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Warm sectors - always milder than forecast

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    #32
    highdef
    Registered Users Posts: 6,140 ✭✭✭highdef


    Without divulging your eircode so that we know your exact location, if you could give a decent idea of where you live (we currently have a very rough description unless I've missed a post where you have better information), then the more seasoned posters here can try give you better answers to your query.

    Topography often has a major effect on temperatures. I live almost at the bottom of a small valley in a small village with Enfield being my nearest town, about 5km to my North West as the crow flies. On a cold clear calm night, if I walk from my house to the lowest point in the area, there's a very obvious drop of temperature. Sometimes it's frost free leaving the house and it's a hard frost at the lowest point. The distance from my house to this point is less than 100m and the difference in altitude is about 3m.

    Other times I have driven to the shops in Enfield when it's snowing and sticking at home. It is quite often completely green in Enfield and it could be very wet snow or sleet. As I get closer to home on the return trip, the sides of the road become progressively snow covered and by the time i get home, all surfaces may be snow covered. This is despite little difference in altitude but in my case I have moderate hills in 3 directions which, depending on wind direction and other parameters, it can often swing me into the right side of marginal.

    So that's why having a good idea of one's location is imperative to try give an explanation for your queries. We are all here to help and you need to understand that. Being rude will get you nowhere here.


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    #33
    Nqp15hhu
    Banned (with Prison Access) Posts: 2,254 ✭✭✭Nqp15hhu


    highdef wrote: »
    Without divulging your eircode so that we know your exact location, if you could give a decent idea of where you live (we currently have a very rough description unless I've missed a post where you have better information), then the more seasoned posters here can try give you better answers to your query.

    Topography often has a major effect on temperatures. I live almost at the bottom of a small valley in a small village with Enfield being my nearest town, about 5km to my North West as the crow flies. On a cold clear calm night, if I walk from my house to the lowest point in the area, there's a very obvious drop of temperature. Sometimes it's frost free leaving the house and it's a hard frost at the lowest point. The distance from my house to this point is less than 100m and the difference in altitude is about 3m.

    Other times I have driven to the shops in Enfield when it's snowing and sticking at home. It is quite often completely green in Enfield and it could be very wet snow or sleet. As I get closer to home on the return trip, the sides of the road become progressively snow covered and by the time i get home, all surfaces may be snow covered. This is despite little difference in altitude but in my case I have moderate hills in 3 directions which, depending on wind direction and other parameters, it can often swing me into the right side of marginal.

    So that's why having a good idea of one's location is imperative to try give an explanation for your queries. We are all here to help and you need to understand that. Being rude will get you nowhere here.

    I am more talking about stable and cloudy air masses, not frosty nights where there will be temperature differences over the distance.

    Regarding my location. I have already said I live east of Limavady, in Northern Ireland. I live about 3 miles from a 1200 feet+ area of land. It is to my Northeast. I am not divulging any further.


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    #34
    Oneiric 3
    Registered Users Posts: 6,235 ✭✭✭Oneiric 3


    The NW of Ireland is pretty hilly though, so temps are naturally going to fluctuate from place to place more than they would in flatter regions.

    New Moon



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    #35
    Nqp15hhu
    Banned (with Prison Access) Posts: 2,254 ✭✭✭Nqp15hhu


    I’m wondering if it’s lough foyle.


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    #36
    Gaoth Laidir
    Registered Users Posts: 8,219 ✭✭✭Gaoth Laidir


    Nqp15hhu wrote: »
    I am more talking about stable and cloudy air masses, not frosty nights where there will be temperature differences over the distance.

    Firstly, I have seen no evidence to support the title that warm sectors are always warmer than forecast. That's not to call you a liar, just stating my opinion. If you have hard data, other than just a station or two, then by all means provide them so we can have a mature debate on the thread that you started.

    I live the following distances as the crow flies from these stations' instrument enclosures:

    Casement - 8.4 km
    Phoenix Park - 13.3 km
    Dublin Airport - 18.5
    Dunsany - 20.3 km

    I'm at 65 m amsl, Casement is at 92, Dublin Airport 75, Phoenix Park 48 and Dunsany 83 m. All pretty much the same altitude, but each station is in very different local topography. The Phoenix Park is poorly sited, being surrounded by buildings and high trees and also the undulating landscape of that end of the Phoenix Park.

    Casement is more open, but still has buildings and a large arpron and hangars to its west, north and northeast.

    Dublin Airport and Dunsany are the most open of all. I haven't been to the Dunsany site but the Dublin Airport one is on flat open grassy ground, a few km away from the airport buildings. Here's a thread I started on all stations, with exact locations.

    We all see greatly varying temperatures at each of these stations on any one night, It still doesn't imply anything about the larger synoptic temperature field of the warm sector, which you say is always warmer than average. Things get complicated when comparing coastal stations (Magilligan, Malin Head and Ballypatrick Forest) with those more inland (yours and then Lough Fea, which has the added complication of being 200 m higher and beside a lake).

    It basically is what it is, I'm afraid. We all know the local intricacies of our own areas and you will build up that picture of yours too, with time. Be carefult when comparing temperatures from your station, which, from the looks of it, seems fairly close to your house. It can, as has been already stated, be susceptible to some spurious readings in certain situations. We've been through this sort of debate ad nauseum before about stations such as Shannon Airport, for example, and the debate will go on and on.


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    #37
    Nqp15hhu
    Banned (with Prison Access) Posts: 2,254 ✭✭✭Nqp15hhu


    Gaoth Laidir wrote: »
    Firstly, I have seen no evidence to support the title that warm sectors are always warmer than forecast. That's not to call you a liar, just stating my opinion. If you have hard data, other than just a station or two, then by all means provide them so we can have a mature debate on the thread that you started.

    I live the following distances as the crow flies from these stations' instrument enclosures:

    Casement - 8.4 km
    Phoenix Park - 13.3 km
    Dublin Airport - 18.5
    Dunsany - 20.3 km

    I'm at 65 m amsl, Casement is at 92, Dublin Airport 75, Phoenix Park 48 and Dunsany 83 m. All pretty much the same altitude, but each station is in very different local topography. The Phoenix Park is poorly sited, being surrounded by buildings and high trees and also the undulating landscape of that end of the Phoenix Park.

    Casement is more open, but still has buildings and a large arpron and hangars to its west, north and northeast.

    Dublin Airport and Dunsany are the most open of all. I haven't been to the Dunsany site but the Dublin Airport one is on flat open grassy ground, a few km away from the airport buildings. Here's a thread I started on all stations, with exact locations.

    We all see greatly varying temperatures at each of these stations on any one night, It still doesn't imply anything about the larger synoptic temperature field of the warm sector, which you say is always warmer than average. Things get complicated when comparing coastal stations (Magilligan, Malin Head and Ballypatrick Forest) with those more inland (yours and then Lough Fea, which has the added complication of being 200 m higher and beside a lake).

    It basically is what it is, I'm afraid. We all know the local intricacies of our own areas and you will build up that picture of yours too, with time. Be carefult when comparing temperatures from your station, which, from the looks of it, seems fairly close to your house. It can, as has been already stated, be susceptible to some spurious readings in certain situations. We've been through this sort of debate ad nauseum before about stations such as Shannon Airport, for example, and the debate will go on and on.

    I am just commenting on the fact that mild or “warm sectors” here at my location often end up being milder than predicted, or forecasted.

    As I said, we were due to reach 6c yesterday and had rose up to 7c. There isn’t much else I can say, you are asking me to provide hard evidence but won’t allow me to use the local weather stations.


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    #38
    Gaoth Laidir
    Registered Users Posts: 8,219 ✭✭✭Gaoth Laidir


    Nqp15hhu wrote: »
    I am just commenting on the fact that mild or “warm sectors” here at my location often end up being milder than predicted, or forecasted.

    As I said, we were due to reach 6c yesterday and had rose up to 7c. There isn’t much else I can say, you are asking me to provide hard evidence but won’t allow me to use the local weather stations.

    0.1 of a degree can be the difference between 6 and 7 degrees (e.g 6.4 and 6.5). I wouldn't lose any sleep over a degree or so discrepancy. It's impossible to be that accurate for a point location, unless using some extremely hi-res local model, to which none of us has any access (if one even exists). Models have topography built into them, which becomes more and more accurate the higher the resolution, however they will never 100% capture every little detail.


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    #39
    Gaoth Laidir
    Registered Users Posts: 8,219 ✭✭✭Gaoth Laidir


    Nqp15hhu wrote: »
    I am more talking about stable and cloudy air masses, not frosty nights where there will be temperature differences over the distance.

    Regarding my location. I have already said I live east of Limavady, in Northern Ireland. I live about 3 miles from a 1200 feet+ area of land. It is to my Northeast. I am not divulging any further.

    It is a bit of a bowl you're in alright. Surrounded by hills on one side, flat coastal plane to the west. I can see how things get complicated a bit there alright.

    https://www.google.ie/maps/@55.0501935,-7.0268229,11.31z/data=!5m1!1e4


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    #40
    Danno
    Registered Users Posts: 8,913 ✭✭✭Danno


    Nqp15hhu wrote: »
    I’m wondering if it’s lough foyle.

    Just went on Google Maps and switched to streetview where the Terrydoo road joins the B66 route east of Limavady. I'm guessing you're not very far from this junction. Not only is it quite exposed to the south, southwest, west and northwest (any cold air will be shunted away quickly) it is also rather elevated when compared to Limavady town also.

    Judging by that area/district the main weather advantages there would be:

    * Decent spot to experience during storms
    * Some snowfall potential owing to altitude and proximity to the cold northern Atlantic, does good in a northerly
    * Occasional summertime heat spot in a SSE or SE airflow

    However there are disadvantages:
    * Poor site for cold pooling
    * Higher rainfalls than say Coleraine further east and probably Dungiven to your south.
    * Despite higher amounts of sunshine in a summertime NW'ly or N you'd be cold at around 14c or 15c.


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    #41
    Nqp15hhu
    Banned (with Prison Access) Posts: 2,254 ✭✭✭Nqp15hhu


    My station and the local station. The middle one is always far colder.


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    #42
    Nqp15hhu
    Banned (with Prison Access) Posts: 2,254 ✭✭✭Nqp15hhu


    Even now that middle station is 2c colder than mines.


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    #43
    Gaoth Laidir
    Registered Users Posts: 8,219 ✭✭✭Gaoth Laidir


    Danno wrote: »
    Just went on Google Maps and switched to streetview where the Terrydoo road joins the B66 route east of Limavady. I'm guessing you're not very far from this junction. Not only is it quite exposed to the south, southwest, west and northwest (any cold air will be shunted away quickly) it is also rather elevated when compared to Limavady town also.

    Judging by that area/district the main weather advantages there would be:

    * Decent spot to experience during storms
    * Some snowfall potential owing to altitude and proximity to the cold northern Atlantic, does good in a northerly
    * Occasional summertime heat spot in a SSE or SE airflow

    However there are disadvantages:
    * Poor site for cold pooling
    * Higher rainfalls than say Coleraine further east and probably Dungiven to your south.
    * Despite higher amounts of sunshine in a summertime NW'ly or N you'd be cold at around 14c or 15c.

    SNAP!


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    #44
    Nqp15hhu
    Banned (with Prison Access) Posts: 2,254 ✭✭✭Nqp15hhu


    Gaoth Laidir wrote: »
    It is a bit of a bowl you're in alright. Surrounded by hills on one side, flat coastal plane to the west. I can see how things get complicated a bit there alright.

    https://www.google.ie/maps/@55.0501935,-7.0268229,11.31z/data=!5m1!1e4

    Yes... wondering what affects may occur


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    #45
    Gaoth Laidir
    Registered Users Posts: 8,219 ✭✭✭Gaoth Laidir


    This is looking out due west from the Keady Hill quarry, almost due east of Limavady, 200 m amsl, with Limavady just left of centre. It's actually fairly flat landscape, by the looks of it. Nice area!


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    #46
    Nqp15hhu
    Banned (with Prison Access) Posts: 2,254 ✭✭✭Nqp15hhu


    Danno wrote: »
    Just went on Google Maps and switched to streetview where the Terrydoo road joins the B66 route east of Limavady. I'm guessing you're not very far from this junction. Not only is it quite exposed to the south, southwest, west and northwest (any cold air will be shunted away quickly) it is also rather elevated when compared to Limavady town also.

    Judging by that area/district the main weather advantages there would be:

    * Decent spot to experience during storms
    * Some snowfall potential owing to altitude and proximity to the cold northern Atlantic, does good in a northerly
    * Occasional summertime heat spot in a SSE or SE airflow

    However there are disadvantages:
    * Poor site for cold pooling
    * Higher rainfalls than say Coleraine further east and probably Dungiven to your south.
    * Despite higher amounts of sunshine in a summertime NW'ly or N you'd be cold at around 14c or 15c.
    I don’t live there but in a similar location. We actually seem to be in a bit of a rain shadow as the average here is only 800mm.

    It is interesting to note in the summer that we are often warmer than areas east, as the Ne winds are blocked by the hill. However, the west wind comes straight through us and this is what I have been wondering about in relation to the warm sectors.

    I have personally recorded 30c here in the summer of 2018 and multiple 20c days this year. It must’ve been over 30, 20c+ highs this summer.


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    #47
    Danno
    Registered Users Posts: 8,913 ✭✭✭Danno


    Nqp15hhu wrote: »
    However, the west wind comes straight through us and this is what I have been wondering about in relation to the warm sectors.

    That is your culprit right there, in colder weather the Foyle Lough will be seeping heat upwards into the calm sky, the minute a west breeze kicks off, it blows eastwards to you and rises your temperatures quickly.

    I've noticed similar differences here between here and Kilkenny city in a westerly based airflow, StratoQ has a station there and posts to www.kilkennyweather.com

    Often his station will drop quickly in the calm air whilst I have a light westerly or northwesterly. I've seen up to 3c differences between here and there early in the night, however often by dawn the breeze drops off here and my station's temperatures will occasionally drop up to 1c cooler than Kilkenny's minimum.
    The reverse then happens if a morning breeze sets in - my station will get back up above 0c quicker than Kilkenny's.

    I'd say in your location that under fairly high pressure on clear sky evenings, you'd get a SSE or E breeze as the cold air sinks down from the hills to your east, combining with an offshore breeze?


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    #48
    Nqp15hhu
    Banned (with Prison Access) Posts: 2,254 ✭✭✭Nqp15hhu


    Danno wrote: »
    That is your culprit right there, in colder weather the Foyle Lough will be seeping heat upwards into the calm sky, the minute a west breeze kicks off, it blows eastwards to you and rises your temperatures quickly.

    I've noticed similar differences here between here and Kilkenny city in a westerly based airflow, StratoQ has a station there and posts to www.kilkennyweather.com

    Often his station will drop quickly in the calm air whilst I have a light westerly or northwesterly. I've seen up to 3c differences between here and there early in the night, however often by dawn the breeze drops off here and my station's temperatures will occasionally drop up to 1c cooler than Kilkenny's minimum.
    The reverse then happens if a morning breeze sets in - my station will get back up above 0c quicker than Kilkenny's.

    I'd say in your location that under fairly high pressure on clear sky evenings, you'd get a SSE or E breeze as the cold air sinks down from the hills to your east, combining with an offshore breeze?

    I don’t know. The warm days this summer all had NE/SE winds. I will have to watch for that wind direction.


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    #49
    Danno
    Registered Users Posts: 8,913 ✭✭✭Danno


    Nqp15hhu wrote: »
    I don’t know. The warm days this summer all had NE/SE winds. I will have to watch for that wind direction.

    Suspiciously like a Fohn effect where you are looking at the geography of the area.

    It's often something that's overlooked is the very important relationship between geography and the weather, especially in a localised sense.

    The lads in Kerry and near the Wicklow Mtns know this only too well!

    I often note a poster on this forum from around the Bray area and he/she remarked on how they'd get consistently good or prolonged sunshine and warmth during those Irish summer days when the southwesterlies bring in alot of cloud.

    It is all down to the mountains and the fohn effects in that particular area of SE Dublin and NE Wicklow.


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    #50
    Nqp15hhu
    Banned (with Prison Access) Posts: 2,254 ✭✭✭Nqp15hhu


    Danno wrote: »
    Suspiciously like a Fohn effect where you are looking at the geography of the area.

    It's often something that's overlooked is the very important relationship between geography and the weather, especially in a localised sense.

    The lads in Kerry and near the Wicklow Mtns know this only too well!

    I often note a poster on this forum from around the Bray area and he/she remarked on how they'd get consistently good or prolonged sunshine and warmth during those Irish summer days when the southwesterlies bring in alot of cloud.

    It is all down to the mountains and the fohn effects in that particular area of SE Dublin and NE Wicklow.

    Yes as I said, often we will drive over the hill to Coleraine and it will be 3-4c colder. Temperatures would rise rapidly coming down the hill on the way back.

    But oddly it doesn’t appear on the Met office maps.


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    #51
    Nqp15hhu
    Banned (with Prison Access) Posts: 2,254 ✭✭✭Nqp15hhu


    Warmish days this summer.


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    #52
    Danno
    Registered Users Posts: 8,913 ✭✭✭Danno


    Nqp15hhu wrote: »
    Yes as I said, often we will drive over the hill to Coleraine and it will be 3-4c colder. Temperatures would rise rapidly coming down the hill on the way back.

    But oddly it doesn’t appear on the Met office maps.

    Unless the UKMO or Met Eireann have a station there it's highly unlikely they'll factor these localised conditions into their forecasts, and as there would be hundreds of these localised effects all around the country, some only covering a few square miles too - it would be impossible for them to afford such a monitoring regime.

    I noticed here in south Laois, before I undertook to maintain a climatological station for Met Eireann that the temperature forecasts were quite a bit out under certain weather conditions (I had my Davis Pro II at the time).

    Since I've got the climatological station, I notice temperature forecasts have improved a bit.

    I guess it's more data they can get in, the better data they can put out - but weather will still be weather and throw up surprises such as the 31.3c recorded here in Summer 2018 - the forecast for here that day was 28c! :D


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    #53
    Nqp15hhu
    Banned (with Prison Access) Posts: 2,254 ✭✭✭Nqp15hhu


    The temperature difference has reversed. My station is now 2.2c, the town station is 2.5c.

    Twas questioning the positioning of my station for a moment.


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    #54
    [Deleted User]
    Posts: 0 ✭ [Deleted User]


    Nqp15hhu wrote: »
    Oh and by the way, regarding Marine flow that many insist affects me. Magilligan is currently 5c, I am 2c.

    Malin Head is 6c.

    Mallin is on the coast,you're not
    It still affects you


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    #55
    Nqp15hhu
    Banned (with Prison Access) Posts: 2,254 ✭✭✭Nqp15hhu


    Oh and by the way, regarding Marine flow that many insist affects me. Magilligan is currently 5c, I am 2c. Malin Head is 6c.

    Danno, for your interest my wind direction is NE. I’m not sure if that’s some sort of flow of the hill.


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    #56
    Nqp15hhu
    Banned (with Prison Access) Posts: 2,254 ✭✭✭Nqp15hhu


    Also 5c in Coleraine

    https://www.wunderground.com/dashboard/pws/ILONDOND3


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    #57
    Gaoth Laidir
    Registered Users Posts: 8,219 ✭✭✭Gaoth Laidir


    Nqp15hhu wrote: »
    Oh and by the way, regarding Marine flow that many insist affects me. Magilligan is currently 5c, I am 2c. Malin Head is 6c.

    Danno, for your interest my wind direction is NE. I’m not sure if that’s some sort of flow of the hill.

    NE at 0 mph. It's calm.

    With slack winds the marine layer won't make it far inland, but you're only around 9 km inland so on most days with any appreciable wind it will.


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    #58
    Nqp15hhu
    Banned (with Prison Access) Posts: 2,254 ✭✭✭Nqp15hhu


    There is no land to my Ne so that will never yield a marine layer.

    The local cold layer must be quite deep as I have just had a graupel shower.


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    #59
    [Deleted User]
    Posts: 0 ✭ [Deleted User]


    Marine layer comes from the ocean
    If you were completely unaffected by it this morning, you'd be below freezing
    The clue is in the word Marine


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    #60
    Nqp15hhu
    Banned (with Prison Access) Posts: 2,254 ✭✭✭Nqp15hhu


    AuntySnow wrote: »
    Marine layer comes from the ocean
    If you were completely unaffected by it this morning, you'd be below freezing
    The clue is in the word Marine

    It’s cloudy so how would I be below freezing? There are only a few places on the island below freezing.


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    #61
    riffmongous
    Moderators, Society & Culture Moderators Posts: 12,626 Mod ✭✭✭✭riffmongous


    What models do the Met Office use? And their resolution?


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