Iceberg

Nhc have upped the feature to 80% chance. Visual shows some turning but it’s struggling to close of the West to east movement to close off the system. This should pick up as it approaches Florida before it enters the gom. Also we we have a lot of convection leaving Africa as an open wave.

Latest vis clearly shows the shear affecting the southern side of the cdo. Despite this a good looking storm with spectacular Banding.

This might well either impact the uk or the east coast if the US. Gfs 06z has again shifted westward, so certainly needs watching. Already quite a large storm with very nice Bandung A recent SSMIS microwave pass has revealed that the cyclone has become much better organized with more pronounced convective banding. Satellite intensity estimates are wide ranging, spanning from T1.5/25 kt from SAB to T3.4/53 kt from the UW-CIMSS ADT. Since the numbers overall have increased, and the structure has improved, the initial intensity is raised to 35 kt, in closest agreement to the TAFB estimate, but this could be conservative. This makes the depression Tropical Storm Florence, the sixth named storm of the season. Florence is moving west-northwestward, or 285/12 kt, and should maintain this motion for the next 48 hours while traveling along the southern periphery of the subtropical ridge. After 48 hours, the storm is expected to reach a break in the ridge, causing it to slow down and turn northwestward by day 5. The biggest change noted among the track models on this cycle was a westward shift in the overall guidance envelope. The European model, in particular, swung significantly to the left, showing a weaker Florence not feeling the break in the ridge quite as much. I'd like to see this trend continue before making a significant change to the forecast, so for now the updated NHC track prediction is only nudged westward. That said, the models appear to be trending away from a definitive recurvature scenario. The environment is mixed with positives and negatives for Florence's strengthening. For the first 3 days, vertical shear over Florence should be quite low, but the cyclone will also be moving through a less-than-ideal thermodynamic environment with marginal sea surface temperatures and decreasing mid-level moisture. After 3 days, the thermodynamic environment should begin to improve, but then the shear is forecast to strengthen. These conflicting signals point to only gradual strengthening, and the suite of intensity models aren't too far off from one another, nor from the previous NHC forecast. For that reason, no significant changes were made in this forecast package.

Gom still looking strong, latest ec has a quickly spun up hurricane at the expect 3-5th range. Also it has the new td 6 travelling much further west.

One of the most boring seasons in years might finally be about to deliver. The gom looks like it will provide a very fertile ground come 3-4 sept onwards. Anything entering it might well spin up quickly. With the moisture and instability coming across the Atlantic. It seems pretty certain that something will develop. Ecm has developed something for the last few runs often from open waves.

Nice looking cell just to the south in Dorset. Sweet and cute. Bless it. A bit of thunder from it.

Sorry if it’s been pointed out. One of the main differences between meto and gfs at t144 is the handling of the lp as it enters into scandy. Meto has a completely different picture, much deeper, therefore dragging down momentum pushing the Greenland high into a better shape. Gfs barely anything. Also the low pressure over Eastern Europe which gfs has and the meto doesn’t. Rather chalk and cheese like at a relatively near timeframe. Hence much bigger differences t168 and beyond. Meto far better for prolonged cold.

For me it’s not the depth of he cold per se but the temp differential caused by the uneven 850s and pockets of shallower warmer air. These will readily form waves, fronts and even low pressure systems with the warmer sector still -7 or so and -12 in the colder sector. These will produce high aptitude snow makers. A shown by gfs. As we get into the t96-120 time range the models will readily start to play with these features.

Ec ops clearly outside the ens window re pressure centring over us. Very little support for t216+ Synoptics

And the gfs shows exactly why this needs to happen. I am very happy that all of the models are moving to the scenario of a quick easterly exit. Some of them maybe reluctantly. The key is how quickly the really cold air can lift out of the states and whether any surface highs form over there. A difficult time for Models.

I think if folks want a a cold to very cold spell they are barking up the wrong tree cheerleading for the easterly. The chances of any significant cold getting dragged in is low thanks to the original direction of air from the high. Lots of middlish waa though, that could well just prolong a spell of rather boring weather. The large portion of pv needs to come out of Hudson. All the models tend to show this exiting on a very favourable se axis down to the southern med. Once this has happened heights should rise to the north east. The current high looks nice and I fully understand folks wanting to clutch to the near term straw but I fear it’s a false hope.

Ukmet is simpler and more amplified. However the angle on gfs at t144 isn’t to be sniffed and a few frames later will probably show some nice blocking the lp should pump up the waa readily on the gfs t144.

Completely agree. The models particularly the ens and eps have been hinting at the this. The trend has been the angle of energy thru the uk into France and then the med by t240. With such an angle a cold spell is always possible. Gfs has the waa to create a high pressure to our ne. Ec first quite fry there. There is also a stalling of the energy over the nw Atlantic. Which is consistent.

Here’s 6 of he first 10 eps members for Monday morning. I haven’t gone thru all of them but it’s pretty clear re the trend.

Control eps has the warm sector much smaller, goes thru quicker and drags in the cold quicker.

Monday morning on the control.

This is the control and probably the furthest north realistically. Most are further south.

The ec members eps are even better for Sunday. The control has snow for everybody away from the sw on Sunday 5-15cm and a majority of the members have snow from Devon upwards.

It’s not what most want to hear but there isn’t quite the blocking to the north to sustain the cold spell later this week. A few folks I am sure will get some snow, but for me it’s a decidedly timid affair. These two anomaly charts show that all isn’t lost though. In around 9-10 days time the blocking around Svalbard etc it much more pronounced and we might be able to tap into this to magic up a 2 week potent cold spell. A bit more waiting and at least it’s an interesting and potential radar watching few days.

And gfs demonstrates why the energy going under might be both good and bad. The angle of the jet needs to dive, for that we need the energy over the top, but we also need heights to build above so that a channel forms for the energy. Gfs 06z does neither we get very little snow and then a flat jet in the medium timeframe.

Energy under the high and not over it. Not sure whether this will be good or bad re snow but it’s certainly a big Change. It kind of supports the ec eps with greater North Atlantic blocking as a viable possible candidate.

Ec eps saves the morning for me. The ops fired the jet a bit too much for my liking with little ridging to the North Atlantic and a prelude to a flatter jet. I had hoped that the eps might help to show the col like conditions being replaced with more heights. Eps avg shows this nicely considerably higher pressure around iceland etc and so many more eps members give us a driver to help maintain the jet further south and west.

As long as the 500 flow remains significantly to the west of the uk and dives south, the low pressure systems will slide in dragging the colder air into the uk. The airmass should be cold enough at the surface 925mb to 1000 for snow for most and the ec snow charts continue to show snow particularly for western regions. It would be strange for a significant shift away from the upper flows for gfs and ec at the important t144-168 range. Hence the ens support from both models. All this being said the jet is ramping up and unless we see lots of help from northern blocking the pattern will kill itself pretty quickly.

Some of the most stunning ec eps runs for snow I’ve ever seen. Out to 10-11 days many, around 50%ish have considerable snow fall 5-15cm for large chunks of the uk. This is the eps master. But various runs have the snow in every section of the uk.

Snow depths from ec run by t240. Several inches 10-15cm in places. Warning though that this is purely an example of potential over the coming 2 weeks rather than a forecast but does chime nicely with the meto forecasts for dec.