3 Reasons Meteorologists Are Talking About Hurricane Florence

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Honestly, a small part of my answer to the question in the title is “I am not sure.”  However, the vast majority of me knows there is a mix of necessary attention, social media hyperventilation, and curiosity whenever there is a hurricane in the Atlantic, especially one that reaches major hurricane status (category 3 or higher). There are times when a “reality check” perspective is needed. Many people may take a cursory look at the storm and ask, “why are all of those weather types talking about this storm when it is far out in the Atlantic Ocean right now?” It is a fair question that deserves an answer.

Hurricane Florence as of the morning of September 6th.NOAA and CIMSS website

It is a Major Hurricane. Florence is a major hurricane so deserves attention based on that designation alone. It is the first category 4 hurricane of the 2018 Atlantic season though it has weakened to a category 3 at the time of writing. The 5:00 am AST National Hurricane Center advisory notes:

the center of Hurricane Florence was located near latitude 24.1 North, longitude 47.9 West. Florence is moving toward the northwest near 12 mph (19 km/h). A turn toward the west-northwest with a decrease in forward speed is expected later today, followed by a turn toward the west by the weekend. Maximum sustained winds have decreased to near 115 mph (185 km/h) with higher gusts…..Some additional weakening is
forecast today, but Florence is expected to remain a strong
hurricane for the next several days…..The estimated minimum central pressure is 964 mb (28.47 inches).

Wind shear and moisture in the vicinity of Hurricane Florence.NOAA and CIMSS website

Two things in this advisory catch my eye as a meteorologist, “turn toward the west by weekend” and “some additional weakening.” The graphic above shows wind shear (red contour lines indicate higher values) and precipitable water (a measure of moisture). The weakening is related to wind shear the storm is encountering and perhaps a little dry air. As the storm makes the westward turn later, it is expected to resume intensification as a large upper-level anticyclone (area of high pressure) is expected to form near the storm, and there is plenty of warm water along the pathway of the storm. An examination of current sea surface temperatures (below) shows 28 to 29 deg C waters around Bermuda and off the U.S. coast.

Global sea surface temperaturesCDAS and tropical tidbits.com website

Social Media Hoopla. The social media hoopla whenever there are certain weather events is a part of the landscape now. There is a “buzz” among meteorologists, weather enthusiasts, and casual followers when a major hurricane, tornadic outbreak, or blizzard is in the forecast. Unfortunately, this leads to a lot of “social media-oology” No-No’s. My good friend and colleague James Spann’s tweet captures the spirit of what I am talking about. Spann, a legendary meteorologist in Birmingham, tweeted on September 5th, 2018:

A friendly reminder; posting deterministic model output with tropical cyclone positions 10 days out to get shares and likes (or to scare people) isn’t cool. It serves no good purpose. A drunk donkey could pull this data and post it.

Weather models, particularly the European model ensembles, have shown a spread in the possible track of Florence. Earlier in the storms development, it seemed that it was going to curve out to sea. However, models continued to offer solutions that included westward tracks that bring Bermuda and the United States into the conversation. There is certainly enough information that Hurricane Florence bears watching but Meteorologist Brad Panovich in Charlotte, North Carolina nails it with the graphic below.

Funny graphic with an important point.Brad Panovich via Twitter

Panovich’s point here is not that we lack skill to make reliable forecast. In fact, we absolutely do within a certain range. My interpretation from his graphic is that anyone that thinks they know this far out where the storm is going to track given the limitations of the weather models beyond 10 days is “full of hot air”  like the eye of a Florence.

Hurricane Florence is pretty north and east of previous storms like it. Another discussion point about Hurricane Florence is its location relative to other storms like it. Outstanding meteorologist and University of Oklahoma doctoral student Sam Lillo tweeted,

In the face of cool ocean temperatures and moderate wind shear, #Hurricane #Florence has rapidly intensified to near category-4 strength. Not only is this rare given the conditions, but also is northeast of the climatological swath of major hurricane tracks.

Lillo produced this graphic below showing where Hurricane Florence is relative to previous major hurricanes in the climatological database.

Hurricane Florence position relative to previous major hurricanes in the Atlantic basin.Sam Lillo, University of Oklahoma

Lillo was not making any statement about climate. I also think speculating on causation of any specific storm is irresponsible and distracts from the immediacy of the threat. However, scientists familiar with the field know that there are peer-review studies in the scientific literature that showing a tendency for tropical cyclone tracks to be migrating poleward (northward in our hemisphere). A 2014 paper published in Nature, one of the top scientific journals in the world, found shifts poleward at the rate of 53 kilometers per decade in the Northern Hemisphere and 62 kilometers per decade in the Southern Hemisphere, respectively. A more recent 2018 paper in Climate Dynamics confirmed this finding. That study also noted “a shift toward greater (smaller) average potential number of genesis at higher (lower) latitudes over most regions of the Pacific Ocean.”

Projected track of Hurricane Florence as of the morning of September 6th.NOAA

 





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