Model Output Discussion 30/06/2012

[Cecil Hogmanay Melchett]

Something of a switch around this morning on the 00 runs . GFS is now being pretty bullish about a much cooler, more unsettled breakdown from the north as early as T+168hrs, whilst ECM which was singing from a similar hymnsheet this time yesterday now maintains relatively high pressure, with the more unsettled stuff heading into S Scandinavia. That said the trend does now look set for this type of evolution, the main questions being can we keep the rubbish far enough east to allow another quick rebuild of pressure, or will this signal the start of significant retrogression and the return of cooler, generally unsettled (tho nowhere near as unsettled as of late) conditions? Personally I still feel the latter is more likely.

interesting,why do you think retrogression is more likely?

iv'e yet to see it in the models?

[shedhead]

interesting,why do you think retrogression is more likely?

iv'e yet to see it in the models?

I've seen no evidence on the 500mb charts that the main trough can build and maintain itself to our east, plus a strong gut feeling born out of seeing plenty of other similar situations in the past.

[chionomaniac]

I've seen no evidence on the 500mb charts that the main trough can build and maintain itself to our east, plus a strong gut feeling born out of seeing plenty of other similar situations in the past.

With due respect MR Shed, this is the model output discussion - not the gut feeling discussion!

[phil nw.]

Just flicking quickly through the 00z runs does suggesst a less straightforward week ahead for Summery conditions.

It looks like Saturday and Sunday will be quite sunny and warm under the ridge before the cloud and rain moves in to the far North West later on Sunday.

As this spreads slowly South and East early next week the high pulls back into the Atlantic leaving mamy parts prone to some cloud and perhaps the odd shower here and there as the front meanders across England and Wales as it gradualy fades.

We really need to see that Jet further north for more sustained fine weather than where it`s currently modelled.

The above is the GFS mean position at T96hrs.

Still a much better week to come and i doubt there will be much rain away from the North West

The London Ens looks quite dry.

So at the moment not a bad looking week for many -warmer and brighter just not wall to wall sunshine- as it currently stands.

[PubliusEnigma]

Some lovely mid summer warmth monday and tuesday, before a northerly flow begins to take shape with temps dropping back to the low twenties. The models generally seem to be firming up on the high pressure establishing itself to our west or north west. The plus points mean no torrential rain is likely in the next week or so as any fronts coming south are squeezed so to speak and more likely to be cloudy affairs, although some rain in the south midweek is likely before the northerly drift reasserts itself to push the rain away south and south east. Then its really a matter of chasing the holes in the cloud. The nights generally under this set up tend to be clearer and cooler with low temps, and mornings often start sunny with cumulus spreading out rapidly to create a cover of stratocumulus. Generally light winds away from any troughs moving south during the week. Of course if later runs bring the high closer or directly over us. The fronts will transfer east. the General rule this week is Ireland, SW will see the most sun, the north, North east, east and south east, will see

the majority of any cloud or rain,

[PubliusEnigma]

Just flicking quickly through the 00z runs does suggesst a less straightforward week ahead for Summery conditions.

It looks like Saturday and Sunday will be quite sunny and warm under the ridge before the cloud and rain moves in to the far North West later on Sunday.

As this spreads slowly South and East early next week the high pulls back into the Atlantic leaving mamy parts prone to some cloud and perhaps the odd shower here and there as the front meanders across England and Wales as it gradualy fades.

We really need to see that Jet further north for more sustained fine weather than where it`s currently modelled.

The above is the GFS mean position at T96hrs.

Still a much better week to come and i doubt there will be much rain away from the North West

The London Ens looks quite dry.

So at the moment not a bad looking week for many -warmer and brighter just not wall to wall sunshine- as it currently stands.

I think this is why the MO keep reasserting the fact that no hot summery weather is on the cards. It will be a notch up on the dire summer we have had so far,

back to nearer the variable normal summer weather. One thing which is highly unlikely is a plume of heat from the south..

[Summer Sun]

Hopefully GFS 00z has gone off on one ECM looks better than GFS this morning for keeping high pressure closer to the UK

[PubliusEnigma]

Hopefully GFS 00z has gone off on one ECM looks better than GFS this morning for keeping high pressure closer to the UK

An unsettled end to next week Thurs & Fri if this verifies.. with the UK summer trough re-establishing itself over the UK.

[johnholmes]

I have to confess to having less confidence this morning than for the past few days in my idea of 40% and 60% that I have quoted over the last day or two.

It might fit what I see this morning if I reveresed the values?

The 500mb anomaly charts have looked fairly solid and reliable over the past week or so. First showing the predicted change from the deep trough close by the Uk to a more westerly type of 500mb flow. Latterly showing a build of heights west of the UK tending to edge closer to the UK with any trough well east of the country (15 or so east). This morning the ECMWF version has some changes but not that significant other than suggesting a cut off low to develop off Iberia. It had hinted at this before and NOAA showed something similar last evening. The main problem, other than the slight changes in ECMWF is the GFS version. This has developed a marked trough covering much of the UK and France! It MAY be it is trying to show an evolution similar to that from ECMWF(see above in my post), I don't know. The fact that they both show differing evolutions does make me very wary of showing much confidence this morning. If it still shows something similar tomorrow then I would feel something is changing in the westerly pattern with the +ve height rises. If it has disappeared then it could just be a one off that does occur with these charts now and then. Equally if the NOAA output this evening suggests something similar then the outlook becomes very uncertain for the end of the month and into early August.

Is'nt it fun model watching no matter which one you choose?

Edited July 20, 2012 by johnholmes

[PubliusEnigma]

Next weekend could be very wet in the south again according to the GFS 00z Great start to the Olympics.. not !!

Cool Britannia :o

Edited July 20, 2012 by PubliusEnigma

[johnholmes]

below is a quick pdf showing the last few runs of GFS for Saturday week-is the 00z today likely to happen?

Saturday week-the weather-20 July 12.pdf

[Summer Sun]

An unsettled end to next week Thurs & Fri if this verifies.. with the UK summer trough re-establishing itself over the UK.

ECM is much better at 168h

[Summer Sun]

Next weekend could be very wet in the south again according to the GFS 00z Great start to the Olympics.. not !!

Again you need to look at ECM before you comment

[chionomaniac]

I have to confess to having less confidence this morning than for the past few days in my idea of 40% and 60% that I have quoted over the last day or two.

It might fit what I see this morning if I reveresed the values?

The 500mb anomaly charts have looked fairly solid and reliable over the past week or so. First showing the predicted change from the deep trough close by the Uk to a more westerly type of 500mb flow. Latterly showing a build of heights west of the UK tending to edge closer to the UK with any trough well east of the country (15 or so east). This morning the ECMWF version has some changes but not that significant other than suggesting a cut off low to develop off Iberia. It had hinted at this before and NOAA showed something similar last evening. The main problem, other than the slight changes in ECMWF is the GFS version. This has developed a marked trough covering much of the UK and France! It MAY be it is trying to show an evolution similar to that from ECMWF(see above in my post), I don't know. The fact that they both show differing evolutions does make me very wary of showing much confidence this morning. If it still shows something similar tomorrow then I would feel something is changing in the westerly pattern with the +ve height rises. If it has disappeared then it could just be a one off that does occur with these charts now and then. Equally if the NOAA output this evening suggests something similar then the outlook becomes very uncertain for the end of the month and into early August.

Is'nt it fun model watching no matter which one you choose?

John the 0z GFS is a marked precipitation outlier for later next week. It doesn't mean that it is wrong, but I certainly wouldn't bet on it being right.

Edit again. Just seen your PDF!!!

Edited July 20, 2012 by chionomaniac
Missed out one very important word!

[Stuart]

Gfs Gone off on this becuse it have litte support from the rest of the Models

Edited July 20, 2012 by Stuart

[johnholmes]

John the 0z GFS is a marked precipitation outlier for later next week. It doesn't mean that it is wrong, but I certainly wouldn't bet on it being right.

yes I saw that as I was typing my query on it!

I don't believe it chio which is why I did the pdf post showing the last 4 or 5 00 and 12z runs from it. What does concern me beyond that is the GFS 500mb anomaly chart. It could well be a one off but it MIGHT just not be

[bluearmy]

too much analysis of a rogue op run this morning. the block may well retrogress a little further than the models have been showing and allow more of an input from the scandi trough (temporarily) but not to that extent. the questionable period where troughing is modelled to move in is the period at the beginning of august.

[NorthNorfolkWeather]

below is a quick pdf showing the last few runs of GFS for Saturday week-is the 00z today likely to happen?

Saturday week-the weather-20 July 12.pdf

That is quite a difference between the different runs, I hope the 00 doesn't verify. In the shorter term we look mostly OK to mid week, only the speed that front comes south to worry about on Tuesday

[Glacier Point]

too much analysis of a rogue op run this morning. the block may well retrogress a little further than the models have been showing and allow more of an input from the scandi trough (temporarily) but not to that extent. the questionable period where troughing is modelled to move in is the period at the beginning of august.

Quite.

Taking the ECM mean position of the upstream ridge over the western US and troughing into NE Canada, allied to the lowering of heights to the north, the only conceivable position for our mean ridge is just to the west or very close to the UK. Trough safely to the east. That's not suggesting major heatwave, and becoming fresher later next week with an absence of a southerly flow thereafter.

With the broad drift of the GWO / MJO heading towards a phase 3 type pattern (noticeably GFS suite is the only one to indicate a move back of the MJO to phase 1), that should lock down our general wavelength pattern across the northern hemisphere.

The pattern change has occured and I would suggest the chances of any return of our early summer mean trough (and all that entailed) are becoming increasingly distant.

[nick sussex]

I think for the timebeing its best to dismiss the GFS 00hrs operational run as being just one of those blips.

Looking at the ECM ensemble maps at 168hrs, there is limited support for troughing developing over the UK at that time. More likely there will be a weakish feature running around the top and in towards southern Scandi.

http://www.ecmwf.int/samples/d/inspect/catalog/samplers/banner/mean_sea_level_pressure_and_temperature_at_850hpa!168!pop!od!enfo!enplot!2009112700!!/

If you look at the morning discussions from NOAA a few key points stand out:

RECOMMEND BEGINNING DAY

3 WITH A 50/50 BLEND OF THE OOZ GFS/ECMWF BEFORE ABANDONING THE

GFS BY DAY 6/THU IN FAVOR OF EITHER THE GEFS MEAN OR ECMWF

ENSEMBLE MEAN. THIS APPROACH IS ALSO PREFERRED ACROSS THE

NORTHWEST AS ANOTHER CUTOFF LOW ATTEMPTS TO SETTLE OVER THE

REGION. OVERALL...CONFIDENCE IS ABOVE AVERAGE DAY 3...AVERAGE

DAYS 4/5...AND BELOW AVERAGE DAYS 6/7...WITH THE MODEL PREFERENCES

WELL SUPPORTED BY TELECONNECTIONS USING A STRONG POSITIVE

MID-LEVEL HEIGHT ANOMALY EAST OF GREENLAND.

The key here is where the positive anomaly is expected to set up, so hopefully we should see the GFS edge back more towards the ECM over the next few runs.

[Summer Sun]

ECMWF ensemble run also fails to support the GFS idea of sending low pressure our way around 168h

Anyway the 06z is on its way out now will it move closer to ECM's run or will we have to wait to later on? only time will tell

[shedhead]

I think for the timebeing its best to dismiss the GFS 00hrs operational run as being just one of those blips.

Looking at the ECM ensemble maps at 168hrs, there is limited support for troughing developing over the UK at that time. More likely there will be a weakish feature running around the top and in towards southern Scandi.

http://www.ecmwf.int...t!2009112700!!/

If you look at the morning discussions from NOAA a few key points stand out:

RECOMMEND BEGINNING DAY

3 WITH A 50/50 BLEND OF THE OOZ GFS/ECMWF BEFORE ABANDONING THE

GFS BY DAY 6/THU IN FAVOR OF EITHER THE GEFS MEAN OR ECMWF

ENSEMBLE MEAN. THIS APPROACH IS ALSO PREFERRED ACROSS THE

NORTHWEST AS ANOTHER CUTOFF LOW ATTEMPTS TO SETTLE OVER THE

REGION. OVERALL...CONFIDENCE IS ABOVE AVERAGE DAY 3...AVERAGE

DAYS 4/5...AND BELOW AVERAGE DAYS 6/7...WITH THE MODEL PREFERENCES

WELL SUPPORTED BY TELECONNECTIONS USING A STRONG POSITIVE

MID-LEVEL HEIGHT ANOMALY EAST OF GREENLAND.

The key here is where the positive anomaly is expected to set up, so hopefully we should see the GFS edge back more towards the ECM over the next few runs.

Well if that is the case Nick, then the 06 seems to be blipping too.

[johnholmes]

Quite.

Taking the ECM mean position of the upstream ridge over the western US and troughing into NE Canada, allied to the lowering of heights to the north, the only conceivable position for our mean ridge is just to the west or very close to the UK. Trough safely to the east. That's not suggesting major heatwave, and becoming fresher later next week with an absence of a southerly flow thereafter.

With the broad drift of the GWO / MJO heading towards a phase 3 type pattern (noticeably GFS suite is the only one to indicate a move back of the MJO to phase 1), that should lock down our general wavelength pattern across the northern hemisphere.

The pattern change has occured and I would suggest the chances of any return of our early summer mean trough (and all that entailed) are becoming increasingly distant.

I agree with all your above points Stewart and the final para is spot on in my view other than the odd niggle from the GFS 500mb output this morning. I do suspect its a one off but would want to see NOAA this evening and then the ECMWF-GFS output tomorrow showing the overall pattern all 3 have shown for over a week. Certainly the 500mb charts gave pretty good guidance of the change in upper air pattern.

[nick sussex]

Well if that is the case Nick, then the 06 seems to be blipping too.

I'm surprised its still showing the same theme on its 06hrs run, but it is the GFS which as we've seen in the past can continue to go off on its merry way right upto T-96hrs.

I think we' will see a weakish disturbance running around the high towards Scandi but can't see this low running south through western parts, anyway we'll see this evening.

[johnholmes]

Well if that is the case Nick, then the 06 seems to be blipping too.

If you look at the last 10 outputs from GFS, 00, 06, 12 and 18, the last 2 are the only ones that suggest anything other than settled in the south which is why I put up the pdf earlier.

Two runs do not make a certainty at all.

if its still showing similar by this time tomorrow then it does change things more towards the 00, 06 idea.