and favours the Northern Hemisphere. Original post: https://community.netweather.tv/topic/99760-model-output-discussion-colder-but-how-cold-and-for-how-long/?do=findComment&comment=5005208

Found this about weather balloons; certainly in my time world-wide ascents main times were 00 and 12Z for all data including balloons. Currently, the global radiosonde network includes about 900 upper-air stations, and about two-thirds make observations twice daily (at 0000 and 1200 UTC). The network is predominantly land-based and favours the Northern Hemisphere.

Max balloon data is 00Z and 12Z

Is it me, perhaps I'm seeing something that is not correct? Most avid followers seem in despair after each 00z GFS run, fairly elated then after almost each 06Z and 12Z runs?

A snap answer would be possibly! Like my post mentioned I need a couple more outputs to make a definite prog

Not got time to post charts etc but 10-14 day NOAA shows a westerly into the UK, still a bit below 500 MB temperatures for UK, 6-10 shows pattern I posted yesterday. ECMWF also v slightly downgraded in its time frame, shows very slack COL situation by end of its period which is a similar time frame to 6-10 NOAA. I prefer to see 2-3 charts being consistent before making any forecasts.

dry with mainly large amounts of CuSc after 1 or 2 light rain showers; 0.4 mm since midnight; current low is 2.3 C

no ppn forecast of snow is accurate even at short times scales. Not that different to the summer forecasts of rain if you look back. How often even at T+24 or less was the ppn not in the right place/not the correct intensity etc. With snow there are further 7 or 8 parameters to consider! Original post: https://community.netweather.tv/topic/99706-model-output-discussion-into-2024/?do=findComment&comment=5003580