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Differences opening up with model forecasts of MJO progression. ECM staying in the neutral zone whilst GEFS and JMA showing progression from Phase 6 into Phase 7. ECM  GEFS  JMA  Phase 7 is

The intense amplification over North America with the Arctic plunge down the eastern half initiates downstream ridging of the subtropical high which simultaneously pumps up the jet.

Quite a good illustration showing absolutely no correlation between the 850mb and surface temps in the relatively 'warm' airmass in an Autumn anticyclone

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1 hour ago, knocker said:

It is rather a tad premature to accuse them in being wrong 36 hours prior to the event but the short answer to your question is that I'm afraid it's  above my pay grade. I assume everyone is aware of the vagaries of model max temps forecasts and don't put implicit faith in them but, short of not posting them at all, I'm not sure what else one can in a model discussion thread. Do you find there are similar problems with min temps, air not grass, as topography might be part of the equation?

I’m not sure at all. It was a genuine question, as I find it happens quite often. Maybe someone knows!

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for 25c tomorrow like the bbc are suggesting is possible, we would need a 17c diurnal temp range ... that is of course possible. but the uppers arent what id have thought are expected to be high enough, being under +10c, and that possible high cloud as knocks points out.

can we really get 25c under those conditions, without importing warmer air?.... personally i cant see it myself.

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15 minutes ago, mushymanrob said:

for 25c tomorrow like the bbc are suggesting is possible, we would need a 17c diurnal temp range ... that is of course possible. but the uppers arent what id have thought are expected to be high enough, being under +10c, and that possible high cloud as knocks points out.

can we really get 25c under those conditions, without importing warmer air?.... personally i cant see it myself.

850s are around 7-8c. They were around the same on the 11th April and we managed 25.5c, so as is always the case, uppers aren’t always the best gauge:

 image.thumb.png.1a4e05208650a792177ac4ed5a686eac.png 

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3 hours ago, mb018538 said:

850s are around 7-8c. They were around the same on the 11th April and we managed 25.5c, so as is always the case, uppers aren’t always the best gauge:

 image.thumb.png.1a4e05208650a792177ac4ed5a686eac.png 

absolutely, they are a rough guess i suppose . what was the overnight minima for the 11th where they got 25.5c?

personally, i wouldnt have gone for 25c, but would be prepared for a pleasant surprise if 25c was reached. if nothing else this is an interesting situation, and one that may well define some boundries on heat potential.

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6 hours ago, mb018538 said:

I’m not sure at all. It was a genuine question, as I find it happens quite often. Maybe someone knows!

One other addition to the equation 'might' be the super adiabatic that does occur, not with much wind mind you. Not sure that is happening this time of the year as it is more a high summer with stable air in the lower layers.

A rough idea would be to add 2-3 C, possibly 4 C to the suggested max value using the appropriate skew-t/t-phi diagram, that was how it was done pre and early computer product days. Not sure what forecasters do in these circumstances currently.

Just a thought.

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According to the ecm this evening the 'pincer' movement of the energy creates a cut off high cell north of Iceland whilst at the same time putting the breaks on the south east movement of the trough over Scandinavia and then having it filling and drifting west again. All of which portends a showery three days with sunny intervals for the UK

ecmwf-deterministic-nhemi-z300_speed-7902400.thumb.png.9e92135f05a48e210131091a2c945ecc.pngecmwf-deterministic-natl_wide-vort500_z500-7988800.thumb.png.5a8cdebef6cc73b2f4e775290e298419.pngecmwf-deterministic-natl_wide-vort500_z500-8075200.thumb.png.3dc59a13686c7b11c12d45c79f593810.png

 

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As the current sat image indicates a fair bit of high cloud around in some areas and this may linger in places through the day. Otherwise another warm and sunny day for many and with the N/S pressure differential easing the onshore easterly does like wise

PPVE89.thumb.gif.622ab3f6ba2fd93dff4caaa05d8a86f2.gifmet_images_aspx.thumb.png.7a4b7dc42ff2a8fc3a60de1ba43981f3.pnggfs-deterministic-uk-t2m_c_max6-7664800.thumb.png.f7124c04a7b15d84199f67ad7a788e7b.png

Tonight clear for most but low cloud spreading inland from the NE coast

PPVG89.thumb.gif.718cbf09a434f96b8af813e885c94c11.gif

This cloud will retreat on Friday leaving another sunny and warm day. But note the weak trough near Iceland

gfs-deterministic-natl_wide-z500_anom-7729600.thumb.png.0dc7c96b2324cea72a441107805a3627.pngPPVI89.thumb.gif.6c152533fd30d49bb8c72803106e9446.gifgfs-deterministic-uk-t2m_c_max6-7751200.thumb.png.edf8c79aaac235bea88bae8009536889.png

By Saturday the trough has tracked south east bringing cloud and light rain to NW areas whilst the rest of country continues warm and sunny. Usual caveat for the east coast

PPVK89.thumb.gif.53ac777c7e78effaff8e82a9f334a159.gifgfs-deterministic-uk-precip_6hr_inch-7837600.thumb.png.363835b0d457b31294405f9affe6c909.pnggfs-deterministic-uk-t2m_c_max6-7837600.thumb.png.5f124b62ac0d0a6fc898e2ba19d0d096.png

By Sunday the trough is starting to phase with the main trough to the NE whilst a high cell develops north of Iceland. Cooler and more unsettled in the north of the country

gfs-deterministic-natl_wide-z500_anom-7902400.thumb.png.c5765a7770deda05becaa90f9c07b6ce.pngPPVM89.thumb.gif.8244cdbf015371c06ebb55e17baaf3bd.gifgfs-deterministic-uk-t2m_c_max6-7924000.thumb.png.8cadbef3647e02385609310701dc20cb.png

Generally cooler on Monday, apart from the south east, with intermittent rain which will be more persistent on the trailing weak cold front

PPVO89.thumb.gif.3650cc39ade900061166041af11d13cd.gifgfs-deterministic-uk-precip_6hr_inch-8010400.thumb.png.29718adc7e28c3a9da5c315a1954390c.pnggfs-deterministic-uk-t2m_c_max6-8010400.thumb.png.28ddb7b8723947ef3a4c7f7d5e60e074.png

 

Edited by knocker
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The detail for the rest of next week is tricky so caution required. According to the gfs initially there are two contesting energy flows around the high cell which is quickly settled in favour of the one running from the tpv lobe n. Canada resulting in a trough tracking east across the Atlantic so that by Thursday much of the eastern Atlantic is under the influence of low pressure, portending unsettled weather for the UK

gfs-deterministic-nhemi-z300_speed-8118400.thumb.png.7d8c446c46231e8f423776aa00c363bc.pnggfs-deterministic-nhemi-z500_anom-8118400.thumb.png.b251a843d10f8843c2ec54eb8210136f.png

132.thumb.png.c76de25312ffcde907a7a13978a4a3f1.png156.thumb.png.862e21364ee6404bc915b2d51cf1071f.pngt180.thumb.png.c5df33d96f366ec5397b27b894f582e0.png

Edited by knocker
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And right on cue the ecm interrupts eastward movement of the Canadian trough as the subtropical high in mid Atlantic amplifies again. This the UK remains unsettled but for different reasons

ecmwf-deterministic-natl_wide-z300_speed-8118400.thumb.png.f309ae84eb219fcafbd6182ffb6a61b3.pngecmwf-deterministic-natl_wide-z500_anom-8118400.thumb.png.46db493f63a2da97f1eee57e1ec1081c.png

132.thumb.png.22e976462267568f3bd7d678786c2bfa.png156.thumb.png.22ab03a9bfa79501cacda6dbcd0df232.png180.thumb.png.4064dfe5855ab805619f3b09216be701.png

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With ref. to yesterday the gfs and ecm max forecasts for today Some significant differences central southern England

ecmwf-deterministic-uk-t2m_c_max6-7664800.thumb.png.cd32cc5ea979fd768f59e111db336826.pnggfs-deterministic-uk-t2m_c_max6-7664800.thumb.png.66b304966b2f15242e2ace9aae347504.png

And a forecast sounding from the gfs and are the differences down to the interpretation of how much cooler advection in the boundary layer suppresses surface heating?

index.thumb.png.9c1a1719bd5cc2bc036294ea25074b2a.png

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2 hours ago, knocker said:

And right on cue the ecm interrupts eastward movement of the Canadian trough as the subtropical high in mid Atlantic amplifies again. This the UK remains unsettled but for different reasons

ecmwf-deterministic-natl_wide-z300_speed-8118400.thumb.png.f309ae84eb219fcafbd6182ffb6a61b3.pngecmwf-deterministic-natl_wide-z500_anom-8118400.thumb.png.46db493f63a2da97f1eee57e1ec1081c.png

132.thumb.png.22e976462267568f3bd7d678786c2bfa.png156.thumb.png.22ab03a9bfa79501cacda6dbcd0df232.png180.thumb.png.4064dfe5855ab805619f3b09216be701.png

MMM, bit like chalk and cheese between the two of them with their surface analysis each day!

Not surprising when you look at their 500 mb charts

And their 500 mb anomaly charts this morning for comparison

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

 

Edited by johnholmes
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13 minutes ago, johnholmes said:

MMM, bit like chalk and cheese between the two of them with their surface analysis each day!

Not surprising when you look at their 500 mb charts

And their 500 mb anomaly charts this morning for comparison

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

 

And the difference is quite marked by t132 at the 500mb level as you will have noticed

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ecmwf-deterministic-uk-t2m_c_max6-7664800.thumb.png.e8e7f3dd71e6c9c70e3b4317dfb9f332.png14.thumb.gif.65bc55649358f35d2041fb704720a85f.gifsat.thumb.JPG.c846da2b7eb29c165c35735d821268ed.JPG

Some surface heating and a super adiabat on the Hurstmoceux sounding but probably not the best location

2020042312.03882.skewt_parc.thumb.gif.50c0a849d2f71e45ce0c32e02460a482.gif

Edited by knocker
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1 hour ago, knocker said:

ecmwf-deterministic-uk-t2m_c_max6-7664800.thumb.png.e8e7f3dd71e6c9c70e3b4317dfb9f332.png14.thumb.gif.65bc55649358f35d2041fb704720a85f.gifsat.thumb.JPG.c846da2b7eb29c165c35735d821268ed.JPG

Some surface heating and a super adiabat on the Hurstmoceux sounding but probably not the best location

2020042312.03882.skewt_parc.thumb.gif.50c0a849d2f71e45ce0c32e02460a482.gif

so descending air has caused a warming?

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3 minutes ago, mushymanrob said:

so descending air has caused a warming?

Not really m, the skew-t k shows is not a ridge of high pressure type ascent, see the Fax chart link below, a sort of flabby trough really. The super adiabatic can sometimes develop when air is fairly stagnant, usually with high pressure aiding this as you commented re descending air. With high insolation levels, slack winds then a super adiabatic can develop in the bottom 15 -20 mb. It is this which forecasters, in the old days, would use to suggest a maximum higher than might otherwise be worked out on the upper air ascent.

Hope that makes sense?

 

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1 hour ago, johnholmes said:

Not really m, the skew-t k shows is not a ridge of high pressure type ascent, see the Fax chart link below, a sort of flabby trough really. The super adiabatic can sometimes develop when air is fairly stagnant, usually with high pressure aiding this as you commented re descending air. With high insolation levels, slack winds then a super adiabatic can develop in the bottom 15 -20 mb. It is this which forecasters, in the old days, would use to suggest a maximum higher than might otherwise be worked out on the upper air ascent.

Hope that makes sense?

 

Thanks john, it helps to a degree, but atm i dont really understand fully the skew-t charts. Ill have to find an explanitory vid on youtube 

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There were major differences between the gfs and ecm this morning post t120 so it will be interesting to see how they go this evening. Although the gfs output is obviously different in detail essentially it follows the same route of ejecting a trough from the tpv lobe northern Canada and tracking it across the Atlantic

gfs-deterministic-natl_wide-vort500_z500-8075200.thumb.png.f8fa2bda1c0627179947dcdabc684013.pnggfs-deterministic-natl_wide-vort500_z500-8161600.thumb.png.099e76d428cb1631728cd7e1151accda.pnggfs-deterministic-natl_wide-vort500_z500-8248000.thumb.png.acb2f78bdb94622e2acc2655eaa72cd0.png168.thumb.png.44038e863a06863e1e60fcd9a4fe95eb.png

Edited by knocker
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The ecm for 1200 Weds on the 00 and 12 runs. From which you may correctly gather it has moved towards the gfs

ecmwf-deterministic-natl_wide-z500_anom-8161600.thumb.png.337713db2cf11cf71cd89dc5574fc309.png144.thumb.png.c72c13bcd460a354f0d11cc65c806249.png

 

Edited by knocker
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6 hours ago, knocker said:

 

Some surface heating and a super adiabat on the Hurstmonceux sounding but probably not the best location

2020042312.03882.skewt_parc.thumb.gif.50c0a849d2f71e45ce0c32e02460a482.gif

Interesting that Hurstmonceux had the max SYNOP temps at 24.3C. And just how tricky this can as Northolt had 24.2C and just down the road Larkhill 22.3C

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Another warm day today as the country resides under a slack pressure gradient but still with an onshore drift so cooler along eastern coastal regions, perhaps with some patchy Stratus, and more cloud in the north as a weak front tracks south down the North Sea

PPVE89.thumb.gif.5e64657d888a9559821689a5fd644a23.gifgfs-deterministic-uk-t2m_c_max6-7751200.thumb.png.fa88d22100c9d93690c30265a9eaaedc.png

Some showers may occur in the south west late afternoon and through the evening courtesy of a trough moving up in the Channel, otherwise a clear night apart from Stratus drifting further inland in the eastern region. But as can be seen the weak trough over Iceland, mentioned in previous posts, has entered the scene

gfs-deterministic-natl_wide-z500_anom-7772800.thumb.png.cac6f730eb0ff7ac22fe0c4523f68423.pngPPVG89.thumb.gif.86b0bf54e2d444460caa0d84c0c38ca4.gif

The Stratus will drift back to the coast through Saturday morning leaving another warm and sunny day for most with perhaps the odd shower popping up in the west

PPVI89.thumb.gif.0b0054ecd55a8e9416e609d44d1e607d.gifgfs-deterministic-uk-t2m_c_max6-7837600.thumb.png.3a1901127e4d556f99ab97ab897e778e.png

By Sunday the aforementioned trough has phased with the tpv lobe to the NE and the associated cold front has introduced cooler air to the north whilst remaining warm in the south where showers could effect many areas under the slack low pressure. To the west another trough has tracked into the Atlantic putting a 'squeeze' on the ridge

gfs-deterministic-natl_wide-z500_anom-7924000.thumb.png.db14e611ad74a566a23da155500306dc.pngPPVK89.thumb.gif.95d73e346ceb48ca534cd5a27b0c0b49.gifgfs-deterministic-uk-t2m_c_max6-7924000.thumb.png.2ca926824b549c056d9d47b79e6ff37d.png

This evolution continues on Monday resulting in a cloudy day with some rain in the north

gfs-deterministic-natl_wide-z500_anom-7988800.thumb.png.b6df3823bd7b8508cd90dc4554f52c4f.pngPPVM89.thumb.gif.0bf7e22df213bd06ed160912817381e7.gif

gfs-deterministic-uk-precip_6hr_inch-8010400.thumb.png.991c76bb9d6b076818fe7ffbd5834204.pnggfs-deterministic-uk-t2m_c_max6-8010400.thumb.png.51ee2d83ff76d51189015ef6875f2eb6.png

By Tuesday there is a cut off high cell over Iceland as the Atlantic trough merges with the positive tilted one aligned the UK > Scandinavia, and thus another say of sunny intervals and showers with some longer periods of rain

gfs-deterministic-natl_wide-z500_anom-8075200.thumb.png.92df4e1149391565d1ca660d020e3fd2.pngPPVO89.thumb.gif.1fc9b8f374df7e6fcd7c802362e6a0d4.gifgfs-deterministic-uk-t2m_c_max6-8096800.thumb.png.22ae5770a233cdf9747931f0bf017ead.png

 

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The detail for next week is tricky so caution recommended but according to the gfs this morning the phasing of the troughs mentioned above has, for a time at least, opened the door to the Atlantic and the twin energy flows northern Canada and the eastern seaboard, particularly the latter. Which results in the main feature for the rest of next week being low pressure in the eastern Atlantic and thus unsettled weather

gfs-deterministic-natl_wide-z300_speed-8161600.thumb.png.f3edcdc347d3e9a21c8c33e91c2a2684.pnggfs-deterministic-natl_wide-z300_speed-8248000.thumb.png.dc439a9847aacfb8cd3dca832e564156.pnggfs-deterministic-natl_wide-z500_anom-8248000.thumb.png.170517612056f914dc37fec331b5f89e.png

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Edited by knocker
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