Windysun1
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Posts posted by Windysun1
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7 minutes ago, Roger J Smith said:
I had a look at temperature analogues from CET and found among those 1881, in fact the mean temperature now is a bit lower than it was on the 10th of that famous cold/snow month (1.2) ... blizzards hit the southern counties in a very similar looking evolution around the 16th to 20th of that month and severe cold followed.
Another interesting factoid is that the only January which ever managed a 2 deg CET increase after the 10th before dropping to a lower end point was 1947 (2.6 to 4.6 to 2.2). Those numbers are all higher than this month's potential numbers, but the severe cold did not start until the 22nd and it did get very mild (probably milder than we'll see mid-week) for a few days after quite a cold start.
I like to see cases where unusual synoptics on model runs have actually happened in the past, shows that nature can accommodate them.
If I had to guess how this particular evolution might actually work out instead of what's shown, it would be a faster drop in the jet stream and for the channel low scenario to push more into northern France but with less slack flow over Britain, in other words getting the full extent of severe cold into the UK faster. It would mean the main mechanism for snowfall would have to be sea effect rather than synoptic however.
These comments from Roger are worth noting. Excellent.
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3 minutes ago, blizzard81 said:
For those worried about the cold goodies staying at day 10 onwards, this is not the case with the gfs para. This is now day 8.
How reliable is the gfs para compared with outher models?
Just wondering is it consistent in showing this outcome? Cheers
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1 hour ago, SqueakheartLW said:
GFS + Parallel
GFS 00z Parallel going for 4 warming in a row here with the initial 3rd warming peaking at -4 at +240 hours away. This is followed by 3 successive warmings all merged into one to make 4 warmings in total with peaks at -12 at +288 hours, another -12 at 324 hours and finally -16 at 384 hours away. Look at how much damage that does to the vortex by the end of the run
How does the operational GFS 00z compare to the parallel. We get the 3rd warming underway which peaks at -12 at +228 hours away. This cools down a bit before another warming which peaks at -16 at +330 hours away. This warming cools slightly but persists at around -20 right till the end of the run when by this stage the vortex is in quite bad shape
Below we have a selection of the most destroyed vortexes from the 00z GFS Runs
14 of 33 options showing a badly beaten up vortex and several runs end with another major warming too. Surely not 4 warmings within the same month
GEFS Legacy
GEFS Legacy still sees the 3rd warming but is less keen to do damage to the vortex afterwards
JMA
JMA has signs of this 3rd warming but unlike other models it also has one appearing on the Atlantic side too
GEM
3rd warming now more clearly visible on the GEM
ECM
3rd warming now more evident with the ECM at day 10
NAVGEM
NAVGEM still not seeing the 3rd warming but it does only go to 180 hours away and it is only starting to show up on the 240 hours away models anyway
NASA
A bit of a 3rd warming showing up at 240 hours but far less warm than on some other models
CMA
CMA already has a significant warming underway before 240 hours and there isn't a lot left of the vortex
FIM
There is a small warming showing up above Siberia on the FIM by 240 hours. Maybe FIM now seeing the 3rd warming too
SUMMARY
Each of the featured models and whether they see the 3rd warming or not
GFS Yes
GEFS Legacy Yes
JMA Yes
GEM Yes
ECM Yes
NAVGEM No
NASA Yes
CMA Yes
FIM YesA increase from 6 of 9 models yesterday to 8 of 9 today is a big step forwards. Now looking even more certain that we are going to get this 3rd warming
Hi Squeakheart, you do excellant research and love your posts.
You say its a big step forward that there is going to be a warming. I have no doubt you are right, but how potentially how does this effect the uk? Does it all depend on where the PV ends up or chunks of the pv ending up if it gets split up?
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4 minutes ago, SqueakheartLW said:
A rather interesting GFS 06z Operational run in regards to the 3rd warming or rather in this case a continuous series of warmings rolled into one
+216 hours
It all begins at +216 hours when the 3rd warming gets underway
+258 hours
We see the first peak of -4 at +258 hours
+276 hours
A slight cooldown takes place and we drop from -4 to -8 by +276 hours
+288 hours
At +288 hours we see another warmup again as we head back up to -4 again
+312 hours
We see a bigger cooldown after this second burst as we drop back to -16 by +312 hours but this isn't the end of the warming either
+384 hours
Instead of the expected cooldown we see yet another burst of warming which sees the peak warming creep back up to -8 where it generally hovers right to the end of the run
I have yet to look through the control and the other ensembles to see if this is a new pattern that the GFS is now seeing with a triple hit warming instead of the double it has been seeing so far
Hi squeakheart,
Thanks for the updates.
But what does this actually mean as regards weather effecting the UK down the tracks. A lengthened continuation of weather coming from an eastely direction, which you would imagine would be colder than average?
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12 minutes ago, WINTRY WALES said:
Has there ever been periods where the US and us in the UK are in a cold (very cold) , snowy weather for lengthy periods of time??
1947 i believe
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6 minutes ago, danm said:
Seems like a growing trend to build amplification north of the U.K. next week and for a PV chunk to drop into W Russia/Scandi. Good trends, as yet not falling into place for the UK on the ops with the Iberian high still being the main spoiler and a little too much energy to our NW. Plenty to keep us interested though, even if we are almost nailed on to endure a less cold/milder spell next week.
How accurate are the forecasts for predicting where the PV chucks drop?
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14 minutes ago, Griff said:
Significant in what sense Griff?
Probably struggling with it himself
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Sorry got it wrong. It is eastern states.
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JUDAH Cohan twitter"Clearly the GFS reads the AO blog because latest GFS is predicting, exactly two weeks after a major #polarvortex disruption, an amplified western ridge/eastern trough with a sharp turn to colder & snowier weather in Eastern US. Models struggle post PV disruption so far from given"
This confuses me as i thought it was predicting western states cold, Eastern not as cold. Euro/Asia cold?
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AO Blog Update | AER | Weather Risk Assessment
WWW.AER.COMDecember 28, 2020 - Dr. Judah Cohen from Atmospheric and Environmental Research (AER) embarked on an experimental process of regular research, review, and analysis of the...
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Just now, Griff said:
Not any better...
Only post the good ones from now on
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15 minutes ago, Bricriu said:
I seem to recall the proposed milder turn in the second week of January was at the far fetched end of fi at one point. we can't outright dismiss something just because it shows something we don't want. It may well not happen, but given how easily things can go wrong for us any cold spell could well be fleeting or, worse still, not happen.
I want a bitter freeze with two foot of snow as much as anyone.
Two foot! A metre at least! With massive drifts. That would keep us all at home...
We can dream. Bricriu you are right of course but i feel things will align for us this time. This delay in cold advancing might be to our advantage in cooling the cold pool further, and when the dam breaks that cold pool will flood right through
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17 minutes ago, Griff said:
Definitely a ramp from Marco P at the Met, along these lines... Maybe....
Hot off the press.
Everything except cold
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8 minutes ago, Tim Bland said:
GFSp you tease!!
I think we will be seeing these colder type charts closer than 2 weeks off tomorrow. Possibly as 7 to 8 days.
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17 minutes ago, Battleground Snow said:
I think maybe a little faster than 10 days, but in relation to the zonal winds, if 06z is correct it may back the whole pattern a little west in the 120-144 period compared the Ukmo/ECM.
Cheers BGS
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9 minutes ago, Battleground Snow said:
I was going to, but thought it may get moved, hopefully someone will read this soon haha. I'm a novice, but I think it can only be positive that the zonal winds are slowing faster than predicted
So if say the SSW kicks in tomorrow or tuesday. Will its effect be a week to 10 days from then?
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2 hours ago, SqueakheartLW said:
It would seem GFS is backing away from the idea of another warming around the 10th or 11th of January now as the number of options featuring this has dropped throughout the day
It was 28 of 32 in the 00z
By the 12z it has dropped to 20 of 32 and at least half of these 20 options only featured minor or very minor warmings of peak temperatures of -30 at best
However there were a few good ones in there and these are below. They start with the warmest warming and get progressively less warm as we go along
GFS 12z Member 1
This second warming is comparable in terms of peak temperature to the first one with a peak of around -4C. Only this time it is attacking a weaker vortex than the current state of the vortex. This should result in either an even weaker displaced vortex or a split
GFS 12z Member 5
A less warm warming but also an even weaker vortex for it to attack and this is already stretched out somewhat with two colder cores. No doubt this warming will fully split this vortex
GFS 12z Member 14
Similar to the above but a slightly in better shape vortex against a less warm warming. This may weaken the vortex further and could result in a split but no guarantees of that
GFS 12z Member 14
A modest warming event here and with the vortex almost in two pieces already then this should be the final blow that sees the vortex split
GFS 12z Member 17
Even though the Siberian warming is quite modest this one has a little backup from a smaller warming on the European side. These two should be able to act together to fully split the vortex
GFS 12z Member 24
My final one to show. This time the stronger warming is an Atlantic based warming with some backup from the Siberian side and also the vortex is in an even more vulnerable state. A split must be certain with this one
After looking at the GFS runs since 20/12/2020 these are the percentage chances of each stratospheric outcome excluding any unknown outcomes that were present at the time and this is based on what was showing at the date listed
Type 20/12 21/12 22/12 23/12 24/12 25/12 26/12 27/12
Av Date 05/01 06/01 07/01 08/01 09/01 10/01 11/01 12/01
Displacement 36.21 45.95 28.21 51.25 61.63 60.67 75.79 63.54
Split 41.38 39.19 55.13 40.00 26.74 30.33 16.84 30.21
None 22.41 14.86 16.66 8.75 11.63 9.00 7.37 6.25It would seem GFS is most keep on a displacement of the vortex overall in recent runs but was going more for a split a few days ago. The latest data shows that the split options are making a bit of a comeback but will this continue?
Dumb ass question i suppose but if the PV splits and part of it ends up over europe and Uk, how long will it stay in that region or is there historical data to show this?
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10 hours ago, MATTWOLVES said:
Hi mate.
The highest daily total in an inhabited area was 173cm..68 inches the location was Huntingdon,Warren, Dartmouth on the 16th Feb 1929.
So far so good with the 18s..improvements.
Cheers Matt,
Well over 5 feet of snow. Thats incredible. Most of been something to watch the flakes fall at that rate.
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Bit off topic but what is the greatest snow depth recorded in UK after a snowstorm or roughly in a 24hr period? Cheers.
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3 minutes ago, West is Best said:
Incidentally, this isn't out of the blue. Different times of year but we had a cold northerly July and again in October.
I think we will require an SSW event to get some sustained cold temps in and around the uk.
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9 hours ago, Catacol said:
A tough call, but I’d go for a fast downwell this time, so broadly speaking last third of January. Until then ongoing trop forcing is what will direct our weather - and a very disturbed and amplified trop it is. If that amplification sticks around until after mid month and then taps into the downwelling effects of the SSW then, with a lucky dice roll or two, we get the potential for proper intensification of the cold that is already looking to bed in.
Thanks for reply. Quiet a complex science indeed.
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1 hour ago, Catacol said:
yep - SSW near certain now. All eyes on the nature of the pattern and how downwelling impacts land.
What date are you thinking that its effects will be felt in the British isles?
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53 minutes ago, Roger J Smith said:
To the extent that there have been downgrades on some models, I can't remember a decent cold wintry spell (for the UK) where there isn't at least one downgrade run or series of runs about this far out, 6-8 days. Seems like a part of the process. Not that a downgrade is therefore proof that good things are about to develop. It could also be a downgrade trend without reverse, seen a few of those also.
There's a rather volatile looking evolution over the eastern U.S. on 24th-25th, all guidance shows a strong cold front, some develop a secondary low that runs almost due north from the Carolinas to western Quebec. How that actually goes may have a major influence on how the west-central Atlantic ridge responds.
I would say the best scenario would be establishment of cold 28th to 1st then battleground lows 2nd to 5th. That could give a lot of snow.
Mr R J Smith knows a thing or 2 or 3
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Sorry but what time does ECM come out again?
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Stratosphere and Polar Vortex Watch 2020
in Spring Weather Discussion
Posted
Is a third warming not forecast?