Weather Nerd

Proto-Fay looking strong

The designation of Invest 92L as a tropical depression — or perhaps a tropical storm — appears imminent. A reconnaissance aircraft is en route to the system, and I suspect the National Hurricane Center will designate the system once they have the data from that plane. [UPDATE: No T.D. yet, as of 2pm EDT: “WHILE THE ASSOCIATED THUNDERSTORM ACTIVITY HAS BECOME MORE CONCENTRATED…MOST OF THE ACTIVITY IS LOCATED WELL EAST OF THE LOW CENTER AT THIS TIME.” Hurricane hunters are still investigating.]

To my untrained eye, the darn thing already looks very impressive on satellite, more like a nascent hurricane than an unnamed tropical wave! But unless there’s a closed low-level circulation, it’s not a T.D. or T.S. — and until the thunderstorm activity wraps around the low-level center, little if any intensification will occur. Apparently there’s a mid-level circulation center directly underneath the impressive-looking, symmetrical thunderstorm CDO…

fay1.jpg

…but a tropical cyclone needs a low-level center. Now, if the low-level circulation manages to re-form in the same spot as the mid-level center, 92L could develop rapidly. But for now, the wave remains very “pretty” but not actually well-organized yet.

That’s likely to change, however. Fay, as it will eventually be called, appears reasonably likely to become a hurricane — perhaps a significant one — this weekend or early next week. One computer model, the HWRF, currently produces the following scary 5-day forecast of a Category Four hurricane just off the Florida coast next Tuesday morning:

fay-cat4-forecast.PNG

That’s just one computer model, and five days is an eternity in forecasting terms, so there’s certainly no reason to panic — but just understand, there is a chance this storm could be a real problem next week.

One reason forecasters expect development is because, as Dr. Jeff Masters explains, 92L seems to have solved its dry air and dust problems. Also, wind shear is low and water is warm. Thus, the only significant obstacle to intensification appears to be the mountains of Hispaniola and Cuba, which could significantly disrupt the circulation, depending on the storm’s track. (That said, the above-linked HWRF model track shows the storm tracking right along the coasts of Hispaniola and Cuba — and still exploding into a Cat. 4 over the Bahamas.)

The storm’s track, of course, is what everybody wants to know about. Recent computer model runs suggest an increasing likelihood of recurvature east of Florida — that atmospheric pattern change hasn’t taken hold quite yet — but it’s way too early to know that with any certainty. [UPDATE: The latest model runs contradict this, shifting a bit left. Further proof that it’s just too early to tell.]

The entire Gulf and East coasts should keep an eye on this thing, just in case. Don’t sleep on it over the weekend! The likely track should sort itself out over the next couple of days. In the mean time, stay tuned.