Model output discussion - 20th Feb onwards

[knocker]

Hourly output. Blimey it'll be like a frenzied piranha attack in here in winter.

[stodge]

2 hours ago, knocker said:

I also don't think it looks that bad. Within the ten day period the upper low looks firmly anchored to the SW which as previously mentioned could portend a gamut of weather conditions ranging from pretty good convective activity in the south but with the odd longer periods of rain thrown in, But it could still feel quite warm in the sunny spells particularly towards the end of the period and overall temps around average.

It appears increasingly likely in the 10 -15 day period that the Greenland blocking will rapidly disappear with the trough to our SW retrogressing to mid Atlantic.leaving the UK in a south westerly upper flow so still remaining somewhat unsettled but temps picking up a little to possibly a little above average.

The low to the SW still dragging cooler air around into Spain.

The key though remains the possibility of the trough moving back NE and linking with the Scandinavian trough to re-enforce the troughing over the British Isles. GFS suggested this at 00Z and dropped it at 06Z and the Ensemble members aren't clear as yet. I'm slightly wary of the speed of the demise of the Greenland Block as shown on GFS low-res as it seems incredibly rapid. I think a west-based negative NAO scenario is possible with the trough close to or just to the west keeping the British Isles ina unsettled but mild SW flow but IF the Scandinavian trough comes down and gets into the mix, it could be a deep hole from us to escape.

[knocker]

16 minutes ago, stodge said:

The key though remains the possibility of the trough moving back NE and linking with the Scandinavian trough to re-enforce the troughing over the British Isles. GFS suggested this at 00Z and dropped it at 06Z and the Ensemble members aren't clear as yet. I'm slightly wary of the speed of the demise of the Greenland Block as shown on GFS low-res as it seems incredibly rapid. I think a west-based negative NAO scenario is possible with the trough close to or just to the west keeping the British Isles ina unsettled but mild SW flow but IF the Scandinavian trough comes down and gets into the mix, it could be a deep hole from us to escape.

I'm afraid I'm not following that although I'm not sure of your time span. I say that as I'm not aware of any Scandinavian trough. Going by the anomalies the only upper trough of significance is the one to our south west which both the EPS and EC32 have retrogressing after the 14th whilst quickly weakening the Greenland block. The GEFs also does this although not so rapidly. This would suggest a flow from the a westerly quadrant and slightly warmer temps. So I'm not sure why the trough should move NE.

[stodge]

38 minutes ago, knocker said:

I'm afraid I'm not following that although I'm not sure of your time span. I say that as I'm not aware of any Scandinavian trough. Going by the anomalies the only upper trough of significance is the one to our south west which both the EPS and EC32 have retrogressing after the 14th whilst quickly weakening the Greenland block. The GEFs also does this although not so rapidly. This would suggest a flow from the a westerly quadrant and slightly warmer temps. So I'm not sure why the trough should move NE.

I'm offering an alternative based on my interpretation of the output as much as dependence on the anomalies (after all we are looking quite a long way out).

This was the evolution where the LP to the SW effectively combines with the trough coming south to re-invigorate the trough over the British Isles. This evolution shows up in some of the 06Z Ensembles as well. I'm not convinced about the rapid decline in the Greenland block - my contention was it could develop into a west-based negative NAO set up but I'm not sure of that either,

[Paul]

4 hours ago, Paul said:

The upgraded GFS has gone into official parallel now, and is due to be live on 11th May. Quite a few upgrades in there, including hourly output up to 120 hours. 

Some info on the upgrade for those interested (quite a lot in there - technical too):

http://www.emc.ncep.noaa.gov/impdoc/GFS/CCBglobal2016.pdf

A few takeaways from it:

Hourly output to 120 hours.
Improved data assimilation
More/improved input from satellite data
Extra levels up in the strat - up to 1hpa
 

[Guest]

MY FINAL “WINTER” REPORT UPDATED WITH APRIL 5TH 2016 INPUT

Please note that most of the charts that I refer to in this post are through “live” links which update periodically. So, if you are reading this a few hours after publication, the charts may already have updated. My comments relate to what the charts showed at the time of this posting.

My Last Regular Report Until Winter 2016/17:

This is my final regular update for Winter 2015/16. I will sign off with a full report and a review. I include Dr Judah Cohen’s latest Arctic Oscillation report which was published late last night as well as all my regular features.

Review of Winter 2015/16:

The overwhelming majority who follow this model thread are “Winter Coldies”. Although we have seen three mild Winters in a row, 2015/16 has probably been the most frustrating of all. Last Autumn, many of the experts were telling us that, due to the strong El Nino, we would probably see a mild first half to the Winter but a rather colder second half. The Winter forecasts issued during November mostly re-enforced this general prediction. There would be a strong likelihood of a Sudden Stratospheric Warming (SSW) event towards the middle or end of January, impacting on the surface by early to mid-February. This would probably produce broad-scale pattern changes, a negative AO with HLB and cold incursions extending down to the mid-latitudes over many parts of the Northern Hemisphere.  

As we know, we witnessed the warmest December on record, a less warm but still mild January and a closer to average February. During the first half of January it looked like things were about to change. Indeed much of the country had a period of colder weather. Some lowland parts even had a half decent snowfall, including a swathe from north-west through to southern England. There were several severe frosts towards the end of that spell but for most it was over in about a week, even briefer in the south west and overall it was difficult to class it as a real cold spell. There were several more attempts at colder set-ups during February. The models kept teasing us with some juicy very wintry F1 charts. There were a number of occasions when the models struggled right up to T+72. On almost every occasion, the predicted cold and/or wintry weather was downgraded or did not materialise at all.

So what went wrong? Why all the uncertainty? Aren’t forecasts and models meant to be getting far more accurate? As we all know, or should know, there is nothing certain about our weather. The experts and the models are making huge advances with ever more accurate short to medium term forecasts but last Winter was particularly challenging throwing up many unusual or unprecedented events. The El Nino was close to, if not, a record breaker. It was basin wide and remained extremely strong right through the Winter, with only slight weakening in the eastern equatorial Pacific towards the end of February. The SSW did start in early February. It then abated and there were further warmings in late Febraury and again in mid-March. In fact, it has been a record breaker. There has been an extremely strong negative AO for the last 4 to 5 weeks. For some reason, this reversal failed to propagate down to the surface. There were several attempts and only now are the stratosphere and troposphere finally coupling with surface impacts just starting to show in the high Arctic (more on this below, in the next part of my report).. Early to mid-Spring SSW events have far less impact than mid to late Winter events.

It may well be that the El Nino was actually too powerful and somehow prevented or delayed the SSW impacting at the surface. There may be other factors. The record low Arctic sea ice extent (see later section) with record high Arctic Winter warmth – certainly on our side of the Arctic. Almost a record strength polar vortex keeping the cold locked up in the high Arctic for long periods. Then this shifting at times to spill the cold down into north-east Canada and eastern USA as well as east Asia. We even saw a January Atlantic hurricance – a once in 50 years (or longer) event!

With so many near “record” breaking events affecting the broader patterns, it is little wonder that the experts have been overwhelmed. My understanding of this science is very limited and I’ll leave it up to experts to unravel what has or did not happen. Computer models and programmes rely on analogue data. As we have experienced such an unusual or unique sequence of events, making comparisons must have been a nightmare. All we can say, is that a huge amount must have been learnt from the Winter 2015/16 experience and I would hope that this will increase the level of understanding and lead to improvements in the models.

Arctic Sea Ice News and Analysis:

I was hoping that the March detailed report would have been published by now but it has been delayed and is due out at any time this week. In my report last week, I commented on their Winter update which was published on March 28th. The link below still shows that report at the time of writing but it will automatically update to their latest monthly report when it is published. You can also view the Arctic ice link that Gibby provides as part of his excellent daily reports on this thread.

http://nsidc.org/arcticseaicenews/

This highlights the record low overall Arctic ice extent. It reached its maximum extent on March 24th which is 2 weeks later than usual. As it was a record low maximum extent, it is not unusual to see a very late recovery. I noted the recent much colder conditions in the Svalbard area (in my last few reports) and in the last 2 weeks the polar ice sheet has finally extended to Svalbard with the east of the islands now engulfed by ice. Although the east Baring Sea remains pretty ice free, the spread to Svalbard is a significant very recent change compared to the whole of the winter (and much of the previous two winters as well). It would probably make any high Arctic northerly outbreak colder than usual (for this time of year).

IMPORTANT UPDATE - the full Winter review has just been published this afternoon (Wednesday, April 6th 2016). The link above now leads directly to that report. It makes fascinating reading. A worrying further decline in the maximum ice extent. Let's hope that pressure patterns, winds and temperatures up there lead to a lower than normal Summer melt and we do not get another Winter dominated by a south-west to north-east jet powering right into the high Arctic east of Greenland. With La Nina conditions likely by Winter 2016/17, I believe that this normally favours greater early season Arctic ice sheet recovery. I shall study this relationship during this Summer and Autumn and include a summary of my findings (with links) in my first Winter 2016/17 report (due around early November 2016).

Dr Judah Cohen’s Latest Arctic Oscillation Report:

Judah Cohen has just updated his weekly AO report on April 4th 2016.

Update (on April 12th, 2016): The weekly report for April 11th has just been published and the link now shows this later analysis from Dr Cohen. This, more or less, mirrors the April 4th report and is in line with all the other indicators. Here is the link:

http://www.aer.com/science-research/climate-weather/arctic-oscillation

I now copy his (April 4th) “Summary” and “Impacts” directly from his report below (but you will need to use the link above for the April 11th report and if you wish to view all his charts, figures and diagrams):

…..”Summary

The Arctic Oscillation (AO) is currently neutral but is predicted to trend first briefly positive and then strongly negative.

The overall strong negative AO trend is reflective of predictions of positive pressure/geopotential height anomalies over the Arctic basin and negative pressure/geopotential height anomalies across the mid-latitudes especially in the North Atlantic sector.

The overall negative trend both in the AO and the North Atlantic Oscillation (NAO) will help to maintain below normal temperatures in eastern North America while temperatures will likely cool relative to normal across northern Eurasia, including Western Europe and East Asia.

The return to a negative AO atmospheric state is consistent with the sudden stratospheric warming (SSW) polar vortex (PV) split that occurred in March. 

The negative AO and related circulation anomalies are slowly propagating down from the stratosphere to the troposphere. These changes include an equatorward displaced Jet Stream and increased chances of cold air outbreaks across the mid-latitudes.

Typically, the negative tropospheric AO is favored for about four weeks following a PV weakening with a two-week lag.  Therefore, the negative AO and relatively cool temperatures in the eastern United States (US) and northern Eurasia are favored through mid to late April.

For the first time we have included precipitation forecast anomalies for the Northern Hemisphere (NH).  Negative AO/NAO favors an equatorward North Atlantic storm track and wet from the Eastern US to Western Europe.

Impacts

We have a text book case currently underway of the downward descent or propagation of the circulation anomalies from the stratosphere to the troposphere that resulted from a record weakening of the stratospheric PV back in March.  This downward propagation is often referred to as “dripping paint” and that description seems appropriate to describe the current coupling between the stratosphere and the troposphere.  The stratospheric PV weakening can be easily identified from the polar cap geopotential heights (PCH) plot with a strong rise or warming of the stratospheric PCH the entire month of March but which peaked during the third week.  Since then fingers or drips of those higher/warmer PCH have extended down into the troposphere.  The first finger or spoke occurred almost immediately after the peak in the PV weakening or split during the third week of March.  Another two weaker fingers occurred at the end of March and the other is current.  The current finger is resulting in a highly anomalous snowfall across the northeastern US and the even more rare subfreezing daytime temperatures in April.  However, the models are converging that the main downward descent will occur next week and continue into the third week of April.  This will contribute to a predicted strong negative trend in the AO and NAO next week and the AO persisting in negative territory for the following week.

With the AO currently neutral geopotential height anomalies are mixed both across the Arctic and the mid-latitudes. Geopotential heights are below normal near the North Pole with a strong trough of low pressure/negative geopotential height anomalies extending equatorward across eastern Canada and the Northeastern US.  The negative geopotential height anomalies coupled with northerly flow is resulting in well below normal temperatures along the East Coast of the US and especially eastern Canada.   Meanwhile positive geopotential height anomalies and warm temperatures dominate western North America.

Across Eurasia there are two troughs/areas of negative geopotential height anomalies.  The stronger of the two is centered on Eastern Europe and Western Asia.  The low geopotential heights and northerly flow is resulting in below normal temperatures to the region. The second is centered over Central Siberia with a trough/negative geopotential height anomalies extending southeastward to Northeastern China.  This trough is also resulting in below normal temperatures for Central Siberia. In contrast, ridging/positive geopotential height anomalies in Central Europe and in Central Asia are resulting in above normal temperatures for much of Northern and Central Europe and widespread warmth across Central Asia.

With the main downward descent of the negative stratospheric AO into the troposphere predicted to occur over the coming week, the tropospheric AO is predicted to turn strongly negative next week.  Therefore, many classical AO circulation anomalies are likely the second week and even into the third week of April.  These include positive geopotential height anomalies widespread across the Arctic but especially in the North Atlantic side of the Arctic.  And with the NAO also predicted to be strongly negative, strong Greenland blocking is predicted as well.  In contrast the mid-latitudes should be dominated by negative geopotential height anomalies.  The regions predicted to experience the largest negative departures are Western Europe and Northern Asia.  Also regions that typically experience below normal temperatures during negative AO regimes are also predicted over the coming weeks to experience below normal temperatures.  These regions include Southeastern Canada, the Eastern US, Western Europe, Siberia and East Asia.  Also the Jet Stream is predicted to be suppressed equatorward especially in the North Atlantic.  This is predicted to lead to a wet pattern in the North Atlantic sector including the eastern United States and Western Europe.

Recent and Very Near Term Conditions

Currently, the AO is neutral and is predicted to trend slightly positive for the remainder of the week (Figure 1).  The current neutral AO is reflective of mixed positive and negative geopotential height anomalies in the Arctic and across the mid-latitudes (Figure 2).

The main region of negative geopotential heights in the Arctic is an area of negative anomalies centered on the North Pole (Figure 2).  A trough of low pressure/negative geopotential height anomalies extend southward across eastern Canada and the Northeastern US.  Northerly flow extending from the North Pole into the Eastern US is bringing below normal temperatures for the East Coast of the US and especially Eastern Canada. In contrast western North America is dominated by ridging/positive geopotential height anomalies resulting in down sloping winds and warm temperatures.

The persistent troughing/area of negative geopotential height anomalies in the eastern North Atlantic and Western Europe persists this period (Figure 2) resulting in seasonable temperatures for Western Europe (Figure 3).  Southwesterly flow between the low pressure in the eastern North Atlantic and positive pressure/geopotential height anomalies centered on Central Europe (Figure 2) is resulting in a of mild flow of air across Central and Northern Europe and above normal temperatures (Figure 3).  Northerly flow between the Central European ridge and a closed low/negative geopotential height anomalies just west of the Urals is resulting in below normal temperatures for Eastern Europe and Western Asia (Figure 3).  Further downstream positive geopotential height anomalies stretching from Western Siberia southward across much of Central Asia and even into Southeast Asia (Figure 2) is resulting in above normal temperatures for Central and East Asia (Figure 3).  Finally a closed low/area of negative geopotential height anomalies in Central Siberia and extending southward to Northeastern China (Figure 2) is resulting in below normal temperatures for Central Siberia (Figure 3). 

1-2 week

The AO is predicted to turn strongly negative during the course of next week (Figure 1) as positive pressure/geopotential height anomalies consolidate across the Arctic with negative pressure/geopotential height anomalies spreading equatorward across eastern North America, Western Europe and Northern Asia (Figure 4a).

The largest predicted positive geopotential height anomaly across the NH is a positive anomaly centered over Greenland.  This is referred to as Greenland blocking and is a common feature of negative NAO regimes.  Greenland blocking strongly relates to or teleconnects with negative geopotential height anomalies over Western Europe (Figure 4a).  The models predict that the greatest negative geopotential height anomaly across the NH will be an area of low pressure centered near Ireland.  Negative geopotential height anomalies across Western Europe will result in below normal temperatures for Western Europe (Figure 5).  The persistent ridging/positive geopotential height anomalies over Central Europe is predicted to temporarily slide eastward this period into Eastern Europe and Western Asia (Figure 4a) resulting in above normal temperatures for the region (Figure 5).  Further downstream, an expansive area of below normal geopotential height anomalies is predicted to stretch from Western Siberia to the northwestern North Pacific (Figure 4a) resulting in below normal temperatures for much of Siberia with possible exception of far Eastern Siberia (Figure 5).  Northwesterly flow around the low pressure will start to filter the cold air in Siberia further south into East Asia (Figure 5).

Greenland blocking is also related to or teleconnects with negative geopotential height anomalies over Southeastern Canada and the Eastern US.  The models predict generally below normal geopotential height anomalies over the region with the greatest negative anomalies over Southeastern Canada (Figure 4a).  General northwesterly flow across Eastern Canada and the northeastern US (Figure 4a) is predicted to result in late season Arctic air to flow south into this region and below normal temperatures (Figure 5).  Persistent ridging and positive geopototential height anomalies are predicted to persist for Western Canada and Alaska maintaining mild temperatures for much of western North America including Alaska (Figure 5).

One predicted change this period for the Western US is more troughing, as energy from the Aleutian Low spins it sway towards the Southwestern US resulting in below normal geopotential height anomalies (Figure 4a).  With low pressure predicted for the region the models also predict a relatively wet period for the Western US (Figure 6).   With a strong negative NAO predicted for next week, the Jet Stream is predicted to be suppressed south across the North Atlantic bringing wet conditions to the Eastern US and Western Europe (Figure 6).  Similarly a suppressed Jet Stream across East Asia is predicted to result in wet conditions for Southeast Asia (Figure 6).

3-4 week

The AO is predicted to remain negative right into the third week of April (Figure 1) as positive pressure/geopotential height anomalies continue to dominate the Arctic with negative pressure/geopotential height anomalies spread across the mid-latitudes including the US, Western Europe and Northern Asia (Figure 4b).

The largest predicted positive geopotential height anomaly across the NH remains a positive anomaly centered near Greenland but shifted slightly west towards Hudson Bay as well (Figure 4b). As mentioned above, Greenland blocking strongly relates to or teleconnects with negative geopotential height anomalies over Western Europe (Figure 4b).  The models predict that the greatest negative geopotential height anomaly across the NH will again be an area of low pressure centered in the eastern North Atlantic west of Ireland.  Negative geopotential height anomalies across Western Europe will result in below normal temperatures for Western Europe (Figure 7).  The persistent ridging/positive geopotential height anomalies over Central Europe is predicted to return this period and extend into Eastern Europe and Western Asia as well (Figure 4b) resulting in above normal temperatures for the region (Figure 7).  Further downstream, below normal geopotential height anomalies is predicted to stretch from Western Siberia to East Asia (Figure 4b) resulting in below normal temperatures for much of Siberia with possible exception of far Eastern Siberia (Figure 7).  Northwesterly flow around the low pressure will likely continue to funnel the cold air in Siberia further south into East Asia (Figure 7).

Ridging/positive geopotential height anomalies are predicted for almost all of northern North America including Canada and Alaska (Figure 4b). Ridging for much of Canada and Alaska will result in above normal temperatures for Arctic North America.  Positive geopotential height anomalies are related to or teleconnects with negative geopotential height anomalies over the US, especially the Southern US.  If the AO and NAO remain firmly negative this continues to favor below normal temperatures for Southeastern Canada and the Eastern US (Figure 7).  Persistent ridging and positive geopototential height anomalies are predicted to persist for Western Canada and Alaska maintaining mild temperatures for much of western North America including Alaska (Figure 5). 

The models predict that the Western US troughing will persist this period resulting in another relatively wet period for the Western US (Figure 8).   The models have had a tendency to over predict wet conditions for the Southwestern US this winter and I feel that some skepticism is warranted for the wet pattern predicted for the Southwestern US this period and probably the previous period as well.  With a continued negative NAO favored for this period, the models predict the Jet Stream to remain suppressed south across the North Atlantic bringing wet conditions to the Eastern US and Western Europe (Figure 8).  Similarly a continued suppressed Jet Stream across East Asia is predicted to result in wet conditions for Southeast Asia (Figure 8). 

Longer Term - 30–day

As I have been writing for sometime now the longer-term prediction of the AO and the NH circulation and sensible weather will end as the late season troposphere-stratosphere-troposphere coupling event finally comes to an end.  For all of March the PV split/disruption has resulted in warm polar cap geopotential height anomalies (PCH) in the stratosphere (Figure 9) accompanied by a negative AO in the stratosphere.  Since the peak of the PV split/disruption the positive/warm PCHs have “dripped” sporadically into the troposphere leading to colder weather and snowfalls in the mid-latitudes. The models are growing more confident that the main descent of positive/warm PCHs will occur mid to late April.  A negative AO is favored in the troposphere four to even six weeks after the peak in the stratospheric negative AO, which occurred in mid-March.  Therefore predictability of a negative AO based on stratosphere-troposphere coupling is coming to an end in the next two weeks and certainly by the end of April beyond which longer term AO predictions are more difficult.    Also the relationship between the AO and the weather across the mid-latitudes is much weaker in summer and can even be opposite of that in winter…..”

My Brief Comments on Judah Cohen’s Latest Update:

After so many false dawns and delays, we are finally seeing the SSW and AO reversal propagating down through the troposphere and to the surface. Judah states that the colder regions will continue to be Eurasia and Eastern North America. He says that Western Europe was currently having more seasonal temperatures but with colder (and wetter) conditions steadily developing as the AO trends further negative during the next week. These conditions will persist until around the 3rd/4th week April.

Overall, Judah Cohen’s analysis is very much telling us what the models have just begun to show. Unfortunately, if anything, he and his model are predicting a longer delay to any Spring warmth than the models that we analyse on this thread are telling us. There is general agreement that the UK will remain on the cold side of the Jet Stream and a low pressure area setting up just to our west or south-west. He does mention that there may be a brief warmer incursion into western Europe. There may also be some “cold” snaps within the predominantly “colder” set-up. So, certainly April showers and some typical Spring variations but perhaps on a rather more extreme scale than normal!

AO Ensemble Charts: 

Right, now on to my usual indicators to see if there is more support for Judah’s predictions and their possible impacts.

http://www.cpc.ncep.noaa.gov/products/precip/CWlink/daily_ao_index/ao_index_ensm.shtml

This is completely in line with Judah Cohen’s recent predictions. The AO index is currently more or less neutral and set to go slightly positive for the next 2 to 3 days before trending very strongly negative by this weekend with all 11 ensemble members in agreement. 9 members remain negative for the remainder of the period, until April 16th. The other 2 go briefly positive around April 12th and again around April 16th.

 MJO Ensemble charts:

Here are today's MJO ensemble charts for the big 4 and Kyle MacRitchie’s for April 5th. 

UKMO: http://www.cpc.ncep.noaa.gov/products/precip/CWlink/MJO/CLIVAR/ukme.shtml

ECM:  http://www.cpc.ncep.noaa.gov/products/precip/CWlink/MJO/CLIVAR/ecmm.shtml

NCEP/GEFS: http://www.cpc.ncep.noaa.gov/products/precip/CWlink/MJO/CLIVAR/ncpe.shtml

JMA: http://www.cpc.ncep.noaa.gov/products/precip/CWlink/MJO/CLIVAR/jman.shtml

Kyle MacRitchie: (this old link is now closed xxx "http://www.kylemacritchie.com/real-time-maps/realtime-mjo/" xxx). Update April 8th: Please note that the previous link is no longer valid. Kyle MacRitchie has just re-vamped his entire website yesterday (April 7th).The new link to his MJO charts can now be found on:  http://weatherandvines.com/?page_id=140

Brief Summary of predictions:

UKMO:  Phase 2 to phase 3 today at low amplitude. Then slowly on to phase 4 during the next 8 to 10 days but at very low amplitude and partly into the circle of death.

ECM: Similar to UKMO today, entering phase 3, then diving into the circle of death for the remaining 2 weeks. Several ensemble members are shown in phases and 3 and 4 but at low amplitude.

NCEP/GEFS: As ECM initially but re-emerging from the COD around days 8 to 10 into phases 8 and 1 at quite low amplitude.

JMA:  As NCEP/GEFS initially but dying in the COD.

Kyle MacRitchie:  All 4 of his ensemble members show the MJO progressing through phase 7 today, into phase 8 on April 9th and phase 1 on April 13th and they remain there until April 18th.  Then all 4 ensemble members enter the circle of death between April 21st and 24th.

Overall: Quite a mixed picture again. A pretty high degree of uncertainty from the big 4 but 3 of them end up killing off the MJO sooner or later. The NCEP/GEFS re-enters the important  phases  8 and 1 next week. Kyle MacRitchie, however, shows the MJO progressing through phases 7, 8 and 1 during the next 2 weeks.

As always, the more I study these charts, the more I realise the understanding of MJO and predicting it, is in its infancy. Quite often the models do not agree where the MJO is currently! Surely, they cannot be so different to Kyle’s predictions and be wrong? Although I still feel that Kyle may have the edge. I shall spend a little time during the Summer trying to find comparative verification statistics, so that we can, hopefully, get some more reliable predictions in time for next Winter. Any feedback or comments from fellow model thread followers/posters would be appreciated.

Current Arctic Regional Surface Temperatures:

GFS – Northern Hemisphere Current Temperatures:

http://www.meteociel.fr/modeles/gfse_cartes.php?&ech=6&mode=9&carte=1

The link to this chart updates 6 hourly with each GFS run. At the time of writing it is showing a chart for 2000 BST today (5th April***). As this is T0 to T6 hours, it should be pretty accurate. Here is a summary of the temperature reading that I have been following in the reports with the previous reading (from my last report) for March 21st in brackets alongside:

North Pole –  around -28c to -32c (-28c).

Barents Sea/High Arctic – around -16c to -24c (-20c to -24c).

Scandinavia – south around 0c (0c to -4c); north around 0c to -12c (-8c to -16c).

Northern Siberia - around -20c to -32c (unchanged).

North West Russia - around -4c to -16c (-12c to -20c).

North-east Europe – around +8c to 0c (-4c to -12c).

Overall:  Europe and Russia have warmed up by varying degrees and the Arctic and Siberia are little changed during the last 2 weeks.

*** Please note:   At the time of posting this link it was showing 2000 BST on Tuesday, April 5th. I always try to show the 2000 BST (1900 GMT) charts for a consistent comparison. The charts are automatically updated 4 times a day, so the temperatures shown will be different to those I just mentioned above. We can follow the trends by looking at the latest data at any time from now on. It is vital to note the time of day to take account of daytime/night time variations. So for like for like comparisons, for example the 2000 charts for each day should be available to view from the 12z (T+6) updates which are published around 1600 to 1700 or about 4 to 5 hours later. This also applies to some of the other charts I link to in this post.

Svalbard Daily “Maximum” Temperature Forecast for 10 Days:

Here are the links to the 3 Svalbard stations that I am monitoring.

Central/West Svalbard – Longyearbyen 28 m asl:   

http://www.yr.no/place/Norway/Svalbard/Longyearbyen/forecast.pdf

April 6th  -6c;    April 10th   -10c;    April 14th  -8c.

North-West Svalbard – Ny-Alesund:                                                            

http://www.yr.no/place/Norway/Svalbard/Ny-%C3%85lesund/forecast.pdf

April 6th  -4c;   April 10th   -12c;    April 14th  -8c.

Central South Svalbard – Sveagruva:                                          

http://www.yr.no/place/Norway/Svalbard/Sveagruva/forecast.pdf

April 6th  -7c;   April 10th   -12c;    April 14th  -12c.

Overall:

The general trend is for the “maximum” temperatures (which fell from much higher levels up to mid-March when they often exceeded 0c), to fall slightly again by this weekend and only rise very slightly in early next week. The diurnal range starts to increase during April and I am quoting “maximum” temperatures. So minimums and means will usually be somewhat lower.

These links will update automatically at frequent intervals throughout the day. They are the Norway met office’s predictions. We need to be aware that these are only a forecast that is subject to change and I am told that the Arctic surface temperature forecasts are not completely reliable even at short range. 

To put the above figures into context, here is a link to the main Longyearbyen site:  

http://www.yr.no/place/Norway/Svalbard/Longyearbyen/statistics.html

This shows monthly means, and actual highest/lowest temperatures recorded during this winter and goes back further. Apart from a couple of days in December, Svalbard has been seeing “maximum” temperatures falling to lower levels compared to much of Winter 2015/16 as well as much of the previous Winter.

Final Comment:

Most of the models are coming into broad agreement of rather colder and wetter than average conditions to predominate for much of the next fortnight. Judah Cohen’s latest report is worth reading in detail as it explains the main reasons behind the current and predicted patterns. Most of my indicators support the general trend. Arctic source temperatures are currently much lower than they have been for much of the Winter. Any Arctic outbreaks could be somewhat wintry – perhaps not unusual for April but possibly a little more extreme than some might believe possible. As we now finally seem to be seeing evidence of the SSW, we can expect several weeks (perhaps until late April) of mostly colder weather with above average rainfall.

I’ll finish on a word of encouragement. Judah Cohen does say that a negative AO at the end of April can produce the reverse effects to that of one in mid-Winter. So, more meridional patterns could give us a really warm spell – perhaps for the early May Bank Holiday! Don’t hold me to it but I expect some sharp switches of patterns through early to mid-May.

Next Update:

That’s it folks until next Winter. I’ll probably re-start these reports in November 2016 – sooner if there is some unseasonable early cold around. I may produce an occasional ad hoc post during the summer months on slightly different topics.

 

Edited April 12, 2016 by Guest
Grammar, spelling corrections + check that all links function properly

[knocker]

The GEFS anomalies tonight continue with the theme of a pattern change around the middle of the 14 day period. The 5-10 still shows a weakening cold trough over N. America and high Atlantic amplification vis the Greenland block and the upper low to the SW of the UK. So the latter still under the influence of the LP giving some varied weather conditions as noted previously with temps around average. But by day 10 the transition is already underway.

The 10-15 highlights this with the N. American trough no more as is the amplification in the Atlantic, Replaced by a weak trough in the eastern Atlantic and a much more zonal flow WSW over the UK. Still the weather prone to be unsettled but chance of drier and warmer interludes particularly in the south

Edited April 5, 2016 by knocker

[damianslaw]

Hallmarks of spring-summer 2015 from the models today - yes the return of the troublesome trough anchoring itself in an unfavourable position for any sustained warm dry weather. It looks decidedly chilly for the foreseeable - the affects of the SSW taking full effect resulting in a negative NAO/AO pattern. Wet for many, snow down to modest levels over northern high ground, some brief sunny breaks and the risk of frost never far away, windy to boot.. 

The cold pool of water over NE atlantic is an ominous feature once again.

Could be some lively April showers in the days ahead, watch the CET about to come tumbling down.

On a personal level, I always remain cautious when we see lengthy dry warm spells appear in April, in recent years they've been followed by poor May's and summers, exemplified in 1987, 2007 and 2011. Much better to have cool northerly, easterly cyclonic outbreaks in April, than the May-Aug period.. lets hope this isn't the start of a new trend, our weather has got locked into lengthy similiar conditions in recent years.

[knocker]

 

[knocker]

The ecm and NOAA 5-10 are pretty much in agreement so really the ten day period looks like a done deal regarding the upper air pattern. Of course this still leaves the surface detail to be resolved but it looks very like a slowly filling low pressure area in the SW but of course  that is still rather open ended. The 850mb anomaly just for a change

In the 10-15 day period the EPS is looking at the pattern change with no Greenland block and a trough in the Atlantic running south from Iceland. Ergo the flow from the SW with temps a little above average but still generally unsettled. The NOAA 8-14 does not go along with this and is still very meridional with positive heights Greenland and the LP still to the SW of the UK. This maybe down to the fact that the pattern is changing rather quickly.

Edited April 5, 2016 by knocker

[knocker]

4 hours ago, Bring Back1962-63 said:

With so many near “record” breaking events affecting the broader patterns, it is little wonder that the experts have been overwhelmed. My understanding of this science is very limited and I’ll leave it up to experts to unravel what has or did not happen. Computer models and programmes rely on analogue data. As we have experienced such an unusual or unique sequence of events, making comparisons must have been a nightmare. All we can say, is that a huge amount must have been learnt from the Winter 2015/16 experience and I would hope that this will increase the level of understanding and lead to improvements in the models.

 

I was under the impression that they used the equations of fluid dynamics and thermodynamics using input data to estimate the state of the fluid at some time in the future. When you say the experts were overwhelmed were the forecasts that far out?

Edited April 5, 2016 by knocker

[Frost HoIIow]

3 hours ago, damianslaw said:

Hallmarks of spring-summer 2015 from the models today - yes the return of the troublesome trough anchoring itself in an unfavourable position for any sustained warm dry weather. It looks decidedly chilly for the foreseeable - the affects of the SSW taking full effect resulting in a negative NAO/AO pattern. Wet for many, snow down to modest levels over northern high ground, some brief sunny breaks and the risk of frost never far away, windy to boot.. 

The cold pool of water over NE atlantic is an ominous feature once again.

Could be some lively April showers in the days ahead, watch the CET about to come tumbling down.

On a personal level, I always remain cautious when we see lengthy dry warm spells appear in April, in recent years they've been followed by poor May's and summers, exemplified in 1987, 2007 and 2011. Much better to have cool northerly, easterly cyclonic outbreaks in April, than the May-Aug period.. lets hope this isn't the start of a new trend, our weather has got locked into lengthy similiar conditions in recent years.

Indeed the models don't look good if warmth is what you are after. Spring 1995 for the most part wasn't great for warmth. And even early June was poor but then a huge change later that month and throughout July & August was fantastic too. It's good to get the upcoming cool weather out the way before Summer proper arrives.

[Cheshire Freeze]

GFS 18Z gave an FI N'ly that wouldn't look out of place in January

Edited April 6, 2016 by CreweCold

[knocker]

The GEFS this morning are still looking at the transition from high amplification to a more zonal set up somewhere in the 9-13 range. NOAA this evening will be of some interest.

[Gibby]

HERE IS MY LATEST ANALYSIS USING DATA SUPPLIED BY THE NWP OUTPUT COVERING 5 OF THE WORLDS MOST POWERFUL WEATHER COMPUTERS ISSUED AT 09:00 ON WEDNESDAY APR 6TH 2016

THE CURRENT GENERAL SITUATION A weak trough will move East over remaining parts of Central and eastern Britain followed by a cold and showery Westerly flow with an occlusion moving SE across England and Wales tomorrow.

http://www.wetterzentrale.de/pics/Rtavn001.gif

CURRENT SNOW FORECAST AND FREEZING LEVEL OVER THE UK The freezing level across the UK will drop to around 3000ft or so today and continue there over the next few days. There will be some snowfall over high ground above around 2500ft today and for the next few so taking in many higher hills and mountains of Scotland, Ireland, Wales and the North.

http://www.snow-forecast.com/maps/dynamic/uk

http://www.natice.noaa.gov/pub/ims/ims_gif/DATA/cursnow.gif

MODELS-2 WEEK HEADLINE  Unsettled with showers or spells of rain with some brighter spells too especially over the North. Near average or slightly below average temperatures. Perhaps warmer later in the SE.

THE GFS JET STREAM FORECAST  The Jet Stream is shown to maintain a trough across the UK over the next week to 10 days with the Jet flow carried well to the South of the UK. It's not until later in the second week when the trough dissipates and the flow becomes much less organized and weaker.

http://www.netweather.tv/index.cgi?action=jetstream

GFS OPERATIONAL The GFS Operational Run today continues to show unsettled and cool synoptics over the next few weeks with Low pressure gradually aligning to a point near SW England by the weekend and persisting there for quite a while bringing spells of rain and showers to many especially the South. Then through the second week the Lows weaken as a ridge moves in off the Atlantic with a drier and brighter interlude before unsettled and cool weather is shown returning from the North at the very end of the run.

GFS CONTROL RUN The GFS Control Run shows unsettled conditions across the UK too for the first week as it too shows Low pressure becoming established to the SW of the UK with rain or showers meandering about for all in among some sunny intervals. Then through the second week warmer air will move across England and Wales as winds turn more South or SW though still with the risk of rain especially over the West and North.

http://www.wetterzentrale.de/pics/Rtavn1441.gif

http://www.wetterzentrale.de/pics/Rtavn3841.gif

http://www.meteociel.fr/modeles/gefs_cartes.php?code=0&ech=144&mode=0&carte=0

http://www.meteociel.fr/modeles/gefs_cartes.php?code=0&ech=384&mode=0&carte=0

GFS ENSEMBLE DAY 14 DATA  The GFS Clusters today show a generally better trend to that of late with the majority now showing either slack conditions across the UK at worst and an interesting 5% of clusters showing an intense anticyclone over Ireland established by then. However, I would estimate a 50/50 split in members between showery and dry conditions at day 14.

http://www.weatheronline.co.uk/cgi-bin/expertcharts?LANG=en&MENU=0000000000&CONT=euro&MODELL=gefs&MODELLTYP=2&BASE=-&VAR=cpre&HH=372&ZOOM=0&ARCHIV=0&RES=0&WMO=&PERIOD=

UKMO The UKMO model this morning shows Low pressure settling down to the SW of the UK over the coming weekend with troughs swinging up into Southern England and becoming slow moving across somewhere across the UK with cold and wet weather where it lies while sunshine and showers with hail and thunder in places look more likely in the South where a few warmer sunny spells between the showers look likely.

http://www.wetterzentrale.de/pics/Rukm1441.gif

THE FAX CHARTS The Fax Charts show a complex situation developing through the latter half of this week and the weekend with rain and showers never far away from all areas. With Low pressure becoming lodged across and to the SW of the UK with rain and showers for all in average temperatures but with some warmer air en-trained across the South at times turning some of the rain thundery.

http://www.weathercharts.org/ukmomslp.htm#t120

GEM GEM today shows an unsettled period to come as the current cool and showery theme is enhanced by renewed Low pressure feeding down over and to the West of the UK over this weekend. So rain and showers for all in rather cool and sometimes breezy conditions look certain. The trend is then for conditions to steadily improve next week as Low pressure fills up in situ to the SW and a ridge slowly builds across the UK by the end of next week with drier and brighter conditions for many areas then as a result.

http://www.wetterzentrale.de/pics/Rgem2401.gif

NAVGEM NAVGEM today shows Low pressure setting up shop down to the SW of the UK with cyclonic winds and rain at times likely for all throughout the weekend and start to next week.

http://www.wetterzentrale.de/pics/Rnvg1681.gif

ECM ECM shows another unsettled run this morning with cyclonic conditions throughout the period. In the first week Low pressure developing over and then to the SW of the UK will give rise to the usual mix of showers or longer spells of rain but with a few warmer brighter intervals between the thundery showers. The North and NE may feel very cool under an Easterly for much of the time. Then towards the end of the run Low pressure realigns towards the North of the UK with a more standard blustery SW flow with rain at times and perhaps warmer and brighter conditions developing at times towards the South and East by the end of the run.

http://www.wetterzentrale.de/pics/Recm2401.gif

ECM 10 DAY MEAN (12z) The 240hr mean Chart from last night continues to predict that in 10 days time we will still lie under a showery Low pressure close to or over the UK.

http://www.wetterzentrale.de/pics/Reem2401.gif

NOTABLE TRENDS & CHANGES FROM PREVIOUS RUNS A changeable and Low pressure driven period of weather for all is maintained from the models once more this morning.

31 DAY HISTORICAL VERIFICATION STATS FOR GFS, UKMO & ECM The verification Statistics of GFS, UKMO and ECM show at 24 hours ECM ahead at 99.6 pts with UKMO at 99.5 pts and GFS at 99.4 pts.  At 3 days ECM is leading with 97.7 pts to UKMO's 97.3 pts while GFS lags behind at 96.2 pts. At 5 days ECM leads with 90.2 pts to UKMO at 89.0 pts and GFS at 85.7 pts. Then at 8 Days ECM has the leading spot from GFS with 66.2 pts to 61.2 pts. Finally at Day 10 ECM has the lead from GFS with a score of 44.6 pts to 41.2 pts.

http://www.emc.ncep.noaa.gov/gmb/STATS_vsdb/allmodel/daily/cor/cor_day1_PMSL_MSL_G2NHX.png

http://www.emc.ncep.noaa.gov/gmb/STATS_vsdb/allmodel/daily/cor/cor_day3_PMSL_MSL_G2NHX.png

http://www.emc.ncep.noaa.gov/gmb/STATS_vsdb/allmodel/daily/cor/cor_day5_PMSL_MSL_G2NHX.png

http://www.emc.ncep.noaa.gov/gmb/STATS_vsdb/allmodel/daily/cor/cor_day8_PMSL_MSL_G2NHX.png

http://www.emc.ncep.noaa.gov/gmb/STATS_vsdb/allmodel/daily/cor/cor_day10_PMSL_MSL_G2NHX.png

MY THOUGHTS  Changes in the weather pattern look very slow over the next few weeks with Low pressure continuing to rule the roost. We currently are undergoing a change towards rather cold and showery conditions which will certainly feel much colder than the last few days across the South. Showers will be focused across the North today and the East tomorrow with the SW fairing not too bad outside of the strong and cold breeze. Then over Friday and the weekend another trough moving across from the west will develop a parent low pressure down to the SW which once established looks like lying in situ down there for some considerable time spiraling spells of rain ad showers North across the UK. The North and particularly NE of the UK could well become cold and grey especially near the East coast while Southern areas seeing some bright weather at times between what would likely be heavy and thundery April showers and here it could occasionally feel less cool. Then as we look over the horizon towards the second week the general consensus sees Low pressure gradually filling but remaining influential to many parts of the UK with slow moving April showers. With pressure high at Northern latitudes and with some output suggesting another surge of cool air moving down from the NE later in the second week it could be that Low pressure becomes established further but hopefully this time more towards the North of the UK and perhaps allowing the South and East to eventually see some drier and warmer periods between more broken spells of wind and rain with the emphasis of the worst weather to be more traditionally towards the North and West. It looks once more this morning that reliable dry, fine and warm Spring conditions are a figment of imagination in this morning's output and it looks increasingly likely that we will have to wait for late April at least to see temperatures comfortably in the mid teens or above regularly. 

Next Update Thursday April 7th 2016 from 09:00

[knocker]

After an unsettled period the ecm ends with a complex area of low pressure in the eastern Atlantic/

 

 

[knocker]

In the 10-15 day period the EPS continues to remove the Greenland block, the retrogressing of the trough to mid Atlantic and heights building central Europe to the Baltic.Thus south westerly streamlines over the UK and remaining unsettled, more particularly in the north with drier and warmer periods in the south. Temps in general around average, perhaps a little above.

[stodge]

Evening all

Some tentative signs on the GFS OP of an improvement into the last third of April but that's a very long way off and frankly we've got a lot to get through before that.

Very poor charts for anyone looking for anything fine, warm and settled. The main difference over the British Isles is whether it will be raining or whether it's going to rain.

Looking at the T+144 charts starting with GEM:

UKM:

ECM:

GFS:

Not difficult to forecast this. The far north of Scotland cold with rain and snow to higher ground. Elsewhere, bands of rain or showers with hail and thunder and perhaps some heavy localised downpours with calm conditions. Can't rule out short-lived wintriness to higher levels further south 

Rainfall totals over the 10-day period not alarming by any stretch (apart from central Scotland) but I suspect the variations between areas could be considerable:

 

[Singularity]

A bit of a move toward more Euro high influence in the 8-10 day range this evening, which may at least help to warm things up - but it may also increase the rainfall amounts until if and when the Atlantic trough backs far enough west.

Very interesting patterns on offer, but with the UK poorly positioned unless you like frontal rain and showery weather in between. The latter I can live with in April.

[knocker]

Signs with NOAA tonight of a weakening of the high amplitude pattern in the Atlantic. The strong Greenland block subsiding along with the trough to the west of the UK. Ergo a south westerly flow ensues which still portends unsettled weather, more particularly in the north with temps around average.

The ecm is pretty much in agreement in the 5-10 range  The EPS is not hugely different either, but does make even less of the Greenland HP.

So the major players are all looking at a SW regime in the middle of April with the usual mix of more prolonged periods of rain, showers and sunny intervals. with temps varying around the average but it's possible that the SE will be lucky and get some drier and warmer conditions.

 

 

 

Edited April 6, 2016 by knocker

[Paul]

18z will be delayed tonight - NCEP having issues loading the data files onto their servers currently. 

[Singularity]

Careful with using means and ensemble-derived plots though; with a spread of possible trough positions from SW of the UK to E or even NE of us, the amplification will be disguised to some extent. Though maybe not much with the NOAA plot - I'm not sure to what extent they try to call a particular outcome or give a broader guide to the most likely outcomes within a range.

The lowering of heights NW of the UK seems real enough though; there's scope for the HP to retrogress to the US and/or Canada. That's when any lingering amplification may allow notable HP development across Europe with extension N reaching near to the UK. Such meridional jet behaviour depending largely on the seasonal weakness of the mid-high latitude westerlies, unless the MJO wakes up again.

[fine wine]

The latest charts are actually suggesting that about area from Bristol to the Wash will become very mild from Sunday afternoon with temperatures reaching 14 - 17c for a few days so not cold for everyone. 

[knocker]

8 hours ago, Singularity said:

Careful with using means and ensemble-derived plots though; with a spread of possible trough positions from SW of the UK to E or even NE of us, the amplification will be disguised to some extent. Though maybe not much with the NOAA plot - I'm not sure to what extent they try to call a particular outcome or give a broader guide to the most likely outcomes within a range.

The lowering of heights NW of the UK seems real enough though; there's scope for the HP to retrogress to the US and/or Canada. That's when any lingering amplification may allow notable HP development across Europe with extension N reaching near to the UK. Such meridional jet behaviour depending largely on the seasonal weakness of the mid-high latitude westerlies, unless the MJO wakes up again.

I think care should be taken whatever criteria one is using. But having said that as a means (no pun intended) of detecting future trends ( in the medium term) of the upper air pattern. IMO the proper use of the anomalies. NOAA, GFS and ecm, is as good as any and better than most. Used correctly, that is a conformity between the three, preferably over two or three days, whilst also keeping an eye on the very variable ops output. That is the case at the moment and although obviously this interpretation can still be incorrect I know of a no better guide. I am of course open to other suggestions that may be superior.

Edited April 7, 2016 by knocker

[knocker]

A showery regime for a day or two before the next frontal system sweeps in Friday/Saturday. After that low pressure to the SW will become the dominant feature for a little while.