ATL: DEBBY - Post-Tropical - Discussion

[toad strangler]

Really? It moved 25-30 miles East while going North. Amazing!

25-30 miles is well within the margin of error for a forecast at that time range.

Not the point. The NHC insisted all night that it was moving North when East jogs where quite evident.

Actually, you changed the original point. Regardless of the east movement landfall was well within the three day cone from the onset. I get that everyone isn't a fan of the cone. But 25 miles? Forecast science ain't that good yet.

[sponger]

25-30 miles is well within the margin of error for a forecast at that time range.

Not the point. The NHC insisted all night that it was moving North when East jogs where quite evident.

The area where it made landfall was in the cone for every advisory. Everyone in the cone should be prepared for a direct hit because it can be hard to forecast wobbles and small deviations from the track.

Still not the point.

[IsabelaWeather]

Really? It moved 25-30 miles East while going North. Amazing!

25-30 miles is well within the margin of error for a forecast at that time range.

Not the point. The NHC insisted all night that it was moving North when East jogs where quite evident.

It was always forecast to move NE toward landfall,, it had a premature bump E then moved back to the N for a while, them moved NE.

[IsabelaWeather]

Not the point. The NHC insisted all night that it was moving North when East jogs where quite evident.

It was always forecast to move NE toward landfall,, it had a premature bump E then moved back to the N for a while, then moved NE. You also DID change the entire point, the day 3 forecast was on point and another win to the NHC, IMO

[ScottNAtlanta]

It looks to me like it is moving again. From what I can tell the center is right on the FL/GA border. Getting close to Valdosta

[InfernoFlameCat]

It seems to be moving nearly due east.

[Vdogg]

It seems to be moving nearly due east.

Due east already is not good as it'll spend more time over water before turning back north and then NW (if that holds, still not quite sold on that turn back just yet).

[chaser1]

Not the point. The NHC insisted all night that it was moving North when East jogs where quite evident.

The area where it made landfall was in the cone for every advisory. Everyone in the cone should be prepared for a direct hit because it can be hard to forecast wobbles and small deviations from the track.

Still not the point.

I see where each of you may be coming from. Sponger's point cannot be disregarded from this perspective. If/when a temporary track change may impact eventual landfall by perhaps as much as 6 or more hours, there can be reverberating impacts to the overall downstream timing of moving back over water, deepening, and perhaps getting (verses not) caught in a COL, forward motion blocked under weak ridging or feeling the effects of deeper flow in response to a trough. A better example might be those on the "fringe" right or left side of where the ultimate track occurred. Such as my close friends in Crawfordville (S. of Tally). They could have been far closer to ground zero and far more rainfall, lost power, etc had Debby's motion continued northward rather than perhaps the 30 miles it jogged to the east. The thing is, NHC is not forecasting to those few in any one small town but to a far larger audience covering a broader area. The eastward job was purely a blip in the broader outcome affecting N. Fla and S. GA and the overall track prediction was correct. I think that's where IcyTundra is coming from, and I agree with that. Still..... one can't lose sight of these small deviations because if I'm in the Ft. Myers/Sarasota/Tampa/Clearwater area (or Jefferson and Wakulla counties Panhandle counties), those distances can make a big difference on the impacts felt.

[tolakram]

The area where it made landfall was in the cone for every advisory. Everyone in the cone should be prepared for a direct hit because it can be hard to forecast wobbles and small deviations from the track.

Still not the point.

I see where each of you may be coming from. Sponger's point cannot be disregarded from this perspective. If/when a temporary track change may impact eventual landfall by perhaps as much as 6 or more hours, there can be reverberating impacts to the overall downstream timing of moving back over water, deepening, and perhaps getting (verses not) caught in a COL, forward motion blocked under weak ridging or feeling the effects of deeper flow in response to a trough. A better example might be those on the "fringe" right or left side of where the ultimate track occurred. Such as my close friends in Crawfordville (S. of Tally). They could have been far closer to ground zero and far more rainfall, lost power, etc had Debby's motion continued northward rather than perhaps the 30 miles it jogged to the east. The thing is, NHC is not forecasting to those few in any one small town but to a far larger audience covering a broader area. The eastward job was purely a blip in the broader outcome affecting N. Fla and S. GA and the overall track prediction was correct. I think that's where IcyTundra is coming from, and I agree with that. Still..... one can't lose sight of these small deviations because if I'm in the Ft. Myers/Sarasota/Tampa/Clearwater area (or Jefferson and Wakulla counties Panhandle counties), those distances can make a big difference on the impacts felt.

If anyone in the cone is expecting a minute by minute more accurate forecast they are doing it wrong IMO. If you look at recon and the radar loop motion was erratic at best, generally northward except for a last minute right turn into the coast. I posted the archive and the radar loop. I don't think I'm going to change peoples minds, but 35 miles is rock star level performance as far as hurricanes are concerned.

[Nimbus]

It seems to be moving nearly due east.

Due east already is not good as it'll spend more time over water before turning back north and then NW (if that holds, still not quite sold on that turn back just yet).

The strongest train is moving into Jacksonville, power outage count starting to climb.

[weeniepatrol]

 https://twitter.com/NWSCharlestonSC/status/1820522960563884366

[chaser1]

It seems to be moving nearly due east.

I think this appearance in part is a result of Debby being on the very west side of the upper high coupled with dry air to its northwest and west and now eroding much of the west side of the storms broader envelop. Meanwhile upper outflow is expanding north and east. Stepping back and not looking too closely at the core, it does appear to be practically on the Fla/GA border as Scott commented.

[tolakram]

saved loop

[tolakram]

longer loop

[sponger]

Last band, most likely, inbound for NE Florida. Not even a flicker on the power so far.

[aspen]

saved loop

https://i.imgur.com/f2pLf6N.gif

Current motion seems to be ENE if I’m not mistaken.

[syfr]

If Debby does indeed park itself just off the coast for a couple days, how does the interaction of land affect it's structure during this time? By the look of the 8AM NHC track , it might sit 50-100 miles off the coast of SC.

That is the thing, after the NHC nudged the track east yesterday the concern is that Debby might stall long enough offshore to redevelop her pressure gradient. Coastal erosion has been a problem since the Childs point disaster and even things like bridge infrastructure take a beating with a storm like that. Tampa bay caught another break as it moved past quickly and many people didn't even lose power.

Sorry, my question was poorly worded

What I meant to ask was how far off the coast does the eye need to be for a storm to be decoupled from the effects of land (in order to intensify or not)?
Is it just that the eye needs to be over water for it to strengthen?

[MGC]

Looks just NW of Lake City moving between NE and ENE. Might make it to the Atlantic by early morning Tuesday.....MGC

[TallyTracker]

https://twitter.com/NWSCharlestonSC/status/1820522960563884366

That’s not good if Charleston is already breaking rain records…this is just beginning for them.

[cheezyWXguy]

longer loop

https://i.imgur.com/Nu2ic7N.gif

This loop illustrates a point I tried to make in several posts yesterday. Debby’s core was tilted all of yesterday until after sunset, which I would guess was due to some mid level shear out of the southwest. This resulted in the eyewall feature observed on radar being pushed further eastward, becoming ragged, and then reforming again in closer alignment to the surface center before being pushed away again. If I remember correctly, recon center fixes throughout the day showed a more consistent northward movement, with some wobbles, but more subtle than radar suggested. Additionally, many of the center fixes earlier in the day and during the prior night did not show the windshift and point of lowest pressure to be colocated.

My point here is, at least as far as I could see yesterday, the surface center’s average movement yesterday was quite consistently north, even if reflectivity radar didn’t suggest it, based on this I side with the NHC’s reporting of Debby’s heading.