cieldumort
(Moderator)
Fri Sep 21 2018 02:41 AM
Re: 98L Lounge

An update on 98L before a look at the models.

Some general surveying of a number of tropical experts today found no consensus on some key things. No consensus as to whether or not 98L should be considered a continuation of Florence, or an all-new cyclone if named, as well as no consensus as to whether or not 98L was on Thursday sufficiently put-together to be classified tropical storm, subtropical storm, or just still an extra-tropical storm (extra-tropical = non-tropical, despite the confusing jargon).

There was broad consensus that 98L had been producing winds to gale and tropical storm force for most if not all of the day and night, and that if it was determined by NHC to be either subtropical or tropical its status would go straight to getting a name (Kirk or Florence, depending on ones read of the matter).

It was and remains my personal "read" that 98L by early evening had become a tropical storm, and probably not Florence 2.0, but maybe.

Outside of the unsettling idea that maybe 98L retain the same name sadly so fresh in everyone's mind, this is really all kind of academic. What is more important right now is, what's it gonna do from here?

98L looks tonight to be a classic case of tropical cyclone been decapitated. North to northwesterly shear on the order of 25 - 50 KTS has pushed away almost all of the organized convection, replacing it with dry air. If deep convection does not return within the next few hours, and there is every reason to believe it won't, not in that environment, it may be that 98L is just one for review post-season the way some other after-the-season additions are.

However, models, and indeed the NHC, anticipate that conditions for development may become more favorable by early next week, and thus especially given that there is actually some consensus of the future track of 98L (a loop back around towards the east coast) it behooves us to know if it is going to be capable of bringing inclement weather. The states recently flooded by Florence do not have the ability yet to take on any more rain. Not one drop.

Run-down of 09/21/0z models so far:

ECMWF: Rounds the building High to the northwest clockwise and crosses coastal North Carolina as a closing off wave between 0z Wednesday the 26th and 0z Thursday the 27th. Likely a coastal rain-maker for 12-24 hours.

GFS: Rounds the building High to the northwest clockwise and comes just ashore in the Carolinas as an open-wave around 06z Wednesday the 26th. Likely a coastal and inland rain-maker for 18-30 hours before zipping off with a front.

GFS FV3: Rounds the building High to the northwest clockwise and comes ashore near GA/SC as a closing-off wave around 12z Wednesday the 26th and zipping off with a front. Likely a coastal and inland rain-maker for 18-30 hours.

CMC: Rounds the building High to the northwest clockwise and brushes the Carolinas as a closing off Low around 06z Wednesday the 26th before being swept up and out by a front. Likely a coastal rain-maker for 12-24 hours.

ICON: Rounds the building High to the northwest clockwise and passes within a few hundred miles at most of the OBX as a reestablished 1012 MB depression by 12z Wednesday the 26th. Likely a coastal rain-maker for 18-24 hours.

HMON: Rounds the building High to the northwest clockwise, maintaining 98L as a closed but often sloppy Low. End of run on 06z Wednesday the 26th as a 1015 MB sloppy closed Low - possibly a TD - centered roughly 150 miles east-southeast of Savannah, Ga.

HWRF: Rounds the building High to the northwest clockwise, maintaining 98L as a closed but often sloppy Low. End of run on 06z Wednesday the 26th as a 1012 MB sloppy closed Low - possibly a low-end Trop Storm - centered roughly 300 miles southeast of Myrtle Beach, SC.



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