Isolated Frost
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Posts posted by Isolated Frost
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I won't say the ECM is a "warm up" just less cold, what might help to balance the margins is that the flow will be continental so will attract lower dewpoints, the bad news is that the lower winds will be coming in from the North Sea.
Maybe people were too quick to dismiss the GFS?
None of the models at 120-144 look anything like the awful GFS. It will be hugely wrong.
It's about which one of the EC, UKMO and GEM output is right. I'm hoping GEM, or UKMO. ECM not that great- but hopefully some cold dp's will keep it wintry on Monday and Tuesday- and the Scandi vortex/weak jet scenario preserves and strengthens the blocking heights.
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If Monday and Tuesday deliver snow (with -5c/-6c uppers mind), then we have a very fun few days to come afterwards.
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Plenty of marginality, both ways. A southward adjustment would be snow-fest. A northward adjustment would be rain, rain, rain.
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Monday and Tuesday look very rainy/sleety on the ECM.
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ECM colder than the UKMO, which is colder than the GEM, which is colder than the GFS for Sunday. And even the GFS doesn't go above -5c.
I'm not scared about thicknesses, they stay below 1290dm on Sunday.
I am scared about Monday- but that's a long time away.
EC slightly milder than GFS on Monday. GEM coldest.
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Geordiesnow, even the diabolical GFS suite has the region under sub -6c air from now until Wednesday 1800 (bar Monday 2100 to Tuesday 0300, at -5c uppers). Sunday has -7c uppers throughout. Very snowy unless you're at the immediate coast, and even then, snow is likely.
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My my, just had a look at the Look North forecast earlier. Tomorrow, Saturday and Sunday looks very fun!
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Dry snow= 1mm around 12mm (1.2cm) of snow
Wet snow= 1mm around 5-10mm (0.5cm - 1cm) of snow
Look at the dewpoints, if they are below -1c, then most snow is dry, and light amounts of 1mm will equate to more than 1cm of snow
but if it is wet, the water content is higher and 1mm is less than 1cm of snow
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UKMO 96 would be -5c 850s for the SW of Scotland to about -7c in the NE, very close and marginal.
-7's and -8's throughout Scotland on the UKMO 120- a very snowy chart.
-7's and -8's also at the 144, which would be bitterly cold and drier.
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Going by the 500-850 temp converter, the UKMO 96 would be about -5c to -6c 850s for this region.
UKMO 120 with -6c/-7c.
UKMO 144, about -7c again.
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Latest big suites out (I'd classify GEM as bigger than GFS after this winter!)
GEM has a more north-east pattern than the UKMO- with a SE flow instead of a ESE, and a slightly less favourable pattern at 70/80 N, 0 W/E. Heavy snow showers on -8c/-9c for the east of Scotland, moving in to many central parts on the UKMO, more likely to be flurries and lighter shrs on the GEM with a strong, marginal SE wind and -6c/-7c uppers.
Both are similar at 0000 Sunday, with -8c uppers into NE Scotland on the GEM with a E/SE flow, and -10c uppers clipping parts of Scotland on the UKMO.
More heavy snow with -8c to -10c uppers across most of Scotland on Sunday... that's 2 days of almost constant convective snow shrs, potentially quite heavy. Significant accumulations possible for the E and NE of the nation especially (note nation!!). The GEM and UKMO are broadly similar with the exceptions of a slightly more favourable tint of the segmented troughing in the atlantic on the GEM- and the Euro trough being positioned further south. Add to that the polar vortex strength is stronger in Scandi on the GEM, I'd say UKMO was a weaker solution when it comes to its outcome after this wknd, which by the way is v snowy for north and east Scotland, potentially snowy, but looking more wet and marginal for the south. We'll see the GEM in a bit when it updates past 72, but I would expect to be more positive on that front.
A very snowy weekend to come for those in the East of Scotland, although the potential is there for all areas of the nation to see some snowfall.
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4.30 N24 forecaster said that focus moves to North East England and Eastern Scotland saturday with snow showers piling in off the North Sea
That's what we like to see!
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Not kidding, thought the lenses out of my reading glasses were missing..!!!
Edited it now
Click it to enlarge -
A little tutorial to the UKMO 120- keep in mind the stuff to the right when I do the ones for the GEM and ECM at the same time, maybe the GFS as well.
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UKMO 96 very marginal across coastlines in N England and S Scotland, but anywhere with
1) elevation
or
2) simply north of Glasgow-Edinburgh
will receive a lot of snow from that
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So UKMO = snow
GFS 12z = sleet/rain
??
Both would have their fair share of sleet and rain and snow- but it is a long way away- the UKMO is much preferred atm
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I always look for sub 528 DAM air as well as -5 or below 850 hPa temperatures whilst looking for snow. The 528 DAM line retreats as early as Sunday on the latest GFS - would this not bring with it the risk of sleet and rain rather than snow? The surface temperatures and 850s etc still look low.
Take no notice of the GFS past +48- another run where it has underdone the retrogression and messed up the atlantic.
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Looking good so far
Really? Heavy rain and sleet from that in the NE. Mostly rain below 150m or by the coast. The low pressure is a touch too far north- uppers would be sub -5c.
The developments in northern latitudes look v promising on the UKMO though- and the extending of the azores high... top notch to come?
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NMM starts with the GFS- it'll be the same solution each time.
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Saturday should be good enough for snow for most, maybe the odd touch of sleet on the coast. Strong SE flow, plenty of convection.
Very heavy snow shrs on Sunday as well, very cold, slack flow with low pressure. ECMWF slightly better than UKMO short-term, but stronger northern blocking on the UKMO at that range.
96 (Monday) should be very snowy at first, with -8c uppers into the top of the NE, strong SE flow with plenty of precip from the UKMO output- as said above, the EC not quite as good, but still very snowy.
At 120, heavy sleet and snow for much of us on the UKMO, more marginal, rain and sleet likely, with less strong cold troughing- and a much lesser 'reverse' zonal flow.
At 144- the vortex is less organised and fluent in Scandi- but the blocking remains in Greenland/GIN corridor instead of sliding back into the mean zonal longwave flow on the EC. An atlantic low is nearby on both- but the favoured solution of the mid-atlantic ridging into Greenland is achieved on the UKMO output- and 168 onwards would be pretty special.
Mind you, the EC 168 is special- but the mid-atlantic ridging doesn't come into play, and the high sinks- the UKMO would give us the NE reload.
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I just have a feeling we're destined to be in the sweet spot, IF... about 100 miles N of the point where convection is on the sleet/rain side. Think positive!
With charts like UKMO, do you think this could be at 2010 levels of snowdepth?
UKMO convection from 48-144 is incredible, if it went out to 168 we'd be in real Nov 2010 territory, and if the block holds to the NW, and doesn't sink (a la ECM), we will get one hell of a run, and potentially, very slack NE winds with PV to the east/scandi, and a blocking high in the GIN corridor/Iceland... this spell could be really special if all the pieces come together.
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UKMO was an absolute stunner- even better than yesterdays 12z suite with convective easterly flows, favourable and aggressive retrogression, a dying atlantic that dislikes the GFS solution and then an attempt at the mid-atlantic ridge late on.
EC not as good as yesterdays- very cold, but uppers not as good as atlantic lows are further north between 96-144, plenty of rain and snow for us.. snow for Scotland, heavy rain for the south- a slight southerly adjustment and it would be even better than yesterdays.
Hell of a chart.
GEM output is marginal but incredible- so much snow from it.
Saturday looks very snowy from the SE here, as does Sunday... another marginal frontal incursion, with the wind here remaining easterly before heights move to the NW, and the PV sets up in Scandi... that could well be the NE reload we're waiting for.
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Adam,
nope, you were just influenced by a stray 18z GFS run and another awful NAE, despite all other model guidance and Met Office suggesting otherwise.
Far North of England Regional - Cold Spell Discussion 15/01/13 12z onwards
in Regional
Posted
Cold, cold, cold here. That BBC Look North forecast was encouraging.
The light snow tonight is really nice- top up the clear places, and now I can't see the grass in my garden anymore