ATL: IDA - Remnants - Discussion

[kevin]

95 kts peak forecast

Wasn't a similar peak predicted on the first advisory for Iota last year?

Yep, Iota and now TD9 are the first TCs to get a 95 kt peak forecast in their first advisory. Doesn't guarantee anything with a sample size of 1 besides TD9, but it isn't a good sign of things to come.

[AlphaToOmega]

The last thing I want for TD 09L is a peak intensity debate

[Shell Mound]

The depression will be moving over the high ocean heat content
waters of the northwestern Caribbean Sea during the next 24-36
hours. This, in combination with low vertical wind shear and a
moist environment, should allow for steady strengthening. The
depression is forecast to become a tropical storm later today or
tonight, and could approach hurricane strength as it passes near
or over western Cuba. Once the system moves into the Gulf of
Mexico, conditions are expected to be conducive for additional
strengthening, and rapid intensification is explicitly shown in
the NHC forecast between 48 and 72 hours. The NHC intensity forecast
brings the system near major hurricane strength when it approaches
the northern Gulf coast on Sunday. This forecast is supported by the
HWRF and CTCI models, and the GFS, ECMWF, and UKMET global model
guidance, which all significantly deepen the cyclone over the Gulf
of Mexico. As a result, there is higher-than-normal confidence
that a strengthening tropical cyclone will be moving over the Gulf
this weekend.

[NDG]

X is where they estimate the CoC to be and initiated advisories. Close to the area I have been looking at this morning.

[Category5Kaiju]

If and hopefully not but if Ida(99L) is as bad as forecast and impacts are large enough to be retired from the rotating hurricane naming lists, should the WMO consider removing the letter "I"?

Why? What would that do? Hurricanes don't choose to become destructive because they know the first letter of their name. It would just mean that J names would be in that sweet spot.

I don't think the WMO will remove 'I', since there are still a few female 'I' names that are recognizable (although we are running low). Interestingly enough, 'J' is actually the most common first initial (by a long shot too), and there would be so many options to replace the 'J' name A lot of our problems would be solved if 'J' were the 9th letter of the alphabet instead of 'I', but alas, that is not the case. The people who came up with the order of the alphabet probably didn't know we'd be using it to name hurricanes!

I have mentioned this in an earlier post on another thread, but it actually would not surprise me if the WMO is forced to resort to I names that are Russian (like Irina or Iosef) or Indian (like Indira or Ishan); at least these particular cultures, for example, possess a lot of I names. However, for now, I still think we have a handful of good I names we could use, such as Irving, Inga, Ivy, or Imogen. I personally would love to see Imogen replace Ida should Ida be retired, but we'll see.

[Woofde]

95 kts peak forecast

Wasn't a similar peak predicted on the first advisory for Iota last year?

Yep, Iota and now TD9 are the first TCs to get a 95 kt peak forecast in their first advisory. Doesn't guarantee anything with a sample size of 1 besides TD9, but it isn't a good sign of things to come.

Well, just like Iota it looks like it will be a low shear, high SST environment. It's hard to put anything lower than that, especially with model support for a Major.

[cycloneye]

NORA will not shear this system.

 https://twitter.com/webberweather/status/1430907314391830537

[ConvergenceZone]

so a cat 2 forecast? Pretty impressive! Wonder if a Cat 3 is possible?

[NDG]

NORA will not shear this system.

https://twitter.com/webberweather/status/1430907314391830537

He was the one wishing for it when no model was showing shear/outflow from the EPAC system affecting TD 9.

[tolakram]

044
WTNT44 KNHC 261456
TCDAT4

Tropical Depression Nine Discussion Number 1
NWS National Hurricane Center Miami FL AL092021
1100 AM EDT Thu Aug 26 2021

Early morning visible satellite imagery shows that the circulation
associated with the area of low pressure over west-central
Caribbean Sea has become better defined. There has also been an
increase in the organization of the associated convective activity,
and based on consensus Dvorak T-numbers of 2.0 from TAFB and SAB,
advisories are being initiated on a tropical depression. The initial
intensity is set at 30 kt, in agreement with the subjective
satellite estimates. The official reporting station in Kingston,
Jamaica, has reported sustained winds of 25 kt with gusts to 35 kt
during the past couple of hours. An Air Force Reserve
reconnaissance aircraft is scheduled to be in the system later this
afternoon to provide more information on the system's structure
and intensity.

The depression is moving northwestward or 325/11 kt, however the
initial motion is a bit more uncertain than normal since the low-
level center has only recently formed. The cyclone is forecast
to move steadily northwestward around the southwestern portion of a
deep-layer ridge centered over the western Atlantic. This track
should bring the center near or over western Cuba late Friday,
over the southeastern and central Gulf of Mexico Friday night and
Saturday, and have the center approach the northern Gulf coast on
Sunday. The track guidance is in relatively good agreement, however
the average NHC track forecast error at day 4 is around 175 miles,
so users should not focus on the details of the long range track
forecast. Some shifts in the track are likely until the system
consolidates and becomes better defined. The NHC track is near the
various consensus model aids and is in best agreement with the GFS
ensemble mean.

The depression will be moving over the high ocean heat content
waters of the northwestern Caribbean Sea during the next 24-36
hours. This, in combination with low vertical wind shear and a
moist environment, should allow for steady strengthening. The
depression is forecast to become a tropical storm later today or
tonight, and could approach hurricane strength as it passes near
or over western Cuba. Once the system moves into the Gulf of
Mexico, conditions are expected to be conducive for additional
strengthening, and rapid intensification is explicitly shown in
the NHC forecast between 48 and 72 hours. The NHC intensity forecast
brings the system near major hurricane strength when it approaches
the northern Gulf coast on Sunday. This forecast is supported by the
HWRF and CTCI models, and the GFS, ECMWF, and UKMET global model
guidance, which all significantly deepen the cyclone over the Gulf
of Mexico. As a result, there is higher-than-normal confidence
that a strengthening tropical cyclone will be moving over the Gulf
this weekend.

Key Messages:

1. Tropical storm conditions are likely in portions of the Cayman
Islands tonight and western Cuba Friday and Friday night, with
dangerous storm surge possible in portions of western Cuba,
including the Isle of Youth, in areas of onshore flow.

2. The system is expected to produce life-threatening heavy rains,
flash flooding and mudslides across Jamaica, the Cayman Islands,
western Cuba, including the Isle of Youth and northeastern portions
of the Yucatan Peninsula.

3. This system is forecast to approach the northern Gulf Coast at or
near major hurricane intensity on Sunday, although the forecast
uncertainty is larger than usual since the system is just forming.
There is a risk of life-threatening storm surge, damaging
hurricane-force winds, and heavy rainfall Sunday and Monday along
the northern Gulf Coast from the Florida Panhandle to the upper
Texas coast, with the greatest risk along the coast of Louisiana.
Interests in these areas should closely monitor the progress of this
system and ensure they have their hurricane plan in place.

FORECAST POSITIONS AND MAX WINDS

INIT 26/1500Z 16.9N 79.2W 30 KT 35 MPH
12H 27/0000Z 18.2N 80.4W 35 KT 40 MPH
24H 27/1200Z 20.3N 82.0W 45 KT 50 MPH
36H 28/0000Z 22.5N 83.9W 55 KT 65 MPH...INLAND
48H 28/1200Z 24.4N 86.0W 65 KT 75 MPH...OVER WATER
60H 29/0000Z 26.1N 88.1W 80 KT 90 MPH
72H 29/1200Z 27.7N 90.0W 95 KT 110 MPH
96H 30/1200Z 30.5N 92.0W 70 KT 80 MPH...INLAND
120H 31/1200Z 33.7N 91.2W 30 KT 35 MPH...INLAND

$$
Forecaster Brown

[ElectricStorm]

so a cat 2 forecast? Pretty impressive! Wonder if a Cat 3 is possible?

Cat 2 is the highest they go on first advisories, at least in the Atlantic. I've never seen them go Cat 3 on the first one, unless it's in the EPAC. So it's likely to get pretty strong unfortunately

[psyclone]

That's one helluva a first advisory. Seems very reasonable and consistent with what happens in peak season. When watches do come out...expect a storm surge watch to extend well east of the hurricane watch. water will stack very efficiently east of the hurricane and ts windfield with this track. this one's gonna leave a mark over a wide area.

[aspen]

A year ago today, Laura was about to make landfall in Louisiana as a major. Now we’re looking at yet another system expected to be a Louisiana major landfall in just a few days. They can’t seem to catch a break this decade so far.

[mpic]

All I know is that people in Houston are writing this off this morning as a Louisiana storm and not looking back. I learned my lesson with Rita and again with Ike.

Everyone should keep an eye out... I am interested in the NHCs track

If i recall, not too long ago all the models had Hurricane Grace going into the central GOM... It ended up burying itself in the BOC & Mexico.

Exactly why I don't write it off this far out.

[petit_bois]

so a cat 2 forecast? Pretty impressive! Wonder if a Cat 3 is possible?

Patience is needed... We will have a lot of answers Friday night and Saturday morning.

[Chemmers]

A cat 2 is a good place to come in at, Unfortunately I think they will keep knocking the winds up each advisory link they did with Mathew, think that was predicted a cat 2 as well on it first one

[PTrackerLA]

Not looking good for Lafayette, current track would cause one of our worst hits ever locally .

[aspen]

Seems like the NHC forecast puts Ida right on top of the broiling Loop Current on Saturday afternoon. Thankfully it won’t stall over the Loop Current and take full advantage of it, but the increased OHC will probably help trigger a RI phase if one hasn’t already started.

This whole storm can just be summed up with “yikes”.

[Jr0d]

Just a little wobble east and the Florida Keys will be getting tropical storm conditions (again).

Not a good sign that both the EURO and GFS take this to New Orleans as a major storm.

[LARanger]

The people who came up with the order of the alphabet probably didn't know we'd be using it to name hurricanes!

Well, had we told them we'd be using the names of people but then retiring them fairly often, they'd have correctly assumed we were stupid for using a system so obfuscatory, ridiculous, and that'll be barely able to last a century without imported names.

We'd be far better off if this was 2021-I, chatting about it being reminiscent of 2005-K, and boy wasn't 2020-D2 / 2020-DD harsh, et cetera. That system could last forever, but even a system like 21I or 05K would be perfectly clear for a century, unlike what we have now.

</soapbox>