ATL: SAM - Remnants - Discussion

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Re: ATL: INVEST 98L - Discussion

#181 Postby abajan » Wed Sep 22, 2021 3:10 pm

SconnieCane wrote:
Iceresistance wrote:
crownweather wrote: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.

That wasn't the question, though.
I'm pretty sure I've seen non-PTC systems given a 100% chance of development. But off the top of my head I can't recall specific examples.
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Re: ATL: INVEST 98L - Discussion Update= Best Track upgrades to TD 18

#182 Postby KirbyDude25 » Wed Sep 22, 2021 3:29 pm

Abajan wrote:That wasn't the question, though.
I'm pretty sure I've seen non-PTC systems given a 100% chance of development. But off the top of my head I can't recall specific examples.


I remember Paulette in 2020 was at 100/100 right before genesis, but I don't know of any besides that one.
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Re: ATL: EIGHTTEEN - Tropical Depression - Discussion

#183 Postby grapealcoholic » Wed Sep 22, 2021 3:40 pm

Image
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Re: ATL: INVEST 98L - Discussion

#184 Postby galaxy401 » Wed Sep 22, 2021 3:46 pm

aspen wrote:
galaxy401 wrote:
aspen wrote: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


Indeed, it appears I reread the previous outlook since the graphic didn't update yet. Now it's about to be upgraded.
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Re: ATL: EIGHTTEEN - Tropical Depression - Discussion

#185 Postby abajan » Wed Sep 22, 2021 3:48 pm


To me it seems like the vorticity signature on that graphic is always a bit south of the actual center of circulation.
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Re: ATL: EIGHTTEEN - Tropical Depression - Discussion

#186 Postby AlphaToOmega » Wed Sep 22, 2021 3:50 pm

Forecasted peak intensity at 100 knots

ESTIMATED MINIMUM CENTRAL PRESSURE 1008 MB
MAX SUSTAINED WINDS 30 KT WITH GUSTS TO 40 KT.
WINDS AND SEAS VARY GREATLY IN EACH QUADRANT. RADII IN NAUTICAL
MILES ARE THE LARGEST RADII EXPECTED ANYWHERE IN THAT QUADRANT.

REPEAT...CENTER LOCATED NEAR 10.1N 33.9W AT 22/2100Z
AT 22/1800Z CENTER WAS LOCATED NEAR 10.1N 33.2W

FORECAST VALID 23/0600Z 10.1N 36.0W
MAX WIND 35 KT...GUSTS 45 KT.
34 KT... 30NE 0SE 0SW 30NW.

FORECAST VALID 23/1800Z 10.5N 38.6W
MAX WIND 40 KT...GUSTS 50 KT.
34 KT... 50NE 0SE 0SW 40NW.

FORECAST VALID 24/0600Z 11.0N 41.1W
MAX WIND 50 KT...GUSTS 60 KT.
50 KT... 20NE 0SE 0SW 0NW.
34 KT... 60NE 30SE 0SW 40NW.

FORECAST VALID 24/1800Z 11.7N 43.4W
MAX WIND 60 KT...GUSTS 75 KT.
50 KT... 20NE 20SE 0SW 20NW.
34 KT... 80NE 50SE 20SW 60NW.

FORECAST VALID 25/0600Z 12.4N 45.3W
MAX WIND 70 KT...GUSTS 85 KT.
50 KT... 40NE 30SE 20SW 30NW.
34 KT... 80NE 60SE 40SW 60NW.

FORECAST VALID 25/1800Z 13.0N 46.8W
MAX WIND 80 KT...GUSTS 100 KT.
50 KT... 40NE 30SE 20SW 30NW.
34 KT... 90NE 60SE 40SW 80NW.

EXTENDED OUTLOOK. NOTE...ERRORS FOR TRACK HAVE AVERAGED NEAR 150 NM
ON DAY 4 AND 175 NM ON DAY 5...AND FOR INTENSITY NEAR 15 KT EACH DAY

OUTLOOK VALID 26/1800Z 14.2N 49.5W
MAX WIND 90 KT...GUSTS 110 KT.

OUTLOOK VALID 27/1800Z 16.0N 52.5W
MAX WIND 100 KT...GUSTS 120 KT.
Last edited by AlphaToOmega on Wed Sep 22, 2021 3:52 pm, edited 1 time in total.
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Re: ATL: EIGHTTEEN - Tropical Depression - Discussion

#187 Postby InfernoFlameCat » Wed Sep 22, 2021 3:52 pm

Actually its 100knots

TROPICAL DEPRESSION EIGHTEEN FORECAST/ADVISORY NUMBER 1
NWS NATIONAL HURRICANE CENTER MIAMI FL AL182021
2100 UTC WED SEP 22 2021

THERE ARE NO COASTAL WATCHES OR WARNINGS IN EFFECT.

TROPICAL DEPRESSION CENTER LOCATED NEAR 10.1N 33.9W AT 22/2100Z
POSITION ACCURATE WITHIN 30 NM

PRESENT MOVEMENT TOWARD THE WEST OR 270 DEGREES AT 13 KT

ESTIMATED MINIMUM CENTRAL PRESSURE 1008 MB
MAX SUSTAINED WINDS 30 KT WITH GUSTS TO 40 KT.
WINDS AND SEAS VARY GREATLY IN EACH QUADRANT. RADII IN NAUTICAL
MILES ARE THE LARGEST RADII EXPECTED ANYWHERE IN THAT QUADRANT.

REPEAT...CENTER LOCATED NEAR 10.1N 33.9W AT 22/2100Z
AT 22/1800Z CENTER WAS LOCATED NEAR 10.1N 33.2W

FORECAST VALID 23/0600Z 10.1N 36.0W
MAX WIND 35 KT...GUSTS 45 KT.
34 KT... 30NE 0SE 0SW 30NW.

FORECAST VALID 23/1800Z 10.5N 38.6W
MAX WIND 40 KT...GUSTS 50 KT.
34 KT... 50NE 0SE 0SW 40NW.

FORECAST VALID 24/0600Z 11.0N 41.1W
MAX WIND 50 KT...GUSTS 60 KT.
50 KT... 20NE 0SE 0SW 0NW.
34 KT... 60NE 30SE 0SW 40NW.

FORECAST VALID 24/1800Z 11.7N 43.4W
MAX WIND 60 KT...GUSTS 75 KT.
50 KT... 20NE 20SE 0SW 20NW.
34 KT... 80NE 50SE 20SW 60NW.

FORECAST VALID 25/0600Z 12.4N 45.3W
MAX WIND 70 KT...GUSTS 85 KT.
50 KT... 40NE 30SE 20SW 30NW.
34 KT... 80NE 60SE 40SW 60NW.

FORECAST VALID 25/1800Z 13.0N 46.8W
MAX WIND 80 KT...GUSTS 100 KT.
50 KT... 40NE 30SE 20SW 30NW.
34 KT... 90NE 60SE 40SW 80NW.

EXTENDED OUTLOOK. NOTE...ERRORS FOR TRACK HAVE AVERAGED NEAR 150 NM
ON DAY 4 AND 175 NM ON DAY 5...AND FOR INTENSITY NEAR 15 KT EACH DAY

OUTLOOK VALID 26/1800Z 14.2N 49.5W
MAX WIND 90 KT...GUSTS 110 KT.

OUTLOOK VALID 27/1800Z 16.0N 52.5W
MAX WIND 100 KT...GUSTS 120 KT.

REQUEST FOR 3 HOURLY SHIP REPORTS WITHIN 300 MILES OF 10.1N 33.9W

NEXT ADVISORY AT 23/0300Z

$$
FORECASTER PAPIN
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Re: ATL: EIGHTTEEN - Tropical Depression - Discussion

#188 Postby Teban54 » Wed Sep 22, 2021 4:02 pm

Recap on history of peak intensity forecasts on first advisory, credits to kevin:

kevin wrote:
ThetaE wrote:
kevin wrote:
Yep, Ida and Iota are the only 95 kt forecasts to date. It's seems to be some sort of unwritten rule never to put the M in the first forecast so 95 kt is the maximum. So the NHC going with 90 kt combined with their hurricane forecast in 60 hours clearly indicates that they're also quite bullish on the system. And I mean, why not, literally every model is big on development for this system. Hopefully it'll remain OTS, I'm not liking these small but consistent SW changes every model cycle.


I think the NHC is just getting more confident/better at determining storms that may quickly or rapidly intensify down the road. It's not like these sort of favorable scenarios for quick ramp-ups didn't happen historically, but prediction skills are definitely a lot better nowadays.


I did some more research and it turns out that there have actually been 3 more 95 kt first advisories. Here's an overview of all 80+ kt first advisories since the modern advisories started (or at least as far as they have been archived on the NHC website) since 1998. A big sidenote is that up until and including 2002 they only did 72hr advisories instead of 120hr. The lowest first advisory ever given to a system that eventually became a MH was to Joaquin in 2015, which was forecast to peak as a 30 kt TD.

Edit: in my initial post I excluded cat 1's due to the time constraint, but I just checked those as well and I found 3 more 95+ kt cases. 2012 Isaac and 2005 Philippe were also forecast at 95 kt. And even crazier, in 2010 Tomas was given the 100 kt forecast. That forecast busted with Tomas 'only' becoming a cat 2 so perhaps that's why they've been reluctant with giving a storm the big M on its first forecast.

100 kt
2010 - Tomas

95 kt
2021 - Ida
2020 - Iota
2019 - Lorenzo
2012 - Isaac
2010 - Danielle
2005 - Philippe
2004 - Karl

90 kt
2021 - TD12
2017 - Jose
2016 - Matthew
2009 - Bill
2007 - Dean

85 kt
2020 - Delta
2015 - Danny
2014 - Gonzalo
2011 - Katia
2010 - Earl
2010 - Igor
2005 - Wilma

80 kt
2020 - Teddy
2019 - Jerry
2017 - Maria
2016 - Gaston
2012 - Leslie
2005 - Rita

TD18 now joins Tomas as the only TCs that were given an intensity forecast of 100 kt on first advisory. Those that were given 95 kt forecasts include infamous names like Ida, Iota and Lorenzo.

Now let's hope future Sam behaves exactly like the current model runs and miss the Lesser Antilles, Bermuda and CONUS. If not... this would be bad.
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Re: ATL: EIGHTTEEN - Tropical Depression - Discussion

#189 Postby Category5Kaiju » Wed Sep 22, 2021 4:05 pm

Teban54 wrote:Recap on history of peak intensity forecasts on first advisory, credits to kevin:

kevin wrote:
ThetaE wrote:
I think the NHC is just getting more confident/better at determining storms that may quickly or rapidly intensify down the road. It's not like these sort of favorable scenarios for quick ramp-ups didn't happen historically, but prediction skills are definitely a lot better nowadays.


I did some more research and it turns out that there have actually been 3 more 95 kt first advisories. Here's an overview of all 80+ kt first advisories since the modern advisories started (or at least as far as they have been archived on the NHC website) since 1998. A big sidenote is that up until and including 2002 they only did 72hr advisories instead of 120hr. The lowest first advisory ever given to a system that eventually became a MH was to Joaquin in 2015, which was forecast to peak as a 30 kt TD.

Edit: in my initial post I excluded cat 1's due to the time constraint, but I just checked those as well and I found 3 more 95+ kt cases. 2012 Isaac and 2005 Philippe were also forecast at 95 kt. And even crazier, in 2010 Tomas was given the 100 kt forecast. That forecast busted with Tomas 'only' becoming a cat 2 so perhaps that's why they've been reluctant with giving a storm the big M on its first forecast.

100 kt
2010 - Tomas

95 kt
2021 - Ida
2020 - Iota
2019 - Lorenzo
2012 - Isaac
2010 - Danielle
2005 - Philippe
2004 - Karl

90 kt
2021 - TD12
2017 - Jose
2016 - Matthew
2009 - Bill
2007 - Dean

85 kt
2020 - Delta
2015 - Danny
2014 - Gonzalo
2011 - Katia
2010 - Earl
2010 - Igor
2005 - Wilma

80 kt
2020 - Teddy
2019 - Jerry
2017 - Maria
2016 - Gaston
2012 - Leslie
2005 - Rita

TD18 now joins Tomas as the only TCs that were given an intensity forecast of 100 kt on first advisory. Those that were given 95 kt forecasts include infamous names like Ida, Iota and Lorenzo.

Now let's hope future Sam behaves exactly like the current model runs and miss the Lesser Antilles, Bermuda and CONUS. If not... this would be bad.


It's interesting, as Tomas only peaked as a Cat 2. Perhaps Sam will be the other way around.... :cry:
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Re: ATL: EIGHTTEEN - Tropical Depression - Discussion

#190 Postby supercane4867 » Wed Sep 22, 2021 4:05 pm

One of the most bullish initial advisories for an Atlantic system ever issued by the NHC

FORECAST POSITIONS AND MAX WINDS

INIT 22/2100Z 10.1N 33.9W 30 KT 35 MPH
12H 23/0600Z 10.1N 36.0W 35 KT 40 MPH
24H 23/1800Z 10.5N 38.6W 40 KT 45 MPH
36H 24/0600Z 11.0N 41.1W 50 KT 60 MPH
48H 24/1800Z 11.7N 43.4W 60 KT 70 MPH
60H 25/0600Z 12.4N 45.3W 70 KT 80 MPH
72H 25/1800Z 13.0N 46.8W 80 KT 90 MPH
96H 26/1800Z 14.2N 49.5W 90 KT 105 MPH
120H 27/1800Z 16.0N 52.5W 100 KT 115 MPH
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Re: ATL: EIGHTTEEN - Tropical Depression - Discussion

#191 Postby ElectricStorm » Wed Sep 22, 2021 4:10 pm

Wow a nearly unprecedented initial forecast :eek:
Oh boy
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Re: ATL: EIGHTTEEN - Tropical Depression - Discussion

#192 Postby wxman57 » Wed Sep 22, 2021 4:11 pm

NHC track is right along consensus (TVCN). My track is about a degree south of the NHC at day 5 and about 100 miles east of the NE Caribbean at day 7. I think models may trend a bit southward over the next few days. I had it at 90 kts as it nears the NE Caribbean next Wed PM. Still think an east US impact is unlikely, given the deep trof projected to lie over the coast next week. Primary land threat will be NE Caribbean, Bermuda, then possibly Newfoundland in 11-12 days.
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Re: ATL: EIGHTTEEN - Tropical Depression - Discussion

#193 Postby kevin » Wed Sep 22, 2021 4:14 pm

As others have already pointed out, a first advisory for the history books. And here's the visual to go along with it. Now let's find out whether this one will reach its full potential, unlike Tomas.

Image
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Re: ATL: EIGHTTEEN - Tropical Depression - Discussion

#194 Postby Category5Kaiju » Wed Sep 22, 2021 4:15 pm

wxman57 wrote:NHC track is right along consensus (TVCN). My track is about a degree south of the NHC at day 5 and about 100 miles east of the NE Caribbean at day 7. I think models may trend a bit southward over the next few days. I had it at 90 kts as it nears the NE Caribbean next Wed PM. Still think an east US impact is unlikely, given the deep trof projected to lie over the coast next week. Primary land threat will be NE Caribbean, Bermuda, then possibly Newfoundland in 11-12 days.


What are your thoughts on a Bahamas impact?
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Re: ATL: EIGHTTEEN - Tropical Depression - Discussion

#195 Postby Stormybajan » Wed Sep 22, 2021 4:17 pm

kevin wrote:As others have already pointed out, a first advisory for the history books. And here's the visual to go along with it. Now let's find out whether this one will reach its full potential, unlike Tomas.

https://i.imgur.com/LvI8VNB.png

Very shocked they went this aggressive with TD18. 100 knot major hurricane FIRST advisory is very rare coming from the nhc :double: . The good thing is that the cone seems to have TD18 move away from the islands as it gets stronger
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Re: ATL: EIGHTTEEN - Tropical Depression - Discussion

#196 Postby wxman57 » Wed Sep 22, 2021 4:17 pm

As I stated above, I would expect the models to shift more westward over the next few days. The depression/Sam-to-be is near the southern edge of a SAL outbreak, which may steer it more westerly for a while. The SAL environment would also favor a small hurricane. Look for the NHC 5 day point to shift south and westward with time. It would have to pass nearly over the islands of the NE Caribbean to produce any strong TS or hurricane winds there, since it will be relatively small in size.
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Re: ATL: EIGHTTEEN - Tropical Depression - Discussion

#197 Postby cycloneye » Wed Sep 22, 2021 4:30 pm

wxman57 wrote:As I stated above, I would expect the models to shift more westward over the next few days. The depression/Sam-to-be is near the southern edge of a SAL outbreak, which may steer it more westerly for a while. The SAL environment would also favor a small hurricane. Look for the NHC 5 day point to shift south and westward with time. It would have to pass nearly over the islands of the NE Caribbean to produce any strong TS or hurricane winds there, since it will be relatively small in size.


Hi. What is your synopsis of the ridge/trough patterns that you see and as you said, track may be a little bit south? You know why I ask. I and other S2K members that live in the NE Caribbean.
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Re: ATL: EIGHTTEEN - Tropical Depression - Discussion

#198 Postby jlauderdal » Wed Sep 22, 2021 4:33 pm

Congrats to South Floridians, we dodged another and looking good for at least two weeks. And before anyone goes with it too soon and all that, I will donate $200 to S2k if this system makes landfall in Monroe, Dade, Broward, Palm Beach or Martin counties.
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Re: ATL: INVEST 98L - Discussion Update= Best Track upgrades to TD 18

#199 Postby Deshaunrob17 » Wed Sep 22, 2021 4:35 pm

KirbyDude25 wrote:
Abajan wrote:That wasn't the question, though.
I'm pretty sure I've seen non-PTC systems given a 100% chance of development. But off the top of my head I can't recall specific examples.


I remember Paulette in 2020 was at 100/100 right before genesis, but I don't know of any besides that one.


I remember Irma being 100% too
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Re: ATL: EIGHTTEEN - Tropical Depression - Discussion

#200 Postby zal0phus » Wed Sep 22, 2021 4:54 pm

What do we realistically expect soon-to-be Sam to peak at? I am reminded somewhat of the early stages of Maria here, worst case. Even the forecasted track seems a little like a more easterly Maria.
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