Nick F

It looks like a reflection in the troposphere of the stratosphere will be in early March, so a little early yet, next week's changes troposphere driven - i.e. amplification of the upper flow from the lag of MJO moving into phase 7 as of today, albeit not a particularly high amplitude with AAM near neutral, hence struggling to get the high far enough north for long.

Yes, EC seems determined to give nothing of note snow and cold-wise for the next 10 days away from the highest ground. But a great deal of uncertainty after T+120 between models over where troughs merge or disrupt, which has knock on effects over how much cold we can tap into

Some possible strat-trop coupling from top down reversal of the 2nd warming still evident on 00z GEFS / EPS height anomalies 60-90N from the tweet below: 12z GFS still not getting the reversal down into the trop as far at 60N yet - but signs of a weakening of zonal winds from above at least.

Not too shabby from UKMO for next Friday, will feel raw in the NE wind, temps in low single figures at noon, DPs sub-zero:

Afternoon, may be back on here a bit more now the weather may turn a little more interesting to end the month and as we head through early March. Quite the difference between UKMO/GFS and EC/GEM middle of next week with regards to the position of the upper trough. UKMO/GFS bullish to have the trough just to the east with a cold northerly Weds-Fri next week. 12z GEM and 00z EC bullish to have the trough further west and disrupting over the UK, with a cold northerly wasted over Atlantic to our west. A look at the 12z GEFS mslp mean supports the UKMO/GFS idea of trough just east mid-late next week, 00z EPS was a little further west with the trough axis but not as much as the 00z EC det/ GEM, so be interesting to see if the 12z EC backs down and moves towards UKMO/GFS (or not!) 12z GEFS mean for 12z Weds next week & 00z EPS for same time

A look back at some notably warm, cold or stormy Valentine's Day in the past View the full blog here

Mostly dry for the first half of this week, with high pressure in control, southerly winds from Iberia bringing increasingly mild air and also Sahara dust by Wednesday. From mid-week, fronts looks to bring cloud and occasional rain east across many areas, perhaps very wet with gales in the north early Friday. View the full blog here

A look at the Sudden Stratospheric Warming next week and what implications this may have on our weather a few weeks later. There's not guarantee that it will bring the Beast from the East like 2018 as suggested by the media, but it may increase the risk of a spell of cold and wintry weather into early March. View the full blog here

Yeah maybe, we await the 12z GFS cross section on weatheriscool.com - but previous runs the downwelling of the reversal didn't appear to reach anywhere near the trop towards then. The late Feb 2018 change in the trop that brought the BFTE not too dissimilar in area that +ve heights appeared over NE Atlantic up to Svalbard: 24th Feb 2018 12z GFS for Sun 26th This was the 15th Feb 2018, note the strong TPV to the NW of UK like we're worried about in next few weeks: Of course, we are dealing with a displacement this time, not a split like 2018, so I would expect it may take longer for a trop response to the sustained reversal way up and perhaps not as similar as 2018 response either, that's if high latitude blocking is the response! Original post: https://community.netweather.tv/topic/98326-model-output-discussion-into-february/?do=findComment&comment=4804817

Yeah maybe, we await the 12z GFS cross section on weatheriscool.com - but previous runs the downwelling of the reversal didn't appear to reach anywhere near the trop towards then. The late Feb 2018 change in the trop that brought the BFTE not too dissimilar in area that +ve heights appeared over NE Atlantic up to Svalbard: 24th Feb 2018 12z GFS for Sun 26th This was the 15th Feb 2018, note the strong TPV to the NW of UK like we're worried about in next few weeks: Of course, we are dealing with a displacement this time, not a split like 2018, so I would expect it may take longer for a trop response to the sustained reversal way up and perhaps not as similar as 2018 response either, that's if high latitude blocking is the response!

MJO phase 7 10 day lag amplification or trop response to SSW displacement / reversal?

IMO going to take a while to break down the trop polar vortex to our NW, looks like it's going strong even into late Feb, but a look at GFS cross section of the u-wind through the atmosphere suggests that although the reversal looks sustained, it's in no rush to propagate down to the troposphere. But hopefully we can get some help from the lag of the MJO speeding through to the western Pacific phases 7-8 by mid-Feb, could see some upper flow amplification over N Atlantic / Europe by 25-28th Feb being picked up by the NWP.

Interesting chart posted on twitter this evening of composite height anomaly 0-30 days following SSW displacement events during La Nina since 1990. Suggests N Atlantic and Greenland ridging and low heights over northern / northeastern Europe. Original post: https://community.netweather.tv/topic/98326-model-output-discussion-into-february/?do=findComment&comment=4804500

Interesting chart posted on twitter this evening of composite height anomaly 0-30 days following SSW displacement events during La Nina since 1990. Suggests N Atlantic and Greenland ridging and low heights over northern / northeastern Europe.

I guess if there is something of interest happening in the troposphere, where our weather happens, there'd be more chat about what the models are showing for mslp/500 hPa for the next 15 days But, alas, there is very little of interest showing from all models at the moment, hence why a lot of posters are talking about the imminent strat reversal, of which is looking 100% likely, and its possible effects, in tandem with possible upper flow amplification from MJO reaching the western Pacific later this month, on the troposphere. We are still some way off the models responding to these two drivers which may force a big change to upper patterns, given the reversal will take a few week to work down and the 10 day lag of the MJO, we may have to be patient until we see more interesting output from the NWP in the trop. At least, for now, GFS is showing the reversal remaining longer-term high up, but it looks like it may take a while to work down at 60N, but perhaps will be quicker at high latitudes. Original post: https://community.netweather.tv/topic/98326-model-output-discussion-into-february/?do=findComment&comment=4804257

I guess if there is something of interest happening in the troposphere, where our weather happens, there'd be more chat about what the models are showing for mslp/500 hPa for the next 15 days But, alas, there is very little of interest showing from all models at the moment, hence why a lot of posters are talking about the imminent strat reversal, of which is looking 100% likely, and its possible effects, in tandem with possible upper flow amplification from MJO reaching the western Pacific later this month, on the troposphere. We are still some way off the models responding to these two drivers which may force a big change to upper patterns, given the reversal will take a few week to work down and the 10 day lag of the MJO, we may have to be patient until we see more interesting output from the NWP in the trop. At least, for now, GFS is showing the reversal remaining longer-term high up, but it looks like it may take a while to work down at 60N, but perhaps will be quicker at high latitudes.

Nice to see some of the Berlin / EC strat charts back, though only the geopotential heights/temps available, be good to see the cross sections and wind fluxes return too.

Little or no rain for much of England & Wales looking likely until at least mid-month, this may be a welcome break from the very wet weather last month, but reservoirs in some parts of the UK still need further topping up after drought in 2022. View the full blog here

We do have a weakening La Nina and MJO moving into the western Pacific to add to the emphasis for a pattern change later this month, perhaps before any downwelling effects of the SSW - which could reinforce any amplification / high lat. blocking that develops from these drivers. But we may have to endure a few weeks of +NAO. GEFS seems more bullish than EPS to hang on to Euro high anticyclonic influence at day 10, EPS more cyclonic, looking at H500 means:

Fog and 1C at Heathrow at the moment. Was quite pleasantly warm in the sunshine yesterday, starting to feel the sun's gaining strength now, but could feel the chill to the air in the shade.

It will liven up in the model output for the troposphere in week or two I reckon, not just from possible effects of the SSW, but also the MJO moving into the western Pacific and the rise in AAM. At the moment it looks like classic La Nina / MJO 'warmer phases' driving the show in the model output for the trop.

It's a classic English metaphor meaning an incentive to keep moving forward to reach the carrot (in this case an SSW)

My goodness, it's as exciting as watching paint dry flicking through each model run through the end at the moment. +heights over Europe, low heights to the northwest. It's a good job we have the carrot at the end of the stick of the likely major SSW mid-month, but at the moment it looks like a displacement rather than split. February with a displacement since 1980: 28/1980; 23/1984; 17/2002; 23/2007; 22/2008. 1981 and 1984 both featured a cold March, 1984 was cold late in Feb via easterlies. But those other years with Feb displacements there was nothing of note. So don't pin your hopes that the SSW will deliver cold and snow, especially if a displacement.

Ground drying out nicely on the hills around here for the dog walk, something about the late afternoon light today catching the bare trees in the woods that looks mysterious, especially the beech trees with their sprawling roots.

Very high atmospheric pressure at the surface this morning, 1048 hPa over Wales, very likely linked to the intense trop PV dropping over the far NW Atlantic that is bringing very cold air to NE USA / eastern Canada atm and causing strong WAA aloft downstream. Highest pressure for February in the UK, appears to be 1052.9 hPa recorded at Aberdeen on 1st Feb 1902. Probably be some individual weather station records being broken today, particularly Wales and parts of the southwest. Original post: https://community.netweather.tv/topic/98326-model-output-discussion-into-february/?do=findComment&comment=4802020