Showers & ME Radar

Discodog

I am puzzled as to why the radar is not showing showers further West. All week I have been checking the radar & showers appear to spring up when closer to land. Is this just due to the radar not spotting them further out or are they not forming until closer to land ?.

DOCARCH

The later I reckon and not helped by the fact that the Dublin radar is offline (and ME for some reason do not use Belfast radar).

Discodog

But why would showers tend to develop/intensify off shore ?. The radar shows tiny showers growing as they get closer to land. Is the sea temperature warmer closer to shore ?.

DOCARCH

Oh sorry, what I meant to say was the former! The radar simply is not picking up the showers further out.

Discodog

But it is managing to pick them up on the limit of it's range over Donegal.

Su Campu

Discodog wrote: »

But it is managing to pick them up on the limit of it's range over Donegal.

That's because there actually were showers near Donegal, and none to the west of Shannon. There are some small convective clouds alright, but much smaller than the ones near Donegal. This satellite pic is from the exact same time.





Showers only formed on the right flank of the upper trough, where deep layer shear was greatest. Further west, deep convection was surpressed.

Discodog

But all week I have been checking the radar & spotting clear spells. Then I have been surprised when a shower arrives that I didn't see coming on the radar. If you run that radar sequence you can actually see tiny showers appearing to enlarge as they get closer to the coast.

Deep Easterly

Discodog wrote: »

If you run that radar sequence you can actually see tiny showers appearing to enlarge as they get closer to the coast.

Most likely because in showery SW/WSW airflow showers can become a little enhanced as they skirt up along Galway Bay coastlines due to the relatively high terrain in south Connamara/north Clare. These can provide a little extra boost to weak coastal showers as moist air rises over them.

Edit: Actually, just looking at the last met radar, there are some showers coming in off the Atlantic currently:



One shower in particular seems to gain a bit of umphh as it passes over the Aran Islands. Possibly because winds are forced upwards as they come in contact with those steep high cliffs those islands are famous for.

Discodog

But look at the one to the South which peps up even though it is no where near land. This seems to happen a lot when showers are well away from land.

Oscar Bravo

A note from the Met Eireann site- Dublin Airport Upgrade works - May/June 2011. For the duration of these works, the rainfall radar images on this page will derive from the Shannon radar only. Users should be aware that radars do not detect all rain/showers within their field of view, and in particular will not detect rain/showers coming from lower cloud in the outer part of the radar range. The land area most affected southern Ulster and the eastern counties of Leinster.

Deep Easterly

Discodog wrote: »

But look at the one to the South which peps up even though it is no where near land. This seems to happen a lot when showers are well away from land.

You'll also note that some showers also weaken as they head towards the coast. One heading towards Clare for example. Showers rarely maintain a constant intensity as they move.