Model Output Discussions 12z 01/09/2016

[summer blizzard]

For late October the amount of cold air around will be pretty remarkable.

[mb018538]

Quite stark differences between UKMO and GFS at 144 hours this morning - GFS starts to turn things unsettled by spinning a low under the block, while UKMO has none of it and keeps the high pressure firmly in charge.

 

[knocker]

Today

Rather cloudy, particularly in the east, where it will be rather cool in the light easterly

As mb mentions above the GFS has made a bold move this morning/.

The upper low to the SE becomes more influential by 00z Monday backing the flow over UK NE and introducing a more showery regime, particularly in the east. It would appear that as the week progresses the low remains adjacent to the south coast and is reinforced by energy spewing out from Canada which reinforces and further activates  the low into a pretty vigorous depression by Wednesday resulting in some very wet and unsettled weather.which hangs around for the rest of the week.

The GEFS anomaly this morning is not completely adverse to this idea and there were possible hints of this last night but at the moment probably best to put on hold certainly until the ecm has rolled out.

 

Edited October 6, 2016 by knocker

[mb018538]

ECM is sort of a halfway house between the two - not as unsettled as the GFS, but not as settled as the UKMO run. You'd have to say that as 2/3 are going for low pressure development around the south of the UK, this is the favoured outcome, with UKMO out on its own.

[knocker]

I think one has to say that given all that is going on upstairs at the moment one would be wise to step back a tad vis developments next week although interesting they certainly are.

The ecm is also not adverse to energy nipping out of Canada and even some trough disruption () mid Atlantic leading on the one hand to the proverbial;e cut off upper low and on the other some reinforcement of the European low. This eventually leads to a general trough area across the Atlantic. The Scandinavian block can only be classified a block providing if it is blocking something.

[BLAST FROM THE PAST]

Remarkable the stability of this true Scandi High.  Anyone got any teleconnections that support this?  Interesting re gfs development, but we shall see.  What I like is that when we have high pressure nudging in from our SW instead of the usual erosion/flattening of the block from NW it absorbs it and the easterly flow maintains.  

BFTP

[Frosty.]

1 hour ago, BLAST FROM THE PAST said:

the easterly flow maintains

Agreed Fred.. let's hope the easterly flow maintains..until next March!

Edited October 6, 2016 by Frosty.

[johnholmes]

Until the current Storm becomes absorbed into the overall northern hemisphere circulation I remain on the fence as to how the upper air may look in 6-10 days time. The persistence of an upper ridge somewhere between Greenland and Scandinavia looks a fair bet. Also for a trough to be somewhere to the south of this ridging. Just where and what shape is not clear. Currently the suggestion seems to be for a split low, east and west of the UK, positions open to change?

Have a look for yourself below on the links, NOAA is as it usually is less prone to changes than the ECMWF-GFS outputs but none are totally without changes in the past 4-5 days.Nothing yet though suggests any early start to a very strong Atlantic dominated upper air pattern.

http://www.cpc.noaa.gov/products/predictions/610day/500mb.php

http://mp1.met.psu.edu/~fxg1/ECMWF_0z/hgtcomp.html

Sticking my thinking cap on what might develop is for the mobility south of the Hudson Bay trough and the one WSW of that (off the west coast of USA) may push east as the ridges tend to move north?

[MR EXTREMES]

17 hours ago, phil nw. said:

Yes it's lovely out there again today Frosty and that east wind feels fresher already especially out of the sun.

The Scandinavian block is still the main feature for us and indeed much of Europe into next week,continuing to bring that easterly feed which will just drop the daytime temperatures a couple of degrees by the weekend as a cooler pool approaches from the east.

Yes Mr.Extremes i was just typing this as you posted above.I spoke around the Icelandic pressure ensembles a couple of days ago as they hinted that the main +ve heights would extend that way in the coming period and indeed that picture as you just showed is still there

Day 10 anomalies

 

and the latest graph for up there

so next week it seems we see the weakening of heights over to the north east but then moving to our north west with corresponding lower pressure over the nearby continent.At the moment then we look like keeping that easterly, even north easterly later, until mid-month.

Not sure how long this -NAO pattern will hold.Those Icelandic and indeed Scandinavia pressure ens. do show some fall off late on but not enough yet to indicate a strong Atlantic jet.It still looks fairly benign currently as we head towards mid-October.

 

 

and this mornings runs phil if only we were into november incredible to see channel runners this early.

theres also something i was interested in the other day that i posted in the hurricaine thread about hurricaine mathew it was broadcast the other day before it hit landfall that it was the most southerly tracked hurricane in history and thats regardless of the energy shown by a more active season not just in numbers but also in strength.

it would seem so far we are very much seeing a very strong surge in retrogressing heights and the heights to are showing far more robust patterns as compared to the last few years.

and this mornings models would make you believe its christmas already.

so glosea was on the money.

also we have had lower at least 50% lower solar output compared to last autumn and still declining.

i think the strong el nino now dropped to just slight la nina is  acting weak el nino,

i also believe east qbo could come into effect around mid nov into december although this is more of a personal idea after such a dominant west phase.

08/09 and 09/10 and 10/11 this was 3 winters with neg nao in winter months.

october 09 and october 10 were incredible neg nao and this did indeed lead to colder winter.

https://crudata.uea.ac.uk/~timo/datapages/naoi.htm

but overall sods law its only october because the model charts being seen now are screaming real hardcore winter weather even if we were into mid november.

 

Edited October 6, 2016 by MR EXTREMES

[MR EXTREMES]

52 minutes ago, BLAST FROM THE PAST said:

Remarkable the stability of this true Scandi High.  Anyone got any teleconnections that support this?  Interesting re gfs development, but we shall see.  What I like is that when we have high pressure nudging in from our SW instead of the usual erosion/flattening of the block from NW it absorbs it and the easterly flow maintains.  

BFTP

its classic start i think displaced jet and vortex could be a possibility and like you say allowing heights to move around to more favourable areas for possible colder conditions.

[feb1991blizzard]

15 minutes ago, MR EXTREMES said:

 

but overall sods law its only october because the model charts being seen now are screaming real hardcore winter weather even if we were into mid november.

 

 

Yes this statement is very valid, looks very unusual pattern, a lot of people make the mistake in spring when we get scandi / Greeny highs of saying 'if only' but the jet does quieten down at that time of year, the jet should be strengthening at this time of year and certainly should be tracking more across Scotland, I still think we could get some wintry weather for the North, that last chart on the GFS 0z rin shows a Northerly about to develop with a pool of -20 uppers, would be severly moderated by the SST's but would still think wintry showers possible with a direct hit.

Edited October 6, 2016 by feb1991blizzard

[knocker]

Not that this time frame is particularly relevant given the current complexities but just to note that the EPS, in the 10-15 time frame, is suggesting a flattening of the pattern with the Scandinavian HP becoming redundant and the main influence becoming the Azores HP pushing north in mid Atlantic. You end up with a somewhat modified westerly upper flow and this applies at the 200mb level as well which is quite weak.

[MR EXTREMES]

its also noted that the last major hurricaine to impact florida was wilma in 2005 and from october november december 2005 were all neg nao although not extremely neg like 09/10.

but add in the much much lower solar values and the enso index was 0.7 el nino.

which would id thought be not far far away from similar conditions to now... although slightly la nina.

qbo was east so im going with the idea a switch to east is on the cards but this is all just information put together just as ideas that ive been working on since i joined this forum some years ago.

but the atmosphere and everything is all interconnected so the answers are out there.

but so far fingers crossed its been interesting start to cotober.

and after what i feel was a nice summer and start to autumn lets hope we have a interesting winter for once. 

[Frosty.]

A very unsettled, rather cold disturbed end to the Gfs 6z with some snow for the scottish mountains and I couldn't help noticing the arctic air bottled up and ready to swing south once that low pushes off further east..it will soon start getting very interesting!

[Matthew.]

The long-range BCC has high pressure domination near the UK all the way through to mid-November. Always to be taken with a pinch of salt but dry, cool with fog and frost could be the name of the game.

[Frosty.]

There are increasing signs today that the prolonged largely settled blocked outlook the models were showing yesterday has downgraded today and there is now a chance that our weather will become more generally unsettled during the second half of next week. In the meantime, the Easterly flow should last until about next tues / wed with cool days and cold nights where skies clear but there will probably be a lot of cloud but still with sunny intervals between and a scattering of showers which become heavier and more frequent across the east during the next 2 or 3 days with the best of the dry weather and sunshine across the western side of the uk..its certainly autumnal.

Edited October 6, 2016 by Frosty.

[Frosty.]

1 hour ago, Matthew Wilson said:

The long-range BCC has high pressure domination near the UK all the way through to mid-November. Always to be taken with a pinch of salt but dry, cool with fog and frost could be the name of the game.

A huge pinch of salt with that Matthew, the MO longer term trend is currently for increasingly changeable weather and progressively more unsettled across  n / nw uk which would actually tie in with the later stages of the Gfs 6z op run. 

Edited October 6, 2016 by Frosty.

[Frosty.]

According to the GEFS 6z mean the uk remains blocked throughout next week with high pressure to the north slowly retrogressing further to the northwest but with 1020 mb or higher across the BI with the easterly flow eventually becoming lighter and more variable with an increasing chance of slight overnight frosts and mist / fog patches.

Edited October 6, 2016 by Frosty.

[Mucka]

5 hours ago, knocker said:

Not that this time frame is particularly relevant given the current complexities but just to note that the EPS, in the 10-15 time frame, is suggesting a flattening of the pattern with the Scandinavian HP becoming redundant and the main influence becoming the Azores HP pushing north in mid Atlantic. You end up with a somewhat modified westerly upper flow and this applies at the 200mb level as well which is quite weak.

True Knocker but would this not be just a transitional phase rather than an established pattern?

IMO it may well be just depicting a transitional phase of shifting mid lat blocking from East to West rather than a slow flattening to a Westerly regime and any polar maritime flow may well be short lived should that transpire because Atlantic troughing looks to keep the pattern amplified to the West.

While the Scandi high has potential to sink SE into the continent within that time-frame it seems another bout of WAA in the Atlantic is expected and possibly a strong mid Atlantic block will form or the Scandi high will be reinforced with undercutting of said trough.

Any unsettled weather as a result of a return to a Westerly flow looks the unlikeliest outcome beyond mid month though there will be small window of opportunity for the jet to push over the block rather than split flow or under.

All a long way out and many ifs and buts but I would be surprised if we saw the demise of mid lat blocking and march of cold air East anytime soon after mid month.

 

 

Edited October 6, 2016 by Mucka

[Man With Beard]

True wintery synoptics are always hard to come by, even harder to get through to T0, but recent GEFS runs are having a good go. The classic Scandi High to Greenland High rebound is showing up on a number of ensembles in the later stages, certainly in the timescale where those north of the border might start to think of white possibilities given the right situation. Such a scenario forces low pressure of Arctic origin to drop towards the north sea, with the UK on the Arctic side. 

Two months ahead of my expected schedule, I declare the winter chase 2016/17 open!

[knocker]

47 minutes ago, Mucka said:

True Knocker but would this not be just a transitional phase rather than an established pattern?

IMO it may well be just depicting a transitional phase of shifting mid lat blocking from East to West rather than a slow flattening to a Westerly regime and any polar maritime flow may well be short lived should that transpire because Atlantic troughing looks to keep the pattern amplified to the West.

 

Quite possible and of course there is a tendency for the mean anomalies to become flatter in the later time frames anyway. But having said that with such differences between the various models vis the upper air I suspect it's a brave person who attempts to proffer anything like a definitive opinion as to the evolution that far out.

Edited October 6, 2016 by knocker

[Cheshire Freeze]

6 hours ago, feb1991blizzard said:

Yes this statement is very valid, looks very unusual pattern, a lot of people make the mistake in spring when we get scandi / Greeny highs of saying 'if only' but the jet does quieten down at that time of year, the jet should be strengthening at this time of year and certainly should be tracking more across Scotland, I still think we could get some wintry weather for the North, that last chart on the GFS 0z rin shows a Northerly about to develop with a pool of -20 uppers, would be severly moderated by the SST's but would still think wintry showers possible with a direct hit.

All academic as it's at day 16 but snow more than possible given the advection of coldest uppers S through the UK. -5/-6 uppers suitable for wintry showers containing soft hail, sleet and wet snow as you say.

[Frosty.]

1 hour ago, Man With Beard said:

Two months ahead of my expected schedule, I declare the winter chase 2016/17 open!

Very bold statement..but I hope you're right

[Frosty.]

Mid month looks very pleasant on the Gfs 12z with above average temps across southern uk.

[Scorcher]

Yes Frosty, if the GFS is to be believed then the supply of cold air from the east is going to be petering out- it's just too early to get anything of note from that direction. On this latest run we pick more of a southeasterly, which would raise the temperatures, particularly further south. Still plenty of time for a proper cooldown when it's actually supposed to happen- November onwards!