The Enforcer

That might explain the aforementioned difference in the precipitation pattern - an upper warm front in the south east corner.

What intrigues me is the marked difference in how north of The Wash and Thames estuary convergence lines look on the radar. The former has produced lines of showers with bright echoes denoting heavier bursts. The latter is a single wider area extending as far west as the showers further north, but consists of mostly light snowfall with heavier elements almost exclusively east of London. This is very similar to the precipitation pattern that developed a few weeks ago. Is there a reason for this difference?

An existing rather than a developing front this time, but has already reached the west coast by 12pm Saturday, when it does weaken. The snow warning for late Friday/early Saturday was eastern coastal counties only, so I'd expect this to get extended further westwards on the basis of these charts and what you are saying about the ECM output.

Appreciate the clarification. A promising development for those who like snow-bearing cold fronts, although met office snow warnings just out ignore this feature with snow warnings late Friday/early Saturday and during Sunday, but nothing when the front is there. Must indicate very low confidence.

Hi, you describe the cold front as a weakening feature, but I thought that a cold front with dots rather than lines between the triangles was a developing feature? Cheers, TE

Ended up with a maximum total of around 5cm once levelled off built up slowly over a few days of mostly light snowfalls with the odd heavier spell. Now melting at 2C. Similar amount to what we had on December 10th.

January 2010, Central Southern England.

Faxmania time again: Thursday: T+96: T+84: T+72:T+48: Friday: T+120:T+96:T+84:T+72: Saturday: T+120:T+96: Sunday: T+120: Commentary: Tendency for warm fronts to make less northward progress before occluding and fading. Surface pressure charts for Saturday looking more similar to a repeat of Friday.

Fantastic work. If you are able to post a comparison between the 00z and 12z rain/snow charts I would be very grateful.

Good - having experienced the 23/24 January 1996 example, that was quite enough.

Here's how the faxes have developed Friday's conditions so far: T+120: T+96: Summary: Low further south-east and flatter. Frontal boundary further south in the south-west and further north in the south-east, occlusion slower. 528DAM line further north.

Apologies, I don't know my east from west either. So, it's reasonable to assume a south-westwards to westwards extrapolation of showers out from the line of the convergence zone. Ok, so the upper front is bad news for snowfall and ideally it should go away.

Two questions: 1. Will showers forming over those convergence zones continue to track in a line moving in a south-eastward direction? 2. What is the difference in relation to snowfall between the upper front and the warm front? Cheers, TE

The last 'big' easterly [December 2010]: If we lose this now...

I noticed earlier that the 850 temperatures on the GFS 06z, having been consistent for around a week have suddenly jumped starting at T+0 both ahead and behind the front, making the mild sector bigger (compare with GFS 00z) to be in line with the limited UK snow on that chart. At least the channel snow anomaly has been removed.