pyrotech
-
Posts
979 -
Joined
-
Last visited
-
Days Won
3
Content Type
Forums
Blogs
Gallery
Events
Learn About Weather and Meteorology
Community guides
Posts posted by pyrotech
-
-
26 minutes ago, IDO said:
Well ECM does love to produce awesome D10 charts, shame each run they are different. Anyway this morning its heights and WAA towards Greenland:
GEM At D10
GEM looking good for a height rise as does the GFS op. However again the GEFS are trending the other way and that now includes the control run, which is now very flat with little amplification. Always the case when a wave is introduced to a stable pattern and I suppose we just have to wait till the models sort it out. What is unfortunate is that both the GFS and ECM op are notorious for over doing the longevity and latitude of these amplifications, however the experts on here are very sure we will get a Sceuro block so its a case of waiting till the ensembles catch up.
The GFS still no sign of any MJO signal for Phase 6 or 7:
Both the AO and NAO were showing signs of going negative but now they look like they were moving into a lower positive range, but now reestablishing into a higher positive stage over time. CFS weeklies for 2 and 3 now showing the sceuro heights, as you would expect as the CFS has been leading the MJO signal:
As for whether this will bring anything other than mild to the UK in the short term (up till D10) is unlikely as the ECM op is showing some very mild uppers from D7-10 inclusive. If the GFS is wrong with the MJO signal then expect flips from its ensembles soon as its D10 and D12 means don't offer much hope of some propagation to the strat:
Strat at D16:
Hopefully the weekend's model output will resolve these issues and we will know whether the strat can get a prolonged attack as currently the strat, although stretched is proving resilient. Its the long way to an SSW via a stretched PV I think. As stated before the experts believe the MJO is very quiet at the moment and that MJO models will flip back into the COD with more runs: https://twitter.com/xerophobe_ww/status/677975990656630785 , so what will actually happen is still debatable till this MJO signal is resolved, as if it is a fast Kelvin wave then it may be a brief meridional flow?
ECM was the only model going for a strong phase 6 and it would appear that its moving towards a weak signal even if it gets to phase 6 it will be a weak affair that has little effect
http://www.globalweathersystems.com/MJO.htm
-
1
-
-
i think looking at the two main models tonight ( GFS & ECM), that the focus is on rainfall between now and Christmas day.
Whilst i do want to see some seasonal weather, my thoughts are with those that have had such a dire start to the festive season. The models hint of those same areas getting large rainfall totals again. The areas namely - southern Ireland, Wales ( Esp North and West) then later to include possibly Cumbria and Western Scotland.
A lot of shannon entropy on how much and where but whilst we model watch here looking for winter, i think this deserves some discussion on each run as it could have some major disruption in some peoples lives.
Does anyone see anything different as my analysis is this is a large risk with over 100mm of rain for some soaked areas over the next week, mainly due to orographic rainfall.
-
1
-
-
GP & Nick sussex
I see a lot of talk about MJO into phase 7 for turn around but my understanding is that phase 8 during strong El nino would be more likely to bring rewards. Also a weak phase 7 or 8 would have little effect and we are looking at a strong signal for any meaningful changes.
I also see little change in strength of El Nino before March if not April.
happy to be corrected as always learning
-
1
-
-
The operational is an outlier but that would be very bad news for Cumbria
lets see what the GFS decides, but yes european Ski looks bad before New year and mild and wet most likely for the UK
-
A little joke to tease us by the GFS for xmas day
-
2
-
-
jon
How do you see the ski resorts over the Alps and Bulgaria between now and new year.
Would any precipitation at those heights be of snow even if warm 850mb temps?
is that all we need (precipitation) or even at the heights of the resorts are temperatures a huge factor?
I was under the impression that from this time of year anything falling above 1800m in Alps and Bulgaria ski resorts would be snow, so all i would be looking for is precipitation, however we are seeing a very warm anomaly in temperature across Europe.
-
Hi Malcolm
yes been using the 850mb and precipitation charts
I more than understand all that, not a newbie intact i own too major weather websites
The issue is that drop in depth and from same source, please note in my post i mention the 60cm today.
I also see possible 850mb temps of 5c between now and xmas as possible but with surface temp of -5
So looking for some local knowledge on precipitation in those circumstances, plus the reason why 90cm becomes 60cm over one day.
Warmer air with sunshine can do similar, it causes a layer of ice on the snow which adds to the chances of avalanche later in season if significant snowfall on top.
However the 30cm drop is very large and your theory of adjustment sounds more feasible
-
looking at the Alpe d'hues resort seems almost 90cm at higher slopes and snow at valley level
I also see signs of snow likely later this week
At a height of 1800m what 850mb temperatures would cause melting at that level?
have friends going out around 27th and to me ( not exactly my field of any expertise) it looks like they would be okay for snow.
Julian et al whats your thoughts
today snow at height lowered from 90cm to 60cm i would suggest due to warm 850mb?
-
I am surprised that there is no mention on here about possible rainfall totals over the next 4 days and again into next week.
Some very large totals are possible for some western areas.
The winds are of obvious concern as its in next 24 hours, but rainfall totals in North West Wales , Western Scotland and North West England look a concern for flooding.
I would think warnings will be issued during tomorrow for this risk.
Major cold looks unlikely for November and Historically El Nino gives the opportunity for snow in second half of winter, however the Moisture presented by El Nino can make any snow events quite significant.
I see stormy until mid December completely Zonal with flooding remaining a risk.
-
6
-
-
UkMo and GFS look good for cold this evening thru too next weekend now looking very likely.
Most interest for me is the surface pressure charts. A nice occluded front moving South East behind the low currently looking to effect North wales thru to Nofolk and all areas below that track. Obviously much can change but its at least something to watch.
What most seasoned posters will realise, is that the first rule is to get the cold over us, then there will be opportunities for Snow. Sometimes these are troughs sometimes slider lows and sometimes just transient snow as we get a breakdown. We now have the Cold and one or all of those will now come into play, The outlook is cold too right thru to the end of the month so more and more opportunities ahead.
So far the models have indicated a mainly North of Uk event with Snow widespread Above the Midlands in general, now they may be hinting at something further South making it a UK wide event but over a week.
The jet stream looks to stay right side of UK thru out, may be a direct North to South run towards end of next week which could help instigate some instability it a positive way. Even when we are wrong side of the jet we are under possible ridge of high meaning nothing particularly warm at ground level and with warmer uppers may be just an opportunity to get out and make the most of the white stuff that after hard frosts may just enough to prolong the enjoyment. After last years winter these model runs are a dream and will bring many surprises to many if they are anything near accurate.
-
7
-
-
Remember that precip type radars depend on model data, it is not necessarily representative of what's actually happening.
I know Nick but its all we got apart from any live reports
I also feel that they are fairly accurate and like model watching trend is your friend.
But your right to point out that the sleet could be snow and vice versa
-
Will it intensify as it crosses the Irish sea?
Yes, heat from the sea will intensify it so as it hits the cold air the warm air that will then hold more water vapour will condense making it more intense again as it heads in land, for a time. After land fall it will have much less fuel and should slowly die off, but such a feature will last much longer than shouts that would peter out over 100 mile
-
1
-
-
Just to add that the North west quarter seems now to be turning more readily to snow as the embedded cold air gets wrapped around.
Certainly more interesting to watch than whats on TV tonight
-
4
-
-
The precipitation turns wintry quickly over Northern Ireland
The first Precipitation is now over the Irish sea where it gets thermal warmth.
This should help increase the intensity as it reaches the West Wales Coast
Currently showers in front of it have turned readily to snow as they moved just a few miles inland over Wales.
Cool air over Ireland will have mixed in somewhat so we now will soon have a better idea of what this will do.
If this turns to Sleet and snow fairly quickly over Wales this gives many areas a chance tonight.
Next hour will iron out how much the cold air mixes with the less cold warm sector.
From whats happened so far i would suggest Met office called this right, but we are approaching a crucial point .
If Met office are right expect it to become snow around Brecon - Newtown line thru Wales, if earlier then its more widespread.
This has a knock on effect further South and East but in the South i suspect best that can be hoped for is 50mile further South for wintry precipitation. Any reports on wind speed increasing and further Sferics
-
2
-
-
Here in the west temperatures have dropped nicely below what was forecast
Also dew points are dropping again so if this is widespread the mixing could bring a surprise covering to many more people.
Better still this is just one of many chances over several days and the models continue to prolong the spell with possibly a disruption to polar vortex to kick it all off again around 7th Feb
I feel the polar low will follow pretty much track North Wales to East Anglia but with two bands of precipitation of interest on its East And North West. Most of Wales away from Coast and far west should get Snow, The Swansea and Cardiff area Probably marginal with dew points, but close call.
Same for South Coast England and Far South East
In between those areas the other band should give a nice few Cm's
The other factor is the winds, which will be very strong, Drifting of snow could be a further hazard. These winds may make the dew points to high, however they could mix the air significantly to just put things on right side of marginal. The other thing is convection over the Irish sea. A plus now would be to see some sferics in the bands of heavy precipitation. Marginal can become quite optimum with evaporative cooling.
-
2
-
-
Don't rule anything out as this polar low comes South.
Yes it has embedded Atlantic (less cold ) air mixed in.
However snow has fallen as low as 25m above sea level today and on some surfaces remained.
Dew points at Barry ( right on the coast are currently -0.3
temperature 2 c on coast.
Inland snow will assist with keeping dew points and temp low
Then as we saw today heavy precipitation will drop temperatures further with evaporative cooling.
today 3c to 1c in a few minutes at around 3pm
So marginal for many on low ground, but not impossible.
Just to add
Maybe thunder snow possible too
-
3
-
-
Snowing in Cardiff ( Cardiff West)
-
2
-
-
Well the ice pellets left a nice covering of white over everything, this may help any snow that may fall later in the night to settle.
-
5
-
-
lots of impressive thunder and lighting in Cardiff
-
Thunder sleet Cardiff West, lots of flakes in the heavier stuff
Gusty winds too
Very unstable atmosphere
-
1
-
-
report of tornado in London
Small tornado damaged a single story building and cars
-
1
-
-
Winds update also now
Similar to previous
-
The latest warnings being updated
Rainfall update is now for less rain 20 -40 mm widely
50 - 60mm west hills
was 75mm
-
Can you copy the actual forecast please and pm me-many thanks
It seems a bit odd you have so little good to say about UK Met. Do they not still have a forecaster on at Sullom Voe? They used to be responsible for sea area Fair Isle, able to over ride Met IF needed and worked closely with local authorities on all the islands as well as with Civil Aviation?
Sorry for being slightly off topic
My parents on on Isle of Lewis and although their house sustained severe damage (30% of roof missing, water pouring in even today) They were keeping on top of forecast and had adequate warning.
The issues are that even with the warnings there is not a lot you can do to stop tiles getting ripped off roof.
Getting repaired with continuation of adverse weather is also impossible.
The effects can be very different depending on wind direction, for instance you could have a 90 mph gust from North that does no damage, then next storm has 80mph from south and does extensive damage.
The Met as always did a vital job at forecasting these storms, today shows just how difficult this can be. Even now many on here are looking at different models and trying to gain an understanding of intensity and track. The Met then have to be careful not to over do warnings or they will not be taken seriously in future, and not under do either. The warnings are based on too factors. The Effect and likelihood. so if track is not known and so where worst winds will be, then the likelihood is low , until decided. The risk is currently greater on effect than likelihood but this can change on both as the storm moves in, its still 48 hours away. As a weather enthusiast myself i can understand just how difficult their job is when you have such a fluid situation.
-
2
-
Model output discussion - 1st December onwards
in Forecast Model Discussion
Posted
Don't rule out the cold that the GFS has been showing, even if just a transient cold spell
This is really quite feasible as the MJO has moved into phase 6 and heading to phase 7
This is a surprisingly strong phase 6 signal too so Scandi high is exactly what you would expect, with blocking in the tropics moving eastwards.
So although the models may play with different data over the next day or so, as the starting data fluctuates, do not write a cold spell off. Meanwhile until turn of the year the models continue to show flooding as a main issue along with possible transport / power disruption with strong winds.
I feel the ECM is moving towards a possible brief easterly scenario although it holds very much in the balance at that timeframe.
Pretty much the movement expected with the MJO actually stronger than i would have expected, i believed that the strong El Nino would make phase 6 so weak it would be irrelevant.
All to watch for but no cigar yet