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Paul

Model Output Discussion - Stormy Period Inbound...

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Morning all

 

In a nutshell a more interesting period coming up but detail wise lacking especially towards the weekend and early next week.

 

Still quite a lot of differences upstream as you can see from the divergence between the GFS's, UKMO and ECM.There are opportunities for some snow either side of the stormy mid week period.

 

However theres not the deep cold to tap into so its one of those set ups where the snow is likely to be often marginal, of course elevation higher north favoured.

 

Somewhat more interest could develop early next week as a low to the nw moves east, although todays ECM has a less sharp trough theres still an opportunity for some snow, inland areas favoured here.

 

In terms of the pattern into next week at the moment the Azores high is more likely to remain displaced especially as theres a possibility the pattern upstream might regain a bit more amplitude after flattening out.

 

So a lot going on weatherwise, detail will have to wait till nearer the time, although not ice days and dry snow it could be worse in terms of potential.

 

Hopefully something might pop up that can deliver to areas that have so far missed out on the snow.

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Some GFS ensembles have picked up on the idea of developing that low and pushing it East rather than South though to different effect. It could happen though.

Otherwise the vortex not looking very "vortexy" in GFS deep FI among some ensemble members and how about this to cheer coldies up.

 

gensnh-9-1-348.png

 

It could happen, right?

 

GFS ensemles Central Egnland

 

graphe3_1000_249_86___.gifgraphe6_1000_249_86___.gif

Certainly quite a tasty looking Easterly on that GFS ensemble member chart! :cold:

For this week, there's some good agreement from the models that the weather will be rather lively, but with something their for a number of weather fans to enjoy. Essentially a week where Atlantic Lows will bring unsettled, windy, and cool weather to the UK. Some days for example, will be dominated by chilly Polar Maritime flows with sunshine and showers for places - tomorrow used as an example from the GFS:

post-10703-0-52505100-1421047919_thumb.jpost-10703-0-25904400-1421047935_thumb.j

Some of the chilly 850 hPa temperatures and the quite low 500mb thicknesses should mean showers could be wintry at times, especially to the North and over high-ground, where they could fall as snow. As it is in these kind of set ups those towards the West will see the most frequent showers (some of those on exposed Western high ground could see some king-sized snow showers for example) while those towards the South-East could stay generally quite dry and bright (although the odd isolated shower at times can't be ruled out in those areas).

Others days like today and Wednesday/Thursday morning should see more general spells of rain accompanied by gusty winds. While some milder temperatures will accompany the rain, the strong winds could still help to make it feel cool for places. This being particularly true in the middle of this week where some disruptive winds are likely from that Atlantic storm...

post-10703-0-17193800-1421047958_thumb.jpost-10703-0-89635300-1421047975_thumb.j

Take extra care if out and about on Wednesday and Thursday, especially if you're towards the Western and North-Western coasts, as it could certainly get very wild out their... and a chance that a white, plastic, chair outside someone's garden getting knocked over. :o

Some disagreemt then evident towards 144 hours where some models, like the GFS Paralell and UKMO runs, go for more of a direct Northerly for the UK. But some models, like the elderly GFS and ECMWF go for more of a North-Westerly influence, while the GEM generally has the pattern a little bit further West around that time-frame (you'll notice it still has a Low Pressure system held out to the West of the UK, while the other models have the Low Pressure concentrated more towards our East/North-East). Having said that, a trend seems to be apparent where the models show a ridge of High Pressure to the West and a cool/cold flow from somewhere between the West and North.

post-10703-0-58220500-1421047991_thumb.jpost-10703-0-45992300-1421048008_thumb.jpost-10703-0-60780900-1421048020_thumb.jpost-10703-0-04724300-1421048035_thumb.jpost-10703-0-81680700-1421048051_thumb.j

It's perhaps also worth saying the UKMO does indeed show the channel Low that Mucka spoke of earlier. Hopefully something that can continue on future runs if you're wanting a Southern UK snow event). Also ideal to try squeeze as much amplification to the West of the UK as possible to perhaps try allow a Northely flow to tuck in behind any possible Channel Lows. This occurring before the possibility of the Lows to the West of the Atlantic ridge try to flatten and/or topple it with less-cold Westerly winds breaking through.

On the whole, some wacky weather in store for many this week - stormy winds, rain, snow (especially over hills and towards the North), brighter and showery interludes, and some chilly and less-cold days. Perhaps some frosts during the chillier Westerly or North-Westerly flows during the night (especially when skies clear and especially if winds can slacken enough).

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airpressure.png

 

 

 

ecmslp.240.png

 

 

ECM and GFS(p) at t240.  Pretty much in tune.  Why am I looking this far ahead one may ask especially with the weather we have coming the week ahead?  Because IMO there's no shift coming over the next week from westerly/Atlantic theme.  For me 20/21 perigee/new moon so another storm/deep depression watch around this time as we may have LP or secondary LP cross the UK (Southern half) so may be impactual one way or another due to track?.  But it leads us nicely into the realm where we may see ramifications of the strat warming we've had with pressure building or in place over Scandinavia and thus trough disruption.  It may occur too far east or we could get lucky.  Also I think we'll see the PV shift itself to a more favourable position to this side of the hemisphere in time for start of Feb.

Now I'm not saying it will all happen by the above chart date, but I'm targeting this period for the start of the change ready for a more wintry Feb.

 

BFTP

Edited by BLAST FROM THE PAST

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airpressure.png

Hi what does that mean in terms of the storm from my perspective it looks a touch further north does that mean more severe winds could be in the south.

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Hi what does that mean in terms of the storm from my perspective it looks a touch further north does that mean more severe winds could be in the south.

This isn't this weeks storm?  that chart is ten days away so I'm using as a general theme.  Detail will no doubt change.  For your location this week looks pretty stormy.

 

BFTP

Edited by BLAST FROM THE PAST

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No real change looks likely to our rather cold westerly,unsettled set up for now with every sign of this continuing into week 2.

Day 10 Ens hts Naefs and ECM

 

post-2026-0-98474100-1421054070_thumb.pnpost-2026-0-10593400-1421054111_thumb.gi

 

still the persistent area of low heights to our nw  which remains the dominant feature.

 

Some strong winds and gales,rain or showers at times through this week with some snow likely over higher levels ,particularly further north.

We just need a little more Arctic air in the flow to really turn things wintry more widely but with this mobile Atlantic pattern and only minor ridging this seems unlikely at the moment.

 

 

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This isn't this weeks storm?  that chart is ten days away so I'm using as a general theme.  Detail will no doubt change.  For your location this week looks pretty stormy.

 

BFTP

Thanks feel pretty silly now lol. Still more learning required in regards to the models.

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Thanks feel pretty silly now lol. Still more learning required in regards to the models.

We all do it, don't feel silly as things are misread in the mire of the model thread!!!  Personally I think this weeks storm will downgrade a touch overall from armaggeddon but still gales for many

 

BFTP

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I think we could still get a cleaner colder Northerly at the end of this week with snow showers and sharp frosts, the Gfs 0z p thinks so, as does the ukmo. There is still time to veer the flow more towards the arctic once the midweek gales and heavy rain push away NE.

post-4783-0-06295400-1421056333_thumb.pn

post-4783-0-49682300-1421056349_thumb.pn

post-4783-0-27622300-1421056540_thumb.gi

Edited by Frosty.

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The GFS P 06hrs run refusing to back down with its view of things, the GFS is very close to a decent snow event, its just the phasing between the upstream troughing and low pressure near Denmark that's the issue.

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I still wouldn't rule out a massive shift in the output in the reliable timeframe.

Note the LP on the southern tip of Greenland.

http://www.wetterzentrale.de/pics/Rtavn1441.gif

What could well develop is instead of the normal W-E movement we see trough distruption with this going SE to the UK bringing a risk of snow. As this occurs do not rule out a weak ridge of HP developing to the N of the UK bringing an E,ly flow. Seen this happen before and could again!

Yea iv been watching this for a while , infact the last 5 days of so when I first noticed it , with the low over Southern greenland having that negative tilt , it looks primed to go under the block , if we can cut the high off toward Iceland , then we could well be on the money .

Certainly in fi the models looking keen on weakening the vortex , with signs of a Scandi high in 10 days time maybe 12 days ? All up for debate , but the models looking like they maybe responding to strat warming , be interesting times into feb .

Edited by Severe Siberian icy blast

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The GFS (P) 06Z is quite action-packed.

 

First, the early hours of Wednesday, a snowy surprise for some southern/midland areas (yes it's GFS snow charts but EURO4s are giving partial backing so I'm happy to accept it this once!)

48-574PUK.GIF?12-6

Onto Thursday's storm, gusts nearing on 90mph just off the south west and 100mph gusts getting close to Ireland:

63-289PUK.GIF?12-6

Surely border counties / S Scotland will need to be included in the warnings if this prognosis keeps up, even inland areas at risk of 70-80mph:

gfs-0-72.png?6

75-289PUK.GIF?12-6

Onto Saturday and hello, is this a decent northerly emerging?

gfs-0-132.png?6

Topples fairly quickly this time but not before giving perhaps the coldest weather of the year so far on Sunday/Monday:

gfs-1-156.png?6

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Hi Everyone, complete novice here but have noticed a chart IDO posted this morning regarding the model outputs for Wednesday/Thursday's storm.

attachicon.gifnmmuk-2-72-0.png  attachicon.gifnmmuk-11-72-0.png

 

I notice that there are quite cold temperatures still hanging around the North West. What are your opinions on the likelihood of the precipitation associated with this event turning to snow in these areas? Are there other factors associated with a storm system (outside of atmospheric temps, dew points etc) that would impact on the precipitation type?

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Hi Everyone, complete novice here but have noticed a chart IDO posted this morning regarding the model outputs for Wednesday/Thursday's storm.

attachicon.gifnmmuk-2-72-0.png  attachicon.gifnmmuk-11-72-0.png

 

I notice that there are quite cold temperatures still hanging around the North West. What are your opinions on the likelihood of the precipitation associated with this event turning to snow in these areas? Are there other factors associated with a storm system (outside of atmospheric temps, dew points etc) that would impact on the precipitation type?

 

Snow on the Northern edge is a possibility according to media sources I've seen. However, even though the event is sitting at t+72 hours right now, a lot can and will change, with regard to rainfall, locations expecting snow if at all, warm sectors within the low, WBFLs etc. Above all else the anticipated windspeeds are of most concern as far as I can tell. I personally wouldn't rule out a secondary depression either, come Friday into Saturday. A nightmare forecast for those in charge, but they have the technologies which we don't have access to. Hope that helps.  :hi:

Edited by gottolovethisweather

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Something like the NAVGEM this afternoon would be good

navgem-0-144.png?12-11

Much better ridge enhancing the possibility of an area of heights developing to our north/north east.

The GEFs will be out soon, so we will see if there is a trend towards some kind of weak heights to our north.

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