Day length & sunshine strength are now equivalent to early October.
Yet sunrise & sunset are an hour earlier by UK local time.
In Early October we were on BST with ~4 weeks until switching to GMT, while today we're still nearly 3 weeks from switching back to BST. Imbalanced!
Handily, this can be clearly seen in the plots in the first post. Using the dashed circles as borders, consider the outermost band versus the middle one.
The anomalies in the tropical Pacific alone cover an area equivalent to about half the mid-latitudes.
Key takeaway regarding this summer:
El Niño doesn't lead to warmer global mean temperatures via making it warmer across much of the world. Instead it's because if favours warmth where the Earth's circumference is longest; the tropics have far greater area than the mid-latitudes.
Two of the most strongly La Niña summers versus two of the most strongly El Niño ones. Selected to have a similar midpoint so as to limit the effect of climate trends.
Clear that La Niña favours cooler tropics, warmer mid-latitudes, while El Niño favours the opposite.
Signs are, vertical instability along the squall line will generally increase over time.
Result being, after an initial peak over northern Scotland, the squall line could peak again while over southern England. Perhaps even exceed its initial peak. Could be pretty wild!
Thursday will see a squall line sweep south-eastward across Ireland & the UK.
Bringing strong winds & short-lived very heavy rainfall, these features tend to occur in brisk westerly weather regimes.
Such a regime was rare last winter, hence very few squall lines featured.
E.g. if the stratospheric cyclonic circulation is anomalously weak in late March & events in the troposphere set up a high latitude blocking pattern, then that pattern could persist will into April.
Personally I'm hoping that scenario doesn't play out.
It looks like this event will go down as a split vortex type that didn't propagate downward to the troposphere, a relatively rare combination.
Instead, we wait to see if anything lingers long enough for a troposphere-led change to interact with late in March.
Polar vortex recovery to just below the long-term average ~17th March makes the recent reversal a major midwinter warming (MMW) event rather than a 'final warming'.
Unclear what happens next, with wide ensemble scatter. Amusing how well the mean hugs the zero line 30th onward.
Meanwhile GEFS has a relatively weak signal for such warmth with a lot of scatter, though the det. run (GFS OP) gave it a good go.
So, a bit to be sorted out, but it looks like the current intermittently chilly weather pattern lasts about a week.
ECMWF's ensemble suggests a good chance of anomalously warm weather returning to the vicinity of the UK soon into the 2nd half of March.
E.g. for Reading, that's a notable signal for 18th-23rd. The mean is held down a bit by variations in the timing of peak warmth.
Looks like we'll avoid a severe windstorm on Thursday, with peak gusts generally in the 40-50 mph range inland & 50-60 mph for western coasts.
Rainfall mostly unremarkable too, so I'm not expecting this to be a named storm.
If that does happen, there will then be a question of how far north the polar jet goes. The overnight GFS run keeps it far south enough that the UK & Ireland sees only intermittently settled weather, while the ECMWF det. run moves it far north enough for much of the UK to be dry.
Fans of dry, relatively warm spring weather in NW Europe best hope that these forecast model runs are onto something with a low dropping down to the west of Iberia next Tue-Wed & becoming cut off from the polar jet stream.
This would allow high pressure to extend over NW Europe.
I don't see SEAS5's current prediction as a blocked pattern, it's only indicating that the mean sea-level pressure may be in the upper tercile of climatology over central-northern Europe, which isn't dependent on blocking highs occurring there.
Also, the MJO activity isn't looking very strong. If it was, we'd probably see the lower stratospheric forcing outweighed with an abrupt switch to anomalously weak zonal winds there.
That being said, not all runs keep the MJO weak, so it bears keeping an eye on just in case.
The muted response with absence of much if any high pressure development around Greenland may be due to the stratosphere, where it appears a 'disconnect' will continue between anomalously strong zonal wind in the lower reaches & anomalously weak zonal wind higher up.
Most forecast model runs predict that the MJO will continue through phase 8 by around 10 days from now, but are only suggesting a partial response of the N. hemisphere pattern.
This makes for a less cold forecast for the eastern US in modelling versus composites.
As the MJO propagates eastward, the hemispheric pattern also shifts eastward during this coming week.
A subtle effect for N. America, but more pronounced for western Europe as the mainly dry, calm setup of recent days gives way to a highly changeable one with some wind & rain.
Recent & near-term northern hemisphere weather patterns look to be highly steered by MJO activity in phases 6-7 (i.e. over the tropical Pacific), judging by how well historical composites match with analysis & forecast modelling.
Zero sunshine for 3 days has wiped out the large surplus March 2026 had accrued by 5th here.
Though outweighed by mild nights, cool days have been enough to bring the mean temperature anomaly to-date closer to average, though still well above as of 8th.
At least it's not rained much!
Through 7th March 2026 is the 5th warmest in the Hadley mean Central England Temperature dataset.
After very mild conditions briefly return early next week, forecast models suggest generally near or below average temperatures. Could early March be the warmest spell of the month?
Had an unpleasant reminder this afternoon how quickly a reckless driver could severely change or end lives.
If I fully trusted driver signals, I'd be in a bad way or gone.
Had the cars collided, I might have been struck by either, or debris.
All because someone was impatient.
Spontaneous examination:
- Normalised global AAM generally follows the RONI but with occasional exceptions
- AAM often increases for a time before the onset of an El Niño event (RONI at least 0.5)
- Mid-2020 to late 2024, AAM was unusually 'choppy' & out of sync with the RONI
The model is unreliable sure, but "never" is going too far.
Despite being well out for the southeast corner, it had the right general theme for summer 2025 in Europe at this point last year.
It is however only a hint, with no clear signal for rainfall.
The temperature signal is however intriguing, as for a change it doesn't suggest an anomalously hot summer in Iberia. I imagine the very wet 2nd half to winter there is playing a role (but isn't the sole reason).
In ECMWF's latest seasonal modelling (SEAS5) for summer 2026, a marked 'cold pool' in the North Atlantic really stands out.
I've seen research tentatively linking that with an increased propensity for high pressure to the east of it, & SEAS5 hints at such a response.
Looks like cool (or relatively so for some) conditions could reach all but the far southeast of England tomorrow.
With a reduced push of warmth from the southeast against that cool air, there might not be much rain along the boundary zone, mostly just grey weather.
If you like spatial contrasts then this afternoon is one to admire, a wide area of England reaching near 17°C in dust-hazed sunshine while the eastern half of Ireland shivers at 4-5°C with persistent rain.
The 1991-2020 average number of days between is 153.
The 5 shortest:
2025, 106
2026, 110
1991, 121
2019, 123
1997, 129
The 5 longest:
1975, 214
2013, 205
1954, 200
1970, 194
1962, 191
Not an important statistic but interesting to those of a certain mindset 😄
