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Texas Major Hurricane Intensity Not Related to Gulf Water Temperatures

August 30, 2017

By Paul Homewood

 

Reposted from Roy Spencer:

August 29th, 2017 by Roy W. Spencer, Ph. D.

As the Houston flood disaster is unfolding, there is considerable debate about whether Hurricane Harvey was influenced by “global warming”. While such an issue matters little to the people of Houston, it does matter for our future infrastructure planning and energy policy.

Let’s review the two basic reasons why the Houston area is experiencing what now looks like a new record amount of total rainfall, at least for a 2-3 day period over an area of tens of thousands of square miles.

1) A strong tropical cyclone, with access to abundant moisture evaporated off the Gulf of Mexico, and

2) Little movement by the cyclone.

These two factors have conspired to create the current flooding catastrophe in Houston. Now let’s look at them in the context of global warming theory.

1. Are Texas major hurricanes dependent on an unusually warm Gulf?

I examined all of the major hurricane (Cat 3+) strikes in Texas since 1870 and plotted them as red dots on the time series of sea surface temperature variations over the western Gulf of Mexico. As can be seen, major hurricanes don’t really care whether the Gulf is above average or below average in temperature:

Red dots indicate years of major hurricane strikes in Texas, plotted on average SST departures from normal by year over the western Gulf of Mexico (25-30N, 90-100W).

Why is that? It’s because hurricanes require a unique set of circumstances to occur, and sufficiently warm SSTs is only one. (I did my Ph.D. dissertation on the structure and energetics of incipient tropical cyclones, and have published a method for monitoring their strength from satellites).

The Gulf of Mexico is warm enough every summer to produce a major hurricane. But you also usually need a pre-existing cyclonic circulation or wave, which almost always can be traced back to the coast of Africa. Also, the reasons why some systems intensify and others don’t are not well understood. This is why the National Hurricane Center admits their predictions of intensity change are not that accurate. Lots of thunderstorm complexes form over warm tropical waters, and we still don’t understand why some of them will spontaneously form a cyclonic circulation.

2. Does global warming cause landfalling hurricanes to stall?

I don’t know of any portion of global warming theory that would explain why Harvey stalled over southeast Texas. Michael Mann’s claim in The Guardian that it’s due to the jet stream being pushed farther north from global warming makes me think he doesn’t actually follow weather like those of us who have actual schooling in meteorology (my degree is a Ph.D. in Meteorology). We didn’t have a warm August in the U.S. pushing the jet stream farther north.

In fact, I dare anyone to look at the August temperature anomalies to date in the U.S. (courtesy of Weatherbell.com) and tell me, exactly what pattern here is due to global warming?

August 2017 (through Aug. 28) surface temperature anomalies around North America (NCEP CFSv2, courtesy of Weatherbell.com).

The flooding disaster in Houston is the chance occurrence of several factors which can be explained naturally, without having to invoke human-caused climate change. We already know that major landfalling hurricanes in the U.S. have been less frequent in recent decades. But once one forms, if it stalls near the coast (a rarity), it can be expected to cause a flooding disaster…especially in a flood-prone area like Houston.

http://www.drroyspencer.com/2017/08/texas-major-hurricane-intensity-not-related-to-gulf-water-temperatures/

15 Comments
  1. Peter Stokes permalink
    August 30, 2017 12:13 pm

    I guess par for the course for the Guardian to publish such rubbish from a completely discredited Michael Mann, indeed how anyone has the effrontery to have any truck with him defeats me. But well said Roy, I think QED!

  2. Gamecock permalink
    August 30, 2017 12:23 pm

    ‘Major Hurricane Intensity Not Related to Gulf Water Temperatures’

    Cringe worthy headline.

    Doesn’t really convey ‘The Gulf of Mexico is warm enough every summer to produce a major hurricane.’ That they are always warm enough means they are related.

  3. NeilC permalink
    August 30, 2017 12:43 pm

    Good analyses by a proper meteorologist, thanks Roy.

  4. Stewart Judd permalink
    August 30, 2017 1:03 pm

    What a pleasure to read a sound analysis by an expert meteorologist.

  5. Athelstan permalink
    August 30, 2017 1:09 pm

    […] Why is that? It’s because hurricanes require a unique set of circumstances to occur, and sufficiently warm SSTs is only one. (I did my Ph.D. dissertation on the structure and energetics of incipient tropical cyclones, and have published a method for monitoring their strength from satellites).

    The Gulf of Mexico is warm enough every summer to produce a major hurricane. But you also usually need a pre-existing cyclonic circulation or wave, which almost always can be traced back to the coast of Africa. Also, the reasons why some systems intensify and others don’t are not well understood. This is why the National Hurricane Center admits their predictions of intensity change are not that accurate. Lots of thunderstorm complexes form over warm tropical waters, and we still don’t understand why some of them will spontaneously form a cyclonic circulation.[…]

    Fascinating stuff, thank you Paul and of course – Prof. Spencer.

    I shan’t dicker about the genesis of this storm, meteorology is not by a long stretch my ‘bag’.

    I am interested in why it has stuck around more or less in one geographical location and for too long.
    Now, this is pure speculation – imho can the blocking highs to the west, north and east have aught to do with it?
    Morphology – relief of the land area, Texas slopes down all the way from the rockies and the shape of the circular coastline…perhaps and just maybe a little to do with it???

    http://hint.fm/wind/ have a looksee here.

    I speculate only.

    • NeilC permalink
      August 30, 2017 3:01 pm

      Athelstan, the warm/hot moist air from the gulf being undercut by the cool air from the north forces the warm air uppwards and causes rotation in this case, giving great depth to the cloud (cumulonimbus). The greater the depth, the heavier the precipitation (rain, hail etc)

    • August 30, 2017 4:09 pm

      This was in a report from Dr. Jeff Masters on August 26:
      ‘Harvey is being sandwiched between a strong upper-level ridge over the western U.S. and another strong ridge extending from the subtropical Atlantic across the Gulf of Mexico.’

      http://www.wunderground.com/cat6/heavy-damage-texas-harvey-now-tropical-storm

      • Athelstan permalink
        August 30, 2017 5:10 pm

        Yes, I see that, correct analysis imho.

      • Athelstan permalink
        August 30, 2017 5:15 pm

        Sorry, I didn’t say thanks oldbrew for info;).

  6. Jack Broughton permalink
    August 30, 2017 1:10 pm

    The saddest thing about all of this is that the “Doom-mongers” have got their publicity and more brainwashing material to convince the plebs that they are right….. and that more money should go to their cause of course.
    As RS noted their were never any real global warming related cause and effects involved. Great that he demonstrates the proof so well, but it will not get any pop-press.
    Maybe Trumps pals will read it as they at least have not been corrupted by the frenzy.

  7. Colin permalink
    August 30, 2017 2:37 pm

    A very inventive way of linking global warming to the unfolding disaster in Houston, and so rapidly conceived that no peer review process could ever keep up!
    Looking at the data it is immediately apparent that there is no statistically significant trend in global rainfall, though I’m sure Mann could fashion a hockey stick from it, given sufficient time.
    What interests me is the year to year variation in global rainfall, as much as ten percent. I would have thought that would be pretty much determined by ocean evaporation and hence by sea surface temperature. In fact the two correlate very poorly.

    • August 30, 2017 4:11 pm

      Is ‘global rainfall’ data reliable?

  8. Bitter&twisted permalink
    August 30, 2017 6:12 pm

    Roy Spencer- causing confusion with facts again.
    Surely he should know better by now?
    (Sarc).

  9. August 30, 2017 7:11 pm

    Reblogged this on Climate Collections.

  10. August 30, 2017 7:28 pm

    Melanie Phillips posted on a link to Spencer’s new book debunking Gore, on her Facebookpage.
    Disappointingly even there : half her readers said “Spencer is a denier so he must be wrong”

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