Winter viewpoint 2018 /19 NH PATTERNS

[cheeky_monkey]

On 19/11/2018 at 13:34, Steve Murr said:

 

Overall pressure anomaly locations for Winter 18-

 

 

 

 

Interesting that all the big hitters over this side of the pond are going for a very negative pressure anomaly over Alaska with a southerly jet running across the southern states and then swinging NE up the east coast..yours shows pretty much the opposite.

[Cheshire Freeze]

26 minutes ago, cheeky_monkey said:

Interesting that all the big hitters over this side of the pond are going for a very negative pressure anomaly over Alaska with a southerly jet running across the southern states and then swinging NE up the east coast..yours shows pretty much the opposite.

Steve's forecast actually looks like this guy's forecast (no idea who he is but some American forecaster apparently)

https://www.33andrain.com/topic/1490-isotherm’s-winter-outlook-2018-19/

Which in turn looks a lot like the GLOSEA output on its latest update.

[Froze were the Days]

4 minutes ago, CreweCold said:

Steve's forecast actually looks like this guy's forecast (no idea who he is but some American forecaster apparently)

https://www.33andrain.com/topic/1490-isotherm’s-winter-outlook-2018-19/

Which in turn looks a lot like the GLOSEA output on its latest update.

Directweather (I think) as I've seen him make one also very similar...always posting on YouTube and yes he is American, posted to him a few weeks back and reckons we're going to have a very cold winter.

Edited November 21, 2018 by Froze were the Days

[SMU]

14 hours ago, cheeky_monkey said:

Interesting that all the big hitters over this side of the pond are going for a very negative pressure anomaly over Alaska with a southerly jet running across the southern states and then swinging NE up the east coast..yours shows pretty much the opposite.

Mine would be an -EPO pattern or a blended -EPO / +PNA pattern

The above blend is to the east coast what a WNAO / ENAO are for the UK

The sharper you amplify the pattern towards the EPO region the more central the trough digs in the states, the net fall out from that- similar to a WNAO is that it encourages a ridge to build in the SE -

So my forecast has taken the generic midpoint of the -EPO / +PNA blend which sends the storm track up the East coast keeping it cold- however if you pull that track back west more the ridge ive put to the SE will come along with it warming up states like SC / NC / Virginia - Maybe even up to NJ -

( The + PNA pattern encourages the deep negative alaskan pressure rather than the -EPO - however moreover its the depth of the positivity that will allign to the depth of 'negativity' to the west of the PNA block if it does happen )

I havent really looked at that forecast ( isotherm ) although I believe its a good thing there alligned- however from my perspective I had already set the tone way back in September ( & mid October ) with direct hits in terms of what the winter may look like -

Todays 10HPA zonals on the GFs beginning to take the plunge alligned to the key date 15th Dec

Cheers

s

Edited November 22, 2018 by Steve Murr

[WINTRY WALES]

Hey Steve

Hope your trip is going well! Based on recent output are you still happy with your forecast as when issued? Hoping nothing in any latest info has made you think differently?

Cheers

[SMU]

Yes mate no issues-

 

Day 8-10 pattern taking shape

[Spanish Dani]

Interesting forecast, for Spain they were saying unsettled winter was coming during September October time but now has changed to high pressure settling over Iberia for whole winter period.

[mountain shadow]

1 hour ago, Spanish Dani said:

Interesting forecast, for Spain they were saying unsettled winter was coming during September October time but now has changed to high pressure settling over Iberia for whole winter period.

That seems to reflect the recent Met Office update for December with Britain & Ireland expected to be around or above average for, where only very recently, below average temperatures were expected.

Still, the top boffins on here remain confident of colder weather taking hold as December progresses into January so it will definitely be interesting to see what actually occurs.

 

[Spanish Dani]

8 minutes ago, mountain shadow said:

That seems to reflect the recent Met Office update for December with Britain & Ireland expected to be around or above average for, where only very recently, below average temperatures were expected.

Still, the top boffins on here remain confident of colder weather taking hold as December progresses into January so it will definitely be interesting to see what actually occurs.

 

Im from Valladolid, they are expecting dry and warmer than normal throughout 

[mountain shadow]

7 minutes ago, Spanish Dani said:

Im from Valladolid, they are expecting dry and warmer than normal throughout 

For us in Britain and Ireland this does not bode well for a cold winter for us and indicates Iberian high pressure so winds from an West to East direction.

However, the Italian weather service appears to indicate low pressure in the Med for Winter. Seems to be a lot of mixed signals around.

[Spanish Dani]

1 minute ago, mountain shadow said:

For us in Britain and Ireland this does not bode well for a cold winter for us and indicates Iberian high pressure so winds from an West to East direction.

However, the Italian weather service appears to indicate low pressure in the Med for Winter. Seems to be a lot of mixed signals around.

Yes I think they are seeing positive NAO.

[Don]

4 hours ago, Spanish Dani said:

Im from Valladolid, they are expecting dry and warmer than normal throughout 

Is this from the Spanish weather service?

[Spanish Dani]

11 minutes ago, Don said:

Is this from the Spanish weather service?

Yes, well very local to where I'm from. They are normal very good, predicted the very dry winters of a few years ago and the very wet one (I think 09/10) ?

[Bristawl Si]

7 hours ago, Spanish Dani said:

Interesting forecast, for Spain they were saying unsettled winter was coming during September October time but now has changed to high pressure settling over Iberia for whole winter period.

Sounds fab. Off to Fuerteventura next Wednesday for one week. Hope the sunny, dry weather stays in the Canaries.

[Don]

4 hours ago, Spanish Dani said:

Yes, well very local to where I'm from. They are normal very good, predicted the very dry winters of a few years ago and the very wet one (I think 09/10) ?

Well, no disrespect to them but I hope they’re wrong this year, otherwise the UK is likely to experience a classic ‘stinker’ of a winter up there with the likes of 1988/89, 1997/98, 2006/07, 2013/14 and 2015/16!  The bugs will like it mind!

Edited November 28, 2018 by Don

[SMU]

Afternoon All - some statistical November analysis on the Arctic Oscillation- Nov 18 has now finished & the im just waiting on the final number which is will be around -1 AO  In terms of the Winter Forecast the data is very pleasing ( especially if we do break -1 AO ) The table below shows all months from 1950 AO - There are 12 Sub -1 Novs the least The 12 -1 Novembers were 1952, 1955, 1957, 1959, 1962, 1965, 1968, 1980, 1985, 1998, 2000, 2002 In terms of the following winters we have a 30/36 hit rate for -AO Months  These winter height anomalies are below A good match for the forecast underpinned by the December theme with lots of Euro troughing

Incidentally the best 3 Nino matches were 1952/1959/1980

 

Heres a final thought- If we take the daily AO data in terms of Depth of AO for final part of the month & compare with November 18 ( Sub -3.5 values we get )

Nov 62 , Nov 65, Nov 68, Nov 85, Nov 2010...

Thanks...

 

[Summer Sun]

November AO confirmed as -1.116

 

[SMU]

On 04/12/2018 at 14:30, Summer Sun said:

November AO confirmed as -1.116

 

Cheers mate

Very good news !

*Update very soon*

[damianslaw]

On 14/12/2018 at 20:31, Steve Murr said:

Cheers mate

Very good news !

*Update very soon*

Update very soon - always enjoy your posts, are you updating before christmas?

December is turning into a damp squib - hopefully January will make up for what could be a snow free month.

[mountain shadow]

Given that many of these D-J-F anomaly forecasts have been showing well above average upper height anomalies in our sector at high latitudes but we haven't really seen them in December, in order for these anomalies to come off I would expect that January and February would need to be off the scale in terms of their anomalies for these to come off.

We either see pretty amazing Northerly blocking in the remaining two Winter months of the year or some of these forecasts will be bust.

[SMU]

Merry Christmas - So now that the first portion of winter is over ( the worst bit ) we look forward to the main event for the next 9-11 weeks...

The forecast periods of stationary heavy rain & a record SSW look to be well founded however the proposed blocking hasnt appeared ... Yet...

We are on the cusp of a SSW which will trigger a chain of events that are set to change our fortunes this winter-

Lets look at the data from 1958-2012

There have been 36 technical warmings ( where the zonal wind has been reversed ) or these 50% have resulted in vortex displacement & equally 50% have been a split.

The most 'current' forecast suggests

- GFS 30/12 - ( ENSEMBLE MEAN)

- ECM 28/28/12 ( Operational )

Split or displacement ??  

After much uncertainty from the GFS & the ECM being robust the GFS is now fairly fixed on a split on the 1st Jan- ECM Slightly later around 2-3rd Jan.

Pretty solid agreement now. ECM + 06z OP/ 06z FV3 & 06z ENS Mean.

So returning to the most important element here the location of the split & the vortex lobe locations based on Historic analogues we can estimate what the blocking may be & the probably propergation time-

This is done by

- Grouping the historic splits before

- Reviewing the AO behaviour post split from the NOAA dataset.

Below are the 16 splits in DJF -

For me the most likely group to be associated with this split is 3,5 & 14

Which are

 23 Feb 1966

16 Jan 1971

17 Jan 2003 best match

For the groupings the dates above now have AO data applied-

23 Feb 1966- peak -AO (-3.5) was as a QTR with the 5 main days 16-21 Feb

16 Jan 71 -peak -AO (-2.8) non QTR was 5 main days 5-10 Feb

17 Jan 03 - peak -AO (-3.5) was a swift response within 5 days 19-24 Jan.

Blocking responses below.

m

What it shows 'generally' in a split where the lobes head into europe & across west into the states there is a troposheric response gravitating towards a strongly negative AO, & low heights extending to out South & East with polar blocking.

No SSW split will be identical but its the charactistics that are key-

The models now for around the 5th - 7th of Jan are alligning very low heights to our East & generally heigher heights to the west NW indicating based on the time of year & the depth of the PV that a Northerly airstream will be favoured to start...

Thanks

 

 

 

 

[damianslaw]

On 25/12/2018 at 14:14, Steve Murr said:

Merry Christmas - So now that the first portion of winter is over ( the worst bit ) we look forward to the main event for the next 9-11 weeks...

The forecast periods of stationary heavy rain & a record SSW look to be well founded however the proposed blocking hasnt appeared ... Yet...

We are on the cusp of a SSW which will trigger a chain of events that are set to change our fortunes this winter-

Lets look at the data from 1958-2012

There have been 36 technical warmings ( where the zonal wind has been reversed ) or these 50% have resulted in vortex displacement & equally 50% have been a split.

The most 'current' forecast suggests

- GFS 30/12 - ( ENSEMBLE MEAN)

- ECM 28/28/12 ( Operational )

Split or displacement ??  

After much uncertainty from the GFS & the ECM being robust the GFS is now fairly fixed on a split on the 1st Jan- ECM Slightly later around 2-3rd Jan.

Pretty solid agreement now. ECM + 06z OP/ 06z FV3 & 06z ENS Mean.

So returning to the most important element here the location of the split & the vortex lobe locations based on Historic analogues we can estimate what the blocking may be & the probably propergation time-

This is done by

- Grouping the historic splits before

- Reviewing the AO behaviour post split from the NOAA dataset.

Below are the 16 splits in DJF -

For me the most likely group to be associated with this split is 3,5 & 14

Which are

 23 Feb 1966

16 Jan 1971

17 Jan 2003 best match

For the groupings the dates above now have AO data applied-

23 Feb 1966- peak -AO (-3.5) was as a QTR with the 5 main days 16-21 Feb

16 Jan 71 -peak -AO (-2.8) non QTR was 5 main days 5-10 Feb

17 Jan 03 - peak -AO (-3.5) was a swift response within 5 days 19-24 Jan.

Blocking responses below.

m

What it shows 'generally' in a split where the lobes head into europe & across west into the states there is a troposheric response gravitating towards a strongly negative AO, & low heights extending to out South & East with polar blocking.

No SSW split will be identical but its the charactistics that are key-

The models now for around the 5th - 7th of Jan are alligning very low heights to our East & generally heigher heights to the west NW indicating based on the time of year & the depth of the PV that a Northerly airstream will be favoured to start...

Thanks

 

 

 

 

Good post - the models are indeed showing a trough forming to our east, but heights don't look like moving to the NW anytime soon, instead they seem to want to languish to the south into early January.

Would welcome your views on timings of expected effects - as these now look like coming later in January. Mind GFS is sniffing out a northerly, and I think there is a good chance the change will come via a northerly.

[Summer Sun]

On 28/11/2018 at 08:43, Spanish Dani said:

Interesting forecast, for Spain they were saying unsettled winter was coming during September October time but now has changed to high pressure settling over Iberia for whole winter period.

This is starting to look like a decent forecast from the Spanish with no sign of the high that's parked over western mainland Europe going anytime soon

 

[Ladyofthestorm]

Yes GFS is forecasting a Euroslug.

[mountain shadow]

13 minutes ago, Summer Sun said:

This is starting to look like a decent forecast from the Spanish with no sign of the high that's parked over western mainland Europe going anytime soon

 

I wonder what model they us? It just be better than EC46, Glosea etc.