|Fig. 1 Did you say u-turn?|
As it turns out and as we all know now, this storm had more surprises, and did not make the u-turn that had been forecast.
Sections I thru IV were the original post sections.
The new Section V below discusses the changes and adds two graphics to portray the current expectations.
I. The U-Turn Surprise
The robust weather software models running on the supercomputers plotted a course for Hurricane Matthew that has been reasonably correct so far (The Path of Matthew).
The diversion from earlier projections and expectations now manifesting is that Hurricane Matthew will make a "U-turn."
That is expected to begin to take place some where off the coast of Georgia, or S. Carolina, or N. Carolina, where it will head east then curve southward and head back down as far south as it was when it was a category 4.
While we are hoping that people have evacuated to inland areas away from the expected storm surges, there is also some interesting thought experiments we can do that may help our future understanding.
II. About The Graphics
To set the stage for that, let me point out some of the characteristics of the graphic detail ("not to scale") related to these phenomena.
|Fig. 2 NOAA|
The graphic at Fig. 1 is a rough depiction of the u-turn that is projected by meteorologists.
I enhanced it a bit to show the expected loop back which they are now forecasting.
The graphic at Fig. 2 is a NOAA depiction of sea surface temperatures along Hurricane Matthew's recent track area, on up to the coordinates where the hurricane is expected to begin to make the u-turn.
The graphic at Fig. 3 is the same as Fig. 2, except that I drew some "Cat ..." (category) squares on it to show what the hurricane category was, is, and what it is expected to become.
It is expected to drop down to a tropical depression ("TD" ), well below hurricane strength, as it makes that turn toward the south and eventually moves on in a slight southwesterly track.
III. Put Your Thinking Caps On
Some in the warming science commentariat tend to gloss over component parts of the damaged global climate system reality.
|Fig. 3 Modified NOAA|
As the eye skimmed along the coast some miles offshore, it dropped from the category 4 rating into a category 3, and is projected to drop to a category 2, then less.
It is projected to drop to a category 1 while tracking along the top arc ("12 o'clock position" - purple color), which is the projected beginning of its loop back to the south.
Note that during that right turn it reenters the warmer green/yellow water in the area shown on Fig. 2 & Fig. 3, and stays in the warmer waters while heading south once again (note: it stayed a category 3 while in that temperature-color through the Bahamas).
But it is not projected to increase in intensity back to a category 2, 3, or 4 while in that warmer water zone during the "loop-back" or "u-turn."
No, to the contrary while in these warmest water temperatures once again it is projected to weaken into a mere tropical depression, well below the category 4 hurricane strength it had attained when it entered that yellow/green zone a few days earlier.
Chuck Todd yesterday asked one of the warming science commentariat folks why it was losing strength as it moved south over those warm waters.
She responded "because upwelling (cooler water forced toward the surface) was caused when it went over the ocean earlier."
The problem with that misinformation is that it did not pass over any of that area before.
The loop back track is over waters way offshore that it did not go over as it skimmed the coast, hundreds of miles to the west of the upcoming southerly u-turn track.
Additionally, that "upwelling" assertion presumes that the water underneath is cold enough to do that, but "that allegation is not supported by data now in evidence" a debater might say (see Fig. 2 here).
Dry air is the more likely cause of demise.
IV. Keep An Eye On It
Some of this hypothesizing, in some degree, is speculation because it depends on a hurricane that has made some surprising turns, zigs, and zags that were not expected.
Likewise, for the most part the path it has taken was reasonably well expected and projected ahead of time.
Just sayin' that this is a opportunity to learn that the damaged climate system will behave in unexpected ways, and over the coming years it will increase its number of surprises we will observe.
|Fig. 4 The New Path|
The intent of the original post was to discuss the question:
"Why would Hurricane Matthew not regain strength as it changed course and traveled over warm waters again?"That question remains.
|Fig. 5 Warm waters in the new path (NOAA)|
That warm water has the same surface temperature color scheme as that water when the hurricane increased in strength.
But the hurricane is not projected to increase in strength.
The point is that there are factors involved which dispel a myth.
The myth is: "a warm ocean surface is all that is needed" to increase the strength of a hurricane, tropical storm, or tropical depression.
That debunking is worth remembering.
|Fig. 6 Split personality (10/9/16 ~7 AM)|
No matter what the surface temperature, dry winds, atmospheric pressures, jet streams, fronts, and the like, also play into the development and persistence of hurricane strength (The Path of Matthew).
Note that Fig. 6 shows the clouds moving along the original path, north along the coast.
But, it also shows the low pressure tropical storm moving east into the warmer waters of the Atlantic (accord Fig. 4).
Keep your thinking cap on.
Some Matthew video ...