ATL: IAN - Post-Tropical - Discussion

[Jelmergraaff]

There it is, I think.

(Last few frames, west of the LLC)

[aspen]

What seems to be missing with Ian is a good circular outflow pattern. Other than the SW end there really isn't much established outflow. Mission 11 is in the air to go investigate Ian

That’s odd. The models have consistently shown an excellent UL setup today into tomorrow, with an okay setup on Tuesday turning hostile on Wednesday.

[ScottNAtlanta]

Wonder if they'll drop the peak intensity to mid-range Cat 3. Given we're in late September and we're going to have frontal interaction that wasn't present with more recent years this time of year, this won't have the opportunity to strengthen all the way to the coast.

As someone stated earlier...this region is notorious for really rapid intensification...I think they would be wise to wait. If it isn't as strong near Cuba, then maybe.

[kevin]

Finally it looks like we might get a convective burst near the center.

[ScottNAtlanta]

What seems to be missing with Ian is a good circular outflow pattern. Other than the SW end there really isn't much established outflow. Mission 11 is in the air to go investigate Ian

That’s odd. The models have consistently shown an excellent UL setup today into tomorrow, with an okay setup on Tuesday turning hostile on Wednesday.

Looking at it, I would not think it's there just yet. That might be changing very soon though. Starting to notice some wispy cirrus blowing off on the west side. If you dont have good outflow to evacuate the heat you can't build t'storms.

[sma10]

Would be great if Ian never gets it’s act together.

There’s a decent chance that happens. Then the models would pretty much lose all credibility this year…but then again, they still haven’t been great — everything about Bonnie, so many August phantoms, Euro correcting to the GFS’s tracks, nothing developing Fiona until it was 48 hours away from being named, etc

Has anyone seen the Euro? It predicts W Cuba 48 hrs from now at 984mbs. Surely that's possible to attain, if not likely.

[fllawyer]

TS watch for lower keys per 5pm advisory.

[HurricaneBelle]

The new NHC track puts the eye of Ian about 50 miles to my west off the Pinellas coast at 28.3/84.0, albeit weakening to a Cat 2 (85 kt)

[tolakram]

000
WTNT44 KNHC 252057
TCDAT4

Tropical Storm Ian Discussion Number 11
NWS National Hurricane Center Miami FL AL092022
500 PM EDT Sun Sep 25 2022

The organization of Ian has not changed much since this morning.
There have been some small bursts of convection closer to the center
of the storm this afternoon, but the activity has not yet led to any
notable changes in its structure. In fact, the most persistent
convection has been in outer rainbands well to the northeast of the
circulation near Jamaica. The SFMR wind data and adjusted
flight-level winds from the earlier reconnaissance flights supported
surface winds of 35-40 kt, and the initial intensity is set at 40 kt
for this advisory. A NOAA Hurricane Hunter aircraft is scheduled to
investigate Ian later tonight.

The center of Ian has jogged a bit northward this afternoon, but its
longer-term motion is west-northwestward at 300/10 kt. A generally
northwestward motion is expected tonight, followed by a
north-northwestward motion on Monday and early Tuesday as it moves
across the northwestern Caribbean Sea and near or over western Cuba.
From there, the track guidance still diverges at days 3-5 as Ian is
forecast to move northward across the eastern Gulf of Mexico. The
ECMWF and UKMET models still lie on the eastern edge of the guidance
and bring the center of Ian over the coast of west-central Florida,
while the HWRF and HMON models are on the western side of the
envelope and show Ian approaching the central Florida panhandle.
Notably, the GFS has trended slightly eastward for the past few
cycles, which has brought the multi-model consensus aids a bit
eastward as well. The latest NHC track forecast has been adjusted in
this direction, but only on the order of 15-20 n mi in the extended
range. Users are reminded not to focus on the details of the track
forecast at longer time ranges, since uncertainty is still high and
future adjustments may be required.

Although the storm has yet to develop an inner core, the conditions
over the northwestern Caribbean Sea appear very likely to support
strengthening once it becomes better organized. Some dry
environmental air may have limited convection today, but the GFS-
and ECMWF-simulated satellite imagery indicate that deep convection
will increase during the diurnal maximum period overnight. Then,
significant strengthening is expected with low deep-layer shear and
high oceanic heat content along the forecast track. There is still
strong support for rapid intensification in the latest intensity
guidance, and the NHC intensity forecast shows Ian becoming a
hurricane on Monday and a major hurricane on Tuesday. This forecast
remains close to the IVCN multi-model consensus, with some model
aids including HCCA showing even higher peak intensities. Strong
southwesterly shear develops over Ian by 72 h related to interaction
with an upper-level trough, and the structure of the cyclone could
significantly degrade before landfall given these hostile
conditions. However, Ian is likely to have an expanding wind field
and will be slowing down by that time, which will have the potential
to produce significant wind and storm surge impacts across portions
of the Florida west coast and the Florida panhandle.


Key Messages:

1. Ian is expected to produce heavy rainfall, flash flooding, and
possible mudslides in areas of higher terrain, particularly over
Jamaica and Cuba. Flash and urban flooding is possible with
rainfall across the Florida Keys and the Florida peninsula through
the middle of the week. Additional flooding on rivers across
northern Florida and parts of the southeast U.S. cannot be ruled out
later this week.

2. Life-threatening storm surge and hurricane-force winds are
expected in portions of western Cuba beginning late Monday, and Ian
is forecast to be at or near major hurricane strength when it is
near western Cuba. Efforts to protect life and property should be
rushed to completion.

3. Ian is expected to be a major hurricane in the eastern Gulf of
Mexico during the middle of this week, but uncertainty in the track
and intensity forecasts remains higher than usual. Regardless of
Ian’s exact track and intensity, there is a risk of dangerous storm
surge, hurricane-force winds, and heavy rainfall along the west
coast of Florida and the Florida Panhandle by the middle of this
week, and residents in Florida should ensure they have their
hurricane plan in place. Follow any advice given by local officials
and closely monitor updates to the forecast.


FORECAST POSITIONS AND MAX WINDS

INIT 25/2100Z 16.2N 80.3W 40 KT 45 MPH
12H 26/0600Z 17.3N 81.5W 50 KT 60 MPH
24H 26/1800Z 19.2N 82.9W 70 KT 80 MPH
36H 27/0600Z 21.1N 83.7W 90 KT 105 MPH
48H 27/1800Z 23.0N 84.2W 105 KT 120 MPH
60H 28/0600Z 24.8N 84.4W 115 KT 130 MPH
72H 28/1800Z 26.2N 84.4W 110 KT 125 MPH
96H 29/1800Z 28.3N 84.0W 85 KT 100 MPH
120H 30/1800Z 31.0N 83.0W 50 KT 60 MPH...INLAND

$$
Forecaster Reinhart

[Hammy]

Hurricane intensity has been pushed back 24-30 hours over the last few advisory cycles and starting to run out of time. Either this is going to do what the season as a whole did continue to struggle, only to explode at the last minute, or we're going to see a major forecasting bust like we did with Debby in 2000 and Erika in 2015.

I'd say the chances are 50/50 in either direction at this point.

[wxman57]

The new NHC track puts the eye of Ian about 50 miles to my west off the Pinellas coast at 28.3/84.0, albeit weakening to a Cat 2 (85 kt)

That point is 75 miles offshore. Consensus is about 30 miles offshore. NHC will be adjusting closer to you tonight. Be prepared for hurricane conditions Thursday.

[Teban54]

Some dry
environmental air may have limited convection today, but the GFS-
and ECMWF-simulated satellite imagery indicate that deep convection
will increase during the diurnal maximum period overnight. Then,
significant strengthening is expected with low deep-layer shear and
high oceanic heat content along the forecast track. There is still
strong support for rapid intensification in the latest intensity
guidance, and the NHC intensity forecast shows Ian becoming a
hurricane on Monday and a major hurricane on Tuesday. This forecast
remains close to the IVCN multi-model consensus, with some model
aids including HCCA showing even higher peak intensities.

[skyline385]

Can anybody justify why Ian is moving almost due north right now? NNW

very likely a temporary jog or wobble, most systems don't follow the NHC forecast to a line...

Obviously no tc travels in a straight line lol but that’s a heck of a wobble.

The jog is in the discussion now

The center of Ian has jogged a bit northward this afternoon, but its
longer-term motion is west-northwestward at 300/10 kt.

[ObsessedMiami]

I don’t see the track shifted much at all this advisory.

[johngaltfla]

The new NHC track puts the eye of Ian about 50 miles to my west off the Pinellas coast at 28.3/84.0, albeit weakening to a Cat 2 (85 kt)

That point is 75 miles offshore. Consensus is about 30 miles offshore. NHC will be adjusting closer to you tonight. Be prepared for hurricane conditions Thursday.

And this is why it is important to read the details (thanks again Wxman57). Some of us have to make decisions to put people on the road and conduct commerce. If we are risking hurricane conditions by Wednesday night/Thursday a.m. we start shutting things down and diverting. That's why knowing the cone and deciding what to do about employees hinges so much on these advisories.

[ScottNAtlanta]

I guess recon flights are able to fly over Cuba now since the newest recon is doing just that.

[Hammy]

very likely a temporary jog or wobble, most systems don't follow the NHC forecast to a line...

Obviously no tc travels in a straight line lol but that’s a heck of a wobble.

The jog is in the discussion now

The center of Ian has jogged a bit northward this afternoon, but its
longer-term motion is west-northwestward at 300/10 kt.

If we're getting the formation of a CDO, I wonder if that rising motion pulled the LLC towards it, essentially sucking it towards a formative MLC

[fllawyer]

I guess recon flights are able to fly over Cuba now since the newest recon is doing just that.

IIRC, there is a long-standing agreement to allow US aerial assets to fly over Cuba for weather missions.

[Blown Away]

I don’t see the track shifted much at all this advisory.

Gotta think the NHC doesn’t really think a 100 mph hurricane into the Big Bend armpit, look a history, it’s so rare. The alternative is adjusting and showing a Major into Tampa. My guess, one more GFS run to confirm this east trend.

[jfk08c]

I don’t see the track shifted much at all this advisory.

Definite shift. Easier to see when you're looking where its projected to cross Cuba