Model Output Discussion - 1st August 00z---------->

[Frosty.]

The next week or so looks generally unsettled with rain and showers and occasionally breezy/windy conditions but with some sunshine and lighter winds at times too, the coolest weather further n/nw but feeling warm in the sunny spells across southern uk and especially towards the end of this week when the southeast could again become very warm and humid for a time during the BH weekend with 27/28c on sunday in the SE but then we are likely to see a gradual change during the second half of next week with high pressure building in from the west which is what the Gfs 6z shows with increasingly fine conditions with temperatures in the mid / upper teens celsius by day, perhaps nudging into the low 20's c across the south/southeast but with chilly nights under clearer skies, coldest nights further northwest with a chance of ground frosts in prone locations. The met office are still predicting a settled spell to develop through the first half of September so the 6z is probably a good indicator of things to come beyond the next 7-10 days.

Edited August 25, 2015 by Frosty.

[Singularity]

No worries there John in a Nino winter. Wet and windy.

 

A lot of variation within that, though...

 

(Link to Generate For Yourself)

 

(Link to Generate for Yourself)

 

 

For these I've chosen the polar opposites from the strongest El Nino events since 1950 to emphasise my point.

 

To relate this to the thread topic, what CFS sees ought to be dependant on some other factor(s) alongside the existence of El Nino, though I'm not at all sure what those are. I've checked out SST anomalies covering the PDO region and seen no real patterns there, for example.

 

In fact, looking at the wider SST pattern, the only notable difference between the 6 months prior to the -ve NAO group (1958, 1968 and 2010) compared to the other is that the -ve NAO group follow the development of negative SST anomalies in the Central Pacific, roughly in line with California (example here).

 

 

That's as far as I dare go in this MOD thread, my apologies to the mods for the short venture into long range prospects 

[Frosty.]

The GEFS 6z mean shows an improving picture through early September with high pressure building in from the w/sw with increasingly settled conditions bringing good spells of sunshine and light winds with temperatures close to average by day but with chilly nights where skies clear and also an increase in overnight mist/fog patches, max temps eventually rise into the low 20's c further south which also looks like holding on to the largely fine conditions for longest. I think we will see an increasingly nice spell of early Autumn weather beyond the next week or so of generally unsettled conditions.

Edited August 25, 2015 by Frosty.

[Cloud 10]

No worries there John in a Nino winter. Wet and windy.

 

I love it when the first winter composites start to appear.

[Methuselah]

 I think we will see a nice spell of[...]weather beyond the next 7-10 generally unsettled days.

I think that just about sums up this summer, in a nutshell!      

[Captain Shortwave]

Still the chance of one last hurrah for warmth and storms this coming weekend.

High twenties in the south with the chance of thunderstorms breaking out, again like so many times this summer, the warmth doesn't really get much further than the Midlands. Still time for change in how much influence the Euro high could have over the bank holiday weekend.

 

Beyond this. looks like a flip in temperatures with a potential plunge of cool weather from the north.

 

UKMO quicker with this

 

I still wouldn't put any bets on anything beyond Friday at this point especially as the models might in the near time frame decide to factor in remaining low heights to our south west.

[Singularity]

Based on the 12z UKMO and JMA runs, there does appear to be at least a small chance that the jet stream cuts off the high heights over Greenland, keeping us in more of a westerly flow or even anticyclonic by early next week (though JMA does about-face a day later):

 

 

Funnily enough I can recall seeing similar issues in late January last year, when the models were struggling to resolve whether we'd have energetic storms powering across to us beneath a cut-off blocking high or not. Thankfully the lows don't look as vigorous under that arrangement this time around!

 

Assessing the currently favoured outcome, there's an impressively long northerly (or close to northerly) fetch on the ECM and GFS 12z operational runs, bringing air south  from high in the Arctic. The high topples before the cold air can really start piling in (is it winter already?!), but we still get some impressively low 850hPa temperatures out of it. The idea of the high gradually drifting over us during the following days is nice to see, hopefully not a red herring. There looks to be a low risk of a major trough dropping down close enough to our east to prolong the chilly northerly, which would certainly have the gas and electric companies rubbing their hands together in anticipation!    (I sincerely hope this smiley is exaggerating)

[knocker]

This evenings GFS ops doesn't agree with the METO or the ecm. It keeps the upper low to NW of the UK and doesn't move the jet SE and thus blocks the HP moving in from the west. I'll stick with the latter for the time being.

http://www.tropicaltidbits.com/

 

[knocker]

Looking at the anomalies the GEFS has sneaked a little upper low in there for Monday (figures) before HP to the NW bringing cool anticyclonic conditions.

As previously mentioned Jan the Knocker is highly dubious of the GFS interpretation for the latter part of the holiday

Charts weatherbell

 

Just seen NOAA so I think Jan might be right.

Edited August 25, 2015 by knocker

[ANYWEATHER]

Hi, Given the high Shannon entropy of the model output and the complexity of the atmosphere especially at the moment, anything for next week ,will have to be washed downed with a truck load of salt No model has a clue quite frankly.  As regards the bank holiday weekend ,it again is and will be a nightmare to forecast. Gfs makes a real mess of the holiday period, Ecm less so, although If I do take sides, Im for the gfs ,which has been more consistent with a very unsettled scenario. Perhaps, well into FI next week high pressure ridges in from the west, but if that happens it certainly wont be warm!

[Frosty.]

The Ecm 12z shows another brief surge of heat and humidity from the continent spreading up across the south/southeast at the end of this week with potential for 30c 86f or thereabouts depending on how sunny it is, there is also a good chance of thunderstorms which would be a repeat of last weekend's hot/thundery weather down south when it reached 31c in london. Looking further ahead, it turns much cooler from the north next week with sunshine and showers and then high pressure starts to build in from the west. With the met office currently predicting a settled spell between early and mid September and the models today heading that way too, signs are good for a spell of pleasant early Autumn weather from later next week.

[bluearmy]

Note quite a few hurricanes showing up in the western Atlantic and gulf on the 12z gefs end week 2. an ex TD/ hurricane into the Atlantic basin early September would stir things up somewhat.

[damianslaw]

Hard to predict how things are likely to pan out as we enter the new month, lots of changes from day to day and from one model to another. I'm not certain projected heights set to develop to the west will anchor themselves across the country and out to our east so easily, indeed GFS and ECM not showing this contrary to BBC/Meto forecast this evening on long range forecast, yesterday they were saying NW airstream for later next week - they change there minds every day..

 

Expect plenty more twists and turns from the models in the days ahead..

 

I've only been glancing at them in recent days and weeks, its been a very tricky period generally to forecast anything other than about 3-4 days ahead. The atlantic trough has been the dominant force for a long long time now, kicking aside any attempts of high pressure building over the country, mind early September is on the way, and the annual change we often see towards predominantly dry settled conditions..

[knocker]

Looking at the ecm anomalies tonight one can see the difference between them and the GEFs on Monday. The ecm has the upper trough NE of the UK not NW which would easily account for surface analysis differences. Further afield good agreement on the increasing HP influence.

http://www.tropicaltidbits.com/

[knocker]

The latest Saturday and Sunday fax charts.

 

[knocker]

The gfs and ecm are still handling the low pressure over Sunday and Monday differently.

http://www.tropicaltidbits.com/

 

[Frosty.]

The Ecm 00z is my pick of the 00z runs with a gradual change next week from unsettled to settled as high pressure builds in from the west and becomes centred over the UK. If this run verified it would eventually bring warm and sunny conditions to most of the UK, this is much better than the gfs 00z which keeps the high further west.

[johnholmes]

The ECMWF-GFS anomaly is even more down the road of the flow being north of west, differences between them in its intensity, see below. The NOAA version last evening is nothing like as marked but looking like trending that way, again link below. All 3 have been showing this change for 2-3 days now.

 

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

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

so no more fence sitting, it is going to be a cooler interval, just how settled or unsettled not yet clear. This from 5-6 days from now, possibly starting to show by Sunday but more like Monday into Tuesday I would think.

[Summer Sun]

UKMO shows a mixed weekend on this mornings run, by Tuesday pressure slowly rises from the south west so this could lead to improvements during Tuesday and more so Wednesday

 

[Polar Maritime]

So no more fence sitting, it is going to be a cooler interval, just how settled or unsettled not yet clear. This from 5-6 days from now, possibly starting to show by Sunday but more like Monday into Tuesday I would think.

 

Yes the GFS has been pretty bullish about a Northerly type flow for a good few days now by the turn of the Month. Quite a cool week on the cards for the start of Autumn, With Mon/Tue as you say the pivotal point. 

Edited August 26, 2015 by Polar Maritime

[Paul White.]

Hi everyone I'm flying to cancun on Saturday Mexico would anyone have any links to the models for the Caribbean please I'm struggling to find some.

Thanks

[knocker]

Hi everyone I'm flying to cancun on Saturday Mexico would anyone have any links to the models for the Caribbean please I'm struggling to find some.

Thanks

 

Levi Cowan's site covers it

 

http://www.tropicaltidbits.com/

Edited August 26, 2015 by knocker

[knocker]

Would you Adam and Eve it. This morning's anomalies are not so keen on moving the HP east particularly the GEFS which is adamant, The ecm less so. They eventually make it by day ten but at the same time develop a deep trough just to the east Scandinavia south to southern Europe.

 

I suspect they heard the clatter as John fell off the fence.

http://www.tropicaltidbits.com/

Edited August 26, 2015 by knocker

[BlueHedgehog074]

Would you Adam and Eve it. This morning's anomalies are not so keen on moving the HP east particularly the GEFS which is adamant, The ecm less so. They eventually make it by day ten but at the same time develop a deep trough just to the east Scandinavia south to southern Europe.

 

I suspect they heard the clatter as John fell off the fence.

http://www.tropicaltidbits.com/

One of those setups the cold enthusiasts would hope to see in Winter, especially with that Iceland/Greenland blocking.

[knocker]

An excellent idea to get it out of way now then to clear the decks for those forthcoming mild, barmy balmy days.