There is an emerging consensus among weather-tweeters I follow that Tropical Storm Dorian is now well & truly falling apart, and is likely on the verge of downgrade and/or dissipation. A few hours ago, it was perhaps “50/50 it makes it through the weekend intact.” Now it seems like 50/50 the storm makes it through today intact. Here’s Brad Panovich, chief meteorologist at WCNC in Charlotte, within the last hour:
— Brad Panovich (@wxbrad) July 26, 2013
Panovich added: “Dorian no longer appears to be a Tropical Storm, may barely be a Depression.” Around the same time, Dr. Ryan Maue of WeatherBell tweeted: “Last few visible images show TS Dorian torn apart, perhaps 2 centers, which means advisories would be discontinued at 5 pm or 11 pm.” Ed Piotrowski of WPDE in Myrtle Beach agreed, saying he sees “two centers oriented SW to NE.” Panovich, responding to Piotrowski, noted, “yeah the mid-level center is way off to the NE now, with dry mid level air can’t hold on much longer.”
As I was typing this up, the NHC’s 5pm EDT advisory came out, roughly a half-hour early, and it maintains Dorian as a tropical storm, albeit weakening its officially estimated top wind speed from 50 mph to 45 mph. However, reading between the lines, and engaging in some “NHC-ology,” it’s pretty clear NHC forecaster Richard Pasch thinks Dorian may be in its final hours:
UNDER THE INFLUENCE OF WESTERLY SHEAR AND DRIER AIR…DORIAN HAS BECOME EVEN LESS ORGANIZED THAN IT WAS EARLIER TODAY. VISIBLE SATELLITE IMAGES INDICATE THAT THE LOW-LEVEL CENTER HAS BECOME DISPLACED TO THE WEST OF AN AREA OF WEAKENING DEEP CONVECTION. ALSO…ANIMATION OF THE IMAGERY SHOWS THAT CIRCULATION IS BARELY CLOSED AT THIS TIME. USING A BLEND OF DVORAK ESTIMATES FROM SAB AND TAFB…THE ADVISORY INTENSITY IS REDUCED TO 40 KT. THE OFFICIAL WIND SPEED FORECAST NOW SHOWS GRADUAL WEAKENING WITH DISSIPATION BY DAY 5…IN GENERAL AGREEMENT WITH THE GFDL AND HWRF GUIDANCE. GIVEN THE CURRENT TRENDS…HOWEVER…THE SYSTEM COULD DEGENERATE INTO AN OPEN WAVE MUCH SOONER THAN THAT.
“Much sooner” like 11:00 PM EDT tonight? I think maybe so. Earlier today, a “pass” by NOAA’s Advanced Scatterometer, or ASCAT, appeared to show a not-entirely-closed circulation. (Here’s the full image.) According to Charles Fenwick, the next pass, assuming the satellite doesn’t “miss,” will be at roughly 8:00 PM Eastern Time. Data from the ASCAT pass would be available 1-2 hours later — in time for the 11pm advisory. If that pass shows no closed circulation, I think it’s lights out for Dorian.
So, barring a comeback by our “survivor” in the next 3 to 6 hours, I’m guessing 11pm will be the final advisory, and the system will be declared an open tropical wave at that time. Alternatively, perhaps NHC will downgrade Dorian to a tropical depression at 11pm, pending visual confirmation in the morning that it continues to look horrible, and then discontinue advisories at 5am tomorrow. Either way, by the time the sun rises tomorrow here at Weather Nerd World Headquarters in Denver, Colorado, I doubt we’ll have Dorian to kick around anymore. We might have to monitor the Artist Formerly Known As Dorian for possible future development once it reaches more favorable climes next week — but in all likelihood, this storm is just about done.
I’ll be at a movie when the 11pm advisory comes out, but I may be able to tweet anyway, as it’s an outdoor movie. :) Anyway, follow me on Twitter (@brendanloy) for the latest. Also, again, Amy Sweezey’s “Wx Tweeps” Twitter list is good.