Atlantic SST – Is this the end of the cold blob?

Figure 1 – 24 November 2015

Figure 2 – 27 November 2016

Figure 3 – 22 November 2017

You can tell just by looking at these sea surface temperature charts since 2015 (figs 1-3) that there’s been considerable warming going on in the last two years. The cold anomaly that was a feature for so long in the central Atlantic is now less intense and much smaller a feature than it once was. It’s shifted and has been squeezed further northeast towards the southeast coast of Greenland and the opening of the Labrador Sea.  The other notable difference that’s appeared in recent months is the area of warmer SST anomalies ~1500 km to the west of Portugal (42N 17W), a warm blob if you like.

The warm blob and this coming winter

To be honest I don’t have a clue if this warm blob will have the slightest effect on the weather in the British Isles this coming Winter. It would be nice to think that the area of warmer SST might weaken the Azores high in some way, and that might increase cyclonic development in the southeast Atlantic which will run northeastward towards Biscay – who knows. Looking at the actual MSLP anomalies (fig 3) for so far this month, it’s true that the Azores high is displaced further to the northeast, but all this has done has been to increase the strength of the zonal flow across the Atlantic. In fact everything seems to be enhanced in some way, if you look at the underlying anomalies (red dashed line) both highs and lows have been more intense in the first three weeks of November 2017 than usual.

Figure 3 – Data courtesy of NOAA/NCEP reanalysis

Autumn Sea Ice figures

Figure 1

It might be thinner than ever, but Arctic sea ice this Autumn is doing much better than it did last year, with the sea ice extents up by around 800,000 square kilometres at 88.2% of the 1981-2010 long-term average, compared with being only 81.0% of average in November 2016 (fig 1).

Figure 2

In the Antarctic things are also not quite as dire as they were last Autumn, and although this Autumns sea ice extent is tracking well below the x 2 standard deviation area (light grey) at 91.6% of the 1981-2010 long-term average, it’s almost a million square kilometres higher than at the same time last year (fig 2).

Early November Arctic temperatures

Figure 1 – Data courtesy of NCEP reanalysis

There’s the usual ring of abnormally high positive temperature anomalies around the Arctic at the start of November (fig 1). I had a theory that the largest anomalies were located in areas of open water where no sea ice had formed, but this theory doesn’t look too plausible judging by the latest sea ice extent chart (fig 2). I notice that the recent cold weather in Canada has encouraged early ice formation around the coast of the Hudson Bay, but the area to the north of the Chukchi sea look severely depleted of any sea ice again for this time of the year.

Figure 2 – Data courtesy of the NSIDC

 

Guardian: Ophelia’s arrival hints at a new vulnerability for Europe

My first reaction to this article in the Weatherwatch section of the Guardian was to measure the distance in miles between the Isles of Scilly and the nearest 26°C SST isotherm and then divide by thirty!

Figure 2

And so if the North Atlantic did continue to warm at this rate (with the 26°C SST moving 30 miles every 10 years), you can expect the 26°C SST isotherm to be lapping on the beaches of the Cornish Riviera in a little over 692.7 years in the late summer of 2709!

I do think Paul Brown did manage to completely miss the point with this article about Ophelia though, and instead of repeating the “hurricanes only form over water of 26°C” mantra like we’ve never stopped hearing from the BBC weather presenters of late, the question that he should have been asking was “why did Ophelia intensify to a major category three hurricane over an Ocean with marginal SST of between just 22 and 24°C“?

Ophelia : The life and death of a hurricane

Figure 1 – Provisional track from NHC and Met Office

Ophelia was born on the 9th of October as a tropical depression at 09 UTC in the mid-Atlantic somewhere to the southeast of the Azores. Her early days were spent meandering around the place of her birth, at times it almost appeared that she was going around in circles. Then suddenly one day her life found a new direction, and she decided to head off and take a swipe at the British Isles, so off she went tracking ever more faster each day in a northeasterly direction. She made good progress, and before long she surprised every on by becoming a category 3 major hurricane! She had become the furthest east major hurricane in the satellite era! But then rather unexpectedly (to some people’s mind’s at least) and just as she was closing in on her intended target, someone called (Ice) Berg in America decided that her life as a hurricane was at an end, and he declared her a post-tropical cyclone! Not to be outdone she put on an extra spurt and deepened from 971 to 958 hPa to show them she was not finished quite yet. The rest as they say is history…

Figure 2

 

For the purists out there that say that hurricanes can only survive in oceans with a SST of around 79 °F (26 °C) or more, how did Ophelia manage to steadily intensify from a category 1 to a category 3 major hurricane in the Atlantic Ocean during on the 14th of October southeast of the Azores, with SST that were much colder (fig 2), between only 22°C and 24°C?

Please don’t bother replying with comments about how “the large temperature contrast between the abnormally warm seawater and the extremely cold temperatures in the upper atmosphere” providing instability for Ophelia’s thunderstorms “which allowed the storm to continue strengthening” because I simply won’t’ believe you!

If Ophelia can intensify over cooler waters like she did, then there is no reason not to accept that the NHC killed Ophelia off around 12 hours too soon, I think she survived till at least 09 UTC on the 16th of October and close to 51° north. She might have looked pretty crappy in the visible images as she approached Ireland  early on Monday but her inner core winds that had driven her down to 951 hPa were still spinning.


FAAM and its relationship with the Met Office

Why wasn’t it possible for the Chief forecaster at the Met Office to call on the services of the Facility for Airborne Atmospheric Measurements [FAMM] and get them to fly their modified BAe 146-301 large Atmospheric Research Aircraft [ARA] to the Azores on Saturday afternoon and back again during Sunday, drop a couple of dropsondes into the eye of Ophelia, and run their fancy array of sensors over her?

All their findings could have been passed onto the NHC and fed directly into the NWP models around the world to get a better fix and track on Ophelia during the next 24 hours, all excellent meteorological research.

How come the Americans can afford to send a hurricane hunter out every six hours to investigate a tropical cyclone whenever an island in the Caribbean or the coastline of America is threatened, and yet when the tail end of a hurricane threatens our shores, we just curl up with a good book and issue a couple of warnings?

Of course it may have been that they did ask them, but maybe they were just too busy investigating stratocumulus, volcanic ash or contrails, and just couldn’t find the time for a jolly to the Azores.

When I was an assistant at Kinloss we had installed a boundary layer sonde [BLS] system from Vaisala, as did a number of other RAF stations across the UK. And when there was anything interesting going on meteorologically, we would fill up a balloon with helium, attach a small package of sensors to it, and throw it into the air. The rest was more or less automatic, a radio receiver attached to a PC processed the upper air data into a regular WMO TEMP message.

What I’m rather long-windedly trying to suggest, is that back then we realised the importance of good observational data, even when we had an excellent upper air network, something we don’t have these days. We don’t launch radiosondes from Weather Ships, we don’t even launch them from Stornoway, Shanwell or Hemsby these days, so why can’t we very occasionally just use something that we do have. I know the FAAM aircraft is primarily for research, but for exceptional hurricanes like Ophelia surely this could have been waived. As far as I know not a single aircraft from either Portugal, Spain, France, the UK or Ireland went out to take a look at Ophelia, surely the air force of one of these countries could have?


Just a ‘normal low pressure system’ says Chris Fawkes

I’m personally fed up to the back teeth of being told by weather presenter after weather presenter that Ophelia was now no longer a hurricane, and as Chris Fawkes so eloquently put it yesterday “is just a normal low pressure system”. Many of us don’t need this constantly rammed down our throats, or the 50 second video of Tomasz Schafernaker waving his arms about like some born again Magnus Pyke describing how a hurricane is formed and what powers them, because we already very well what the latest theories are.

National Geographic: Weddell Sea polynya increases in size

The National Geographic magazine have just noticed a large increase in the Weddell Sea polynya (south of south America) that I brought to your attention earlier last month in an article that I found on the phys.org website. I can confidently predict that the polynya will continue to increase in size till it totally disappears later in the Antarctic summer!

Yesterdays 33 feet wave heights

Looking at the instrumental wave heights and winds from some of the UK weather buoys, low Victor certainly generated some big waves yesterday in the eastern Atlantic.

Figure 1

At 22 UTC yesterday the weather buoy 62095 also known as M6 (fig 1) had reported a wave height of 9.0 metres (29.5 feet), whilst at 09 UTC that morning, 457 kilometres further south (fig 3), weather buoy 62442 also known as ‘Pap’ (fig 2), reported a wave height of 10.1 metres (33.1 feet). It should be interesting to see what wave heights they’ll be measuring as the remnants of hurricane Maria pass close by this Sunday.

Figure 2

The strongest winds didn’t occur at either of the above two weather buoys, but from weather buoy 62105 also known as K4, which reported a means speed of 45 knots and gust to 66 knots (76 mph) at 23 UTC yesterday evening, although there may well have been higher values that were missed due to instrument failure (fig 3).

Figure 3

My SYNOP program has been an ongoing project now for almost 20 years, and in all that time I’ve never thought to plot the instrumental wave height from weather buoys, so I’ve decided to correct that omission and add it to my plot from now on. I didn’t know where I should place it, so for the time being I plot immediately below the station circle in a blue font. Here are the relative positions of the three weather buoys that I’ve included plot grids for.

Figure 4

New record low maximum Antarctic sea ice by a whisker

It looks like this Winters maximum sea ice extent has been reached in the Antarctic a little earlier than average. The spot value for the 12th of September was 18.023 million square kilometres was the lowest maximum in the satellite record that started in 1979, but it was a very near thing, because the 2017 figure was just 4,000 square kilometres lower than the previous lowest maximum of September 1986. The sea ice could surge again and prove me a liar, but I got it right with the Arctic minimum, so maybe I’m on some kind of roll (pardon the pun).

Figure 1

Here is the table sorted from lowest to highest on maximum extent (fig 2). Before you ask 1978 is top of the list because the satellite record started on the 26th of October 1978, and the maximum for that year will have occurred a month earlier and been considerably higher than that figure, blame it on the programmer.

Figure 2

I would say on balance that the Antarctic sea ice extent has bounced back extremely well after what was a pretty dreadful start, back on the 1st of March sea ice extent was just 69.8% of the long-term average for that date, on the 12th of September they were back up at 97.4% of the long-term average for that day. This is the latest rather interesting ice extent picture for the Antarctic from the NSIDC (fig 3), which shows another polynya in the Weddell sea similar to the one in the news item I posted earlier this month. Who knows, maybe if that polynya hadn’t opened up, 2017 might not have been the new record low year!

Figure 3 – Courtesy of the NSIDC

2017 Arctic sea ice minimum only 8th lowest

Figure 1 – Courtesy of NSIDC

I might be jumping the gun here but…

I think the Arctic sea ice minimum as measured by the NSIDC, reached its summer minimum on September 12th at 4.611 million square kilometres, making 2017 the 8th lowest minimum in the satellite series that started in 1978. The value was over 500,000 square kilometres higher than last years minimum. I’ll bring you the latest news from the Antarctic about the maximum, because the season down there has still not quite finished.

Figure 2

How openings in Antarctic sea ice affect worldwide climate

I noticed this interesting article about polynya on the Phys.org website (you might what to add this to your favourites because it looks a great site) that might interest some of you out there. I was thinking, it’s only because the upwelling of warm water occurs under an ice sheet that we realise that they’re happening at all. They must happen all the time in the worlds oceans, but we just don’t see them, apart I suppose from anomaly charts of very sensitive SST satellite sensor data.