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Paul

Model Output Discussion - The Start Of Summer

Paul

This thread = Models, models and more models
Please remember that this thread is for discussing the model output only. If you want to chat about the summer weather more generally, please use the Summer chat and moans thread.

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46 minutes ago, Man With Beard said:

here's the summary ECM ensembles for London - the spread for uppers well into the 20s later next week, the op at the cold end 

graphe_ens3.php?mode=0&x=&y=&run=0&ville

I was thinking the ECM op looked a bit too swift and ‘clean’ with the set up of what becomes one of the strongest Arctic dipole patterns I’ve ever seen... but only briefly.

That brevity reflects an important signal for poleward AAM transport to occur and drive the Greenland heights downward. This emanating from the W-C. Pacific thanks to the MJO just about making it far enough east.

This in turn makes for a good chance of following up the hotter spell with some classic ridging through the UK from the Azores.

Then toward mid-July, either the Africa-Indian Ocean pushes back and it turns cooler again via retraction west of the ridge, or we follow the most common long-range forecast path for this summer and see more Nino-type forcing leading to further rounds of heat and humidity building, thundery breakdowns freshening things up, then the cycle repeating.

Prospects could certainly be worse for July 🙂. Albeit things appear a bit ‘in the balance’.

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It would have been interesting if that same airmass that may hit us next week occurred this time last year. The ground was dried out, lawns were parching, moorland fires. Doesn't dry ground favour higher maxima in summer?

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8 minutes ago, Weather-history said:

It would have been interesting if that same airmass that may hit us next week occurred this time last year. The ground was dried out, lawns were parching, moorland fires. Doesn't dry ground favour higher maxima in summer?

There are normally four prerequisite conditions for very hot weather in the British Isles (loosely, maxima of 33–34 °C or above):

(i) An established high soil moisture deficit (dry soil absorbs less solar radiation in evaporating moisture, leaving more energy available as sensible heat).

(ii) A high solar angle.

(iii) A warm anticyclone allowing a feed of warm air from a hot Continent on a south or south-easterly flow.

(iv) Anticyclonic subsidence ‘capping’ vertical mixing of strongly heated surface air.

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6 minutes ago, Weather-history said:

It would have been interesting if that same airmass that may hit us next week occurred this time last year. The ground was dried out, lawns were parching, moorland fires. Doesn't dry ground favour higher maxima in summer?

Yes it does, higher temperatures are achieved more quickly in a set up that favours warmer temperatures when the ground is parched. When the ground is wet it takes a little longer to achieve the really high maxima. However we will probably see higher minima then last year if the same synoptics occurred now.

I think the intensity of the warm uppers though should still allow for some very high temperatures and after a few days under the same set up we would be approaching some records, once the hot air becomes embedded and dries things out further.

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Just now, Quicksilver1989 said:

Yes it does, higher temperatures are achieved more quickly in a set up that favours warmer temperatures when the ground is parched. When the ground is wet it takes a little longer to achieve the really high maxima. However we will probably see higher minima then last year if the same synoptics occurred now.

I think the intensity of the warm uppers though should still allow for some very high temperatures and after a few days under the same set up we would be approaching some records, once the hot air becomes embedded and dries things out further.

I suspect the potential for some truly epic thunderstorms is there next week, could be very explosive !!

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Right individual ECM ensemble data is out on weather.us, and it is every bit like yesterday's 00Z (it was more muted last night on the 12Zs).

Monday/Tuesday very likely to be very warm/hot in places, but the fun and games is at the end of next week.

By Thursday/Friday, there's pretty much a 50/50 split between a) members returning to normal or slightly below-normal and b) insanely hot runs never seen before in the UK, threatening the June temperature record and some maybe even the 100F mark.

Here's my craziest chart of the day: https://weather.us/model-charts/euro/united-kingdom/m10_temperature-850hpa/20190628-1200z.html. Uppers of 25C on the south coast, 24C in Wales, 23C in Dublin and 22C in Northern Ireland!!!! That is really quite mad. But honestly, it wasn't hard to find a crazy chart, a good 15 or 20 out of the 51 ensemble members could have been described as mad.

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LOL imagine that run coming off !!:crazy:

Model watching suddenly became intriguing !!

I got everything crossed for a memorable week ..

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6z is looking potentially even hotter than the 0z.

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GFS 06Z so far, up to Tuesday:

gfs-1-132.png?6

Could this be even better for heat than the 00Z? Is that even possible?

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48 minutes ago, Scorcher said:

Interesting that the temperatures are very conservative still on the BBC website- if anything they've dropped them for NW England this morning for Monday onwards! If we get anything like the chart that the GFS is showing for Thursday we will be easily making 30C in these parts too. Potential for this spell to be hot away from the SE as well.

You have to take into account the Beeb team like the Met team have to have meetings, produce reports, IT department construct the code/graphics and finalise what is on TV and or websites.  So they will be behind any models by several hours.     The forecasts this evening will most likely have the upgraded temps.

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Gfa 06z continues to put us into the oven from sunday onwards!!!amazing heat spewing out of france and spain!!

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Extraodinary stuff from GFS 6z. By T171 it has the 26'c isotherm over the far SW.

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It's interesting that the 2m max temps are nothing like as impressive as the 6z operational 850's / dam charts suggest, apart from the south / southeast with some areas not even reaching the high teens celsius.

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Good grief! An insane 06z, will have to wait until saturday / sunday before calling any prolonged heatwave but the GFS has certainly being consistent.
image.thumb.png.4d21fc16c17b0f058a97d445ec0c1236.png

I think we can be confident about some hot weather and thunderstorms on Monday and probably Tuesday. Anything after that is still uncertain!. Quite concerning levels of heat there...

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1 minute ago, Jon Snow said:

It's interesting that the 2m max temps are nothing like as impressive as the 6z operational 850's / dam charts suggest, apart from the south / southeast with some areas not even reaching the high teens celsius.

Looking at the skew T's posted in the convective thread there's a decent easterly flow at the surface, this may be pulling cooler air in below 850mb.

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GFS 6z even more incredible, Wow! Saving the hell out of these screenshots.

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Posted (edited)
8 minutes ago, fujita5 said:

Looking at the skew T's posted in the convective thread there's a decent easterly flow at the surface, this may be pulling cooler air in below 850mb.

The relationship, or more to point, non relationship, between 850mb temps and the surface has been covered ad nauseam in here

Edited by knocker

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Highlighting the futility of jumping on every run, particularly in F1. when tricky energy distribution is involved. In just 6 hours

1097716535_gfs-natl_wide-vort500_z500-16584001.thumb.png.663a5cad7999a9f45c56ffd7dc14410c.png1423525052_gfs-natl_wide-vort500_z500-16584002.thumb.png.d4fd328b1487a44c15cae80be2ee5267.png

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Posted (edited)

GFS 06z must be using its cold bias and undercooking the temps given the extremely high 850 values. Showing maxes of 30 to 33 for London area. Id say 36 to 40 is likely to be achieved, definitely a potential for the highest max on record never mind the highest June max. The 2m temp chart below (from July 2018) is what GFS should be showing

plume.png

Edited by 38.5*C

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12 minutes ago, 38.5*C said:

GFS 06z must be using its cold bias and undercooking the temps given the extremely high 850 values. Showing maxes of 30 to 33 for London area. Id say 36 to 40 is likely to be achieved, definitely a potential for the highest max on record never mind the highest June max. The 2m temp chart below (from July 2018) is what GFS should be showing

plume.png

Totally agree!!with the synoptics on show i dont care if there an easterly at th surface with 850 temps such as those shown there is no way we gona get a max of just 24 or 25 degrees!!gota get these temperature projections on the gfs sorted out asap!!

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Remarkable that this incredible 850hPa chart is apparently only going to produce these sort of temps at the surface- surely not!

GFSOPUK06_177_2.png

GFSOPUK06_177_17.png

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52 minutes ago, Quicksilver1989 said:

Good grief! An insane 06z, will have to wait until saturday / sunday before calling any prolonged heatwave but the GFS has certainly being consistent.
image.thumb.png.4d21fc16c17b0f058a97d445ec0c1236.png

I think we can be confident about some hot weather and thunderstorms on Monday and probably Tuesday. Anything after that is still uncertain!. Quite concerning levels of heat there...

Sorry to bring eveimage.thumb.png.380a50e1c1362057c385ff9aafbe27c8.pngryone back down to earth but GFS 06z is terrible by the end of the period 

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Posted (edited)

I was expecting widespread low 30's celsius on the Gfs 6z operational next week looking at the 850's etc, not pathetic mid to high teens / low 20's c away from the usual hot spots in the s / se.

Edited by Jon Snow

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