"Isaac" Remnants in the Gulf of Mexico But Would Get New Name if it Develops; "Leslie" & "Michael" (Not Buresh) Become Hurricanes...........
***** A high rip current risk at First Coast beaches due to easterly swells from "Leslie" through at least Fri. *****
The mid & upper level disturbance that was "Isaac" has made it back into the Northern Gulf of Mexico & is accompanied by a persistent cluster of showers & t'storms, especially in the south & southeast quadrant of the circulation. "Ivan" made a somewhat similar loop in 2004 (see 4th & 5th images below). Forecast models have now pretty unanimously jumped onboard in developing a weak surface low over the North Central Gulf of Mexico the next couple of days as the disturbance returns to the warm water. Based on history ("Ivan" in 2004), if another tropical cyclone were to develop & could be traced to what was "Isaac", it would again be named "Isaac" (which appears to be the likely scenario). Models do not develop a strong low, but this is something to watch as there should be eventual interaction with a strong upper level trough that will move into the Eastern U.S. this weekend. There is a good deal of shear over the Eastern Gulf which could limit sustained strong redevelopment, at least the next couple days. Something to watch is the trough this weekend that could enhance the low in the Gulf & should also pull the system northeast. The combination of the tropical disturbance + the strong upper trough could lead to the potential for heavy rain for the First Coast (& much of the Southeast U.S. & Gulf Coast) by the weekend. In fact, heavy rain is already occurring -- & will continue -- along & near the Gulf Coast. The Nat. Hurricane Center says they would give this disturbance a new name ("Nadine"):
Our analysis of the satellite, surface, and lower-tropospheric radiosonde data suggested that the disturbance we're currently following originated within Isaac's broad circulation, but that it had its own surface pressure minimum distinct from Isaac's. This was perhaps most apparent late in the day on Monday, when the residual surface center of Isaac was located over western Kentucky while a second weak low was located over northern Mississippi and Alabama. Isaac's circulation continued to weaken after that and became difficult to track, while the new disturbance moved slowly toward the Gulf coast. So what basically happened here is that a little piece of Isaac broke away and moved south.
OK, now everybody get your lawyer and grammar hats on. The National Weather Service rule that applies here reads: "if the remnant of a tropical cyclone redevelops into a tropical cyclone, it is assigned its original number or name".
Notice the rule says "the" remnant, and not "a" remnant. This means that the storm's primary remnant (and not just any old part of it) has to re-develop in order for the name to be retained. Since the primary remnant of Isaac was still in Kentucky when the new low formed and broke away, the rule dictates that the new low is not entitled to the name Isaac.
This rule actually makes a lot of sense. If a storm died and each of two parts re-developed, we couldn't give the same name to both parts. Only the primary remnant would retain the name, while a lesser remnant or part would get a new name.
IMAGE FROM LAST THU., AUG. 30TH:
IVAN'S TRACK IN 2004:
is still battling some shear & dry mid & upper level air but remains a broad hurricane. The upper level trough in the NW Atlantic will not entirely pick up the cyclone leaving "Leslie" in a weak steering flow which will cause the storm to stall at or just north of Jacksonville's latitude in the Central Atlantic. There could be a momentary jog west but indications are that "Leslie" will still get steered north then northeast in time. If we look at the W. Pacific last week, the 2nd typhoon moved to the China coast west & southwest of Japan, so we'll have to beware of a farther west track in the long run than forecast models are currently indicating but still no threat to the First Coast other than rough seas/surf. All will hinge on the timing & intensity of what will be a strong upper level trough that will dig into the Eastern U.S. late this week into the weekend. "Leslie" should start to increase its forward speed to the north or north/northwest as the trough approaches. This move north could be helped by an upper low near Florida as the upper low moves east/northeast. In the long run, however, the expansive "Leslie" circulation could end up absorbing the upper low. Very rough surf will likely affect New England this weekend & parts of Nova Scotia &/or Newfoundland could be directly impacted late in the weekend into early next week.
In any case... "Leslie" will be strong enough & large enough to continue to send an easterly swell to First Coast beaches this week increasing the rip current risk.
"Michael" (not Buresh!) became the 7th hurricane this season in the Atlantic Basin Wed. undergoing rapid intensification. The hurricane is likely to only move very slowly to the north then turn northwest & is no immediate threat to any land areas. There may be some eventual interaction with much bigger "Leslie" in the N. Atlantic next week.
A wave in the far E. Atlantic well south of "Michael" & southeast of "Leslie" at a much lower latitude has been stretched by shear. This wave will move just about due west the next few days. Other waves will start to come off Africa with renewed vigor by the weekend into next week. There is the potential for long term development.