Autumn blast on its way

Friday 21 September 2012, 16:12

Paul Hudson Paul Hudson

A deep area of low pressure looks set to dominate our weather late in the weekend and into next week as the official start of autumn (which is the 22nd September this year, defined as the day the sun crosses the equator into the southern hemisphere) coincides nicely with the first meteorological blast of the season.

The track of this low pressure is still open to question, and has been causing real problems for forecasters in the last few days.

It's down in part to ex-hurricane Nadine which is in the mid-Atlantic near the Azores.

Computer models invariably struggle to handle these storms because such systems are relatively small but intense, and as such can be difficult to model with any consistency.

What Nadine does in the next few hours will help determine where an associated area of low pressure will develop and track, drawing in some of Nadine's warm sub-tropical air, hence the uncertainty regarding the timing and location of potentially heavy rain and strong winds for the UK.

The chart below is the best estimate of its position at midday on Monday, based on the UK Met Office Global model.



The current best estimate for our area is for the heavy rain to hold off until late Sunday, with much of next week then very unsettled, at times windy, with showers or longer spells of rain.

On a more positive note, if timings remain the same, it does mean that much of this weekend across Yorkshire and Lincolnshire will be fine and sunny, albeit cold at night with a risk of rural frost.

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Comments

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  • rate this
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    Comment number 1.

    Hi Paul. that's a pretty big call. NADINE has been on a holding pattern south of the Azores unable to make up it's mind for some days now.
    http://www.nhc.noaa.gov/refresh/graphics_at4+shtml/143657.shtml?5-daynl. The USNHS consensus forecast is for the remnants to be somewhere WNW of the Cape Verde Islands come Wednesday. Are you sure you've got the right week?

  • rate this
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    Comment number 2.

    I hope you are right about it being a nice weekend for my sins i'm in Skegness!
    #grumpyoldman58 correct me if I'm mistaken, but Paul isn't saying Nadine is coming our way, but is playing a part in where another area of low pressure heading for the UK will form and develop.

  • rate this
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    Comment number 3.

    Is it advisable to get some Braising Steak and Stew meat in then maybe some Lamb for a Hotpot or are we likely to be on salads again early October like last year

  • rate this
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    Comment number 4.

    "The track of this low pressure is still open to question, and has been causing real problems for forecasters in the last few days."
    24 hours ago, the web forecast for the NE said there was going to be heavy rain and strong winds today, but neither haver materialised.
    The strong winds forecasted for Monday appear to have been delayed until Tuesday.

  • rate this
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    Comment number 5.

    We have already had a touch of rural frost here a couple of nights ago. Only ground frost so far. Seems like a fairly chilly early autumn is setting in. Going by natural "signs" I am guessing this year as a whole will turn out to be the coolest for some time unless there is a dramatic change very soon.

    #4 - we had quite a bit of rain today.

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    Comment number 6.

    According to my data, the lowest max temp set in Sheffield this early in Sep was 10.0C in 1976. We must have been pretty close today. I reckon we made it to 10.0C in Stocksbridge, but Sheffield is usually half a degree higher.

    Either way it has probably been in amongst the top 10 coldest.

  • rate this
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    Comment number 7.

    This year has proven to be quite volatile, certainly in the UK with a poorer than usual growing season, which is the basic bottom line where weather is concerned. Three months to go and I am certainly thinking that 2012 will be a lot closer to 2011 than I originally thought, perhaps we are at solar max now.

    Thoughts on this winter, a lot of agencies are saying average to slightly warmer than average temperatures as their forecast at this stage. Maybe, maybe it could get a bit colder, if not this year then certainly for Jan, Feb.

    My original forecast of 0.28 for 2012, this may be a little low but still, I think, closer than the MO, perhaps an increase for this years prediction and a lowering of next years in my mind, QV AT 0.34 could hit the spot this year, but three months is a long time where weather is concerned.

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    Comment number 8.

    Herewith the latest, and possibly last, post-tropical NADINE Forecast discussion by NHS. Note particularly Para 3.

    http://www.nhc.noaa.gov/text/refresh/MIATCDAT4+shtml/220237.shtml

  • rate this
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    Comment number 9.

    Once again, the forecast for the NE has changed, with strong winds and heavy rain now forecast to start on Sunday night, instead of Tuesday.
    Monday, having been wet but without strong winds is now down for heavy rain all day and strong winds, peaking at about 07:00.
    All this proves is that 5 day local forecasts are pretty much a waste of time.

  • rate this
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    Comment number 10.

    #7. - ukpahonta wrote:
    "My original forecast of 0.28 for 2012, this may be a little low but still, I think, closer than the MO, perhaps an increase for this years prediction and a lowering of next years in my mind, QV AT 0.34 could hit the spot this year, but three months is a long time where weather is concerned."
    I think my forecast is looking on the low side now and I expect a final figure of around 0.42c.
    I do expect temperatures to decline on average, over the next 5 years, but getting the timing exactly correct is difficult.
    I certainly don't expect any new records, as forecast by the MO.

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    Comment number 11.

    #5. - jkiller56 wrote:
    "Seems like a fairly chilly early autumn is setting in. Going by natural "signs" I am guessing this year as a whole will turn out to be the coolest for some time unless there is a dramatic change very soon."
    I am not sure if you are referring to your local temperature as a whole, but the rolling 12 month CET figure is currently running at 10.4c, compared to the 1961-90 average (which may be a bit low), of 9.45c, so about 1c above normal.
    The year to date figure, according to the MO is 10.27c, against a 61-90 of 9.78c.
    The rolling 12 month CET reached 8.85c in December 2010, which was the lowest figure since March 1987, and this year looks like being cooler than last year, but warmer than 2008 and 2009.

  • rate this
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    Comment number 12.

    The first part of the first sentence should haver read;
    "I am not sure if you are referring to your local temperature or the U.K. as a whole"
    Why is there no retrospective edit facility on this blog????

  • rate this
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    Comment number 13.

    Briefly, from the 'Wet end to September raises autumn flooding concerns' thread, but probably also relevant to this one.

    101. 21st Sep 2012, ukpahonta wrote:

    "[ENSO] gives the process of the ocean absorbing energy from the Sun and then releasing it to the atmosphere. La Nina, and neutral conditions to a lesser extent, absorb energy into the ocean, El Nino releases energy into the atmosphere."

    That explains ENSO's role in distributing heat energy at the atmosphere/ocean interface. But it doesn't explain the steady rise in global temperatures observed throughout the 20th century, and especially in the past thirty years. Distributing heat is not the same thing as creating it.

    5. 21st Sep 2012, jkiller56 wrote:

    "Going by natural "signs" I am guessing this year as a whole will turn out to be the coolest for some time unless there is a dramatic change very soon."

    Not sure whether you're referring to local, regional or global temps here. But according to MO data year-to-date (Jan-Aug) in the UK 2012 is a little above average for the past 30 years, and spring 2012 (Mar-May) was in the top ten warmest on record (started 1910).

    So temperatures in the UK would actually have to *fall* dramatically relative to average throughout the rest of 2012 to be considered one of the coolest on record, or even to match those seen in 2010.

  • rate this
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    Comment number 14.

    newdr54 - it is apparent from your posts that you either briefly 'scanned' the Tisdale post or did not bother reading it at all. This is a shame, since it clearly explains that the amount solar energy entering the tropical oceans is a variable, governed by cloud cover variations which are in turn, influenced by ENSO. Ukpahonta's excellent 'ENSO 101' does not require any magical creation of heat energy - it's right there before your eyes.

    You persist in saying that ENSO must have a net neutral effect since it is an oscillation. Tisdale specifically explains why this is not the case. Presumably you already know that ENSO is difficult (impossible beyond a year or so) to predict. That in itself shows that ENSO isn't a self contained system working to clockwork precision, alternating in a simple fashion. The release of stored ocean heat during el nino is complex, as it can dissipate in a variety of ways, over different distances and timescales.

    Not for one minute did I expect you to simply accept Tisdale's alternative theory for the cause of the late 20thC warming. What had I hoped though, is that through reading the Tisdale post, you would no longer misrepresent ENSO as some sort of clockwork style, one cancels out the other, must be net neutral oscillation - it clearly isn't. Neither is it rocket science to understand this principle. Figuring out it's overall contribution to observed warming - yes, that's another matter.

    Ukpahonta - nice job with your ENSO 101

    jkiller - I'm with you. Intuitively, expected the numbers to be lower for the UK than those posted above.

  • rate this
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    Comment number 15.

    Anybody see the meteors last night? Sounds like a great display.
    http://www.bbc.co.uk/news/uk-19684876

  • rate this
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    Comment number 16.

    15. - lateintheday wrote:
    "Anybody see the meteors last night? Sounds like a great display.
    http://www.bbc.co.uk/news/uk-19684876"
    This could have been a bolide/fireball or some space debris re-entering the atmosphere. Personally I think the latter as it was relatively slow.
    Either way, unpredictable, so the chance of seeing them was very low.
    More likely to be seen by late night revellers than amateur astronomers.
    Normaly meteors only last for a second or so and these seem to have lasted for about 1 minute, long enough for people to get their mobile phones out.

  • rate this
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    Comment number 17.

    14. lateintheday wrote:

    "newdr54 - it is apparent from your posts that you either briefly 'scanned' the Tisdale post or did not bother reading it at all. This is a shame, since it clearly explains that the amount solar energy entering the tropical oceans is a variable, governed by cloud cover variations which are in turn, influenced by ENSO."

    It must be me, because I still have no idea how that process is supposed to explain the bulk of the global surface warming observed since the mid 1970s? Nobody is claiming that ENSO doesn't shift heat between the atmosphere and the ocean. If that's all Bob Tisdale is claiming, then I don't know who he thinks he's disagreeing with.

    And I did not at any time refer to ENSO as a 'clockwork mechanical process'. I referred to it by its name - an *oscillation*. An oscillation, according to Wikipedia, is "the repetitive variation, typically in time, of some measure about a central value (often a point of equilibrium) or between two or more different states." Therefore, by their nature, oscillations in ocean cycles that absorb and redistribute heat must have a net neutral influence on climate over time, otherwise they wouldn't be called 'oscillations'.

    "jkiller - I'm with you. Intuitively, expected the numbers to be lower for the UK than those posted above."

    Thankfully we don't have to rely on intuition.

  • rate this
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    Comment number 18.

    #17 newdr54

    ENSO does the opposite of what you described, heat from the ocean is moved to the atmosphere. The amount of heat depends upon how much the ocean has absorbed from the sun, this varies as to how much cloud cover there is. Less cloud more energy into the system, higher OHC, higher surface temperatures, higher temperature in the troposphere. More cloud, less energy into the ocean, more energy reflected out of the system, cooler OHC, cooler surface temperatures, cooler troposphere.

    Think of it as one way traffic, from the sun into the ocean, from the ocean into the atmosphere, from the atmosphere into space.

    The relationship to TSI can be observed in the out going long wave radiation. If there is an increases in outgoing radiation without an increase in TSI then there is more energy being reflected out, from clouds, and less going into the system.
    http://tallbloke.wordpress.com/2012/09/21/a-simple-logical-argument-about-global-warming/

  • rate this
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    Comment number 19.

    18.Sep 2012, ukpahonta:

    As I said @17, as far as I know ENSO shifts heat *between* the atmosphere and the ocean; I didn't intend to suggest that I thought it was all one-way traffic. I think we are more or less agreed on the mechanics of the ENSO system.

    I have to admit at this point that lateintheday was right; I didn't read through Tisdale's (very long!) post at WUWT. I just read the intro and conclusions.

    I have now printed the whole thing off and am currently struggling through it, making notes as I go. I have to say the start has not been encouraging.

    So far he has, in so many words, said that "climate scientists" (for apparently they are a collective) are perpetuating "myths" about CO2 warming the oceans, and are all "alarmists" and "liers".

    Also, climate scientists all (again, they are a collective, apparently) perpetuate "falsehoods" and "fairy tales"; they "manufacture" data; they are "goofy" and "attempt to conceal" evidence.

    Bob Tisdale seems to think there is (and I hesitate to use the term given recent blogosphere events) a *conspiracy* against him and his views.

    But I'll persevere, aided by a few gin and tonics (it's Saturday, and it's after 9 am...)

  • rate this
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    Comment number 20.

    Have fun.

 

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I worked as a forecaster with the Met Office for nearly 15 years locally and at the international unit, after graduating with first class honours in Geophysics and Planetary physics at the University of Newcastle upon Tyne in 1992. I then joined the BBC in October 2007, where I divide my time between forecasting and reporting on stories about climate change and its implications for people's everyday lives.

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