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Higher Ground

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Posts posted by Higher Ground

    Model output discussion - August hot spell - how hot, how long?

    in Forecast Model Discussion

    Posted · Edited by Higher Ground

    1 hour ago, General Cluster said:

    Just like when I use to regularly see temps of 34-35C, when in the NW Highlands... which was quite obviously down to back-radiation for my white-painted house...But, if I know that and you know that, don't you think the Meteorological Office also knows that...?

    So, no, I really don't think there's a 'case to answer'...?

    You're actually making the same point as me with your first para. I don't think the Met Office would dispute research showing that both city-wide UHI and local heating effects can be very significant (e.g. up to 5C in extreme cases for UHI at night-time). We may be considering different questions here - perhaps I've misunderstood the history of the debate on these forums as I'm a rare visitor.

    My question would be, how much warmer are the recent record max temps at Heathrow than they would be if the site was in a location away from the airport with average levels of vegetation/trees around etc. There is a case to answer in this context, and it is nothing to do with whether Heathrow site meets official guidelines. I don't believe I've accused the Met Office of anything.

    I won't post any more on this, as I know how annoying it can be when the model discussion is derailed. Please don't think I'm trying to stir things up; the opposite is the case. I think dispassionate analyis of UHI and hyper-local warming effects is really useful, and I'm very receptive to anyone who engages in this, whatever their findings.

    • Like 1

    Model output discussion - August hot spell - how hot, how long?

    in Forecast Model Discussion

    Posted

    20 minutes ago, MattStoke said:

    The way some go on, weather stations should only be placed in the middle of nowhere where no-one lives. They seem to think the station is in the middle of the main runway and being blasted by jet exhausts. I’m surprised they haven’t claimed that the fire at Heathrow yesterday was the station being set alight by the Met Office and blaming the high temperature reading on that. It’s tiresome reading the same comments every time we get a hot day. As if the Met Office aren’t careful and don’t take certain factors into consideration when locating a weather station.

    Well there's a couple of extreme views which are common: (1) Runways etc cause all the excess heat, end of story; (2) We can essentially ignore such factors as tarmac. Expressing one of these views will tend to bring out people with the opposite view.

    But hyper-localised heating effects are real, and often bigger than city UHI effects. For example in the Feb mini-heatwave last year, the thermometer in my back yard recorded 26C in the shade near to sunlit fence and decking, even though the temp at local wx stations only got up to the high teens. So there seems to be at least a case to answer here.

    As Daniel (I think it was?) suggested, I'd like to see a further breakdown of observed temps between Kew and Heathrow, and for more recent years. Adjusting for how sunny it is around typical time of max temperature, wind speed/direction etc.

    • Like 1

    Model output discussion - August hot spell - how hot, how long?

    in Forecast Model Discussion

    Posted

    30 minutes ago, B87 said:

    They are average max temps, and Kew usually has warmer days than Heathrow. Kew has a frost hollow effect, and has some of the lowest average minima in London. Heathrow minima are also cooler than most of London. 

    If the Met Office hadn't shut down weather stations at Greenwich, Camden, LWC and Gravesend, Heathrow wouldn't be claiming all of the temperature records. The PWS in Whitton closely matches Heathrow temperatures.

    Ah yes - in my defence I thought looking at the title of the bar chart: "Average monthly temperature" and the closeness of the Kew and Heathrow temps was enough to extract the vital information.... Glad you corrected me, and useful info in your post, thanks 

    • Like 2

    Model output discussion - August hot spell - how hot, how long?

    in Forecast Model Discussion

    Posted

    1 hour ago, johnholmes said:

    I thought this might be of interest in the, what seems like, perennial discussion about the Heathrow temperature readings

    image.thumb.png.2845672d1c054d87f7786ccae0be8cbc.png

    Tarmac at Heathrow causing higher max on sunny days would also likely cause lower min on clear nights - especially as Kew more surrounded by city (UHI more pronounced at night-time as I understand it). Hence similar mean temps but Heathrow breaks the max temp records?

    July 2020 CET & EWP forecast contests

    in Spring Weather Discussion

    Posted

    3 hours ago, summer blizzard said:

    I wonder if anybody has considered the prospect of sub 07/11 after corrections especially. 

    Looking at both models their are small up and down movements for 23rd-26th however afterwards even the Euro does not get the warmer air in until the 31st (and even then mainly in the west) and the GFS would deliver several days of small downward pressure. It seems to me that to the 30th at least we are unlikely to be any higher than we are now. 

    Yes I was considering that possibility quite seriously, especially if my hunch is correct that relatively cool minima seem to result in a bigger correction sometimes. However, the last few model runs have increasingly seemed to suggest that chances will be scuppered at the final hurdle - even if the night of 30/31st is average under high pressure, a hot sunny day on 31st would be likely to tip the balance away from a more notably low CET.

    • Like 1

    July 2020 CET & EWP forecast contests

    in Spring Weather Discussion

    Posted · Edited by Higher Ground

    33 minutes ago, summer blizzard said:

    As per the annual CET thread we should drop to fourth as a result of the cool July (2017 and 2014 were both warm to this point and 2007 will stay ahead since we will finish lower than 15.8C) however 2007, 2014 and 2017 all had cool Augusts so we have a chance to jump into first for a month before 2006 and 2014 see their thrashing march to victory. 

    Interesting comparisons thanks! I've just been on a trip down memory lane to a time when I used to follow these things a little more closely. Specifically I found the July CET thread for 2007! Makes for fascinating reading. A couple of points caught my attention:

    Firstly, CET was 15.5c to the 21st July in 2007, so we are actually 0.2c cooler at the same point in July 2020. I'm guessing it will be tough though not impossible to remain cooler for a few days longer...
    https://www.netweather.tv/forum/topic/39130-july-cet/page/12

    Secondly, people seemed almost more surprised by the cool temperatures then, e.g. a comment in the 2007 thread mentioned that "Philip Eden in today's telegraph was saying that it will be the coldest July for England and Wales since 1993, for some parts it could even be the coldest since 1988, quite some feat in these times of rising temperatures..."
    https://www.netweather.tv/forum/topic/39130-july-cet/page/15/

    Oh and thirdly there was still talk of a possible plume or 'much warmer southerly draw' in the comments up to 19th July 2007!  
    https://www.netweather.tv/forum/topic/39130-july-cet/page/11
    (Similar this year in the model thread - significantly warmer weather to end the month still possible, but has been becoming less likely...)

     

    • Thanks 2

    July 2020 CET & EWP forecast contests

    in Spring Weather Discussion

    Posted · Edited by Higher Ground

    3 hours ago, Relativistic said:

    What's interesting is that this July may be a consequence of the warming climate. Arctic sea ice is doing terribly at the moment, and this may be influencing the anomalously cold sea-surface temperatures in the north Atlantic. Our north-westerlies have been subject to less thermal modulation as a consequence, which has led to some of the very cool minima and maxima we've seen this month. Even some air frosts in a select few spots.

    This is something I had been looking at myself - noticed a similarity to 2007 with both CET and arctic sea ice area:

    CET June and July 2007: 15.1c and 15.2c
    CET June and July 2020: 15.3c and 15.3c (provisional to 21st)

    Arctic sea ice area June 2007: 8.2 million sq km
    Arctic sea ice area June 2020: 8.4 million sq km
    https://nsidc.org/data/seaice_index/bist ('Sea Ice Conc' gives area)

    - Note that sea ice more concentrated this year hence higher area but lower extent in June. Probably both lower now due to big July losses.
    - CET averages for first half of year were 9.7c for January-June 2007 and 9.6c for January-June 2020
    https://www.metoffice.gov.uk/hadobs/hadcet/cetml1659on.dat

     

     

     

    • Thanks 2

    Midlands Regional Discussion

    in Regional

    Posted

    1 hour ago, Dancerwithwings said:

    18 hrs of Rain for a large part of our region since yesterday evening ...Shame it wasn’t in just a few week time, you imagine ❄️18 HRS of none stop SNOW ❄️ 

    Well let's just wait and see what happens in a few weeks time... or less!?

    • Like 1

    Midlands Regional Discussion

    in Regional

    Posted

    30 minutes ago, Snowyowl9 said:

    Yes indeed,the older snow is much more dirty now,can certainly spot the difference.

    Even the biggest drifts didn't quite make it until the second Beast From The East here - though it was a close call, just a couple of days. But then again you had the Pest From The West to help tide you over, from what I remember...

    Midlands Regional Discussion

    in Regional

    Posted

    1 minute ago, Snowyowl9 said:

    Double drifts left still the late feb one now showing up again.

    Snowcover 2 days again.

    mapa_duza.png

    Still good drifts here as well. Amazing isn't it how they've almost replicated the drifts (in the same places) from the last Beast From The East - such similar events

    Model output discussion - the beast arrives

    in Forecast Model Discussion

    Posted · Edited by Higher Ground
    didn't specify monday's chart

    6 minutes ago, Quicksilver1989 said:

    Yes for the Midlands maxima is still struggling by Monday, although by then dew points have risen to the extent that any precipitation would fall as rain. The best scenario for all would be:

    1) The cold air fights off the incoming milder air from the Atlantic
    2) Cold uppers move in off the back of an eastward moving low.
    3) The angle of attack changes from S-N to SW-NE with pressure increasing over Scandinavia.

    A big ask but you never know. The 00z would certainly leave the far north more then happy.

    Are you sure re the dew points and precipitation?

    https://www.meteociel.fr/modeles/gfse_cartes.php?&ech=156&mode=2

    • Like 1

    Model output discussion - the beast arrives

    in Forecast Model Discussion

    Posted · Edited by Higher Ground
    changed 6z to 0z

    40 minutes ago, Quicksilver1989 said:

    Thanks, yup for the Midlands saturday looks like as though temperatures will struggle to get above freezing, support is widespread for a warm up on Sunday though sadly but small changes and that could look a lot better.

    Something like P7 with a few southwards adjustments would do me very nicely.

    In terms of wanting to see a historic cold & snowy spell, I actually wouldn't change a single frame of the GFS 0z op run, for my location in the Midlands at least. At any 'normal' time I suspect model-watchers would regard most of the synoptics we're seeing as phenomenal or even borderline impossible - certainly for the time of year. Surely there's a very tricky compromise between hanging onto the coldest air, and allowing enough moisture to feed in to produce snow - even though the moisture is inevitably associated with milder air. I think GFS 6z strikes this balance very well, and still leaves scope for almost everyone to see significant snow depending on subtle changes closer to the time. Tantalising as it is for those in the most southern/south-western areas, it's their knife-edge situation that corresponds to the greatest chances of a nation-wide snow fest. (As I understand things, at least). 

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    Model output discussion - the beast arrives

    in Forecast Model Discussion

    Posted

    9 minutes ago, Quicksilver1989 said:

    image.thumb.png.b6c6b45b0c8506e115133580a120ad76.png

    Finally coming to a consensus on the 00z GFS ensembles it appears, with cold air hanging on for another day. Many ensemble members show maximums around freezing on Saturday now, can we also get Sunday to join in with the cold? I'm not getting my hopes up but fingers crossed....

    Thank you so much for coming up with this metric, and updating it consistently over the last few days. It really helps to have an objective way of trying to determine if there really have been 'downgrades' or 'upgrades' over time.

    • Like 12
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    Model output discussion - winter proper underway

    in Forecast Model Discussion

    Posted

    5 minutes ago, LRD said:

    I'm not talking about the effect, or not, on our winters Feb. I'm worried about the planet. Having an arctic region that warm is massively worrying. But I'll leave it there as we're going off topic

    You might also want to look at Arctic summer snow cover, which was the highest for over 10 years this June and July, and the highest for nearly 20 years this August https://climate.rutgers.edu/snowcover/chart_anom.php?ui_set=1&ui_region=nhland&ui_month=8

    Also Arctic ice volume which is still up if anything since 2011 http://psc.apl.uw.edu/wordpress/wp-content/uploads/schweiger/ice_volume/cryosat_piomas_awi_ts.2011.2017.Oct.png

    How can you be sure high sea surface temperatures around Svalbard aren't a release of heat (cooling), rather than a warming? Bear in mind that the North Atlantic at 0-700m depth is still the coldest for 15 years despite an upturn this year www.climate4you.com/SeaTemperatures.htm#North%20Atlantic%20(60-0W,%2030-65N)%20heat%20content%200-700%20m%20depth

    Not wanting to go off topic either, just trying to add some more pieces to the jigsaw in understanding how it's still possible to get severe cold despite longer term warming.

     

     

     

    • Like 10
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    Model output discussion - 20th Feb onwards

    in Forecast Model Discussion

    Posted

    6 hours ago, Bring Back1962-63 said:

    With a little more fiddling around I came across a 2 week forecast and….bingo!!! For the first time this winter, temperatures are forecast to fall below average!

    Thanks for the interesting stats about Svalbard temperatures over the past year, and it definitely seems relevant to me in terms of how deep any cold is that we tap into.

    I just wanted to point out that I used to check the Svalbard forecasts/recent temps for similar reasons to those you have outlined. However, I found that actual temperatures would often turn out to be several degrees C warmer than those forecast. (I think I tried using at least a couple of different weather sites.) Think there was an issue there that I never quite got to the bottom of.... I suspected the microclimate of the airport affecting the observations but not the forecasts.... but that's only a guess.

    Let's see how it turns out, and do update us in a couple of weeks time with the actual temps.

    The Midlands Regional Discussion 26/03/13 21z ------->

    in Regional

    Posted

    I can confirm SNOW in the West Midlands! It was at about 10.45am, during a sleety shower - when it got heavier it was proper snow falling for a couple of minutes (i.e. all flakes floating around). Maybe 15-30 minutes before that we had hail/melting hail and I know the difference. I've been a snow fan for years, and I'm happy to declare this a record here for latest snow falling - 23rd May 2013 at 286m/940 feet. Awesome! (p.s. now starting to hail.......)

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