How long will Bertha last?

[Sunday July 13 update follows original entry]

Bertha slowing down to a painfully slow crawl as steering currents became weak and nebulous was not unexpected; it was just a question of exactly where, and it's happened a couple hundred miles southeast of Bermuda.

Although bigger in size than it once was, Bertha is a shadow of its former self intensity-wise. The aircraft reconnaisance that just arrived reported a central pressure 984 millibars, or 29.06", in the middle of the large 57-mile diameter eye, up from what it was yesterday and undoubtedly much higher than at Bertha's peak (when there were only satellite estimates). In general, the lower the pressure in the middle of a hurricane, the tighter the pressure "gradient" and the stronger the winds.

Also, the convection (deep thunderstorm and rain clouds) is less robust and more disorganized than earlier in Bertha's life. So while Bermuda will at least be brushed by Bertha, its intensity and track will mitigate the effect there unless the hurricane were to suddenly reintensify a lot and make a beeline northwest, which is not likely.

Bertha is now one of the longest-lived tropical storms and hurricanes on record in July, and its longevity has already exceeded that of any storm in the 2007 season!

The question has been whether the weather system which brought severe weather to Minnesota and thereabouts on Friday would fling Bertha away once and for all. It'll probably give Bertha a shove, but downstream over the North Atlantic between Bermuda and Europe, the steering pattern is about to get rather blocked up.

While Bertha may subside below hurricane intensity, and the precise answer to the question in the title of this entry is unknown, it's going to continue to hang around as a tropical cyclone for quite awhile.

SATURDAY EVENING ADDENDUM

This is the peak of the beachgoing season in the Mid-Atlantic and Northeast, and please be careful in the water. There were many rescues today and the rip current risk will be quite elevated again tomorrow as a result of swells from Hurricane Bertha.

UPDATE NOON SUNDAY EDT

Bertha is still not moving much, although it may have begun a slow NNW drift. There's a well-defined swirl on visible satellite imagery (top), but the infrared image (bottom) shows that the convection (deeper clouds) is weak and disorganized, and NHC has finally lowered the official intensity to tropical storm status.

Meanwhile, the next system to monitor ("invest 94L") in the tropical Atlantic is east of the Lesser Antilles.

There's also a large low-cloud swirl centered east of Virginia Beach, a small spin evident on satellite loops just southeast of Myrtle Beach, and a zone of showers and thunderstorms from the eastern Gulf to the Bahamas. No tropical cyclone development is imminent, but all of this, in combination with Bertha and 94L, seems to be a sign that the atmosphere is primed as we head toward the peak of the season ...