rwtwm

I know this is just a bald look at the stats, but I've been mentally preparing for a 'was spring really that bad' debate, where the counterargument is based on the CET. I didn't expect to use it until September, but it can have a trial run here. (...I know you've asked was it 'cold', not was it 'good', but the same argument applies, as will become obvious...) Perception of warmth in April, May and to a lesser extent June is at least as much based on Sunshine amounts as it is on the amount of thermal energy in a shaded area. The sun is as high as in August for much of April, and the sun retains decent power after schools and offices kick out. A still day with a maximum of 14 and sunshine is going to be perceived as much warmer than a cloudy 16 with a north sea breeze. Sunshine also makes a big difference to how much people have to heat their homes. Warm air prevents cooling, but sun on open windows can warm rooms to much above the ambient temperature outside. If the heating's always on, or you're wearing a jacket indoors because you don't want to pay for hearing in Mid April, it's going to be hard to consider a month warm! So yes the temperature was overall above average, but other than a couple of days, it's unlikely that many will remember it as so. Having made this argument, I do get that the post above is from an academic perspective. The temperature was above the long term average. But most people don't really perceive the weather that way.

There was a real cluster of forecasts around the consensus this month. And the consensus was a really impressive guess! (Well done everyone) That means that despite a good (for me) delta with the real value, I'm quite a way down the CET table!

12.8c and 51mm please

Yet another day this April that would be disappointing in November. Cold and miserable yet again. @Alderc 2.0 - Really sorry to hear about your injury. That sucks.

A quick survey of the accum precip charts available now suggests is in the realms of the possible, if not the probable. From what I've seen there's anything from 15-30mm modelled. Models aren't reality of course, but were I forced to go over under on 50mm for Heathrow, I'd go over.

I have nothing useful to contribute. But after being cold all weekend, and then looking at the models this morning, I needed to moan into the virtual void. This high pressure has been further West, and had more cloud mixed in, so it doesn't have the benefit of a surplus of April sun, a la 2021. In fact I preferred the mild sunshine and showers of earlier in the month. If I dodged the showers and went outside in the narrow sunny windows, I could almost fool myself it was springlike! The fact I still warmly recall one settled week in January this late in the year is a sign of just how bad it's been.

danm You've got me peering out the window! I'm only a few miles up the road. No sunshine yet, but if I squint and look north I can make out a few breaks in the clouds. That said, though dull, April hasn't felt so bad so far. Probably because my expectations have lowered massively from the last few months of deluge. I've also been lucky that when I've wanted to be outside, there's been some brightness. Sometimes ones impression of a month is based on little more than coincidence.

Metwatch I should have gone to the express with that forecast, as it was much better than their usual nonsense!

donnerundblitzer The NAO is basically the difference in pressure between the Azores and Iceland. The North Atlantic Oscillation WWW.METOFFICE.GOV.UK The term 'North Atlantic Oscillation' is used by meteorologists to refer to variations in the large-scale surface pressure gradient in the North Atlantic region. So low pressure over the Azores and higher pressure to the north gives a negative NAO. This has been the case a few times this winter, but the jet hasn't been south-shifted enough for the low pressure to miss the UK. Instead low pressure has been tracking along the south of the country. The rainfall anomalies in March had Southern England in particular, much wetter than normal. In the northwest of Scotland, where the low pressure would normally track, they had a drier and sunnier month than normal.

BlueSkies_do_I_see I'm not certain I've done this right, but I think if you round each month's record down to the nearest integer, the mean across that hypothetical year would be around 12.6c. I'd be happy for someone to check my work on this. Also worth noting that neither January or March reached the required value, so we'd probably need to hit at least one record to make 12c, even from this very mild start.

Mild and damp continues. 9.3c & 91 mm please

Bats32 You're not joking! A low sets up on the 26th, and just festers for 9 days. The best conditions on offer over that period are - "not too windy I guess". You'd struggle to draw a less pleasant run.

Wynn D Woo There is a good reason why it's not symmetrical though. Solar noon is 30 mins later at the end of Feb than it is at the end of October, so we get half the benefit of DST for free! As we move through March, Noon slips back and that benefit is partly lost by the end of the month. My personal preference would be to switch around the second week of March. By then Sunrise would be earlier than after the October change, which feels reasonable.

The models have been hinting at more suppressed temps towards the end of the month. Once we hit April though, with the strength of the sun and the warmth of the Atlantic, I'd expect the first SW waft of the month to push us over 20c. Beyond that it's tea leaves really. But I have a feeling we might struggle for Maxima until a little later in the summer. 20c - 4th April 25c - 18th June

My recollection of the March is that it was pretty dismal up until the day lockdown was announced. From then on it was blue skies every day! That was the end of a notably wet spell too, so like now we were desperate for high pressure. (I've just gone and checked the Met Office look back, and it was the wettest Feb, and 5th wettest month full stop)

Don Another related question. Could the March absolute max come in lower than January's? Still very early days, but if we end up with mean winds East or North of East due to the SSW we'd struggle to hit the 20c needed.

6.6c & 82mm please

Good point. We've seen apparently nailed on patterns switch at relatively short time scales, more than once. Most of the time disappointment follows a fuzzy ensemble resolving the wrong way. Does this mean that the ensembles are insufficiently perturbed? If guess that In an ideal world the ensembles will cover the broad probability space, with at least one of them getting it right.

Past mild and into warm today out there IMO! I left my jacket indoors for my lunchtime walk, and was still warm. Lots more gaps in the cloud here than originally modelled, and the sun has a bit of oomph to it at last. I'd enjoy it more were it rarer, but days like this in February are becoming troublingly common.

It's a matter of fact that (with the recent of the exception of the AI models) the models work from observations and apply physics from there. Agreement is irrelevant. Updates seem to be every 18 months or so, but it varies by model. Whenever people post parallel outputs, that's because the met organisations are testing updates to their models. At lot of the MJO predictions have been based on composites. That's good old fashioned pattern matching to my mind. Just looking at different patterns!

Ok, so the winter has been a let down. That on its own isn't worth much investigation in a warming climate. That said, I'm interested by the NWPs persistent forecasting of HL blocking. Particularly in the last 3/4 weeks. Remembering that the NWP models are just the physical interactions between packets of air, there was something leading the suggestion that a mid-atlantic ridge or even a north Atlantic block would set up at day 12. For me it's not sufficient to say there is a bias towards blocking. That's the symptom. It's not on every run all the time, so something in the configuration would have led to blocking but for an unmodelled interaction. Or there's something about the initial configuration that allows the bias to take hold. I assume much smarter people than I are already looking at it to improve modelling. If anyone is aware of any blogs or papers on the topic I'd be interested in seeing them.

I've done a very crude eyeball of the GFS for the next week. I estimate a CET of around 8.5 for the next 7 days, putting the rough running total by the 19th at 7.9ish. I'm not sure that the last 10 days of the month are going to return a high enough value to keep the Feb record in sight. But I'd be intrigued to see how this impacts the winter 30 day record.

damianslaw I know what you're getting at, much March 2013 probably isn't the best illustration. We had snow cover for about a week during that spell, even down here.

That's tantamount to saying that we only got stuck to the ground once Newton spotted gravity! One thing that does strike me though is that a lot of the predictions driven from these phenomena seem to be based on correlations. That may just be a weakness of my knowledge, but the discussion is often X promotes Y, or makes Z more likely. But rather than seeing a phenomena and then hoping something should happen after n days, we should be able to trace the ripple effects from the initial forcing. If enhanced convection in a certain part of the Pacific is the butterfly that leads to a Jet Stream rising over Greenland and diving into Spain, it should be possible to construct the chain of events that leads to it. Or conversely, see what interactions broke the chain if the expected or hoped for result failed. Correlations based on a small sample of past events in a rapidly changing climate are unlikely to be very useful. Understanding the mechanisms and following them will be much more instructive. (FWIW, this is why I'm dubious of AI models. I think they can be useful, but you need the physical equations to describe how things change when the energy balance changes)

The full ensemble suite on the ECM is run at the same resolution as the op. The Control and Operational are therefore always going to align. It's only a relatively recent thing, but the two lines moving in tandem doesn't provide the same insight it once did. https://www.ecmwf.int/en/about/media-centre/news/2023/model-upgrade-increases-skill-and-unifies-medium-range-resolutions