scotland Scotland Regional Discussion - 29/11/2013 ---->

[Ravelin]

Is that before or after the Scando-Russian monster high? I don't have time to post the ECM at +240hrs but sweet mother of charts Hats off to certain posters on the MOD thread if that comes to pass

Yeah, now that they've decided the Northerly is going to be a non-event for most people they are on the search for a Scandi High and a resulting Easterly. Well, those that haven't written off the month of Dec are, or those that aren't claiming to be digging out their BBQs for a mid Dec party.

 

You know, for a while I rated yr.no's forecast for this area but I'm beginning to have my doubts. Their long range forecast has this area cooling down rapidly on Thu with a mixture of rain & snow. That I could believe, but after that it keeps us dry and cold right out until the end of it's forecast on Wed 11th, with temperatures only getting above freezing for short spells during that period. OK so it's showing light winds from the south, so the surface temps could stay low despite the warmer uppers the models have moving in, but even so, it's hard to believe it'll stay quite that cold.

 

On to reality...started off at -2C in Kemnay at 9am with my predicted frost. A bit of sun around early on but there's a uniform layer of white cloud now that's keeping the sun under wraps. Enough of a breeze to occasionally move the flag outside my office at work. Oh, and my wife is hopefully making a stop off at Lidl on her way home from work (she goes right past one store). Don't know if I'll get to play with my new toy tonight, or have to wait until Santa delivers it officially (cue much searching through cupboards for a sneaky peek just like I used to do 35yrs ago).

[Scottish-Irish Skier]

I switched from using ethanol in my homemade screenwash to methanol, you need a lower percentage for the same freezing point and it gets rid of the salt stains off the windscreen better. Plus you don't get that wiff of jakie every time you hit the screenwash.

 

I like the wiff of Jakie.

 

Isopropanol (isopropyl alcohol) is another option; good to -20 C before effects tail off due to hydrate formation. Normal propanol is not as good as it forms hydrates at -10 C.

 

Data for i-propanol which should be good enough.

 

http://www.engineeringtoolbox.com/ispropanol-water-d_988.html

[lorenzo]

Well the main models have shifted a fair bit since yesterday morning and the Epic output on offer, 12z last night saw the Eastward shift in the cold plunge, which may be some short term pain for longer term gain as this will serve to give Europe a real chill.

 

Looking at the impact of the northerly, we are still on course for a solid cold blast, don't let the downbeat thoughts in the model thread kid you. 

 

Thursday Fax from 6am this morning, will see what the 850hPa temps look like on UKMO 12z run later, still a good true Northerly hit, so whilst transient, it is decent.

 

Few charts from the GFS this morning too..

 

Snow still on the cards for some, however wind becoming the other main part of the story, with some strong gust profiles being modelled now.

 

It seems that so far this Autumn / Winter the models themselves are attracting as much debate as the actual output. Yesterday morning runs were at the top end of the scale for what we could get, and this is still a tricky one to call at 84 hrs out. No denying the depth and duration have downgraded since Sunday a.m.

 

Simply put, the models don't like the vortex shifting around as SK pointed out the in model thread, for me the transfer from Scandi > Canada looks even at present a little quick. Let's hope it slows a little and lets the Northerly extend.

 

And, it wouldn't be a Winter on Netweather without the annual hunt down the Easterly !! 

 

 

Edited December 2, 2013 by lorenzo

[blitzen]

I am beginning to wonder if all this model watching is worth it! You would have thought that with all the technology available they would be getting progressively better as the years clock on. To me, the appear to be getting progressively worse instead!  Takes all the interest out of watching quite frankly as you can never believe what you are seeing.  *rant over.*

Currently 6.5c after an overnight low of 3.3c with a WSW wind. Just had a light shower of rain.

Edited December 2, 2013 by Blitzen

[Hawesy]

Morning all,

 

Very dull here today - noticeably so after all the recent sunshine. Currently 7.3c.

 

Nice summary by Lorenzo, and the Met Office warnings are now out: wind warnings for all of us, snow for the northern half of Scotland as you would expect. I'd reckon that Aberdeen would see 5cm of snow (based on current output).

[Ravelin]

I am beginning to wonder if all this model watching is worth it! You would have thought that with all the technology available they would be getting progressively better as the years clock on. To me, the appear to be getting progressively worse instead!  Takes all the interest out of watching quite frankly as you can never believe what you are seeing.  *rant over.*

 

Certainly much less disappointment involved if you avoid the models and take what you get on the day. 

 

Despite what may be perceived, the models probably are improving all the time, albeit slowly. Having worked with software, but not NWPs, for over 25yrs, I have one caveat to that though. When programming the models you'll start with a position as best you know. From then on you'll attempt to refine that initial model, not only through incorporating new data and theories/understanding, but by comparing it's output to what actually happens and trying to tweak it to produce the same the next time around. The problem with that could well be that when you get a situation that is different from what you've seen previously, your model hasn't been tweaked to cope with that, or indeed could have been tweaked in the opposite direction.

 

Weather is notorious for being a chaotic system and as such is going to be almost impossible to model accurately some of the time. In fact, from what I can glean from the last few weeks the current weather patterns in the NH are probably rather different from the norm. Lots of people were claiming that the strong vortex, cold strat etc meant 'raging zonality' was the form bet, which has not been the case so far, and looks entirely possible not to be the case for a week or two at least. The current situation could be one that all the models are just not set up to deal with very well at all, especially if it's a pattern that is rarely seen. That's not necessarily the fault of the models though, just a reminder of how we've still got a long way to go to understand the weather and to accurately predict it.

 

Oh, and despite the inevitable disappointments, it'd be rather boring if the models all nailed it at T240 every time. After all, even if they did it wouldn't actually change the weather, we'd just be disappointed earlier.

 

Oh and I hate all this ECM v GFS v UKMO rubbish. The fact is that it's actually good to have a range of different models that all spit out different results. In certain situations one may produce more accurate results than the others but next time around the situation may be reversed. Years back when I was working with software for aircraft, flight critical systems were required to be dual redundant, with the software in the computers often written by different teams to produce the same output. This was more expensive but the theory was that if you stick the same software on 2 computers, if that software has a bug, it's possible it could cause both to fail at the same time and the aircraft falls out of the sky. Write the software twice, differently, and that's much less likely to happen. Say meteorologists just decided to bin all models except the ECM (or GFS, or UKMO, it doesn't matter which), would we be in a better or worse position than now? I'd say much worse!

Edited December 2, 2013 by Ravelin

[snowy owl]

Today, i sat in the "car park" aka the Edinburgh City Bypass en route to the airport and had loads of time to think of the impending cold blast.

 

It is so exciting watching the models try and find a pattern, and i just have a sneaky feeling that something BIG is in the offing.(apart from thurs/fri/sat)

 

The synoptics for this time of year are still quite unusual and appear to be trending much differently from our previous winters.

 

Maybe its just a feeling i have but being an optimistic lass today bring on the charts...

[November13]

I hope the charts are wrong after Saturday as they suggest the mild southern Atlantic air coming North again. Could be a very mild December if they are correct. The high pressure system is a weak affair so will get pushed away. That's todays charts it could all be changed by Friday fingers crossed!

[SW Saltire]

From what I can understand of today's models is that for us in Scotland it's still on for a cold blast.  What I'd worry about is if the cold uppers are in place early enough for us to get snow. For me yr .no has us getting over 13mm of rain on Thu with a temp of 6 degrees before it turns colder,  but drier.  Then again it's early to predict exact rain/snow fall patterns and being in NE I'm probably better positioned than most since we can do ok from a northerly and will probably hold the cold uppers longest. 

 

Not a bad day here today. Felt colder than the 8C the car thermometer said,  especially when the sun went down. Clear skies and no wind means I expect to be scraping the car tomorrow morning. 

Sorry, i've only just seen your post. The cold uppers were never forecast to anywhere near undercut the front on thursday sufficiently to turn rain to snow away from high ground. The main event was the copious snow showers brought in on a raging northerly wing which was to last for sebveral days with uppers as low as -14. However, since that earlier prediction it looks like a 36 hour event maybe 48, with far less showers (they'll still be of snow) and not as impressively cold uppers either unfortunately  

[LomondSnowstorm]

Certainly much less disappointment involved if you avoid the models and take what you get on the day. 

 

Despite what may be perceived, the models probably are improving all the time, albeit slowly. Having worked with software, but not NWPs, for over 25yrs, I have one caveat to that though. When programming the models you'll start with a position as best you know. From then on you'll attempt to refine that initial model, not only through incorporating new data and theories/understanding, but by comparing it's output to what actually happens and trying to tweak it to produce the same the next time around. The problem with that could well be that when you get a situation that is different from what you've seen previously, your model hasn't been tweaked to cope with that, or indeed could have been tweaked in the opposite direction.

 

Weather is notorious for being a chaotic system and as such is going to be almost impossible to model accurately some of the time. In fact, from what I can glean from the last few weeks the current weather patterns in the NH are probably rather different from the norm. Lots of people were claiming that the strong vortex, cold strat etc meant 'raging zonality' was the form bet, which has not been the case so far, and looks entirely possible not to be the case for a week or two at least. The current situation could be one that all the models are just not set up to deal with very well at all, especially if it's a pattern that is rarely seen. That's not necessarily the fault of the models though, just a reminder of how we've still got a long way to go to understand the weather and to accurately predict it.

 

Oh, and despite the inevitable disappointments, it'd be rather boring if the models all nailed it at T240 every time. After all, even if they did it wouldn't actually change the weather, we'd just be disappointed earlier.

 

Oh and I hate all this ECM v GFS v UKMO rubbish. The fact is that it's actually good to have a range of different models that all spit out different results. In certain situations one may produce more accurate results than the others but next time around the situation may be reversed. Years back when I was working with software for aircraft, flight critical systems were required to be dual redundant, with the software in the computers often written by different teams to produce the same output. This was more expensive but the theory was that if you stick the same software on 2 computers, if that software has a bug, it's possible it could cause both to fail at the same time and the aircraft falls out of the sky. Write the software twice, differently, and that's much less likely to happen. Say meteorologists just decided to bin all models except the ECM (or GFS, or UKMO, it doesn't matter which), would we be in a better or worse position than now? I'd say much worse!

 

Excellent points, what you were saying about how the models are improved through tweaking towards 'what works' rather than strictly looking at the additional physical factors which affect the weather and modifying the equations towards that is one that was brought up at the MJO talk at the uni that I believe Lorenzo was also at. All models do seem to have different inherent biases - the ECM towards overdoing northerly blocking, the GFS towards low heights to the north particularly in FI (there's a graph somewhere showing the biases that Lorenzo posted up which does show this up quite well, particularly post D4) and during northerlies a frequent occurence is the entire pattern getting shifted eastwards. I did worry about this occuring but as the models were broadly in agreement on the east-west thing until yesterday it seemed as though we might avoid it this time. However, one positive is that the upper air profile for Wednesday seems to be a bit more conducive to snowfall, so Wednesday might stil be quite interesting:

950s are marginal but given that the precipitation is coming in the form of showers and in the middle of the day we can probably get them pushed down fairly readily during precipitation:

e

Another interesting one is the signal for snowfall on Thursday morning from the extended NMM. Not sure how good it is for picking up on accumulations but very interesting chart nonetheless:

http://www.meteocenter.eu/fajli/index.php?domain=euNMM12km&region=NW&forecast=Snow&time=84

[lorenzo]

Just re-posting from the mod. GFS invigorates the LP and it is looking pretty lively to say the least..

 

 

 

In fact very lively..

 

Somewhere is going to get an absolutely wild time from that..!

 

[A Winter's Tale]

Just re-posting from the mod. GFS invigorates the LP and it is looking pretty lively to say the least..

 

 

 

 

 

 

In fact very lively..

viewimage.pngviewimage (1).png

 

Somewhere is going to get an absolutely wild time from that..!

Thursday afternoon has certainly caught my eye. Very tightly packed isobars, sub -6C uppers and widespread and heavy precipitation.

 

 

 

 

 

Some places could in for gale force winds and on the higher ground blizzard conditions are possible.

[spindrift1980]

 on the higher ground blizzard conditions are possible.

 

For the West Highlands, I think that might well be something of an understatement, if the current charts are accurate!

 

MWIS currently reckons there'll be a prolonged period of thaw on all but the highest summits after the cold snap is over, mind you.  Presumably he thinks westerlies and southerlies will be in charge from next week onwards. 

[Ravelin]

It'd be a real pity if the ski resorts got a good dump of snow, only for it to all melt over the subsequent few days. Kind of par for the course for Scotland though. Maybe the best we can hope for is thaw/freeze cycles during the day/night. May not provide much that is fun to ski on but could at least set up a decent base for falls later on.

[Glaswegianblizzard]

I hope the charts are wrong after Saturday as they suggest the mild southern Atlantic air coming North again. Could be a very mild December if they are correct. The high pressure system is a weak affair so will get pushed away. That's todays charts it could all be changed by Friday fingers crossed!

 

Well, as much as cold weather is preferred in winter, it would be interesting if a milder period happened as there seemed to be a fair few predicted a mild December.

 

Those doing so were also predicting a colder January.

[BleakMidwinter]

 possible Polar Lows (bows in obeisance) 

!Try saying that six times quickly after a few festive bevvies!

[Zenarcher]

Looking stormy on Thursday 80 to 90mph gusts could be recorded in very exposed parts of Scotland if the current GFS is to be believed. Some very cold temperatures will arrive as well with wintry showers being widespread.

 

Interesting week ahead.

[doctormog]

Look at the dewpoints, that's got rain to very heavy snow written all over it:

 

2nd Dec GFS +72hrs Surface Panel.png

 

925hpa temps are falling away below freezing at that time, and remember that the atmosphere is "lower" down at that time due to low heights.

 

Central Highlands are going to get pasted.

Indeed, although looking at the discussion elsewhere you would think that nothing is happening anywhere in the UK this week and a potential blast from the east in three weeks or so is more noteworthy!

[November13]

Yes the secret is to enjoy the snow if it comes.Hopefully if it snows Wed night.We could have three days of snow before the hairdryer treatment.I would rather have constant snow above 2000ft.Than 3 days snow at low levels for it all to melt even on the hills.We need usable weather for the ski resorts to get going.

[lorenzo]

Into Sting Jet territory now...

 

 

 

 

[edo]

Ravelin did you get the weather station?? currently trying to calibrate mine as not convinced I have managed to set to north as batteries inserted....wind direction seems to be a bit off and my temp appears to be high.....need HS readings to see if I'm in the right ball park....to be fair I should have waited till daylight hours to install as setting up in dark with just an iPhone torch was probably not sensible.....I just couldn't wait lol #bigkid

[Ravelin]

Well it looks kinda like the model thread has had a serious outbreak of the easterlies. All gone stark raving easterly mad and forgotten that only hours ago every model was 'useless beyond T72'. Now they are showing an easterly at T240+ they are bound to be correct, surely? 

 

In the meantime, us north of the border better start strapping stuff down if the winds turn out as predicted. 

 

On a lighter note,  there is a Lidl weather station hidden somewhere in this house that I'm not allowed to play with until Xmas day. How cruel is that? Must be approaching divorce levels of cruelty that,  surely? 

[edo]

After finding HS weather station on wunderground I can now confidently give the weather from Luncarty as calibration appears a success

Temp 7.8c

Few point 5.8c

Wind ssw 1kmh

Unlucky ravelin I just treated myself to an early Christmas

Wife said what is that

Me a weather station

Wife What does it do

Me gives me weather information

Wife why do you need that

Me I don't need it but I want it

Wife and how much did that all cost

Me £9.99 (white lie)

Wife waste of money

stained glass window knows what she would say to the cost of Highland Snows system

Anyway impressed with the offering from lidl so far

[Hairy Celt]

Well it looks kinda like the model thread has had a serious outbreak of the easterlies. All gone stark raving easterly mad and forgotten that only hours ago every model was 'useless beyond T72'. Now they are showing an easterly at T240+ they are bound to be correct, surely? 

 

In the meantime, us north of the border better start strapping stuff down if the winds turn out as predicted. 

 

On a lighter note,  there is a Lidl weather station hidden somewhere in this house that I'm not allowed to play with until Xmas day. How cruel is that? Must be approaching divorce levels of cruelty that,  surely? 

I'll score that a 6/10 for cruelty because... in my office there's a Davis vantage pro wireless, been all boxed up for about 2 years and I dare not liberate it despite its nominal owner trying to give it away - because it wasn't me thaat was the supposed recipient (frekin office politics eh )... I look at the blooody thing every time I go in the office. Cruelty = 9/10 , seeing as I had a temporarily splendid weather station that rotted away after just 3 years.

[Bullseye]

Quick question, how do i view the 1962/63 winter graphs? Cheers