Tropical Storm Arthur – There Is Nothing Unusual About the Sea Surface Temperatures Off the East Coast of the U.S.

Map 1

UPDATE (July 2, 2014):  See the correction at the end of the post.

# # #

This post was prepared in anticipation of the usual nonsense we hear whenever a tropical storm or hurricane forms and is expected to strike the U.S.  The map to the right (Map 1) presents the weekly sea surface temperatures (not anomalies) for the Eastern U.S. Coastal Waters from Florida to Massachusetts (26N-42N, 82W-70W), for the week centered on Wednesday June 25,2014. (Please click the map to enlarge it.)  Seasonally warmed sea surface temperatures from the east coast of Florida northwards to North Carolina are well above the 26 deg C (79 deg F) value needed to generate and maintain tropical storms and hurricanes.

Before we look at the recent sea surface temperature anomalies, let examine longer-term data to put it in context.

Initial note:  The anomalies presented in this post are referenced to the base-year period of 1971-2000, which are the base years used by NOAA for their Reynolds OI.v2 sea surface temperature data through the NOMADS website.


When Hurricane Sandy strolled up the eastern extratropical waters off the east coast of the U.S. back in 2012, we presented sea surface temperature data for its storm track in two posts:

So there should be no surprise that the sea surface temperature anomalies (NOAA’s ERSST.v3b data) for similar coordinates also show cooling since 1938, the year of the Great New England Hurricane—also known as the Yankee Clipper, Long Island Express, or the Great Hurricane. See Figure 1.  The coordinates used for this post are 26N-42N, 82W-70W, and they are shown above in Map 1. The ERSST.v3b data are available through the KNMI Climate Explorer.

Figure 1

Figure 1

In anticipation of someone accusing me of cherry-picking the start date, Figure 2 presents the sea surface temperature anomalies and linear trend, for that coastal region, for the past 100 years.  Sea surfaces warmed there primarily in the first half of the 20th Century, not the second. The linear trend is basically flat, which means, based on the trend, sea surface temperatures along the east coast of the U.S. have not warmed since 1915.

Figure 2

Figure 2


Let’s switch datasets to NOAA’s Optimum Interpolation (version 2) satellite-enhanced sea surface temperature data, aka Reynolds OI.v2.  It is available through NOAA’s NOMADS website in monthly and weekly formats. That monthly data start in November 1981, and, as of today, they run through the preliminary monthly data for June 2014.  (The final June 2014 values will be available on Monday, July 7th.)  Figure 3 presents the monthly sea surface temperature anomalies for the eastern coastal waters from Florida to Massachusetts, using the same coordinates as above: 26N-42N, 82W-70W.  The red horizontal line is not the linear trend; it is the June 2014 value.  It was +0.21 deg C.  I suspect that value will increase in the final version, but there’s nothing unusual about that value.

Figure 3

Figure 3

Looking at the data on a weekly basis for such a small region leaves us with lots of weather-related noise. As we can see in Figure 4, the sea surface temperatures for that region have increased, cycling higher in the past few weeks, up to almost +1.0 deg C.  But even that anomaly has been exceeded in the past.

Figure 4

Figure 4

And referring to the monthly data back to 1915 (Figure 2) anomalies that high were more commonplace in the first half of the 20th Century than in recent decades.


While we’re discussing sea surface temperature anomalies and hurricanes, for information purposes, the next two graphs present the weekly sea surface temperature anomalies through June 25, 2014 for the Atlantic Main Development Region (10N-20N, 80W-20W), Figure 5, and for the Gulf of Mexico (21N-31, 98W-81W), Figure 6.  Again, the horizontal lines in these graphs are the values for the week of June 25th, not the linear trends.

Figure 5

Figure 5

# # #

Figure 6

Figure 6

Note: Hurricanes DO NOT CARE about temperature anomalies.  The actual sea surface temperatures (absolute) from June to November have and will continue to rise to values capable of spawning hurricanes…a result of the normal seasonal variations in surface temperatures.  And while El Niño conditions in the Pacific tend to suppress hurricane development by effectively chopping the tops off the developing hurricanes (the result of wind shear in the tropical North Atlantic caused by an El Niño in the tropical Pacific), hurricanes can still form and will likely continue to do so this season.


Joe Bastardi’s very popular post at WattsUpWithThat Bastardi: ‘potential nightmare.. a tropical cyclone coming at the outer banks on the July 4 weekend’ included a sea surface temperature anomaly map from the NOAA OSPO website.  See Map 2.

Map 2

That map is based on the NOAA NESDIS Coral Reef Watch analysis, which excludes daytime satellite observations. See their discussion of sea surface temperature data hereAs a result, their maps have a warm bias, which they believe is important for their Coral Reef Watch program.  But it also explains the apparent difference between that map and the satellite-based data presented in this post, which include bias-adjusted daytime values.


As blogger “Steve from Seattle” pointed out in his comment on the cross-post at WUWT, the NESDIS data should not have a warm bias.  My mistake.  It’s the color-scaling of their maps that give them the warm appearance.  The NESDIS does not have a range of grey or white near zero (+/- 0.5 deg C for example), as is common with many other maps.  (See example here.)  The NESDIS starts with the yellows anywhere above a zero anomaly.

About Bob Tisdale

Research interest: the long-term aftereffects of El Niño and La Nina events on global sea surface temperature and ocean heat content. Author of the ebook Who Turned on the Heat? and regular contributor at WattsUpWithThat.
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4 Responses to Tropical Storm Arthur – There Is Nothing Unusual About the Sea Surface Temperatures Off the East Coast of the U.S.

  1. craigm350 says:

    Reblogged this on CraigM350.

  2. Thanks, Bob. A good post.
    This “continuing global warming” is very strange, no wonder it is weirding the climate.
    Red ink must be cheaper than blue!

  3. craigm350 says:

    But Bob, Greg Laden had this to say…(my emphasis)

    There are competing strengthening and weakening factors and the storm is a bit lopsided, so future strengthening may be delayed. But, perhaps more important, the sea surface in the area is warm, as expected with global warming, and the vertical wind sheer is minimal, which is counter to expectations of global warming. THEREFORE THERE IS NO GLOBAL WARMING. Only kidding about that last part.

    But then we get this exchange with a very strange period of climatological reference (again my emphasis and comment inside [brackets])..

    Michael Whaley
    United States
    July 3, 2014

    How much warmer than usual? That question stems from your statement: “But, perhaps more important, the sea surface in the area is warm, as expected with global warming,…”

    Greg Laden
    July 3, 2014

    Michael, at the moment a couple/few degrees C above a climatology of 1985-1993. But I’m not sure of the exact configuration of SST and the storm’s current or projected position. The North Atlantic in general is warmer. [than what? than when?] What I don’t know off hand and which may not matter with at category 1 hurricane is if we’ll see medium depth effects like with Katrina and Yolanda, where the normally cooler (less than 80F) water meters below the surface is actually way warm, so as the storm churns up the normally cooling water it just churns up more hurricane-inducing warm water. I don’t know if that is the case with the Atlantic now.

    So Greg doesn’t actually know much/anything but blusters along anyway. It’s not exactly hard to get the information he’s got no idea of but facts are tricky things when you are full of it and best avoided in case it ruins the narrative.

  4. John F. Hultquist says:

    Thanks, Bob.

    You know about what follows but a few readers might not.

    The mapping programs that produce images such as that used in this post will all have default settings for such things as map projection and color schemes and category boundaries. If a person has an “artistic eye” there will likely be a desire to tweak the map’s look but this does damage to the standard presentation, thereby making comparisons difficult. The map you link to (with white for -0.5 to +0.5) also has eliminated the category of -4.5 as black (land) and provided an outline. That seems good.
    Both maps use a non-equal-area projection (Mercator ??) so at the 40th Parallel the red area off the NE coast of the USA appears incorrectly as large as the warm area west of Peru – along the Equator. This is best seen in the linked to map with the white color.

    Your readers not familiar with this issue should get the following 2 images on their screens and compare the sizes of Greenland and South America.

    Regarding color coding (not related to SST):
    I was looking at charts in a money magazine and the topic was allocation of assets among stocks, bonds, and cash. A pie-chart on the left side page had the stock wedge colored red and the bond wedge black. On the facing page another similar graphic had the stocks as black and the bonds as red. That really makes me wonder if there was an adult on-board.

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