FI Charts (T120+ onwards) Summer/ Autumn 2018 **READ MOD NOTE IN FIRST POST**

Villain

ECM 0z has backed away from the wet mess that 12z was showing yesterday, slack usual temps with showers mainly in west and north would be my reading of it

hatrickpatrick

12z ECM another improvement for next weekend:



12z GFS still showing low pressure areas loitering to our north and south:



Pretty massive divergence between the two at the moment. FI has really become FI again, unlike most of June when FI was somewhat accurate for most of the month across all of the models.

EDIT: I think that depression near Iceland on the ECM is ex-hurricane Beryl. Could the divergence be related to uncertainty as to whether its remnant will redevelop off the US coast? NHC is backing away from redevelopment, but until yesterday they were giving it a 50% chance.

Meteorite58

Trough could produce rain around Thurs/ Fri over the country .




Good chance of showers the weekend coming going by present charts although the last two runs showing heights building more and squeezing out the area of LP.



The end of the ECM run finishing up with warm humid SW'ly as heights build again with a ridge extending over Ireland, possibly short lived.

BliainanAir

After midweek it seems the azores high is attempting to build again on the 12Z UKMO and GFS. See what 12Z ECM brings. I'm no expert others may elaborate.

sdanseo

GFS and ECM are both showing a big ridge of warm air over us again next weekend.

The Azores high looks anomolously further west than it should be on both as well. Combine that with the post in Hurricane thread about rising sea temps possibly fuelling more storms and we could be in for some visitors from stateside later in the season.

sryanbruen

FI to me currently is beyond 72 hours thanks to the uncertainty so that's why I haven't bothered with NWP for the past few days. Since you brought the above up, I guess I'll post my thoughts on the bigger picture of those charts.

GFS shows contrasting temperatures over Greenland and us by +192 hrs which would most certainly lead to a more powerful jet stream. However, what's holding this back is the potential conjoined blocks of high pressure from the Azores, over us and Russia to form another Omega block. But this is more of a cherrypick than anything with these particular charts the 12z run generated today because the high over Russia looks weak in comparison to the jet stream caused by the temperature contrast. Not to mention, the model shows relatively high pressure over Greenland at that time frame which to me suggests the Azores High retrogressing and this in turn would force the jet stream to be pushed southwards either just to the north of us but close enough to bring unsettled weather, over top of us or to the south of us.

I don't know what to think of the UKMO at +144 hrs, everything is just so "weak" and uneventful.

BliainanAir

sryanbruen wrote: »

FI to me currently is beyond 72 hours thanks to the uncertainty so that's why I haven't bothered with NWP for the past few days. Since you brought the above up, I guess I'll post my thoughts on the bigger picture of those charts.

I posted to try and stir up some debate on this particular thread Really because I'm very keen to hear expert opinion, given how serious any prolongment of the current drought will be.

sryanbruen

ECM seems to be similar to the GFS.

sryanbruen

Well well well, what do we have here?

GFS 0z builds a ridge for the latter part of next weekend into early next week before the Atlantic tries to invade in against a block of high pressure over Scandinavia. The low pressure cannot get much further eastwards than the north and west and as a result, they just get pushed northwards. Looks fairly warm.

GFS 06z squeezes out the low pressure on Friday/Saturday then a little ridge (like the 0z) builds in bringing warmer and drier conditions again for a time before a return to westerlies but at the very end, high pressure builds over us again.



ECM builds a ridge of high pressure bringing more very warm air (see the 850hPa and thickness charts below) then everything becomes slack but staying warm at the end of its run. Over three consecutive runs or so now that this has been shown by the model.









ECM clusters have all gone to the warm or hot scenario but unlike Summer so far, this high looks further eastwards with low pressure in the Atlantic. This would mean that we would have some very hot days developing for some especially in the UK and if the low invades from the Atlantic after these hot interludes, we might start thinking about thunderstorms.

hatrickpatrick

I'm still learning about the synoptics of thunder, but if I'm reading this right there could be a possibility of a few thunderstorms if this chart verified next weekend?

MJohnston

hatrickpatrick wrote: »

I'm still learning about the synoptics of thunder, but if I'm reading this right there could be a possibility of a few thunderstorms if this chart verified next weekend?

wxcharts has a great Convective Overview visualisation, and yes, there's a small bit of potential on Saturday:

sdanseo

A few runs in a row now on the GFS are showing almost an inverted version of the Omega block we saw a couple of weeks back.

Question for those more experienced here, what are the chances that the HP "wins" here and closes in that area of relatively lower pressure in the centre, thus putting us back in heatwave territory?

sryanbruen

sdanseo wrote: »

A few runs in a row now on the GFS are showing almost an inverted version of the Omega block we saw a couple of weeks back.

Question for those more experienced here, what are the chances that the HP "wins" here and closes in that area of relatively lower pressure in the centre, thus putting us back in heatwave territory?

It's a matter of just how ridgey or strong the areas of high pressure are. On that particular GFS run, the low is forced southeastwards by the Azores High and Scandi High trying to conjoin with one another the day afterwards but a few days later, this doesn't come to full fruition as the westerlies take over. There are two possible reasons for this:

1. GFS' westerly bias
2. The temperature contrasts in the North Atlantic which I described yesterday powering up the jet stream.

The second reason is questionable on this run though because there is no retrogression of the high pressure up to Greenland and the jet stream is still quite a bit northwards.

Why this week's showers or rain from Wednesday to Saturday are uncertain or downgraded after looking like decent spells of rain, is as a result of the jet stream. It's still quite a bit to the north of us and it's weak in its current state regardless of Chris therefore, there is no "real areas of low pressure" to be seen and brought across the North Atlantic through us.

sryanbruen

GFS 12z continues the saga, perhaps a stronger ridge on this run.

Met Éireann suggest Friday to be a fine day generally, see their wording below. However, the GFS show Friday as quite a wet day (see its precipitation chart).

Friday: Latest indications suggest brighter fresher weather for Friday with sunny spells and well scattered showers and temperatures of 16 to 21 degrees Celsius.

UKMO 12z is trying to build up that ridge.

sryanbruen

The models have really upgraded the heat overnight for next weekend and beyond with heatwave conditions again likely to take place over the UK and Ireland though as you'd expect by the timeframe, there are some differences among the models. Here I discuss what the latest runs of the two models, GFS and ECMWF, show. The wording might sound a bit weird since I originally made it for my blog which is for both the UK and Ireland.

The GFS 06z shows high pressure from the Azores ridging to us by Saturday 21st July which gradually over time pushes to our east and draws in a southerly to southeasterly flow with hot air from Europe. Low pressure is stalling in the Atlantic as a result of this area of high pressure and if that low were to invade a few days following the establishment of hot weather over us then there'd be some severe thunderstorms. This is a proper hot scenario with temperatures easily getting into the 30s across England and Wales whilst mid to high 20s over Ireland and Scotland. If the wind was to sustain a southeasterly airstream along with the high pressure not going too far east, then 30°C is not out of the woods for Ireland.







ECM 0z is kind of different. It ridges in the high pressure similar to the GFS during next weekend (even hotter air on this model) but the jet stream is closer to the north of Ireland and over Scotland. This would mean it'd be cooler and cloudier up there with temperatures stuck in the high teens and low 20s mainly in any sunshine but generally mid to high teens. Elsewhere, we'd be talking mid to high 20s and low 30s over England & Wales. The high pressure also doesn't push east over to Scandinavia, it stays over top of us. The heatwave conditions dam line (564) is across Ireland on Saturday on the ECM whilst it makes its way to most parts then afterwards.

sryanbruen

GFS 12z is very strange, it gets the jet stream southwards but low pressure is still well to the north and going by the first chart here, you would think that the Azores High would fully ridge up to us like how the 06z showed?





UKMO 12z suggests a warm to hot Sunday 22nd July.

sryanbruen

ECM 12z goes the high pressure route though at +192 hrs, it goes a bit "wonky" in weakening the high pressure along with looking like cool 850hPa temperatures coming down from the northwest but at the end, there is a thundery trough just to the southwest of Ireland with both countries in a hot plume of air.















Different solutions are still being thrown around as shown from the 12z runs so none of this certain and is to be taken with a pinch of salt for now.

esposito

Just watched the extended outlook on bbc news 24.

Turning increasingly hot, humid and mainly dry in the southern half of the UK by this weekend as high pressure pushes north from the Azores. Hopefully that means most of Ireland will benefit too. We shall see.

daphne

Will North west and Ireland escape low activity though? The Met Eireann pressure charts out to 22nd looking like we would get a ridge of high forming over us again...

sryanbruen

GFS 18z and 0z were changeable westerlies with day to day variation in temperatures but for the south and east, not a lot of rain. The 06z looks to me like following similar suit going by its progression so far up to the FI period.

ECM 0z builds the high for Sunday/Monday but the jet stream is close to the north and west so perhaps not all that sunny. Afterwards, the Atlantic tries to break through and does so for Ireland on this run but the lows can't budge eastwards cause of the high pressure over Scandinavia and they just get shoved to the north of Scotland.

Sunday/Monday still looking like very warm days.

Meteorite58

GFS and ECM for once quite similar from +192 hrs to +240 hrs. A decent Lp which you would imagine could produce a fair amount of rainfall. 12Z ECM rolling out atm, we will see if it holds it.

Meteorite58

12Z ECM quite similar at +240 hrs . Been showing a large area of LP towards the end of next week ( along with some smaller areas of LP and troughs possible mid week ).

sryanbruen

After a warm weekend, the GFS 06z brings down a cold front for Monday into Tuesday next week which will bring cooler temperatures again for a time and some light rain. After that, high pressure starts approaching from the south (again) and ridges to the east with low pressure stalling to the west by Thursday forcing the wind direction to go into a humid southwesterly to southerly. This goes on for a few days before low pressure successfully makes it through. Very hot temperatures over the UK in that kind of setup and evident of a heatwave whilst for Ireland, mainly around the high teens out west and low 20s elsewhere though possibly higher once the sun shines. The GFS 0z was very similar.



GFS 06z ensembles are in agreement at +240 hrs as shown by the chart below. The first ensemble diagram is for London whilst the second and third ones are Dublin and Cork respectively. Just look at how much the white line (ensemble mean) is above the red line (30 year average) for London. Some real serious heat coming to them if the GFS 06z ensembles are correct. Even if it's not as warm here as it is there, it will be very humid!









ECM 0z is similar to the GFS but it delays the real push of heat for the UK for a day whilst low pressure anchors itself over Ireland.





Still all to play for it seems.

sryanbruen

Pub Run has arrived early with the GFS 12z :pac:. This run goes all out crazy with the heat for the UK and is trying its best to keep the Atlantic at bay. Tuesday's cold front doesn't make it through the whole country with 850hPa temperatures staying above 5c through much of the southern swave of Ireland on this run. After this, the high intensifies to the south and east turning up the furnace for real in the UK. I'm showing some of these charts just for a good laugh here because this run is sensational. The southerlies go on and on before being cut off bang on the first of August but high pressure continues.

*IF* the GFS 12z were to verify, UK temperature record of 38.5c from August 2003 would be under threat. The model itself shows maximum of 36c and as we know, it usually underestimates temperatures. I'm not saying it isn't possible but this run is almost certain to be an outlier in the ensembles with the extreme side of its heat. This is truly dangerous level of heat for the UK. For Ireland, we'd be more mid-20s but still very humid! Also, if this heat were to happen or sustain throughout the rest of July, the CET could have its first ever 20c month! (The warmest month on record was July 2006 with a CET of 19.7c)

Little rain again by the way away from the west.

















Maximum temperatures (remember to add 1 or 2c for more accurate values) on GFS 12z for Sunday 29th July:



Latest GFS ensembles have pretty much vanished the negative NAO signal and the NAO will be staying positive meaning Azores High will continue to be strong and ridgey.



If you didn't think it was crazy enough going by all that above, well......

https://twitter.com/TWOweather/status/1019625137560346624

sryanbruen

ECM 12z is warm again. Tuesday's cold front pushes southwards for a time but then can't budge much further thanks to the blocking area of high pressure to the east and gets shoved back westwards or fizzles out. The Atlantic trying to come back but just doesn't on this ECM run with a low just out to the west whilst the wind is coming from a southerly direction drawing in hot, humid air. This is mainly to England but even Ireland would be warm widely in the 20s and humid.

Chris_5339762

I have 20 miles per day to walk in England right where that 36C blob is. Lovely.

Meteorite58

Out into FI only slack areas of LP coming across the Atlantic it would seem which look too weak to make any inroads on the HP over Europe and as has been the case so far having little impact on the rainfall deficit here. On the end of the ECM 12Z run looks like a shallow area of LP could stall or make slow progress to our SW or S. GFS similar.

Meteorite58

An interesting set up the end of next week for sure. Fine margins indeed.

https://twitter.com/SimonLeeWx/status/1019639326970433536

pauldry

Yes if the Scandi High gets going we could be in for a repeat of August 1995.

Its a very mixed picture of charts. One run hot one run not so hot.

Remember the middle of June they promised an end to heatwave but then it reappeared in the charts a few days later.

Definitely think England is due some real heat still this Summer if not us. Think away from North and West will definitely get warm spells of sunshine and these areas too on specific days.

Looking at charts there certainly could be another 30c somewhere in Ireland yet in the coming fortnight. But rain too at times mainly in more Western areas.

MrDerp

This is nuts.

Technical question: What kind of energy would be needed to break down this blocking? I've always read with interest here about SSWs and their impact on winter time blocking. Is there a low pressure event that can break down this weather, or is it a self-reinforcing pattern (summer solar energy plus established block, for example) that actually requires winter to break it down? Could some hurricane remnants steer the jetstream and provide a weather bomb and break it?

I read sryanbruen's comments on the analogs with 1995 previously with interest, is a similar pattern (local swings of 100-200km notwithstanding) looking more and more likely?