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

[summer blizzard]

GEM has low pressure victorious by 7 and builds a strong Greenland High afterward..

 

 

GFS keeps pressure high days 5-9..

 

 

Euro keeps a stalemate but the Scandinavian High dies pretty quickly..

 

[mushymanrob]

.... And on the plus side todays noaa anomaly charts support the positive heights to our northeast building ssupport for a dry wrm settled spell.

Im looking northeastward for pressure build, not towards greenland.

Interesting times, an easterly draft at this time of the year is a rare bird, will be interesting to see what an easterly draft will bring assuming it materialises.

[mushymanrob]

Ps.... In about 1984 we had a strong scandi high in summer that produced a persistent northeasterly breeze, but we still got 28c.

[knocker]

That strong GEM GH by day 8 is interesting...produces nagging NE winds...takes sting off any warmthimage.jpg

 

It might be interesting to you but could you more specific regarding the NE winds on day 8 because I seem to have a shallow low over the UK and it's not nagging at all  The GH producing nowt.

Edited August 13, 2015 by knocker

[mushymanrob]

If that developed into the 84 85 winter mushy I'd take it nowimage.jpg

Yeah, i detested that winter... Sorry old chap.

[stainesbloke]

Ps.... In about 1984 we had a strong scandi high in summer that produced a persistent northeasterly breeze, but we still got 28c.

We can but dream!! 28C with a nice NE breeze would be absolutely perfect, hopefully not too much North Sea clag to spoil things. Easterlies this year have been rare, I wonder which model has this right.

[johnholmes]

The NOAA 6-10 still leaves doubt as to which will be the dominant feature at 500mb. The increasing values of +ve heights to the north or the still present trough just west of the UK.

Not possible to call just yet but IF the +ve heights continue to increase then that may become the dominant feature with the surface high beneath the maximum +ve heights holding the surface features under the trough to the west but I would not call it yet.

link below

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

[summer blizzard]

18z somewhat closer to the GEM in that it parks a low over the UK days 8-10.

[knocker]

EC32 update

 

Starting on Sunday 23^rd. Ridge N. Scandinavia  Trough Iceland SE to a swathe of lowish pressure across western Europe. Quite a messy surface analysis with the UK in col. (worth mentioning but for the five days prior to this should see Scotland get some better weather)

 

In the next week up to the 30^th August the ridge to the NE weakens and the trough to the west of the UK becomes the influential factor returning the UK to a south westerly airflow. Although basically zonal with the Azores out of the picture.

 

No sense in trying to over analyse the weak signals until the 14^th September but suffice it to say it’s a familiar story of low pressure to the NW with trough and the Azores moving back to it’s position to the south west. This leads to a westerly zonal flow which if influenced more by the Azores HP could be reasonable pleasant but keep in mind this scenario is always prone to the north/south divide if the trough intermittently flexes it’s wings.

 

Summary

The rise of pressure to the NE next week is not sustained and after a brief transitional hiatus ten to fourteen days away when some interesting weather could again materialise in the south we revert to a familiar scenario.

 

Taking an overview the picture could be a lot worse and the temps should be around average or even above for periods and generally pretty dry.

[knocker]

This morning's GFS has an interesting sequence early next week. At 12z Tuesday it has a shallow low 1007mb in the North Sea which it has whipped up from central Europe. (the latest fax has a low 1014mb over N. Scotland). At the same time another low 1003mb west of Ireland. Forty eight hours later the NS low has disappeared NW and the low west of Ireland has moved SW into SW France leaving the UK in a dry, warm, SE airstream.

http://www.tropicaltidbits.com/

Edited August 14, 2015 by knocker

[Gibby]

HERE IS MY LATEST ANALYSIS USING DATA SUPPLIED BY THE NWP OUTPUT COVERING 5 OF THE WORLDS MOST POWERFUL WEATHER COMPUTERS ISSUED AT 08:00 ON FRIDAY AUG 14TH 2015

 

THE CURRENT GENERAL SITUATION. A trough of Low pressure will move east across the UK and weaken as it does leaving a light and fresher Westerly flow over the UK later tonight and tomorrow.

 

http://www.wetterzentrale.de/pics/Rtavn001.gif 

 

MODELS-2 WEEK HEADLINE Remaining somewhat mixed with a lot of dry weather for all but with occasional rain too at times.

 

THE GFS JET STREAM FORECAST The GFS Jet Stream Forecast shows the flow with two arms, the main one running ESE over the Atlantic to Northern Spain while another weak arm moves North over Eastern Britain. Next week the flow becomes weak and well broken around the UK before later settling again across the Atlantic towards Western Britain at the end of the period.

 

http://www.netweather.tv/index.cgi?action=jetstream 

 

GFS OPERATIONAL The GFS Operational Run today shows the main focus being the build of High pressure across NE Europe next week. This follows a period of very slack winds and a few showers between tomorrow and then when East to SE winds take over and drag warm weather over from Europe. Pressure is shown to be low over France and this would spawn thundery showers across Southern areas at times while the North stays largely dry. Late in the period slack pressure gradients return for a time before Atlantic Westerlies with low pressure to the North drive wind and rain across the UK from the West to end the period.

 

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

 

http://www.wetterzentrale.de/pics/Rtavn3841.gif 

 

THE GFS CONTROL The GFS Control Run today also shows High pressure developing to the North and NE next week but no as effective to the SW of the UK as the operational as it allows Atlantic Low pressure to slide SE across Southern and western Britain with rain at times. The North would stay drier for much of next week before all areas have a quiet interlude of light winds and fair days before Atlantic Low pressure feeds fronts West to East across the UK towards the end of the run with rain at times for all. 

 

THE GFS CLUSTERS(14 Days) The GFS Clusters this morning show High pressure to the NE and SW of the UK with varying degrees of influence between them on how much influence the ridge between them has over the UK. Confidence is low percentage wise on any one outcome verifying.

 

http://www.weatheronline.co.uk/cgi-bin/expertcharts?LANG=en&MENU=0000000000&CONT=euro&MODELL=gefs&MODELLTYP=2&BASE=-&VAR=cpre&HH=372&ZOOM=0&ARCHIV=0&RES=0&WMO=&PERIOD=

 

UKMO UKMO today shows slack pressure gradients to start next week before Southerly winds develop and fronts push in from the SW in association with a mid Atlantic depression towards midweek.

 

http://www.wetterzentrale.de/pics/Rukm1441.gif 

 

THE FAX CHARTS The Fax Charts this morning show the complex system of troughs currently affecting the UK moving East and clearing the UK tomorrow setting up a period of slack synoptics therefore light winds and fair weather in average temperatures. This scenario lasts until Tuesday when troughs approach the NE with some rain.

 

http://www.weathercharts.org/ukmomslp.htm#t120.

 

GEM GEM today shows High pressure developing well to the NE of the UK soon. This sets up the slack pressure gradients over the UK that the other output shows and brings about fair weather with a few showers. NE areas could also see rain early next week as a small Low moves NW close to the NE coast while soon afterwards a strong Atlantic depression trundles slowly into the UK from off the Atlantic turning things unsettled and breezy for all with rain at times to end the period.

 

http://www.wetterzentrale.de/pics/Rgem2401.gif 

 

NAVGEM NAVGEM is a bit more optimistic about things later next week as the slack and benign pattern of the early weeks strengthens into more of a link between High pressure to the NE and SW bringing fine and warmer weather to the South late next week with just the far NW seeing a little rain.

 

http://www.wetterzentrale.de/pics/Rnvg1681.gif.

 

ECM ECM this morning shows a lot of changebale synoptic patterns over the next 10 days. The current Low pressure system is shown to clear away North leaving a tenuous ridge across the UK from High pressure to the NE. One Low then move NW over NE parts early next week with some rain there followed by an Atantic depression and SW winds with rain at times for many soon after midweek. This also clears North with High pressure transiting East over the UK to end next week followed by a warm and probably turning thundery end to the weekend from the SW.

 

http://www.wetterzentrale.de/pics/Recm2401.gif

 

ECM 10 DAY MEAN The ECM 10 Day Mean Chart  from last evening continues to point towards uncertainty in the 10 Day point as slack pressure over and around the UK remains the order of the day. This is no doubt compiled by members splitting between influence from Low pressure to the NW to a strong influence of a High pressure belt from the NE and SW.

 

http://www.wetterzentrale.de/pics/Reem2401.gif 

 

NOTABLE TREND CHANGES FROM PREVIOUS RUNS The models are trending towards  a strong build of pressure over NE Europe which on this morning's charts continue to show varying degree of influence to the weather over the UK.

 

31 DAY HISTORICAL VERIFICATION STATS FOR GFS, UKMO & ECM The Verification Statistics of GFS, UKMO and ECM. This morning's verification statistics show ECM leading the way at 3 days with 95.7 pts followed by UKMO at 95.4 pts and GFS at 94.4pts. At 5 days ECM is stll king at 85.6 pts followed by UKMO at 84.5 and GFS at 83.3 pts. Then at 8 Days ECM still leads at 59.1 pts over GFS's 55.2 pts. Finally at Day 10 ECM leads GFS at 40.3 pts to 36.5 pts from GFS.

 

http://www.emc.ncep.noaa.gov/gmb/STATS_vsdb/allmodel/daily/cor/cor_day3_PMSL_MSL_G2NHX.png 

 

http://www.emc.ncep.noaa.gov/gmb/STATS_vsdb/allmodel/daily/cor/cor_day5_PMSL_MSL_G2NHX.png

 

http://www.emc.ncep.noaa.gov/gmb/STATS_vsdb/allmodel/daily/cor/cor_day8_PMSL_MSL_G2NHX.png

 

http://www.emc.ncep.noaa.gov/gmb/STATS_vsdb/allmodel/daily/cor/cor_day10_PMSL_MSL_G2NHX.prig

 

MY THOUGHTS This Summer has been one of the most difficult for the models to handle efficiently for as long as I remember. I have been doing these reviews for several years now and confidence on what the models show verifying at even short time spans leave me with low confidence at any particular model run verifying. However, here's todays attempt. What we have currently is the remains of yesterdays thundery Low (which in itself has proved very difficult to pin down fine details) ebbing North and East over the next 24 -36 hours. Pressure then builds slowly over the UK but more markedly over NE Europe with a tenuous ridge developing from it across the UK in very slack winds. Then a NW moving small Low could bring rain to NE Britain early next week with fine but never overly warm weather especially by night occurring elsewhere with the caveat of the risk of isolated showers. Then as we move into the latter stages of next week models diverge to various types of solutions ranging from a return to an Atlantic Low with it's wind and rain for all to High pressure building over the UK for a time with fine, sunny and warm weather developing as per ECM next weekend. The GFS operational goes for a warm and thundery spell in the South with the best weather further North while ECM seems to run with a variety of synoptics all within a short time span. All this shows to me that current hemispheric air conditions are difficult for the models to get a grip with as a lot of slack pressure patterns can evolve into almost anything thereafter if there is no one driving Low or High pressure to drive the weather. What I have noticed this Summer is that the UK has hardly ever had Low or High pressure directly over the UK dictating conditions with an array of slacker scenarios instead driving things which sometimes the models have made a real dog's dinner at forecasting and at others have been moderate at best in predicting outcomes correctly. This morning's crop of output comes with an equal amount of low confidence beyond early next week and while nothing remarkably bad or good is shown from what we see today that's not to say that the next set of outputs in subsequent days will not come up with another set of variables. There will be no report from me tomorrow morning but I will return for Sunday morning's set.

 

Next update from 09:00 Sunday Aug 16th 2015

[summer blizzard]

GFS out on its own today. GEM and Euro are much more aggressive with the low days 5-8.

[Summer Sun]

Nw/se split according to ecm 00z ensembles, the se getting the better conditions and warmer weather wheras nw get it cooler and more unsettled:

http://www.meteociel.fr/modeles/ecmwf.php?ech=240&mode=1&map=0&type=1&archive=0

Hope it comes off.

 

Those in the NW won't agree with that they've had a poor summer

[phil nw.]

As Gibby states above this has been a difficult period to gauge any trends into the medium term.

The only real constant as far i can see this Summer has been the Atlantic trough and it does look like hanging on until the bitter end this season although with some waxing and waning.

We almost get a tenious link up between the buiding hts over Scandinavia and the Azores high next week but it seems destined to fail before another approach from the Atlantic.

We can see after the current low moves away into the N.Sea the UK is left in a COL or slack area of surface pressure with highs and lows either side.

 

so a few quieter days with perhaps just the odd shower but sunshine for many but again no great heat which apart from the odd day in the se quadrant seems to have been the main theme this Summer.

 

Days 5 and 10 on the overnight ECM ens show a very similar pattern continuing.

with a similar outlook from the CPC site

 

the last half of August doesn;t promise much if any change to the 500 pattern.

It all looks very underwhelming,no real heatwave but no prolonged wet spells either,some decent days to be had but a case of watching the daily forecasts to pick out the best of any weather to come.

 

[Milhouse]

'It could be a lot worse' is the way i'd sum up the models today. Temperatures will be around or just below average over the weekend then after that things are looking up. Its still unclear how close unsettled conditions will come to the NW but the further east you go it will be once again a case of warm-very warm conditions with a lot of dry weather around. Temperatures hotting up on the GFS

 

[Geordiesnow]

the last half of August doesn;t promise much if any change to the 500 pattern.

It all looks very underwhelming,no real heatwave but no prolonged wet spells either,some decent days to be had but a case of watching the daily forecasts to pick out the best of any weather to come.

 

Too me, I think the signs are more promising in respect we may see less of an influence of any Atlantic trough and more in the way of higher pressure, yesterday model runs have the Scandi high coming into play with the threat of Easterlies but today's output seem more in the way of Southerly and SW'lies. 

 

As per ever, some chopping and changing will occur and the question will be, just how close will the Atlantic troughing get to the UK.

 

Do agree about no real heatwave on the cards but some useable weather is on its way and the temperatures should gradually rise as we head into next week. 

[Man With Beard]

Well this very strange week ends at last, a reminder that decent uppers mean little for heat without decent weather, a mistake I made when trying to gauge this week's weather 7-10 days out!

 

I dare some of next week looks like going the same way

 

 

In one sense, the chart doesn't look too bad, no upper trough, no northerly draw, slack winds - but can we be sure the little areas of lower 500mb heights won't translate into something slightly more unsettled come the time? Fax charts are front-free at the moment but low pressure a little close for comfort

 

Later on, it's looking like back to square one. Heights over Scandi quickly knocked over - though models do get the speed of Scandi High demolitions wrong sometimes so I fancy this chart may be pushed back a day come the time. Looks disappointing for Scots but not all over yet, could easily be 200/300 miles west

 

[Singularity]

Check out that strong jet diving almost straight south in 6 days time. It's no wonder that the model develops low pressure in the vicinity of Iberia over the following few days. The position is ideal for bringing very warm air to the UK from the heart of the Mediterranean, which takes some 5 days to reach a peak - at which point temps are hitting 30*C or so across parts of the SE.

 

I particularly like the weekend charts, given that I'll be attending an airshow on Saturday and a car show on Sunday:

 

High 20's across the S and SE 

 

The important question is whether this run too good to be true? 

 

Well... sharp dives south of the jet as we see in 6 days time do tend to at least attempt to produce cut-off lows, usually level with central or southern Europe, but for the low to remain in such a state for as long as the 12z has it, there needs to be a quick change in the jet stream to a west-east track, so that the upper level winds associated with the low become disconnected. The GFS op has a strong surge of westerlies associated with an active low tracking to Iceland, which does the job nicely:

 

 

The 06z GFS operational run was remarkably similar, just a day slower with the Icelandic low. This raises confidence in the cut-off low coming into fruition, though not so much the import of warm air, as it was less pronounced on that run compared to the 12z GFS operational.

 

However, glancing at the GEFS, I can only find 3 or 4 perturbations that have a cut-off low in the right sort of place for warm, settled conditions, which is rather alarming... or is it? There are other scenarios that seem at least reasonable or in some cases better, depending on where you stand on late summer heat;

 

5 or 6 have warm air advection ahead of a large Atlantic trough, similar to this morning's ECM 00z operational, so warm but perhaps increasingly unstable through next weekend (some maintain the ridge throughout).

 

A couple have the cut-off low in place, but some way west of Europe, with a large Euro High bringing very warm to hot conditions.

 

The remainder have the low very close to the west, unsettled but still on the warms side. It's striking that not one run manages to power the low right the way through the UK and only two have the UK fully at the system's mercy by the start of the following week.
High pressure is keen to put up a fight, and all this coming after a fine, dry week for the south in particular - and for once the north isn't getting entirely left out 

 

 

ECM's rolling out as I type, and as of T+168 (for next Friday) it still has the jet stream heading more SE than S, which by Saturday leaves us with a large Atlantic low to the NW and a weak ridge across southern parts of the UK. It's a shame, given that the 00z was more in line with the GFS 12z.

 

ECM even dares to raise heights dramatically over Greenland, a scenario for which I see little support elsewhere.

 

Yet we don't see much cross-model support for GFS either, with GEM and UKMO sticking with the jet diving south, but choosing to have the Atlantic trough move with it rather than spawning a cut-off low.

 

I can see a cut-off low on the JMA run, but it ventures into Southern England by the weekend, producing a warm but showery outcome.

 

 

To summarise, GFS unfortunately represents the most optimistic outcome for next weekend, with JMA, GEM (and probably UKMO) offering warm but unsettled solutions, and ECM going with a fairly benign setup for most of us (but unsettled in the NW).

 

What I've done here tonight is taken you through the model output exactly as I have viewed it tonight - a 'live' analysis, you might say!

 

I'm left cautiously optimistic about next weekend, but pleased to have such a fine looking run of days leading up to it, even if I won't be able to make the most of those... the fine evenings will be much appreciated, while the daylight still lasts! 

[Roadrunner]

Thanks for that summary, Singularity. I too am hopeful of a good next weekend or at least dry as we're going camping in East Sussex. Seems like it will be warm at least and here's hoping the rain stays away as camping in the rain, or at least packing away a wet tent, is not fun!

Edited August 14, 2015 by Roadrunner

[damianslaw]

The outlook remains uncertain, with the UK is the middle of competing airstreams, the theme of the summer has been for polar maritime airstreams and returning polar maritime airstreams to gain the upper hand with the atlantic trough just close enough to edge out any strong influence from other airstreams. The models are showing a strong build of heights over Scandinavia with the UK left in a slack airstream come early next week, but with a diving southerly jet, lower heights to the NW are most likely to sink our way eventually I suspect. Not a bad outlook by any means, indeed a very decent spell of dry sunny pleasant weather ahead in the coming days, but certainly time is running out on this summer now if your wanting a sustained long spell of very warm/hot summer, it will be sod's law early September delivers such goods (as often seems the norm).

[summer blizzard]

Euro has the low gradually winning through days 5-10.

 

 

GEM largely agrees and has the low victorious by day 8..

 

 

GFS on its own.. 

 

[mushymanrob]

Euro has the low gradually winning through days 5-10.

GEM largely agrees and has the low victorious by day 8..

GFS on its own..

Assuming that happens of course

Edited August 14, 2015 by mushymanrob

[stainesbloke]

Thanks for that summary, Singularity. I too am hopeful of a good next weekend or at least dry as we're going camping in East Sussex. Seems like it will be warm at least and here's hoping the rain stays away as camping in the rain, or at least packing away a wet tent, is not fun!

Echo the great post from Singularity. GFS leading the way for a nice weekend next week. Am on a mini break on the south coast (Hayling Island) so praying for sun and warmth too!

[BlueHedgehog074]

Both of the 6 to 10 day and 8 to 14 day 500mb anomaly charts from the NOAA tonight stick to a similar theme - troughing out West in the Atlantic with areas of higher than average heights and ridging to the North-East of the UK over Scandinavia. Looking at both versions of the chart, the troughing in the mid-Atlantic doesn't show much signs of progressing Eastwards, although the Scandinavian ridging on the 8 to 14 day chart would probably become a little flatter - the bump in the upper flow to the East/North-East of the British Isles is smoother and a bit less steeper compared to the more kinkier 6 to 10 day version.

 

On the whole, the worst of any unsettled conditions would likely be concentrated to the West/North-West of the UK with the East and South-East of the UK seeing the best of the warmest and less disturbed conditions at times. No evidence unfortunately (for those who want it) for the Azores High to influence the UK. Additionally, the lower than average heights that occupy the Atlantic troughing is more marked on the 8 to 14 day version which could suggest that areas of Lows to our West could become more organised and deeper. With blocking to our North-East and the low anomalies to our West, it may allow for Lows to drop far enough South in the Atlantic to bring some very warm air up from the continent and lead to a risk of thundery breakdowns. This especially the case on the 6 to 10 day version where the sharper dip in the 500mb flow to the West of the UK gives more of an impression of a negative tilt to the Atlantic toughing. 

 

While there's no real signs of ridging in that area, the higher than average heights over North-East America could help assist with troughs dropping far enough South in the Atlantic to draw up warm continental air Northwards over the British Isles, particularly towards the East of the UK, on the Eastern flank of Lows. 

 

 

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

http://www.cpc.ncep.noaa.gov/products/predictions/814day/500mb.php

Edited August 14, 2015 by DiagonalRedLine

[Polar Maritime]

The GFS this morning shows a mainly settled/dry week coming up with quite a deep low spinning in from the West by next Sunday. Towards the end of the run a much warmer flow is showing from the S/E, Pushing High Pressure over the UK as we enter the new Month/Season..

Edited August 15, 2015 by Polar Maritime