Atlantic wave heights – Ophelia v Brian

Figure 1

During the gales of the last week across the country from ex-Hurricane Ophelia and storm Brian there have been some quite stormy seas, so I thought I would just compare the wave heights from three of the fixed weather buoys in the network of buoys that’s maintained by the Met Office around the British Isles. They aren’t quite as good as the weather ships of old such as Juliet, Lima and Kilo, and neither do they launch radiosondes or pilot balloons, but they are much more cost-effective. It’s hard to believe that some old observers in the Met Office made a career of manning these weather ships but they did. I never did get the chance to volunteer for that, neither did I get that detachment to Gan, or get a chance to fly in a F6 Lightning,  but that was my fault because I chickened out.

Figure 2

To the northwest of the British Isles (fig 1), neither Ophelia or Brian produced anything particularly high at weather buoy 64045 (K5), although you will notice that wave heights have picked up in the last couple of days thanks to the deep low Florenz much further to the west (fig 2).

Figure 3

Weather buoy 62095 situated to the west of Ireland (fig 1), was obviously too far west to be affected very much by Ophelia, but Brian did produce some 8 metre waves, and like 64045, there have been waves of 6 metres or more there in the last 24 hours or so (fig 3).

Figure 4

Finally 62029, which is situated to the southwest of Ireland (fig 1) responded to both Ophelia and Brian with 11 metre waves (fig 4). The winds from Brian lasted much longer than they did with Ophelia, and produced a 11.9 metres wave (39 feet) at 22 UTC on the 20th of October. This is far from the record wave height reported from an automatic weather buoy of 19 metres (62 feet and 4 inches) that occurred at K5 on the 4th February 2013, but still impressive nonetheless. Can you imagine what it would be like being in a ship with waves that high?

We’ve had Brian now it’s Florenz’s turn

Figure 1

An interesting cap of upper cloud which must be associated with a warm sector at 22° west in the Atlantic associated with an intense occluding low at 35° west, which believe it or not the BMI have called Florenz!

Figure 2 – Courtesy of the Met Office

Storm Brian a bit of a no-show

Figure 1

I have to admit it that in the cold light of the synop observations of wind speed for yesterday until 08 UTC this morning, storm Brian was a bit of  a no-show, and the Met Office were correct in distancing themselves from the naming of it. It looked pretty ferocious on Friday, but Brian was already occluding and starting to fill when it arrived in northwest Ireland, as the models correctly said it would be. The yellow warning issued by the UKMO, could have mentioned possible gusts to 80 mph (fig 2), and the state amber issued by Met Éireann was not really necessary, but they are probably still jittery after the intense exposure they got from Ophelia on Monday.

Figure 2

Coastal waters and headlands took a pounding as they always do, but actual gales when 10 minute mean speeds reach 34 knots or more, were confined mainly to the Atlantic coasts of southwest Ireland and southwest England, the eastern coast of the Irish Sea from St Bee’s head south and the Bristol Channel (fig 3).

Figure 3

I’m personally glad to see the back of Brian and move onto Caroline.

Cherry picking wind speeds

Figure 1 – Courtesy of Twitter & the Met Office

It strikes me as strange that when the Met Office need to justify a named storm or a yellow or amber warning that they’ve issued for strong wind, how they can seemingly pluck observing sites out of thin air, some of which you might never have heard of before, such as:

  • Berry Head, Devon
  • High Bradfield, South Yorkshire
  • Needles Old Battery, Isle of Wight
  • Orlock Head, County Down
  • Salsburgh, North Lanarkshire
  • Avonmouth, Avon
  • Lydd, Kent

But when the winds have been a little stronger than they forecast, as was the case today with storm Brian, they seem to be able to exclude some stations from the graphics they generate (fig 2) as if the offending station didn’t even exist. In fact the winds are higher in western coastal districts of Wales than anywhere in Ireland, the difference is that Met Éireann did issue an amber warning for gusts to 80 mph, and the Met Office didn’t. I would like to use observational data from these sites myself, but I can’t access them, the reason being that they don’t have a WMO number, and don’t report a regular SYNOP observation, more’s the pity.

Figure 2

Overnight gusts from Brian

Figure 1

Met Éireann might have a state amber warning in force for gusts to 80 mph, but the highest gusts overnight (as there were with Ophelia on Monday) have been in the southwest of England and the west of Wales, with gusts to 78 mph at the Sevenstones lightvessel and 71 mph at Mumbles head at 06 UTC this morning, both exceeding the 70 mph in the yellow warning issued by the Met Office yesterday. I doubt if the Met Office will update this warning, and are just hoping that the gradient doesn’t tighten anymore and there won’t be anymore gusts over 70 mph.

Brian is a stereotypical low that you get every so often in Autumn and Winter across the British Isles, but the way the threshold of the yellow and amber warnings are pitched means that we get into this situation with almost every low that comes along. Is it yellow or is it amber, which is complicated further with the storm naming. Perhaps if the thresholds were based on mean speeds as well as gust speeds, then a mean speed of 34 knots at a coastal site could be the yellow threshold, and a mean speed of 34 knots (gale force 8 or 39 mph) at an inland site amber? Well it’s just an idea.

Dangerous Brian

Figure 1

Two spiralling extratropical storms in one week as dangerous Brian moves in off the Atlantic. I notice that the pressure at 62095 (‘0’ marks the position of weather buoy 62095 in figure 1, and the inset plot grid in figure 2), which is just to the north of Brian, has started to bottom out at 975.9 hPa, but Brian will continue to deepen to 964 hPa by midnight according to the forecast chart from the Met Office. I notice that the wave height being reported from the weather buoy 62442 at 49° north are already 9.2 metres (30 feet), and the wind there has veered westerly gale force 9.

Figure 2

Storm Brian

Figure 1

Storm Brian was named by Met Éireann yesterday, and reading the news item that the Met Office issued, it looks like if it had been left up to them they wouldn’t have even bothered. As well as naming the storm Brian, Met Éireann have also issued a status amber and yellow wind warning for Saturday for gusts of up to 80 mph (fig 1), and notice that in their warning they specifically mention the expected maximum mean wind speed of 40-50 mph, which makes for a textbook warning as far as I’m concerned (fig 2), and which the Met Office refuse to do.

Figure 2 – Courtesy of Met Eireann

Arguably, the gradient on the latest T+36 from the GFS model is just as tight across the southwest of Wales as it is across Ireland (fig 1), but the Met Office are sitting on their yellow warning, but have enlarged the area (fig 3). This time the Met Office have chosen to use the old 45-55 mph but with 60-70 mph gusts around the coast ploy. I would have thought that there would be gusts to at least 80 mph on the Welsh coast on Saturday, as there were gusts to 90 mph there on Monday when they only had an amber warning for gusts of 80 mph in force.

Why take any chances?

Why not just issue an amber warning for gusts to at least 80 mph for coastal areas, and leave the yellow alert for inland areas?

Half the problem, I’m sure, of why they don’t do this is because of their reliance on hand drawing the various warning areas. If this web interface was improved by the use of a GIS system, they could then much more easily highlight an amber area at regional authority level or even postcode level around the coasts. The finished product would be more accurate, professional and directly tied to the individual grid point wind gusts from the NWP model.

Figure 3 – Courtesy of the Met Office

Whether the wind gusts will reach the yellow or amber threshold (which I guess is 80 mph) depends on when the rapid intensification of Brian occurs, if it’s later, or if it goes on slightly longer the winds will be that much stronger. The Met Office are in no doubt that it’s already underway and by the time the low reaches Ireland it will be already well occluded (fig 4).

Figure 4 – Courtesy of the Met Office

I notice that the process is already well under way at 62095 (fig 5).

Figure 5

For God’s sake just give it a name!

One of my subscribers asked me a good question in a comment he made: Why haven’t Met Éireann already renamed Ophelia storm Brian?

The answer to that is that it’s just a matter of time before Met Éireann do name it storm ‘Brian’, but because Ireland will be impacted first, they probably get to make that call.

To my mind this is a unique and very unusual event, it’s already memorable, and it hasn’t even happened yet!

Here are a couple of questions for you to ask yourselves:

First question : Can you remember storm Clodagh? I’ll give you a clue, it occurred on the 29th of November 2015?

Answer : No, that must be one that passed me by.

Why couldn’t I remember Clodagh? Because like 90% of all named storms it was completely forgettable, that’s of course if Clodagh hadn’t blown a tree down on top of your car or house!

Second question : Can you remember Ophelia?

Answer : Yes, that’s the hurricane than spun up out of the blue in mid-Atlantic, bringing severe gales to Ireland, exactly thirty years TO THE DAY since the ‘great’ storm of the 16th October 1987, how could I possibly forget that!

Come on for God’s sake Met Éireann just name it Brian and be done with it!

Hopefully, in years to come, people will look back and remember it as Ophelia, and not storm Brian.

Was the October storm of 1987 the result of ex-hurricane Floyd?

Figure 1 – Image courtesy of NOAA & Wikipedia

With the 30th anniversary of the ‘great’ storm of October 1987 now just a few days away, I thought it was about time that I looked into the rumours that ex-hurricane Floyd had something to do with it. After looking at some surface pressure charts for the Atlantic from the 12th to the 15th , I can now see how this speculation came about, and also better understand that Floyd was the hurricane that Michael Fish was referring to in his now infamous forecast when he said:

“Earlier on today, apparently, a woman rang the BBC and said she heard there was a hurricane on the way… well, if you’re watching, don’t worry, there isn’t!”

In the prologue to the book ‘Storm Force‘ which he co-authored, Michael Fish does explain that he was talking about hurricane Floyd and:

“…my remark had NOTHING to do with the storm”

He goes on to add that the infamous forecast:

“…was NOT made the evening before and NO woman rang the BBC

Looking at the video on YouTube of the now infamous forecast, it’s not entirely clear to me at what time it was broadcast. It could have been from late the evening before (14th), but it seems more likely it was the broadcast after the midday news on the 15th, because rolling 24 hour news from the BBC started much later than 1987 as far as I remember. Michael Fish reminds us in his prologue is at pains to explain that it was Bill Giles who was the duty forecaster that evening (15th), and it was he who uttered the immortal line:

“…it will be a bit breezy up the channel”

As Michael Fish reminds us:

He kept quiet about this  until he had collected his OBE and retired!

The culprit as we know was not any of the messengers, but a combination of poor guidance from Bracknell, poor forecast from what now looks a rather crude and unsophisticated NWP model, which itself was due in no small part to a dearth of ship observations from Biscay during the afternoon. Anyway I digress, as I so often do these days, so back to the main point of this blog.

Is there any truth in that speculation, that the October storm was the remains of ex-hurricane Floyd?

Figure 2 – Data courtesy of the NHC

Floyd had just slipped past the southern tip of Florida as a hurricane on the 13th of October 1987, here’s the reanalysis chart for 00 UTC (fig 3).

Figure 3 – Data courtesy of NCEP/NOAA reanalysis

The chart below (fig 4) shows the last position listed in the Hurdat2 archive for ex-hurricane Floyd, and this is how Wikipedia described the demise of Floyd.

Unexpectedly the storm turned sharply northeastward into the southeastern Gulf of Mexico. Based on reports from the Hurricane Hunters, Floyd briefly attained hurricane status on October 12. Around the same time, the nearby cold front spawned a low pressure area that cut off the hurricane’s inflow. While moving through the Florida Keys, Floyd became the only hurricane to affect the United States that year. However, its convection was rapidly decreasing over the center due to the front, and shortly thereafter Floyd weakened to tropical storm status. The circulation became nearly impossible to track on satellite imagery, although surface observations indicated it passed just south of Miami, Florida. The storm underwent extratropical transition as it weakened over the Bahamas, and Floyd was no longer a tropical cyclone by late on October 18*. The circulation dissipated within the cold front early the next day.

Figure 4 – Data courtesy of NCEP/NOAA reanalysis

And below (fig 4) is the position of the embryonic low that became the ‘great storm’ at 00 UTC on Thursday the 15th of October. I’ve measured the approximate distance between the last observed position of ex-hurricane Floyd and the first of the October storm, and its a whopping 2,600 nautical miles, and even if it had been doing over a hundred knots as a surface feature, Floyd just couldn’t have made it. Perhaps at the middle and upper levels if there had been a jet that spanned the Atlantic from the Bahamas to western France which was blowing at 240° and 100 knots, tropical air from Floyd could have been pulled eastward to fuel developments in mid Atlantic. I’m no expert, but I suppose it’s possible that tropical air somehow got entrained into a developing extratropical low, Floyd did rather mysteriously turn to the northeast and lose intensity as the Wikipedia article points out, but I would have to download more reanalysis wind data for 500 hPa and above to check if that could have been the cause, there’s nothing quite like a good conspiracy theory is there?

Figure 5 – Data courtesy of NCEP/NOAA reanalysis

As we now know the rest is history (fig 5) even though the coarse grid of the NCEP reanalysis doesn’t quite get the intensity of the October storm.

Figure 6 – Data courtesy of NCEP/NOAA reanalysis

*This slip may be intentional or not, but I reckon that 18 should be a 14 according to the NHC record.

Met Office: 30th Anniversary of the 1987 Storm

There’s been an interesting news release from the Met Office late this morning regarding the anniversary of the October storm in 1987. The best thing about it the news release that it includes a full size jpg of the machine plotted and hand contoured chart for 02 UTC on the morning of the 16th, what a busy night shift that must have been!  I hope they don’t mind me including a snippet from the bottom left hand corner of it in this blog! The news release makes interesting reading about how times have changed in the last 30 years as regards communications, and the power of supercomputers, that now allow NWP models to be run at even higher resolutions.

There’s an interesting video of just how the forecast would be handled thirty years later by Alex Deakin, which unfortunately has an image of a typhoon or cyclone behind him (0:47) rather than a hurricane. The puzzling thing that I can’t understand in the video is the reference to it as storm ‘Quentin’?

The news release even makes a brief, but indirect mention to the possibility that Ophelia might be another one, but if it does, it would be from the remains of a tropical cyclone, which the October 1987 storm wasn’t.

We can’t say we won’t see another storm like the one in 1987, but we are able to better forecast and warn of severe weather, helping to minimise the impacts by working with our partners and emergency responders, and the general public to prepare and take action all helping to protect life and property in the future.