Tropical Depression Ernesto - 35 mph - 1004 mb - W 14 mph

[phil882]

Hot Tower is showing up on radar:

[Amped]

1003.7 MB lowest extrap. 45kt winds. Has not deepened as satellite presentation would suggest.

[phil882]

1003.7 MB lowest extrap. 45kt winds. Has not deepened as satellite presentation would suggest.

And that pass they made did not even indicate a closed circulation. They might have missed the center, but they were definitely in the cirrus canopy thats covering the system currently. Looks like they are going home early too at a very pivotal time. Shame.

[Ed Lizard]

if I'm reading the HDOBs right, there is a 5ºC or greater delta between T and Td. And the plane is climbing...

[Ed Lizard]

And that pass they made did not even indicate a closed circulation. They might have missed the center, but they were definitely in the cirrus canopy thats covering the system currently. Looks like they are going home early too at a very pivotal time. Shame.

Don't think they are going to try to find the 700 mb center?

[CUmet]

And that pass they made did not even indicate a closed circulation. They might have missed the center, but they were definitely in the cirrus canopy thats covering the system currently. Looks like they are going home early too at a very pivotal time. Shame.

Oh the center is closed all right, but you won't see it from a NW-SE pass through a TC that's rapidly moving to the west. The fast forward speed will distort all the wind vectors to make it look like an open wave, especially if the NW-SE pass is the only one.

[lakeeffectkid383]

[Ed Lizard]

Oh the center is closed all right, but you won't see it from a NW-SE pass through a TC that's rapidly moving to the west. The fast forward speed will distort all the wind vectors to make it look like an open wave, especially if the NW-SE pass is the only one.

I thought (maybe wrongly) relative doesn't count, that if a TC were moving so fast the flow on one side was nil it wasn't considered a closed system.

Not that that is what happened here, just an apparent lack of a sharp center.

ETA- a wind between 180 and 360 would have been nice to see, however. Don't see that in that graphic above...

[phil882]

Oh the center is closed all right, but you won't see it from a NW-SE pass through a TC that's rapidly moving to the west. The fast forward speed will distort all the wind vectors to make it look like an open wave, especially if the NW-SE pass is the only one.

But doesn't the center need to be closed on planetary relative frame and not storm relative for a TC to be classified as such?

[Ed Lizard]

But doesn't the center need to be closed on planetary relative frame and not storm relative for a TC to be classified as such?

I have the Bob Sheets book in my bathroom somewhere, and he had an entire chapter on Andrew. There was a point where aircraft could not close off a West wind South of the center, but, IIRC, flight level winds were near 50 knots North of the center, and they anticipated Andrew moving into a more favorable environment, and decided to keep Andrew as a TS rather than declare it a wave, issue a "final" advisory, than start advisories again 12 or 18 hours later.

Not saying there are 50 knot winds or this is Andrew...

[gulfcane]

Keep in mind the ECMWF breaks the ridge down faster than GFS and digs deeper with the next trough too. If it becomes a hurricane during the next 48 hours or so I think a track through the channel is more likely and an ultimate threat to the central gulf coast. Weak = MX, strong = USA

[Analog96]

But doesn't the center need to be closed on planetary relative frame and not storm relative for a TC to be classified as such?

Like Ed said from the Sheets book, I wouldn't stop writing advisories based on one pass. They should probably wait for a few passes before they would decide to write off advisories.

[Analog96]

Keep in mind the ECMWF breaks the ridge down faster than GFS and digs deeper with the next trough too. If it becomes a hurricane during the next 48 hours or so I think a track through the channel is more likely and an ultimate threat to the central gulf coast. Weak = MX, strong = USA

That's exactly why NHC decided to ignore the models that had a way South track, because those models are too weak with the storm.

[Riptide]

Like Ed said from the Sheets book, I wouldn't stop writing advisories based on one pass. They should probably wait for a few passes before they would decide to write off advisories.

You mean 'start' writing advisories; I thought we could finally manage to get rid of the open wave talk but it appears not. Ernesto is clearly a healthy and developing TC.

[thewxmann]

Keep in mind the ECMWF breaks the ridge down faster than GFS and digs deeper with the next trough too. If it becomes a hurricane during the next 48 hours or so I think a track through the channel is more likely and an ultimate threat to the central gulf coast. Weak = MX, strong = USA

Let's make sure this gets past Central America first. Not really going to matter much anyway since either model depicts a ridge in the western U.S. (so either FL or MX).

[Analog96]

You mean 'start' writing advisories; I thought we could finally manage to get rid of the open wave talk but it appears not. Ernesto is clearly a healthy and developing TC.

No, I meant writing the storm off, as in cancelling advisories, based on one pass. If they don't find a closed center tonight, and continue to not find a closed center tomorrow, then stop writing advisories.

[CUmet]

But doesn't the center need to be closed on planetary relative frame and not storm relative for a TC to be classified as such?

Yes, but the circulation is elongated in the earth-relative sense because of the storm motion, so there are some cross-sections through the storm that are more "unfavorable" than others for determining whether it's closed. If you think about it in terms of adding the TC circulation wind vectors with the storm motion vectors, you can see what I'm talking about.

Because of the fast storm motion relative to the TC vortex strength, all of the earth-relative wind vectors will have an "anomalously easterly" component compared to what you're used to seeing. Thus, in a NW-SE pass, in the NW quad when you would usually see a NE wind in an axisymmetric wind field, you would see a ENE wind. In the SE quad when you would normally see a SW wind, it becomes more SSW or southerly, giving the appearance of an open wave. This is why, for example, if you're first pass through is NW-SE for a westward moving TC, you need an additional SW-NE pass through to close the center. However, if you did the latter first and found a west or northwest wind, your job is done confirming a closed center.

The reason why I'm confident that it's closed now is because it was closed earlier, and if anything the low-level swirl became better defined throughout the day. There's no reason why it wouldn't be closed now.

[Ed Lizard]

Half an hour w/o an HDOB on the NHC site, while they were maintaining about 700 mb altitude on the last HDOB, they were flying Northwest. I fear Phil is correct, they had an issue.

EDIT TO ADD

Oh, sugar

URNT11 KNHC 032300

97779 23004 60166 64000 30300 11032 09042 /3170

RMK AF309 0305A ERNESTO OB 06

SWS = 30 KTS

LAST REPORT

;

[bluewave]

Tomorrow should be the moment of truth for the Euro. It weakens Ernesto right around 70W

during the afternoon. At least right now, the satellite presentation is as good as it has looked

so far.

http://www.meteo.psu.edu/ewall/SAT_ATL/animir.html

[phil882]

Like Ed said from the Sheets book, I wouldn't stop writing advisories based on one pass. They should probably wait for a few passes before they would decide to write off advisories.

No, I meant writing the storm off, as in cancelling advisories, based on one pass. If they don't find a closed center tonight, and continue to not find a closed center tomorrow, then stop writing advisories.

No, I agree that its foolish to stop writing advisories based on one pass through a storm. I was more frustrated than anything because recon only made one pass which did not confirm a closed circulation.

Yes, but the circulation is elongated in the earth-relative sense because of the storm motion, so there are some cross-sections through the storm that are more "unfavorable" than others for determining whether it's closed. If you think about it in terms of adding the TC circulation wind vectors with the storm motion vectors, you can see what I'm talking about.

Because of the fast storm motion relative to the TC vortex strength, all of the earth-relative wind vectors will have an "anomalously easterly" component compared to what you're used to seeing. Thus, in a NW-SE pass, in the NW quad when you would usually see a NE wind in an axisymmetric wind field, you would see a ENE wind. In the SE quad when you would normally see a SW wind, it becomes more SSW or southerly, giving the appearance of an open wave. This is why, for example, if you're first pass through is NW-SE for a westward moving TC, you need an additional SW-NE pass through to close the center. However, if you did the latter first and found a west or northwest wind, your job is done confirming a closed center.

The reason why I'm confident that it's closed now is because it was closed earlier, and if anything the low-level swirl became better defined throughout the day. There's no reason why it wouldn't be closed now.

I agree with you. It just bugs me a tad that the first recon pass that they best they could do was find a wind shift from ENE to S on a NE/SW leg through the storm. Even the winds in the NE quadrant were weaker than the last two recon missions, which is a little perplexing given the improved satellite presentation. Sometimes convection when not directly co-located with the center can actually distort the definition of a circulation. I don't think thats happening in this case, but that recon mission in my opinion created a lot more unknowns rather than clearing up anything.

[ams30721us]

Who disturbed the sleeping giant this afternoon?

[Analog96]

No, I agree that its foolish to stop writing advisories based on one pass through a storm. I was more frustrated than anything because recon only made one pass which did not confirm a closed circulation.

I agree with you. It just bugs me a tad that the first recon pass that they best they could do was find a wind shift from ENE to S on a NE/SW leg through the storm. Even the winds in the NE quadrant were weaker than the last two recon missions, which is a little perplexing given the improved satellite presentation. Sometimes convection when not directly co-located with the center can actually distort the definition of a circulation. I don't think thats happening in this case, but that recon mission in my opinion created a lot more unknowns rather than clearing up anything.

Maybe there was a problem with the recon?

[phil882]

Maybe there was a problem with the recon?

Most likely... probably radio transmission issues as they often are.

[turtlehurricane]

Now this is a tropical cyclone I can get excited about. Nice overshooting tops at sunset.

[HurricaneJosh]

Now this is a tropical cyclone I can get excited about. Nice overshooting tops at sunset.

Totally, dude. I'm feeling better about this one today.

[Amped]

I think having a tutt to the east of the cyclone helps as opposed to having the tutt to the west which usually shreds the storm. It maybe helping todays convective blowup. I am still hugging the GFS/EURO unless the storm breaks 995mb or the GFS/Euro change their minds.

[Snow_Miser]

Ernesto looks the best that it has ever looked in it's lifetime. Look at those cold tops near the center of the storm and the impressive outflow to the north. As others have said, shear is still present with this storm, which may hinder rapid intensification, but slow intensification is still possible over the next couple of days.

[gulfcane]

Shear is not an issue going forward. SHIPS diagnosed the shear at 4kts at 0z and I concur with that.

[tmagan]

00Z Saturday Observations

[phil882]

00Z Saturday Observations

Buoy 42059 should be interesting to watch over the next 12 hours... center should pass close by.