Blessed Weather

Hereby known as the Fujiwhara Effect: The Fujiwhara effect, sometimes referred to as Fujiwara interaction or binary interaction..... The effect is named after Sakuhei Fujiwhara, the Japanese meteorologist who initially described the effect in the 1920s. Binary interaction of smaller circulations can cause the development of a larger cyclone, or cause two cyclones to merge into one. Extratropical cyclones (mid and high latitude lows) typically engage in binary interaction when within 2,000 kilometres (1,200 mi) of one another........ ......with significant acceleration occurring when the low-pressure areas are within 1,100 kilometres (680 mi) of one another. Interactions between their circulations at the 500 hPa level (18,000 feet above sea level) behave more predictably than their surface circulations. This most often results in a merging of the two low-pressure systems into a single extratropical cyclone, or can less commonly result in a mere change of direction of one or both of the cyclones. The precise results of such interactions depend on factors such as the size of the two cyclones, their distance from each other, and the prevailing atmospheric conditions around them.

Could we stick to model output discussion in here please folks. There's a bit too much off-topic chat in here tonight so I'm afraid posts will likely start disappearing. Please use the Winter Chat thread. Many thanks.

Is this the one @Battleground Snow:

There is a dedicated thread on the forum for posting and discussing Met Office and BBC updates:

Model Output in here please! It’s very busy now and whilst it’s great to have the thread buzzing could I ask that we please try and stay on topic. Here are some other threads to use: Winter 2023/24 - Moans, Ramps & Chat Met Office and BBC Weekly/Monthly Outlooks Historic Weather Thank you.

Yes, arguably that low amplitude transition of the MJO through Phase 8 during 17-19th November that you show played its part to give us the current model attempts to amplify the Azores High mid-Atlantic block and transition it to a Greenland/Iceland high latitude block around the 25-26th of the month. But this shortlived because not only was it was a rapid transition thru Ph 8 but as @Met4Cast says above, there wasn't enough "oomph" (amplitude).

I started a 'Teleconnections - Interactions and Impact' thread back in 2019 which ran for a couple of years. It's still there and not locked, so if you fancy using it again and I'll happily join in. Original post: https://community.netweather.tv/topic/99428-model-output-discussion-mid-autumn/?do=findComment&comment=4955034

Yes, same when a northerly flow hits the Alps, as seen in the GFS chart below for next Saturday (where a big fall of snow is being forecast). For info, both your answer and the previous answers given to the question raised by @The Enforcer on the previous page are correct, i.e. kinks in isobars are caused by the temperature contrast between land and sea or between either side of a mountain range, with a cold front marking the boundary between the airmasses. When mountain ranges separate colder air on one side from warmer air on the other, isobaric spacing is much closer (packed) over the range. Along coastlines in the winter, when continental arctic or polar air moves offshore over much warmer water, the isobars will pack over the water. The greater the temperature contrast between the air mass and the water, the tighter the gradient (spacing). Source: Aerographer/Meteorological website Original post: https://community.netweather.tv/topic/99428-model-output-discussion-mid-autumn/?do=findComment&comment=4955012

I started a 'Teleconnections - Interactions and Impact' thread back in 2019 which ran for a couple of years. It's still there and not locked, so if you fancy using it again and I'll happily join in.

Yes, same when a northerly flow hits the Alps, as seen in the GFS chart below for next Saturday (where a big fall of snow is being forecast). For info, both your answer and the previous answers given to the question raised by @The Enforcer on the previous page are correct, i.e. kinks in isobars are caused by the temperature contrast between land and sea or between either side of a mountain range, with a cold front marking the boundary between the airmasses. When mountain ranges separate colder air on one side from warmer air on the other, isobaric spacing is much closer (packed) over the range. Along coastlines in the winter, when continental arctic or polar air moves offshore over much warmer water, the isobars will pack over the water. The greater the temperature contrast between the air mass and the water, the tighter the gradient (spacing). Source: Aerographer/Meteorological website

Not long to go before we enter meteorogical winter so a good time to start the Winter Chat thread. In line with forum Guidelines please keep things friendly and respectful in here.

This isn't the thread for discussing CC please folks. Head over to the Climate Change area of the forum for that. Thank you.

Happy Birthday for yesterday Dami. Yes, it was a lovely day and some wonderful autumn colours on display out on my walk. Today not so clever, although the worse from the warm front has passed through overnight. We're now in the more fragmented rainfall from the cold front. Hopefully some sunshine by this afternoon. 05.30 07.45

My neighbour has just sent me a text whilst out with his dogs, having a pop at the Met Office for their "sunshine" forecast on his moby app. I can see his problem, he's been caught in one of the narrow but nasty lines of showers moving thru atm. I shouldn't laugh but..... 10.30

A very wet night as the warm front associated with Storm Debi crossed the Region. Had 8mm here in Suffolk. It was one of those night's where the temperature slowly went up, from 8C at 22.00 last night to 11C this morning imby. 04.35 And now the following cold front is moving through, just in time to give some nasty conditions during the commute. 07.20 A windy day ahead with gusts up to 90 kmh (55 mph) on the South Coast and 75 kmh (46 mph) on the Norfolk Coast according to GFS. Gust sequence from this morning through to 22.00: Source: https://www.meteociel.fr/modeles/gfs/royaume-uni/vent-rafales/3h.htm

Storm Domingos 4th November Whilst the worst effects of Storm Domingos were felt along the Atlantic coasts of France and Spain with heavy rain and wind gusts of up to 80mph, for our Region it brought yet another spell of unwelcomed rain to already saturated southern counties. For the record here's a tweet from Roost Weather showing local amounts: Rainfall over the past 12 hours, associated with #StormDomingos (totals >10mm shown only) Source: https://x.com/RoostWeather/status/1720809757080957147?s=20

October 2023 overview just posted in the Regional Weather Records and Stats thread:

October 2023 Well what an interesting month of weather. From the 7th - 10th the Region recorded four consecutive days of +25C and since 1900 this has only happened twice before, in 1921 and 1959. Then all change with the second half of the month, memorable for the amount of rainfall and flooding and Storms Babet and Ciaran. As a result the Region ended up with around average sunshine but above average temperatures and way above average rainfall. Here's the summary charts and analysis from Dan Holley, Weatherquest. For East Anglia: Joint 8th warmest Oct on record Wettest Oct since 2000 (ranked 12th) Near-average sunshine Wettest October on record: - Brooms Barn - Cambridge NIAB - Cavendish - Charsfield - Cromer - Houghton Hall - Santon Downham - Wattisham - Wittering Source: https://x.com/danholley_/status/1721090381540999193?s=20 And digging deeper, some further analysis courtesy of Starlings Roost Weather using the SYNOP automated weather stations data: East Anglia Rainfall: Anomaly: SE Rainfall: Anomaly: Top 10 Rainfall Anomaly: Top 10 Sunshine Anomaly: Source: http://starlingsroost.ddns.net/weather/ukobs/summary_month_summary_map.php?month=10&year=2023

Storm Ciaran 2nd Nov 2023 Track and MSLP of the storm courtesy of Dan Holley, Weatherquest: #StormCiarán produced the lowest mean sea level pressure since February 1989 across a large swathe of southern and eastern England, and across the English Channel... Source: https://x.com/danholley_/status/1720527764862709805?s=20 The Netweather Hi-Res radar calculation of the rainfall from the storm during 2nd Nov: The Region missed the strongest winds from the storm which tracked further south than forecast, taking the strongest winds on its southern flank with it. Surprisingly Cambourne near Cambridge appears to have recorded the highest in the Region, rather than a south coast location. Sources: Track of Ciaran: https://x.com/danholley_/status/1720170155047546913?s=20 Wind Gusts: https://x.com/metoffice/status/1719994902648369548?s=20

A good explanation from Dan Holley of Weatherquest as to why some areas expecting severe gales today have escaped the worst of the winds. In a nutshell Storm Ciaran tracked further east (and I would suggest further south as well) than the models were suggesting, taking the worst of the winds on the southern flank with it. A look back at the deterministic runs of the main global models from Wednesday (00z) for the expected track of #StormCiarán. Much of East Anglia and inland SE England narrowly missed the very strong winds as Ciarán tracked further east than forecast. Source: X https://x.com/danholley_/status/1720170155047546913?s=20

From Dan Holley of Weatherquest, a comparison of model forecasts for the track of Storm Ciaran versus the actual observed: A look back at the deterministic runs of the main global models from Wednesday (00z) for the expected track of #StormCiarán. Much of East Anglia and inland SE England narrowly missed the very strong winds as Ciarán tracked further east than forecast. Source: X https://x.com/danholley_/status/1720170155047546913?s=20

Nice to read this on the Weather to Ski website today. Resorts over 2,300m could be seeing up to 40cms. Extract: Today in the Alps... Updated: 11am Thursday 2 November 2023 - Significant snow at altitude in the Alps! The weather in the Alps remains very unsettled today, with a new storm crossing the Alps from west to east which will deliver significant snow at altitude to many regions. Link and full story: https://www.weathertoski.co.uk/weather-snow/ The webcams confirming it's definitely snowing at altitude in the Alps. Here's a few resorts - there were some enjoying a whiteout and you couldn't see a thing! Les Arcs 1,950m Solden 2,500m Val D'Isere 1,800m Val Thorens 2,300m Webcams images from Bergfex https://www.bergfex.com/schweiz/webcams/

This thread is now locked. A new thread is here:

With November a couple of days away, right on cue the GFS model is forecasting the first notable accumulation of snow in the Alps and Pyrenees during the next week. So a good time to relaunch the Worldwide Mountain and Snow Sports thread for the upcoming season. It's very early days of course with no doubt much waxing and waning to come as we move towards the start of the season, but nevertheless nice to see and adds to the sense of anticipation for those of us who love the mountains and winter snowsports. 30th Oct 7th Nov And what are the prospects for the upcoming season in an El Nino year? A little early to quote winter forecasts (other than preliminary thoughts that have been published) but there are a couple of interesting charts shown in the Severe Weather Europe preliminary Winter 2023/2024 Snowfall Predictions that I'd like to show. The first shows the 500mb geopotential height anomaly for Dec - Feb for the last eleven El Nino winters. The above average heights to the west of the UK and below average heights to the east suggests an increased chance of cold northerly incursions bringing snowfall to the northern Alps in an El Nino winter, and if that happens Austria would be best placed. And for the USA/Canada prospests the above chart suggests the more southern resorts along the Rockies will stand the better chance of seeing 'normal' snowfall amounts. This is confirmed by the second chart showing the variance from long-term average snowfall experienced during El Nino years, suggesting resorts in California, Nevada and Utah might fare best. Here on Netweather there's lots of skiing related content to be accessed during the season, including: Netweather Ski Centre - from here you can view the snow report, weather forecast, and resort information, for just about every mountain resort in the world, including a dedicated page for Scottish resorts. Ski &amp Snowboard Weather Forecast & Snow Report - Netweather.tv WWW.NETWEATHER.TV Weather forecasts & snow reports for ski and snowboard resorts worldwide. There is also a special Alpine Charts page where you can zoom in on GFS charts showing precipitation, freezing level, temperature, etc. Here's hoping for a snowy winter! And for those lucky enough to get away, don't forget to post your pics!

Great idea. A lovely pic there to wet the appetite for the coming season. I'm taking a break in West Wales atm and the mobile coverage very poor, but will start a new thread Monday when back home unless Julian has done the deed in the meantime.