If Wishes made Weather
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Posts posted by If Wishes made Weather
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Wild night here. I have either just seen a bit of lightning, or its some power line arcing.
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I would suggest that Stansted observations are a little higher than the MO forecast.
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2 hours ago, Wivenswold said:
I'm finding the area of higher winds across the fens interesting, I'm assuming the lack of friction with hills is why it's forecast to be worse there.
It's a day for charging up devices if you're in a rural area that's prone to power cuts. I'm going to stay indoors with a crackling fire, Big Jet TV and my cat Ziggy who hates high winds and will be a needy but cuddly pest tonight.
It’s interesting this area of higher winds that are being shown on the models for the area around the Wash, but also stretching down across the Gog-Magog hills and away more south-westerly towards the Severn. It’s visible on all of the charts I can see, but the MO are not showing higher windspeeds for places in this area. For example: Cambridge at 54mph, Andrewsfield at 54mph, St Neots 50mph, Ely 52 and so forth. All the models - even those giving ground speeds and not 10m speeds - are higher. Time will tell I suppose.
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3 minutes ago, inkermanhero said:
Interesting that all this expressed in wind speed, rather than force, which is what causes damage. As a good rule of thumb, 50 mph generates c10 lbs/sq ft, 60 mph c15 and 70 mph c20, so you can see that a 70 mph gust is likely to be twice as destructive as a 50 mph gust, other things, like air density, being equal. It also means that a 70 mph gust of dense, cool moisture-laden air will be a lot more destructive than the same gust of dry, warm air. Sustained Atlantic winds of 70 mph in January are likely to be destructive in the wrong place!
Yep - I’ve been concerned about this sort of ‘it’s only 5mph difference’ thing as when wind speeds are high, it represents a very significant difference in force. Also, at the macro level, when we have different models showing differences in wind-speeds of 15mph (55 to 70), then it shows how differently they apportion energy in the atmosphere.
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31 minutes ago, cj114 said:
Just had a look at Dark predictions. I was surprised to see that most of the UK seems to be in Ireland. Had no idea it had moved!
Seriously, I do hope people are not taking this Guy seriously.
It’s a generational thing. My lad sent me a link to this Dark predictions thing. I was slightly amused, but not at my lad who is in university studying maths …
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5 minutes ago, minus10 said:
Yes widespread wind event later today...wouldnt want to be travelling up or down the country later...
As far as I can see, all models to one degree or another are showing this belt of stronger inland winds between the Severn and the Wash. Notable for the places that would be affected. Here the GFS showing up to 120kmh at 10m height. MO app at various places throughout this area showing 55mph ground level and appears to be the lowest. As noted by Snowshine above, the move to an amber alert at just be one of certainty in the predicted area.
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I would suggest that the point of ‘impact’ is probably what concerns most people, rather than the measurable element of the weather itself. This makes the warning system a little complex. For me then there are two salient points. Firstly, the degree of deviation from what is normal for your particular area. So here in East Hertfordshire houses, garden fences and other built environment elements are less stable than a stone roofed and walled farmhouse in upland places. Hence, less windspeed here has more impact (as well as a greater population to be impacted than, say, Dartmoor). Secondly is the range of possible maximum gust speeds currently being forecast. The MO app for my location is the lowest at present stating 53 mph. Arpege suggests around 70 mph. The difference between the two matters because the energy in the 70 mph gust is more than twice (perhaps nearly three times) that of the 53 mph gust and the effect of this 17 mph difference would then be really substantial. I don’t recall seeing a 70 mph gust anywhere near here for the past 10 years or more - though if anyone has access to historical data it would be interesting to know.
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1 hour ago, Jordan S said:
A bit of an update and last one from me on this storm, though not much has changed since my post on Tuesday. This is not your run of the mill storm if you live inland over England and Wales although at the same time, not exceptional. It does resemble storm Ciara, with one of the similarities being the uncertain strength of winds over western Scotland although they probably will receive very strong winds at some point tomorrow night into Monday.
9th February 2020..
Tomorrow/ Monday morning
Gusts will likely peak up to around a damaging 75mph inland for parts of Wales and northern England, it’s largely what I’ve already said so apologies for being a broken record! For people unsure of what to possibly expect with those speeds, this could cause some locally significant damage to weaker temporary structures, significant damage to fences, damage to stronger and more sturdy trees with some being blown down and minor damage to homes directly impacted by such speeds which mainly consists of tile roofs (blowing some tiles off) and potential damage to gutters and siding which are exposed to those winds along with locally longer term power cuts of up to a few hours..
Extremely strong winds for parts of the west coast of Wales,northern England with gusts up to 85mph possible in one or two locations, these could effect western Scotland too late Sunday/ early Monday morning but less certain.
55-65mph for most of the rest of England tomorrow evening and overnight into Monday morning causing some local tree damage in places, perhaps blowing a few weaker trees down. Maybe a few roof tiles exposed to those actual speeds being dislodged or blown off with one or two places seeing power flickering on and off with gusts that exceed 60mph.
Important to note, Isolated wind gusts of 70mph is possible in one or two inland spots over central England towards and around midnight tomorrow night, possibly eastern England too, I think the Icon and Arpege are over doing things ever so slightly for maximum gusts shown over slices of central/eastern England England that show 72/73mph but Icon overall having a better and more accurate handle on those fierce gusts over west Wales and northern England, so i suppose more faith can be put into this model compared with Arpege..
with maximum isolated gusts of 70mph if they where to occur you’re talking of an increased number of trees at risk of being damaged or blown down along with short term power cuts for some, with minor damage to buildings and homes exposed to those wind speeds which mainly consist of increased number of tiles potentially being dislodged/ blown off.
The longevity of these wind gust speeds will ofcourse increase the likelihood of the above occurring. This all accompanied at times by heavy rain and squally conditions.
I suppose sometimes it’s useful to put perspective on what wind gusts values will likely do as I’m sure some will imagine they are strong but not know what to expect with particular strengths.. hopefully it’s of some use.
All in all a stormy several hours tomorrow evening/night for the majority of the uk with the widespread nature of such speeds being quite uncommon.
With another spell of damaging winds in some areas for Scotland, Northern Ireland and possibly northern England midweek next week but less so compared with tomorrow night.
Excelllent post. I note also that the Arpege is up there with the Icon at winds quite exceptional for inland southern parts:
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As noted in an excellent detailed post by JordanS in the storm Isha thread, for our region, things have been a tad ‘upgraded’ for parts of our region. Generally, 10m wind gusts can be expected to be up to the 110kph / 68 mph mark. Here from the WRF:
The MO showing slightly lower around the 100 kph / 62 mph mark as here:
The Arpege though ups the anti by indicating 120 kph / 75 mph gusts inland:
This difference between the two extremes here seems fairly small here at 13 mph, but it matters because there is something like a cubic relationship between wind speed and energy involved.
So, even at the lower indicated speed here I would suggest that there will be quite significant impacts from this storm such as we haven’t seen for perhaps 10 years or more. At the upper end of the estimates, exceptional for inland southern UK.
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The 0z suite confirms the MO position of the worsening of this storm. Looking like gusts of 75 mph inland are now reasonable to expect across swathes of the country including the south eastern quadrant. Add 10 mph to this for areas with altitude or costal or otherwise exposure. Don’t forget that the increase in energy that the energy in wind increases proportionally to its speed, but not at a 1 to 1 ratio, its more than that. Roughly, in terms of energy output on turbine blades wind speed has an approximately cubic relationship. For the purposes of ‘impact’ then when imagining the damage that a storm can do, a 5mph estimated increase in the speed of gusts from, say, 60 to 65 mph has a much greater effect than from 50 to 55 mph. Much more energy is involved now and I cannot imagine anything other than almost blanket amber warnings being issued soon.
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If the forecasts are about correct for what actually happens then this will have a high impact across inland and lowland areas in the south east as they only rarely see these sort of wind speeds. Overhead line pickup railways always fair badly - especially in built up areas - as rubbish that is lying around like plastic sheeting gets wrapped around the wires. Certainly on the rail line from here to London there is 10 miles or so where it passes through industrial and suburban north London where the trackside contains a constant stream of rubbish, fences are dilapidated and so forth.
As the MO include impact in their warning system rather than just weather conditions I would expect an Amber warning for the south east at some point.
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As far as I can see so far, the 12z suite continues the theme and strength of the winds. I wonder if the MO are keeping their powder dry by showing western areas only so far, and then expanding areas and severity of the warnings on Saturday or so?
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Icon and MetOffice continue to indicate 60 to 70 mph (100 - 110 kph) gusts in their raw output this morning for the first system Sunday to Monday.
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Impressive looking system this for Sunday. The minimum 10m gust speeds being shown on the UKMO and GFS for any place in the UK except for an area around the Moray Firth is 60mph with many areas in excess of that. Rather than the strongest winds being reserved for an area of the southern quadrant around the core of the low pressure system, in this case the strong winds are being modelled right along the frontal line which is orientated NE-SW and will cross the country during a period of around 12 hours on Sunday with Northern Ireland being impacted first, and East Anglia and Kent last.
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It looks like there is the possibility of a belt of 60(ish) mph gusts across the northern Home Counties early evening. For all of you in costal or more upland areas this would clearly be a regular occurrence, but in the areas highlighted by the amber warning and shown quite nicely on various models this is notable. Undoubtably there will be some disruption later on - weak fences, trees in waterlogged ground, bins, rubbish etc blowing around.
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18z GFS puts anywhere in the south and east of the Wash to IoW in line for 100 kph gusts by 4am. Worse for coasts. That would be disruptive in a part of the country that does not normally see these sort of winds.
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I think that there is something in this. To call something a disaster is to quantify it in purely human terms.
Weather events can be determined ‘extreme’ when they are a certain position away from a norm for a given place - for example a wind speed >3x greater than average. This (meta and possibly quantum physics aside) will simply occur irrespective of humans observing or feeling any effect. It becomes a disaster when the human created environment is adversely affected or lives are damaged or lost.
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14 minutes ago, leedsnowfan said:
Squall Line looking V Nasty in Anglia Region atm......take care
It has just gone through here - like a very mild tornado.
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Very impressive squall run through. Like a mild tornado.
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I have just checked the fire department twitter ‘live’ feeds across the new red zone, and none of them except Bedfordshire have been updated with any wording at all overnight.
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MetO model is now showing the ‘sting jet’ feature/possibility a little further south than other models. As Marky notes this matches the red alert zone:
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3 minutes ago, North Easterly Breeze said:
Must be a red warning for the SE imminently surely. Look at those numbers.
I am right under that and not all that amused. Arome is showing a similar thing as the system pulls away:
and the ICON is simply horrendous.
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Storm Isha, Amber ⚠️
in Storms & Severe Weather
Posted
Looks like both the average and gust wind speeds at our local MO station (Andrewsfield) are exceeding the MO predictions and are nearer the numbers forecast on XCWeather who I believe use GFS? Currently showing 38 mph average and 58 mph gusts. MO going for 30 and 53.