Penellype's Weather Channel

[Penellype]

Lots of rain today in the north west, courtesy of a front which is finding it hard to make progress because of the high pressure to the south and east. This should start clearing slowly from the west soon, but it has dumped enough rain to cause some flooding in Cumbria.

The weather over the next few days is going to depend on what happens to hurricane Ophelia, which is behaving most unusually. Currently it is in the middle of the atlantic, but instead of moving towards America as most do, it is due to head towards Portugal and then turn north towards the UK. This is giving the models some headaches, although it is very clear that the first effects of Ophelia will be to bring us unusually warm temperatures for the time of year over this weekend.

Wednesday next week is the 30th anniversary of the Michael Fish hurricane and the media are having a field day as that is around the time when Ophelia may hit. Or may not hit. It is too soon to tell where it will go - currently models have anything from a glancing blow to the west and it remaining in the atlantic and affecting us for days to it passing to the north west of Scotland and disappearing fairly quickly into the continent to it sitting slap over the top of us. Wind strengths are equally various, with one reporter (not sure how reliable he is) saying one of the models has a category 1 hurricane off the coast of Ireland.

Hurricanes are not (supposed to be) able to maintain their strength this far north, although hurricane force gusts are very possible. This situation is so unusual that I haven't a clue how to predict what will happen, and I'm not sure the models are much ahead of me, so its a case of watching what happens over the nest week before getting too excited or worried by this.

Today's position:



Monday (according to the GFS model):



Not a very nice chart, especially for the west of Ireland.

[Lumpy]

This is probably a bit of a numpty question but......could the hurricane be acting unusually because of the near miss comet that went past us at 5am this morning. I know that the moon has a affect on our tides and weather but could something whizzing past only 30,000 miles away cause the difference?

p.s don't blame me if I've got it all wrong as th weather man was going on about it last night on the local news.

[Penellype]

Its possible. I don't know how big the asteroid was - any effect would be related to its distance away from us and its mass. I think this particular hurricane has formed rather further north than usual, and therefore is more under the influence of the jet stream, pushing it from west to east rather than east to west as usually happens in the tropics. But I don't know for sure.

[Martin H]

I thought it was an interesting question so I did an estimate of the gravitational pull of that asteroid. It got as close as one eighth of the distance that the moon comes, so the pull per ton would be around 64 times stronger. But the disparity in sizes is so huge that the gravitational pull of the moon would be 50,000,000,000,000 times stronger than that of the asteroid at its closest approach.

(The asteroid was said to be between 50 and 100 feet in diameter; I assumed 75 feet and assumed the same density as the moon).

Anyway, this should mean that the weather was not affected by asteroid 2012 TC4.

[Penellype]

Models are getting in a right state with next week's weather with some fairly extreme charts appearing at times. This one, from the GEM model for a week today looks somewhat hair-raising:



I think I prefer the GFS model for the same time:



Fingers firmly crossed!

[Greenleaves]

^^what do they mean please Penellype?

[lottie dolly]

IT looks like it might be,batten down the hatches,and any thing that can get blown or washed away,oooh errr,take precautions.

[Penellype]

^^what do they mean please Penellype?

The first chart shows a very deep area of low pressure sitting slap over the top of the UK. Low pressure generally means wet and windy weather. The blue colours also indicate cold upper air temperatures, which usually translates to cold or cool at the surface (but not always). However, the main concern here is the wind. The black lines on the charts are isobars, which connect areas of the same atmospheric pressure. Air flows from high pressure to low pressure in an attempt to even it out (which never happens because of temperature differences and the fact that the earth is spinning amongst other things) and the closer together the isobars are the stronger the wind. So if the first chart was correct it would be very wet and stormy, with severe gales across the whole country.

The second chart shows a weak ridge of high pressure over the country, with the yellow and orange colours showing warmer upper air temperatures. While there is no guarantee that this would be completely dry (because there is a low not that far away in the atlantic) the isobars are much further apart so it wouldn't be particularly windy, and would therefore be infinitely preferable to the first chart.

[Greenleaves]

Thanks for the explanation Penellype

[Chippy Minton]

Hmm, MetOffice seem to have something in between but more like the top one

Ophelia looks like trundling straight over Ireland so we'll be on the Eastern flank. Tie everything down, mark it with your name and phone number, close the curtains, open a bottle of something and turn up the telly!

[Penellype]

It is currently looking like being a very windy week next week. Hurricanes and ex-hurricanes are very hard to forecast accurately and can lead to big changes in weather patterns because they are so powerful. It is very rare to get a real hurricane off the coast of Portugal, which is what is happening this time, so the models are really struggling. But the most likely outcome at the moment does seem to be a change to wet and windy, if not stormy weather for a while.

[WPG]

We've had all sorts of weather warnings here about the imminent tail-end of Ophelia, expected late Monday.
There's been a craze for putting up those lightweight polytunnels at our allotment this year....I'm wondering how many will still be standing by next Tuesday.

[Thelma Sanders]

Wondering where they'll land - will be interesting - free bean frame anybody?

[Penellype]

Ophelia has strengthened to a category 3 hurricane this afternoon - the furthest east ever recorded for a major hurricane in the atlantic (not sure how far back records go). The Irish met agency have issued a RED wind warning for Galway, Mayo, Clare, Cork and Kerry and an orange warning for the rest of Ireland https://www.met.ie/nationalwarnings/default.asp:

STATUS RED

Wind Warning for Galway, Mayo, Clare, Cork and Kerry

Hurricane Ophelia is expected to transition to a post tropical storm as it approaches our shores on Monday bringing severe winds and stormy conditions . Mean wind speeds in excess of 80 km/h and gusts in excess of 130km/h are expected, potentially causing structural damage and disruption, with dangerous marine conditions due to high seas and potential flooding.
Issued:
Saturday 14 October 2017 13:18
Valid:
Monday 16 October 2017 09:00 to Tuesday 17 October 2017 03:00

STATUS ORANGE

Wind Warning for The rest of the country

Hurricane Ophelia is expected to transition to a post tropical storm as it approaches our shores on Monday. Mean wind speeds between 65 and 80 km/h with gusts between 110 and 130km/h are expected, however some inland areas may not be quite as severe. The winds have potential to cause structural damage and disruption, with dangerous marine conditions due to high seas and potential flooding.
Issued:
Saturday 14 October 2017 13:21
Valid:
Monday 16 October 2017 09:00 to Tuesday 17 October 2017 03:00

This is developing into a dangerous situation. Please be aware that the majority of fatalities from hurricanes are due to flooding, often from storm surges, so stay away from the coasts and stay safe if you live in the affected area.

[WPG]

All schools across Ireland - north and south - will be closed on Monday as a precaution.
I can't remember a precedent for that, think we're in for a rough time.