summer blizzard

Yes, here in BD19 we've seen thunder, lightening and a degree of hail although mostly rain.

Is any of this thundery, it's pretty muggy for what the sensor says is 18C.

Addicks Fan 1981 Thought you'd like this. It will probably change so don't base a forecast or anything meaningful from it but for the first time, the GFS is forecasting a wall of trades to be strong enough to kill the progression of convection across the Pacific. Notice the fairly vertical blue just east of the dateline.

Addicks Fan 1981 As Don says, cycle 25 is stronger than 24 but below 23 which was almost statistically bang on average. One hemisphere already peaked so 2025 is likely to see the outright peak but after the first hemispheric peak you normally start to level. I also doubt that solar activity produces warm months overall. Enhanced westerlies in winter are warm but in summer are potentially cool at our latitude.

No 20C here as yet, not especially late though. Hopefully a signal.

24APR2024: Nino3: 0.6, Nino3.4: 0.8, Nino4: 0.9 April ONI is +0.9.

Suspect the model differences relate to the progression of convection through the Pacific. Although I don't have the Euro chart, the GFS has weakened this a lot in recent days though it is still progressing.

WYorksWeather I'd be pretty dubious of that and suggest it's likely noise rather than signal. That is to say that years with a late final warming and stronger than average vortex may be followed by a +AO but the forner is not likely the cause. I don't really see much reason why slightly weaker net easterlies in the stratosphere would result in westerlies further down the troposphere. They are still trying to impinge net easterlies on the troposphere.

Addicks Fan 1981 Posted earlier in this thread but essentially the La Nina's that are not declared by JJA on ONI tend to be relatively blocked with the Azores High close to the UK. 2016 was in that group. La Nina's which go guns blazing tend to have a cyclonic July and August and end up stronger on average. Currently we are marginally on course to be in the slower group (dropping around 0.3 per month).

SqueakheartLW An above average season is very likely but shear profiles make or break ACE and that might not be extremely high this season. While we have the weak La Niña strengthening (likely) and warm SST’s, we also have a very negative PDO and for some reason this has in some seasons been correlated with an imperfect shear profile.

reef I suspect that the SSW impact is producing the blocking episodes given that the tropics have been fairly muted but SSW’s dont guarantee everlasting north blocking and cool weather here. In this case it’s just produced downwelling periods of weaker zonal winds that we’ve occasionally tapped into. With the tropics becoming active again in the west Pacific, I’d imagine we will lose any northern blocking into early to mid May.

12.4, 54mm. For the first time in some time, i see an anticyclonic pattern. Blocking over the UK and to the north and east. Shades of last May.

Something to watch but signs of a WWB progressing east into May which may generate mid-lattitude blocking closer to mid month.

17APR2024: Nino3: 0.5, Nino3.4: 0.7, Nino4: 0.8

B87 Strong trades around the dateline (easterlies) typically strengthen the mid-lattitude jet in response (stronger westerlies) and suppress AAM. It's why a lot of people tend to think that La Nina produces less favourable summers for the UK.