Model Output Discussion 01/09/17

[ACCOUNT DELETED]

Such a shame that "High" can't hold on for a bit as it now looks increasingly likely that there'll be some very challenging conditions primarily gales & rain next week for my mate and the other 4 boys who are well into their bike ride right around the UK coast for Children In Need. Currently they're in the far north of Scotland, left Thurso at 6am and reached John o' Groats and now slowly dropping back down the east coast. Eventually, they'll end up back where they started here in Porthcawl, South Wales not sure when but they are doing really well fair play, cycling for up to 14 hours on some days only taking brief breaks for food. Sounds great, I might do this next year, the scenery must be fab! 

Anyway it's the very mild weather that will be noticeable next week with some models showing 15C here by Monday and perhaps lasting until Thursday with some nights dropping no lower than 13C, we've already got some Daffodils appearing, at this rate they'll be out to see in 2018 and with meteorological Autumn ending in 12 days, if it's anything like the last few years 1st December could be the start of a very long Spring before a brief Winter occurs next April here  

[blizzard81]

Let's just hope the polar maritime air gets in next weekend. Thankfully the blow torch runs didn't last long and good riddance to them. 

[Iceaxecrampon]

At least the Jet is at the right orientation next weekend

Cumbria ensembles in temp swing agreement for cold mild cold for the 25th - 26th  - well used phrase of a rollercoaster......

Edited November 18, 2017 by Iceaxecrampon

[Dennis]

lets hope for an new setup..... for now 

[Man With Beard]

EC ensembles: top two clusters at T240 maintain a hint of heights over Greenland, but still doesn't push the Atlantic trough through into Europe. Could be a very wet end to November for most. The outlier cluster may see a Sceuo High developing but the UK just about on the Atlantic side rather than the continental side

[Brucie]

I actually think we have not had any very mild spells of weather this November, unlike a lot of recent Novembers.  It is usual to get some very mild weather at some point.  This potential mild weather is not forecast to be prolonged though and if it is to remain unsettled, then I can foresee a polar maritime airflow continuing into the start of winter, particularly as the Azores high seems to be displaced further N in the Atlantic currently.  

Cold, ice and snow can wait for the winter months.

David

[Frosty.]

16 minutes ago, blizzard81 said:

Let's just hope the polar maritime air gets in next weekend. Thankfully the blow torch runs didn't last long and good riddance to them. 

I would prefer arctic maritime and who knows, perhaps we will see more meridional  patterns as time goes on..fingers crossed!..certainly better output than yesterday for seasonal weather and hopefully we won't see a repeat of that dreaded blowtorch shown on the Gfs yesterday and no repeat of December 2015 which included all that shocking flooding!

Edited November 18, 2017 by Frosty.

[Dennis]

new round of trying.....

Edited November 18, 2017 by Dennis

[nick sussex]

Just caught up with the outputs. The models are really making a hash of shortwave energy with still no agreement at T96hrs. The UKMO which was a horror show last night now jumps from coldies nightmare to the best this morning. The ECM 00hrs has gone backwards, the GFS 00hrs in between.

The medium term on the face of it looks a bit more promising with a bit more easterly push to clear troughing but uncertainty upstream regarding how amplified any troughing might be in the eastern USA will dictate whether we can see heights drop in central Europe and remove limpet high pressure from the south.

Remembering here you don't want upstream amplification until the troughing has cleared east otherwise the dig in the jet will be too far west.

 

 

[Singularity]

That trough disruption to the west Fri-Sat of the GFS 06z is just the sort of thing that, during periods of increased westerly progression, ensembles tend to mask in the mid-longer range, even in cluster format, due to the differences in timing and placement of what tend to be fairly short-lived resultant ridges.

So - it rings an alarm bell for me; one that says 'short-notice cold snap potential'. Not saying it's likely by any means, just that it's possible enough to cause an undesirable level of uncertainty. A common situation in the winter season of course!

[Singularity]

  
Nasty little nipper in the flow from the GFS 12z for Wed evening. Any further east and it's not just the likes of Sidney facing some serious weather...! Could easily disappear again on the next run, of course.

Secondary low on the SW side of the trough resembles the 06z more than the 00z so may see that hang-back of low heights to the SW again, leaving any cold weekend conditions down to the next trough off the U.S. to be slow and/or disrupted enough to permit mid-Atlantic ridging.

Okay yes - as of +120, the hang-back is occurring. Could be a full working week of very balmy temperatures with the mid-teens being reached somewhere or other on each and every day! 

Edit: On the other hand, the UKMO +96 just updated and bears closer resemblance to both its 00z and the GFS 00z;


We'll just have to wait and see how close to the UKMO 00z that run turns out to be.

Edited November 18, 2017 by Singularity

[NorthYorksWeather]

4 minutes ago, Singularity said:

  
Nasty little nipper in the flow from the GFS 12z for Wed evening. Any further east and it's not just the likes of Sidney facing some serious weather...! Could easily disappear again on the next run, of course.

Secondary low on the SW side of the trough resembles the 06z more than the 00z so may see that hang-back of low heights to the SW again, leaving any cold weekend conditions down to the next trough off the U.S. to be slow and/or disrupted enough to permit mid-Atlantic ridging.

Okay yes - as of +120, the hang-back is occurring. Could be a full working week of very balmy temperatures with the mid-teens being reached somewhere or other on each and every day! 

UKMO quite a bit different to GFS at 120 hrs. Cold air filtering in from the NW.

[Singularity]

1 minute ago, vizzy2004 said:

UKMO quite a bit different to GFS at 120 hrs. Cold air filtering in from the NW.

Wow, that's even more different than I just anticipated in my edit on the earlier post .
Not clear if it will achieve the split away of the SW extension of the trough like the 00z did, but an alternative of shortwave lows running into the base of the deep low to the NE would be even more interesting, though probably not in the south unless you're a fan of heavy rain.

[Singularity]

  
 
Whole pattern has jumped west. Looks better than 06z for the extent of trough disruption and heights are higher to the NW. 
Awaiting UKMO +144 with interest to see if upstream sees any similar adjustments.

[Polar Maritime]

A continuation of a cool/cold N/W flow turning Northerly at times.

[The PIT]

Sadly the return to more normal conditions is way into lala land. Before that plenty of t shirt weather after this Sunday. Not a lot of rain for us southwards so the dry month looks like continuing but the main interest is the earlier hours of Thursday at T111 where it maybe quite windy with some very strong gusts going up the Irish sea.  No sign of any real cold weather away from Scotland on this run.  However it's a good run for Scotland.

[Singularity]

Yes, unfortunate that the main trough drifted so far NW as otherwise those shortwave lows splitting off the disrupting trough could have made for some interesting interactions with the cold PM/AM airmass.

Might be less of that trouble going forward from the UKMO 12z +144 chart though;

The trough by us is further east here compared to GFS, but at the same time, the one SW of Greenland is not disrupting anywhere near as much. So a mix of wins and losses perhaps - making it unclear how things would really unfold during the weekend. More runs needed... maybe many more!

[blizzard81]

2 minutes ago, Singularity said:

Yes, unfortunate that the main trough drifted so far NW as otherwise those shortwave lows splitting off the disrupting trough could have made for some interesting interactions with the cold PM/AM airmass.

Might be less of that trouble going forward from the UKMO 12z +144 chart though;

The trough by us is further east here compared to GFS, but at the same time, the one SW of Greenland is not disrupting anywhere near as much. So a mix of wins and losses perhaps - making it unclear how things would really unfold during the weekend. More runs needed... maybe many more!

Can't see many if any upgrades to this one to be honest. This is now zonal and the models generally are in their comfort zone with such synoptics. They tend to be very accurate with the tracks of lows in these circumstances. The UK will be around 600 miles too south to experience anything other than cold rain (apart from N Scotland). Seen it too many times before. Excruciating to watch. 

[booferking]

Yea this is becoming a regular event downgrades, starting to get annoying now likely change again next run snowfest then to be dropped again.

 

[Man With Beard]

15 minutes ago, Singularity said:

Yes, unfortunate that the main trough drifted so far NW as otherwise those shortwave lows splitting off the disrupting trough could have made for some interesting interactions with the cold PM/AM airmass.

Might be less of that trouble going forward from the UKMO 12z +144 chart though;

The trough by us is further east here compared to GFS, but at the same time, the one SW of Greenland is not disrupting anywhere near as much. So a mix of wins and losses perhaps - making it unclear how things would really unfold during the weekend. More runs needed... maybe many more!

If a deep low could get established in that location, it would encourage a run of NWlies and generally colder weather with snow for north + western hills

[knocker]

I'm not going to attempt any detailed analysis (did I hear thank god for small mercy's?) merely just to note the pattern and energy flows midweek leading to the Friday surface analysis.

Edited November 18, 2017 by knocker

[nick sussex]

As is the way with these set ups the UK tends to always find itself on the wrong side of the trough. The UKMO isn't as good as this mornings run early on with the cold boundary shifted much further north.

The rapid deepening of that low to the sw takes the track too far to the nw.

With these west neg NAO when you're hoping for eastwards corrections they never happen, when we see northerly topplers though that's the default!

Even though the UKMO isn't as good as this morning it still offers the chance of a bit more interest if further shortwaves to the sw remain shallower features as they run ne.

The UKMO T120hrs  shows some decent depth of cold heading se and there could be enough embedded cold at the surface for that shortwave to run into as it heads ene at T144hrs:

The pattern can't really progress east until those low heights over the UK separate from shortwave energy to the sw, in terms of the shortwave circled the track in these set ups is often dependent on how much it deepens, the shallower the depth the less northwards movement.

At this point given the luck over the last few days certainly don't expect anything however if by some miracle things change its possible some lucky areas could see some snow.

 

 

[ANYWEATHER]

Looks like gfs is gearing itself up for a wet and wild ride from later this week. Batten down the hatches comes to mind

[Mucka]

A good number of GFS ensembles attempt to reestablish some form of blocking before end of November with varying degrees of success, but enough to suggest there is no reason to consider zonal conditions are guaranteed to last into December and beyond.

Of course blocking is only half the battle to get a cold spell for the UK but until then the mild conditions do not look so long lasted at the moment anyway with possible transient cold air drawn in from on the back-end of troughs passing through - typical autumnal fare.

Edited November 18, 2017 by Mucka

[knocker]

There is a lot of energy leving the eastern seaboard south of the trough which actually a lobe of the vortex and can be seen in the lower strat on this loop

http://weather.uwyo.edu/cgi-bin/model?MODEL=GFS003&TIME=2017111812&REGION=NHEM&FCST=all&LEVEL=200&F1=none&F2=none&C1=hght&C2=none&VEC=none