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Risk Of Heavy Snow Showers As It Turns Extremely Cold Sunday Night/Monday
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Midday Monday from ECM
I remember precip like this turning out much more than forecast as model will not pick up the power of our snow machine until the final hour.
It all starts THE DAY AFTER TOMORROW.
Yep, once you see anything on them type of charts things are usually a lot more active, they just don't have the resolution.
Going to be interesting no matter what happens. There will be a slot where we simply won't have to worry about marginality with subzero dewpoints and 850hPa temps near -12c:cool: 0 -
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Severe snowstorm to blast nw france perhaps southern UK Sun into Mon. Coldest air of winter into UK on the way
Joe B has also tweeted these. Out of date now but you get the idea.
week ago tweeted for the UK to not buy false spring I saw being touted. Truly amazing snow/temp 4cast for coming wk pic.twitter.com/gtwmAucYF2
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Not inclined to change much about the east coast streamers in the forecast, as some have pointed out, global models do not generally forecast these very well and I have been relying more on a meso-scale modelling based on the general input from the model consensus. The other portion of the snowfall potential, namely parts of south being hit Sunday night from the low tracking towards Cornwall, remains a possibility but I was always more concerned about large-scale streamer development merging with that feature.
As to the suggested "half-way house" forecast being a case of Met-E and MT equally wrong, I don't think that's valid, the half-way house sounds almost like my forecast and widespread accumulations of snow is a lot closer to what I'm saying than "severe frost and mixed wintry showers" -- not that I'm here to make trouble with the Met service, but I don't see that as half-way at all. It may however prove to be correct, when I say something about "blizzards" I am going by what I perceive to be common perceptions of that term as disruptive snowfall events, and to me, 5-15 cm of snow in Dublin coming down fairly hard in the daytime would be disruptive. Whether that's technically a blizzard or not, I don't know, over here it would need to be more like 30 cm of snow and strong winds, limited visibility. There may be some of that by Monday in parts of England and possibly in Wicklow.
The guidance has not changed much overnight (in my time zone) and continues to spread over a slight range, so the best idea for now I believe is to concentrate on the potential for significant streamers and keep a watch on the south coast for any incursions from the Atlantic system (which I think is going to brush past but sometimes you can get a parallel inland band representing the arctic front in the circulation, fed by streamers). I am expecting that streamer development will be robust starting about midnight Sunday and that there will be two main bands, one running across Drogheda into Meath and Kildare and possibly Laois before weakening around Tipps, and one possibly over Dublin at times then shifting south later to cover most of Wicklow.
If these streamers develop then they have potential to become heavy, and being steady-state then some heavy amounts can be created in some locations. I guess what surprises me about the Met forecast is not the conservative approach but the lack of coverage of what appears to be at least a 50-50 chance of accumulating snow right in the heaviest population zone that they serve. But kudos to them if it doesn't snow (and I won't try to spin a 2cm flurry in Arklow or some minor event, let's set a reasonable bar and say there would have to be lying snow reported by 25 different observers at their homes not driving around the Sally Gap or wherever).
In the back of my mind also is the "what if" scenario of that low pushing north of the forecast track, they seem to do that almost effortlessly on the other side of the country. In that case, we would be looking at a very severe event. I haven't looked at all permutations of the GFS but I'll bet there's one or two showing that scenario. But for now, that very disruptive scenario seems likely to be heading towards Cornwall and Devon, Somerset, inland south central counties of England and later on northern France and southeast England.
Somebody was wondering about travel disruptions later in the week -- don't think that will be a problem for you unless you're trying to drive into some isolated high elevation location in Dartmoor, by Wednesday any disruptive snow in England should be either cleared away or melted in the daytime sun, but some higher parts of Devon and Somerset could be cut off for a few days, as well as conceivably a few parts of north Yorkshire, if the North Sea develops its share of streamers. Now if this had been January, there would be a longer spell of lying snow after any storms.
I think in general we dodged the bullet of last-minute downgrade at 12z, can see from the 18z map that all elements of the developing scenario are coming together (cold advection into Poland and northern Germany is rapid) and that brings me to the last part of my homily, which is, respect the thickness advection. Ireland is well into the 522 dam contour and almost into the 516 dam contour by Sunday midnight as it approaches Belfast and then all models show the -10 C 850 mb zone covering all of Ireland at some point Sunday night. There's a 30 knot E-NE gradient and dew points near -7 C in England advecting across the Irish Sea. It takes a brave soul to picture no snow in this scenario, I guess some are saying I'm out on a limb, would have to wonder if it isn't the other way around given the synoptics. Probably as always a middle course will verify but it's interesting I just went through the exact opposite of this on an American weather forum by suggesting (in a contest rather than a discussion) very low snowfall numbers for DC and BWI, in fact one person suggested that my forecast be edited out of the thread because it would prevent the spread of panic -- and in the end my low numbers were too high (I said something like one inch of snow at DCA, consensus was ten or fifteen, actual was a rather embarrassing 0.2). That thread has never received a comment since the storm didn't happen.
I am guessing this thread will receive a comment or two if this one doesn't happen. Keep your fingers crossed, and remember Nov/Dec 2010 -- the Irish Sea rules.0 -
Just looked at Met Eireann forecast after the 9pm news, dont see much to get excited about, few snow showers on Monday the dry and cold after that.
As mentioned before, this will be more than likely a streamer event, ME generally don't take these sort of event into account in their forecasts, they seem to forget that the Irish Sea is a snow making machine especially with the synoptic's that are nailed in for Sunday and Monday.
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M.T. Cranium wrote: »Not inclined to change much about the east coast streamers in the forecast, as some have pointed out, global models do not generally forecast these very well and I have been relying more on a meso-scale modelling based on the general input from the model consensus. The other portion of the snowfall potential, namely parts of south being hit Sunday night from the low tracking towards Cornwall, remains a possibility but I was always more concerned about large-scale streamer development merging with that feature.
As to the suggested "half-way house" forecast being a case of Met-E and MT equally wrong, I don't think that's valid, the half-way house sounds almost like my forecast and widespread accumulations of snow is a lot closer to what I'm saying than "severe frost and mixed wintry showers" -- not that I'm here to make trouble with the Met service, but I don't see that as half-way at all. It may however prove to be correct, when I say something about "blizzards" I am going by what I perceive to be common perceptions of that term as disruptive snowfall events, and to me, 5-15 cm of snow in Dublin coming down fairly hard in the daytime would be disruptive. Whether that's technically a blizzard or not, I don't know, over here it would need to be more like 30 cm of snow and strong winds, limited visibility. There may be some of that by Monday in parts of England and possibly in Wicklow.
The guidance has not changed much overnight (in my time zone) and continues to spread over a slight range, so the best idea for now I believe is to concentrate on the potential for significant streamers and keep a watch on the south coast for any incursions from the Atlantic system (which I think is going to brush past but sometimes you can get a parallel inland band representing the arctic front in the circulation, fed by streamers). I am expecting that streamer development will be robust starting about midnight Sunday and that there will be two main bands, one running across Drogheda into Meath and Kildare and possibly Laois before weakening around Tipps, and one possibly over Dublin at times then shifting south later to cover most of Wicklow.
If these streamers develop then they have potential to become heavy, and being steady-state then some heavy amounts can be created in some locations. I guess what surprises me about the Met forecast is not the conservative approach but the lack of coverage of what appears to be at least a 50-50 chance of accumulating snow right in the heaviest population zone that they serve. But kudos to them if it doesn't snow (and I won't try to spin a 2cm flurry in Arklow or some minor event, let's set a reasonable bar and say there would have to be lying snow reported by 25 different observers at their homes not driving around the Sally Gap or wherever).
In the back of my mind also is the "what if" scenario of that low pushing north of the forecast track, they seem to do that almost effortlessly on the other side of the country. In that case, we would be looking at a very severe event. I haven't looked at all permutations of the GFS but I'll bet there's one or two showing that scenario. But for now, that very disruptive scenario seems likely to be heading towards Cornwall and Devon, Somerset, inland south central counties of England and later on northern France and southeast England.
Somebody was wondering about travel disruptions later in the week -- don't think that will be a problem for you unless you're trying to drive into some isolated high elevation location in Dartmoor, by Wednesday any disruptive snow in England should be either cleared away or melted in the daytime sun, but some higher parts of Devon and Somerset could be cut off for a few days, as well as conceivably a few parts of north Yorkshire, if the North Sea develops its share of streamers. Now if this had been January, there would be a longer spell of lying snow after any storms.
I think in general we dodged the bullet of last-minute downgrade at 12z, can see from the 18z map that all elements of the developing scenario are coming together (cold advection into Poland and northern Germany is rapid) and that brings me to the last part of my homily, which is, respect the thickness advection. Ireland is well into the 522 dam contour and almost into the 516 dam contour by Sunday midnight as it approaches Belfast and then all models show the -10 C 850 mb zone covering all of Ireland at some point Sunday night. There's a 30 knot E-NE gradient and dew points near -7 C in England advecting across the Irish Sea. It takes a brave soul to picture no snow in this scenario, I guess some are saying I'm out on a limb, would have to wonder if it isn't the other way around given the synoptics. Probably as always a middle course will verify but it's interesting I just went through the exact opposite of this on an American weather forum by suggesting (in a contest rather than a discussion) very low snowfall numbers for DC and BWI, in fact one person suggested that my forecast be edited out of the thread because it would prevent the spread of panic -- and in the end my low numbers were too high (I said something like one inch of snow at DCA, consensus was ten or fifteen, actual was a rather embarrassing 0.2). That thread has never received a comment since the storm didn't happen.
I am guessing this thread will receive a comment or two if this one doesn't happen. Keep your fingers crossed, and remember Nov/Dec 2010 -- the Irish Sea rules.
Ladies and Gentlemen that is how to ramp, MT, I tip my hat to you, and even if this doesn't come off at least you had the cojones to call it as you see it. Respect.
In my humble and untrained chart reading opinion we are in for a pasting 0
This discussion has been closed.
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