Model output discussion-mid Autumn and beyond

[BlueHedgehog074]

Indeed! The models continue to go for a generally dry day on Christmas Day.

The 06Z GFS, 00Z ECMWF, 00Z UKMO and 00Z GEM (in that order below), show High Pressure rock and rolling over, and to the South East of, the U.K on that day (96 hours):

[knocker]

Not surprisingly the ecm has high pressure in charge post Boxing Day but a front associated with a low in the Denmark straits does push east on Friday bringing some patchy rain to western regions as it fizzles out courtesy of the high pressure.

meanwhile the next trough deconstructs under renewed amplification of the high pressure but there is still a lot of energy exiting the eastern seaboard

[knocker]

The EPS has gone off piste this evening and disagrees quite markedly with NOAA and GEFS in the ext range, In particularly vis the amplification in the Atlantic with the EPS being much flatter than the other two and thus we have a declining ridge over the UK. This is a trend that the EC46 was indicating. Of course great caution is also indicated given possible developments via the Strat.

[northwestsnow]

2 minutes ago, knocker said:

The EPS has gone off piste this evening and disagrees quite markedly with NOAA and GEFS in the ext range, In particularly vis the amplification in the Atlantic with the EPS being much flatter than the other two and thus we have a declining ridge over the UK. This is a trend that the EC46 was indicating. Of course great caution is also indicated given possible developments via the Strat.

Looks to be energy going under that block to me

Edited December 21, 2018 by northwestsnow

[knocker]

4 minutes ago, northwestsnow said:

Looks to be energy going under that block to me

I'm afraid youv'e lost me as I don't see any block

[Rocheydub]

1 minute ago, knocker said:

I'm afraid youv'e lost me as I don't see any block

Alas, some just see what they want to knocker.

[northwestsnow]

1 minute ago, knocker said:

I'm afraid youv'e lost me as I don't see any block

High anticyclone block , i thought they meant the same thing ?

OK,, looks like energy going under the high..

[northwestsnow]

Looks like theres only me who thinks the ext eps look decent ..

Oh well, you live and learn,..

(Toddles off back to the mad house)..

[knocker]

Just now, northwestsnow said:

High anticyclone block , i thought they meant the same thing ?

OK,, looks like energy going under the high..

Actually I wasn't being pedantic but my original comment was because, imo, the ridge is much weaker than previously and there is quite a strong westerly upper flow over the UK.

[northwestsnow]

Just now, knocker said:

Actually I wasn't being pedantic but my original comment was because, imo, the ridge is much weaker than previously and there is quite a strong westerly upper flow over the UK.

I dont dispute the flow Knocks, i'm of the opinion there is scope for retrogression of the high-

[bluearmy]

There are some discrepancies between WeatherBell and weathermodels on their 5 day charts. I think I’m going to wait till the 00z run before making any changes to my thoughts (maybe the clusters will return to assist) 

Edited December 21, 2018 by bluearmy

[knocker]

15 minutes ago, bluearmy said:

There are some discrepancies between WeatherBell and weathermodels on their 5 day charts. I think I’m going to wait till the 00z run before making any changes to my thoughts (maybe the clusters will return to assist) 

I hadn't looked at WeatherBell but I did notice the ridge fell away quite quickly at the end in Weathermodels. Certainly the former is nearer NOAA and GEFS. As you say best left for the moment

Edited December 21, 2018 by knocker

[phil nw.]

Just for comparison day 15 from gefs/geps 

The UK ridging is still there but what energy there is- as the Atlantic jet is looking quite weak- is over the top with that mean westerly flow.

 

Edited December 21, 2018 by phil nw.

[feb1991blizzard]

16 minutes ago, phil nw. said:

Just for comparison day 15 from gefs/geps 

The UK ridging is still there but what energy there is- as the Atlantic jet is looking quite weak- is over the top with that mean westerly flow.

 

looks to me like the GEFS are on there own with a bit more amplification.

[knocker]

10 minutes ago, feb1991blizzard said:

looks to me like the GEFS are on there own with a bit more amplification.

NOAA IS very amplified

[bluearmy]

3 minutes ago, knocker said:

NOAA IS very amplified

As you mentioned earlier , the big drop away in the upper ridge is at the back end of the 12z eps and NOAA cpc never incorporates same day 12z eps data. 

The eps 12z have lower anomolys at both ends of the scale in the extended period .....it could be some very different clusters affecting the mean output 

[feb1991blizzard]

5 minutes ago, knocker said:

NOAA IS very amplified

Yes true, although don't forget that could be skewed by around days 8-9 being a little bit amplified on say just for arguments sake, the GFS op, so they might think that it will be amplified (albeit slightly) around 8-9 and then flattened again in deep FI.

[knocker]

The story from the gfs this morning for the rest of the period post Xmas until the beginning of next week is simple. The UK remaining under the influence of the high cell generally centred just to the south or south east. Thus generally dry, quite cloudy, and temps a tad above average. Just possible that the odd weak system slipping around the high with bring some patchy rain/drizzle to the far north.

[knocker]

Looks like the end of the EPS last night was a tad fishy as the ridge is still solid this morning out to the end

meanwhile the high cell in charge in the ten day time frame with temps a tad above average but later western and central Europe slipping a tad below whilst the NW stays above.

Possible indications of less energy exiting the eastern seaboard resulting in some slight adjustment of the ridge/trough alignment?

Edited December 22, 2018 by knocker

[knocker]

Not surprisingly the full quota of clusters in the ext EPS this morning but a resealable signal for the ridge/high cell staying in the vicinity of the UK albeit getting a tad more problematic by the end.

[knocker]

A nice example of the fluidity within the pattern as it resets with the high reoriented into a new position. During this process a front accompanied by rain/drizzle traverses the country on Saturday

[knocker]

And the wrap around at the end of the ecm run. Will the energy to the west relax enough to facilitate further incursions from the east?

Edited December 22, 2018 by knocker

[knocker]

No significant change with the ext EPS anomaly this evening; perhaps a slight relaxation of the ridge in situ by the end.

[knocker]

At 1200 Friday the ecm has a front just to the west of Ireland on which a small wave has formed, This develops and moves across southern Ireland overnight Friday bringing some rain to western parts, particularly the south west, through saturday morning before moving south again into Biscay. From then until the end of the run high pressure in charge with a few chilly mornings with widespread frosts

At the end of the run there is some renewed amplification over eastern North America and the western Atlantic resulting in the intensification of the high cell over the UK.

 

Edited December 23, 2018 by knocker

[knocker]

Some signs of the high pressure losing some intensity and slipping a  tad west which allows the European trough to do similar on the ext EPS. Temps a little below average although there is no particularly cold air over Europe

Edited December 23, 2018 by knocker