cieldumort
(Moderator)
Mon Sep 20 2021 06:51 AM
Sam Lounge



A tropical wave that has rolled off western Africa and is now located several hundred miles southeast of the Cabo Verde Islands in the far eastern Atlantic is being monitored for development.

This disturbance has a setup favorable for long-track and high-ACE. If indeed 98L does develop, it could threaten land closer to the US based on long range modelling. As such, we are now opening up a Lounge.

Long range forecasts for systems this far out in the Atlantic are often deviled by a dearth of data and aren't the most reliable, but we could have a lot of time to watch this one, and should it come close enough, recon would go in.

NHC development odds at the time of this post of 10%/60% at 2D/5D, respectively.

98L became EIGHTEEN on Sep 22 and the title has been updated


cieldumort
(Moderator)
Mon Sep 20 2021 03:37 PM
Re: 98L Lounge

Based on visible and IR satellite, 98L appears to be organizing at a good clip in the extreme eastern Atlantic.

Given that it is starting out at a lower latitude, it could, as modeling suggests, track farther west than the several wave-to-named-storms that recently came before it.

NHC odds as of the 2PM TWO are 30%/80% and this could be conservative. The next name on the list in the Atlantic basin is Sam.

A rundown of some 12z Global Runs:

GFS has it as a 965mb Major Hurricane off the coast of NC on Oct 5th
CMC end of run as a 992mb storm while northeast of the Leewards islands tracking WNW or NW on Sep 30
ECMWF end of run has it as a 962mb Major Hurricane north of PR tracking WNW or NW on Sep 30

A potential wrinkle in these (and other) model forecasts is should 98L develop ahead of schedule, it could naturally want to gravitate poleward sooner rather than later, and head north out to sea.


Mike V
(Weather Watcher)
Wed Sep 22 2021 05:21 PM
Re: 98L Lounge

Now TD18, Forcast to be a major storm in 5 days

Kraig
(Weather Hobbyist)
Thu Sep 23 2021 06:32 AM
Re: 98L Lounge

There's not much to hold the future Sam back, and I fully expect him to be at least a Cat 4 at some period. Hopefully he is simply a beach issue with large swells along the East Coast.

With the first significant cold front making it to the GOM and Florida area we will soon need to begin to watch that area and the NW Caribbean for short fused storms from stalled frontal boundaries....


doug
(Weather Analyst)
Thu Sep 23 2021 08:39 AM
Re: 98L Lounge

Exactly…this is the time of the season to look for development in the southern and western Gulf

cieldumort
(Moderator)
Sat Sep 25 2021 06:57 PM
Re: Sam Lounge



IsoFlame
(Weather Guru)
Thu Sep 30 2021 12:42 PM
Re: Sam Lounge

My memory is fading (early onset?), but I can't recall a (potentially) longer-lived Major Atlantic hurricane than Sam., forecast to remain a Major until passing east of Bermuda over the weekend. Sam's Accumulated Cyclone Energy (ACE) is sure to be impressive- I don't know at what point the ACE stops accumulating (extra-tropical?), but the forecast suggest Sam will remain a strong extra-tropical hurricane for several days after the transition:
"Around day 5, global model fields suggest that Sam will be merging with a baroclinic zone and transition into a large and powerful extratropical cyclone over the north Atlantic."



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