[5hort5]

Hi - With Ex-Katia approaching why does it merge with the low presure that's already just off Ireland and not swing around the bottom or top of it?

[Howard Kirby]

Looks like Ex Katia has got a deeper upper trough associated with it as it moves to the cold side of the jet. While the old low is being affected by the warm ridge that's being pushed ahead of Ex Katia.

[Cliffyboy1962]

I have another question.

How can such an innocuous area of cloud, that looks like an open wave, contain 60 mph winds ?

Ex-Katia's satellite presentation does not look anywhere near as impressive as the models show on the surface pressure charts. Is it going to interact with the existing low to somehow strengthen the existing low ? The models don't seem to show two distinct areas of low pressure, but one, suddenly deepening.

Or have the models simply overdone the strength of Ex-Katia ?

[Dave W]

Not that innocuous as it has deep low pressure contained within it - about 958mb at 00Z acc to UKMO. Theres only the 1 area that develops a strong baroclinic gradient Cliff in what UKMO think is a blended between classic Norwegian low and a SK low , it starts more like an SK low as a kind of warm seclusion develops but it has an upper cold front that does meet the warm front eventually & occlude ; the other low low fills and decays , which gives the strong winds, as usual mainly to the south & SW of the low centre. The strongest gusty winds dont reach Scotland till late Monday now.