ATL: SAM - Remnants - Discussion

[ElectricStorm]

Looks like it's just about there to me. I'm thinking they upgrade at the 4pm advisory. 10pm at the latest

[grapealcoholic]

Looks like it's just about there to me. I'm thinking they upgrade at the 4pm advisory. 10pm at the latest

I agree. TD is likely at 4pm, not sure if it has TS winds yet

[Hurrilurker]

Looks like it's just about there to me. I'm thinking they upgrade at the 4pm advisory. 10pm at the latest

I agree. TD is likely at 4pm, not sure if it has TS winds yet

I've seen TS that look a lot worse, this thing has fully-wrapped spin (if not perfect stacking yet) with excellent outflow.

[SconnieCane]

Looks like it's just about there to me. I'm thinking they upgrade at the 4pm advisory. 10pm at the latest

I agree. TD is likely at 4pm, not sure if it has TS winds yet

I've seen TS that look a lot worse, this thing has fully-wrapped spin (if not perfect stacking yet) with excellent outflow.

Three of them over the last week, to be exact. This one should finally buck the trend of systems looking better before classification than after.

[gatorcane]

Looks to be well on its way, could get a designation by 5pm EST from NHC:

[ouragans]

The 2pm TWO will probably use the “if these trends continue, advisories will be initiated later this afternoon/evening” wording. It’s so close now that I bet it gets designated at 5pm.

I do too. TD at 5PM

[underthwx]

https://youtu.be/0mm1Q7ADoe8

After watching this update...it's sensible for those residing in the Caribbean...and the Southeast CONUS to pay attention to future "Sam"....

[aspen]

Looks to be well on its way, could get a designation by 5pm EST from NHC:

https://i.postimg.cc/1XygDkMg/goes16-vis-98-L-202109221445.gif

It still has that “umbilical cord” on its east side that it first had last night.

Also, since 98L is developing a full day earlier than most of the models have forecast up until this point, the HWRF’s solutions of a major on Saturday seem quite possible.

[galaxy401]

The 2pm TWO will probably use the “if these trends continue, advisories will be initiated later this afternoon/evening” wording. It’s so close now that I bet it gets designated at 5pm.

The 2pm Outlook appears to just be a copy-and-paste from the previous one...

[crownweather]

TD at 5 pm?? Maybe....

Showers and thunderstorms remain well organized in association with
a tropical wave located several hundred miles southwest of the Cabo
Verde Islands. In addition, recent satellite wind data indicates
that the circulation is gradually becoming better defined. If these
trends continue, a tropical depression could form as soon as this
afternoon or evening. This system should move westward at 10 to 15
mph across the eastern and central tropical Atlantic Ocean.
Additional information on this system, including gale warnings, can
be found in High Seas Forecasts issued by the National Weather
Service.
* Formation chance through 48 hours...high...near 100 percent.
* Formation chance through 5 days...high...near 100 percent.

[aspen]

The 2pm TWO will probably use the “if these trends continue, advisories will be initiated later this afternoon/evening” wording. It’s so close now that I bet it gets designated at 5pm.

The 2pm Outlook appears to just be a copy-and-paste from the previous one...

No, they included this:

“ If these
trends continue, a tropical depression could form as soon as this
afternoon or evening.”

We’ll probably have TD18 at 5pm

[Steve H.]

Definitely something to keep an eye on.

[Iceresistance]

TD at 5 pm?? Maybe....

Showers and thunderstorms remain well organized in association with
a tropical wave located several hundred miles southwest of the Cabo
Verde Islands. In addition, recent satellite wind data indicates
that the circulation is gradually becoming better defined. If these
trends continue, a tropical depression could form as soon as this
afternoon or evening. This system should move westward at 10 to 15
mph across the eastern and central tropical Atlantic Ocean.
Additional information on this system, including gale warnings, can
be found in High Seas Forecasts issued by the National Weather
Service.
* Formation chance through 48 hours...high...near 100 percent.
* Formation chance through 5 days...high...near 100 percent.

Does anyone recall a Non-PTC system that had a near 100% chance of development before?

[supercane4867]

TD at 5 pm?? Maybe....

Showers and thunderstorms remain well organized in association with
a tropical wave located several hundred miles southwest of the Cabo
Verde Islands. In addition, recent satellite wind data indicates
that the circulation is gradually becoming better defined. If these
trends continue, a tropical depression could form as soon as this
afternoon or evening. This system should move westward at 10 to 15
mph across the eastern and central tropical Atlantic Ocean.
Additional information on this system, including gale warnings, can
be found in High Seas Forecasts issued by the National Weather
Service.
* Formation chance through 48 hours...high...near 100 percent.
* Formation chance through 5 days...high...near 100 percent.

Does anyone recall a Non-PTC system that had a near 100% chance of development before?

It happens frequently prior to the beginning of PTC designation

[SconnieCane]

TD at 5 pm?? Maybe....

Showers and thunderstorms remain well organized in association with
a tropical wave located several hundred miles southwest of the Cabo
Verde Islands. In addition, recent satellite wind data indicates
that the circulation is gradually becoming better defined. If these
trends continue, a tropical depression could form as soon as this
afternoon or evening. This system should move westward at 10 to 15
mph across the eastern and central tropical Atlantic Ocean.
Additional information on this system, including gale warnings, can
be found in High Seas Forecasts issued by the National Weather
Service.
* Formation chance through 48 hours...high...near 100 percent.
* Formation chance through 5 days...high...near 100 percent.

Does anyone recall a Non-PTC system that had a near 100% chance of development before?

PTC advisories are only used if proximity to land is such that TS watches/warnings need to be issued before tropical cyclogenesis actually occurs.

[Shell Mound]

An intriguing tidbit: since 1851 twenty-three hurricanes have passed within 60 n mi of Bermuda during the month of October. Here is the decadal breakdown:

• 1851–60: 2
• 1861–70: 2
• 1871–80: 1
• 1881–90: 2
• 1891–00: 4
• 1901–10: 1
• 1911–20: 0
• 1921–30: 1
• 1931–40: 1
• 1941–50: 2
• 1951–60: 0
• 1961–70: 1
• 1971–80: 0
• 1981–90: 0
• 1991–00: 1
• 2001–10: 1
• 2011–20: 4

Based on the data at hand, the past decade was the most active for Bermuda during the month of October since the last decade of the nineteenth century.

[Sciencerocks]

[wxman57]

Certainly appears to be more of a TD than Peter or Rose. Expect an NHC upgrade shortly. Big upper low/trough over the East U.S. Coast next week should turn it well east of the U.S. Possibly a Newfoundland threat in 12 days or so. Can't rule out any threat to Nova Scotia, I suppose.

[AlphaToOmega]

AL, 98, 2021092218, , BEST, 0, 101N, 332W, 30, 1008, TD, 34, NEQ, 0, 0, 0, 0, 1012, 120, 40, 40, 0, L, 0, , 0, 0, INVEST, S, 0, , 0, 0, 0, 0, genesis-num, 038,

There it is: Tropical Depression 18L

[zzh]

AL182021 - Tropical Depression EIGHTEEN

https://rammb-data.cira.colostate.edu/tc_realtime/season.asp?storm_season=2021