Model Output Discussion - What does April have in store?

[Frosty.]

Tonight's Ecm 12z ensemble mean suggests next week will continue with above average temperatures, it's very noticeable how less unsettled next week looks compared to what the models were showing yesterday..and warmer!

Edited April 17, 2019 by Frosty.

[Don]

20 minutes ago, 38.5*C said:

There doesn't really need to be a lengthy dry spell to get high temperatures. July 1st 2015 can prove that. If that set up had occurred 4 weeks later I bet a certain record would've easily got broken.

Very true.  The heat of 1st July 2015 was proceeded by a generally cool May and June, too!  In fact, summer 2015 was pretty mediocre overall.  All the more reason for records to be broken following a lengthy dry spell!

Edited April 17, 2019 by Don

[Mike Poole]

So here's a kind of summery (sic!) of my view of what the models and other drivers might be saying as we head into the second half of spring and thence summer:

1. A settled and warm Easter virtually guaranteed, thereafter a less settled spell, but looks short lived or even very short lived before a high pressure regime takes hold again, as per ECM 12z by T240.

2. Quite a lot of this looks like last year all over again, but there are differences, one is SSTs close to UK, these were really cold last year following the Beast from the East, but now are considerably warmer than average:

3. AAM is higher than it was hovering about last year at the same time, possibly driven by warmer Pacific (ENSO), plot shows AAM anomaly for last year:

Effect maybe to draw up a series of stronger ridges for UK than this time last year, if I recall correctly the very dry weather was more in the NW at first before spreading to the whole UK in June.  If I'm not reading this completely wrong I think there could be more UK wide heat in May than last year.  

4. Seasonal models.  GloSea5 was strongly suggestive of a hot summer in March, toned down a bit in April, but still above average probability.  CFS remaining steadfast in a high likelihood of a Scandi high throughout late spring early summer, and even further.  

5. Some comment earlier re drought.  I don't think this is likely to be a major issue because of the heavy rains rains in March, that is rain which will be able to percolate down to the aquifers fine without evaporation, which becomes a problem later into summer. 

All in all, a very interesting late spring early summer season ahead, let's see how it pans out.  

Regards

Mike

[Mapantz]

We have appropriate threads for discussing record temperatures and other weather stats. Please use them.

[Frost HoIIow]

15 minutes ago, 38.5*C said:

There doesn't really need to be a lengthy dry spell to get high temperatures. July 1st 2015 can prove that. If that set up had occurred 4 weeks later I bet a certain record would've easily got broken.

True but that event was a proper plume dragging up air from a long way south. Plumes are pretty rare & when they happen tend to be short lived. It's like last Summer's hot temps were mostly the result of persistent areas of high pressure influencing our weather rather than hot humid plumes. Sorry mods off topic I know.

[Earthshine]

I'm confident we'll be on the milder side of average for the rest of the month.  Seems the region of high pressure to our east is robust and stable.  Will be interesting to see just how much we deviate from average this month despite a rather cool start.

[Earthshine]

5 minutes ago, Mike Poole said:

So here's a kind of summery (sic!) of my view of what the models and other drivers might be saying as we head into the second half of spring and thence summer:

1. A settled and warm Easter virtually guaranteed, thereafter a less settled spell, but looks short lived or even very short lived before a high pressure regime takes hold again, as per ECM 12z by T240.

2. Quite a lot of this looks like last year all over again, but there are differences, one is SSTs close to UK, these were really cold last year following the Beast from the East, but now are considerably warmer than average:

3. AAM is higher than it was hovering about last year at the same time, possibly driven by warmer Pacific (ENSO), plot shows AAM anomaly for last year:

Effect maybe to draw up a series of stronger ridges for UK than this time last year, if I recall correctly the very dry weather was more in the NW at first before spreading to the whole UK in June.  If I'm not reading this completely wrong I think there could be more UK wide heat in May than last year.  

4. Seasonal models.  GloSea5 was strongly suggestive of a hot summer in March, toned down a bit in April, but still above average probability.  CFS remaining steadfast in a high likelihood of a Scandi high throughout late spring early summer, and even further.  

5. Some comment earlier re drought.  I don't think this is likely to be a major issue because of the heavy rains rains in March, that is rain which will be able to percolate down to the aquifers fine without evaporation, which becomes a problem later into summer. 

All in all, a very interesting late spring early summer season ahead, let's see how it pans out.  

Regards

Mike

Any ideas on what (if any) impacts warm SST around the UK will have?  

[Mike Poole]

1 minute ago, Earthshine said:

Any ideas on what (if any) impacts warm SST around the UK will have?  

Any high pressure inspired warmth given a boost in temperatures particularly near the coasts, probably, but more importantly increased likelihood of a northerly tracking jet stream allowing high pressure to dominate in the first place, although that might be via the difference between higher SSTs here and lower SSTs SW of Iceland (see chart in my previous post).

[shaky]

Fantastic 18z gfs up to 168 hours so far!!better with trough further south and west for much of next week!!very warm conditions continue up to wednesday at least so far on the 18z!!

[CheesepuffScott]

Out to next Wednesday on 18z.. perhaps 24/25C in London/SE on Wednesday, maybe even add 1 or 2 degrees on knowing GFS usually undercooks temps. Looking good for a continuation of the warm spell!

Edited April 17, 2019 by CheesepuffScott

[CheesepuffScott]

Even by day 10 high pressure and warm air is still in control... uppers of 13/14C edging into the south by then

Edited April 17, 2019 by CheesepuffScott

[Cheshire Freeze]

Looking at the modelling (including the longer range, seasonal stuff), I'm still of the opinion I was 2 months ago- that this will be a significant drought year. Nothing seems to have changed substantially for months and months in the grander picture. We're seeing any HLB over our side of the hemisphere struggling to maintain any foothold- mostly sinking and being reinforced by the Azores HP.

GFS illustrates this below-

Thus we end up with the jet ploughing merrily away far to the N of us.

Here's the CFS averaged pressure anomaly chart for June...It has shown little fluctuation in months. Moreover, there's not one month between now and October that shows a below average SLP return.

We'll do well to even see any storms out of that.

Not sure how we break out of this entrenched general pattern. I don't particularly fancy seeing scorched earth for several months like last year. So depressing after a while.

Edited April 18, 2019 by CreweCold

[Godber 1]

2 hours ago, CreweCold said:

Looking at the modelling (including the longer range, seasonal stuff), I'm still of the opinion I was 2 months ago- that this will be a significant drought year. Nothing seems to have changed substantially for months and months in the grander picture. We're seeing any HLB over our side of the hemisphere struggling to maintain any foothold- mostly sinking and being reinforced by the Azores HP.

GFS illustrates this below-

Thus we end up with the jet ploughing merrily away far to the N of us.

Here's the CFS averaged pressure anomaly chart for June...It has shown little fluctuation in months. Moreover, there's not one month between now and October that shows a below average SLP return.

We'll do well to even see any storms out of that.

Not sure how we break out of this entrenched general pattern. I don't particularly fancy seeing scorched earth for several months like last year. So depressing after a while.

most people seem to be hankering after hot sunny weather, when what's needed is an extended period of wet weather.

[knocker]

The 500mb NH profile and the Atlantic surface analysis for midnight and the 0400 UTC UK chart

A fair bit of Stratus and mist around over England and Wales at the moment. This will generally clear with perhaps broken cloud still around central parts during the day but again Stratus lingering around coastal areas, particularly those adjacent to the North Sea. Thus temps still depressed a tad in these regions but elsewhere getting quite warm

Staying dry overnight with not much cloud but still the chance of  mist/Stratus in the north east. No frost

Less cloud tomorrow and warming up nicely, albeit the usual caveat vis coastal areas.

Staying very warm and sunny for most on Saturday but the block is coming under some pressure from the trough to the north west and a cold front will encroach bringing cloud and cooler conditions to NW Scotland and N. Ireland

Generally another warm and sunny day with a very slack gradient over the UK but still a front hanging around the north west so cooler with patchy rain over northern Scotland

We are now entering a period of uncertainty so confidence in the detail becomes less by the day. The gfs this morning reinforces the ridge on Monday which keeps any frontal systems at bay and thus another warm and sunny day for most

[knocker]

Continuing for a couple of days. Tuesday a bit of a mixed bag. Still very warm in central southern areas of England but some convective nativity may creep up from the south and back to markedly cooler in the NE and along North Sea coasts A not dissimilar day on Wednesday, perhaps less showery activity

 

[daz_4]

2 hours ago, CreweCold said:

Looking at the modelling (including the longer range, seasonal stuff), I'm still of the opinion I was 2 months ago- that this will be a significant drought year.

I'm afraid you are correct. We are already struggling in Central Europe - forests dying at large, harvest problems etc.. The last four years have been horrible with drought and it's getting worse and worse. No rain in sight. Just sun and warmth. 

[shaky]

Massive change on the ukmo 00z!!trough hardly gets in now and the sunny warm weather continues all the way to the end of the run!!

[knocker]

Just to illustrate the uncertainty next week involving the ridge and the upper trough to the south west

[Frosty.]

Oh my...still looks warm / very warm @ T+144

[shaky]

5 minutes ago, Frosty. said:

Oh my...still looks warm / very warm @ T+144

Yup the trend is clear!!ecm looks like playin catch up aswell!!backed everything west over the last 24 to 36 hours!!its further west compared to the 12z last night aswell!!theyre could hardly be a breakdown in the warmth at all!!

[knocker]

Taking another snapshot later next week with the ecm just to illustrate again the uncertainty as we progress The interaction between the troughs and the ridge and subsequent energy flows are causing this uncertainty I assume (perhaps wrongly) Thus by the end of the week unsettled with temps varying regionally but still above average. But as previously stated, merely a watching brief for the moment

Edited April 18, 2019 by knocker

[MP-R]

2 hours ago, Godber 1 said:

most people seem to be hankering after hot sunny weather, when what's needed is an extended period of wet weather.

If it weren’t for the very wet November and December and first half of March, I’d be more worried.

As somebody said on here the other day, there really has been a propensity for high pressure over the UK since last April. It’s done wonders for sunshine totals.

[Coopsy]

3 hours ago, Godber 1 said:

most people seem to be hankering after hot sunny weather, when what's needed is an extended period of wet weather.

I've mentioned this before - people are unduly worried about this. The UK's reservoirs are at generally high levels across most of the UK. (some regional exceptions)

Put that into context - we had one of the driest summers on record last year and there were little issues. The media fans peoples fears and there's no need. We'll be OK. We can enjoy a nice summer...

Read the UK reports here: https://www.gov.uk/government/publications/water-situation-local-area-reports 

Even Kent and South London is at close to full which is arguably one of the driest parts of the country: https://assets.publishing.service.gov.uk/government/uploads/system/uploads/attachment_data/file/794178/Water_Situation_Report_Kent_South_London_March_2019.pdf

Honestly - no need to worry.

Edited April 18, 2019 by CanadianCoops

[Summer Sun]

Whilst it does look likely we'll lose the high pressure currently over the UK by Sunday or Monday the amount of rain we see away from the far west is extremely low

[Frosty.]

• Looking at the Ecm 00z ensemble mean, the warmth goes on, and on, and on..speaking of warmth..Easter looks very warm!