ATL: Tropical Depression Fay

[cpdaman]

While Fay seems to have slowed to reorganize, she's still moving W-NW or NW - on track with the NHC. This discussion about stalling is really irritating since one cannot discern the LLC from IR and you need RECON for fixes to establish that. The storm has always been progged to slow as it rounds the edge of the ridge. I don't see anything in the recent guidance to change the NHC's track signifiantly. By the way, the axis of that northern GOM trough is already near Mobile and will be lifting out the next 24 hrs with Atlantic high pressure building in from the east.

ronjon although i disagree with your current belief about the track (mostly because she is not moving as fast or even close to what the NHC says) i think you have a good point about the axis being by mobile , and that is why i believe the NNW drift that i believe i see will be relatively short lived. this thing may snake it's way to florida

[lbvbl]

So do you guys think they will adjust the track East tonight, or wait until the morning. I would assume it would happen tonight to give people as much warning as possible, but do you think they might want to wait for more concrete evidence? Seems the general consensus is that the track will shift E... but any input would be appreciated

[CalmBeforeStorm]

While Fay seems to have slowed to reorganize, she's still moving W-NW or NW - on track with the NHC. This discussion about stalling is really irritating since one cannot discern the LLC from IR and you need RECON for fixes to establish that. The storm has always been progged to slow as it rounds the edge of the ridge. I don't see anything in the recent guidance to change the NHC's track signifiantly. By the way, the axis of that northern GOM trough is already near Mobile and will be lifting out the next 24 hrs with Atlantic high pressure building in from the east.

She may, and I stress may, be on the NHC track but at the least she is significantly slower which should effect the forecast track.

[ronjon]

Clear as mud, eh?

[KWT]

Exactly my point ronjon you just can't see the LLC to know exactly the foward speed.

Saying all that looks like its moving NW to me now, I think some are getting fooled by deep convection near 80.0W being the center when the center is probably a little to the west thanks to the shear displacing the convection but either way its crawling.

[CalmBeforeStorm]

So do you guys think they will adjust the track East tonight, or wait until the morning. I would assume it would happen tonight to give people as much warning as possible, but do you think they might want to wait for more concrete evidence? Seems the general consensus is that the track will shift E... but any input would be appreciated

It has to shift east some based at least on the shift east by the models. Current lack of mevement might shift it even more.

[HURAKAN]

[NEXRAD]

Please correct my assessment of this data, if I have any errors, but it suggests that: 1) ridging is shallow, extending only to about H85, 2) Tampa Bay seems to be outside of the surface ridge's influence given that northwesterly surface wind, 3) the shallow, narrow nature of the ridge lends itself to additional weakening and that the shallow nature of the ridge will prompt it to have less influence on Fay if the system deepens.

On the third point, I notice the West Coast sea breeze front on the ADAS Mesonet. It seems to me that this boundary may have eroded some of the near-surface ridging (?).

- Jay

Your points are pretty much on target. What is to be taken from this is that is you were to start computing mean layer winds steering winds, you'd get SW-NE for any layer that you picked. This begs the question just how far north between central and south Florida the ridge north of Fay extends. Check out Key West...

http://www.rap.ucar.edu/weather/upper/eyw.gif

The low to mid level ridge is pretty stout there...and the axis is to the north. Now Miami...

http://www.rap.ucar.edu/weather/upper/mfl.gif

A tad weaker above 500MB but still strong below. There's a pretty pronounced shift in the flow pattern once you get to central Florida. Just where between 26N and 28N this occurs is crucial to the specific track and eventual landfall. And of course, do the models have a good feel for what the evolution of the ridge and trough to the north will be.

These are some great pointers, AJC3. I'll pay more attention to the vertical profiles as Fay continues to approach the Keys. Towards the models, I'm skeptical of the west shifts today, especially considering that from my brief consideration of 1995 to 2005 tropical cyclones that moved south of Cuba and were under a ridge weakness/trough influence. I noticed that a majority of those tropical cyclones trended towards the east-side of guidance. Of course, that's not to say the same will prove true with Fay.

- Jay

[Canelaw99]

It seems like a wet and windy birthday for me tomm in miami

Happy birthday to you and me both! I turn 32 tomorrow Guess Fay wants to come by and say happy birthday too LOL

[NEXRAD]

Clear as mud, eh?

Now that's a true "spagetti chart".

- Jay

[Aric Dunn]

Please correct my assessment of this data, if I have any errors, but it suggests that: 1) ridging is shallow, extending only to about H85, 2) Tampa Bay seems to be outside of the surface ridge's influence given that northwesterly surface wind, 3) the shallow, narrow nature of the ridge lends itself to additional weakening and that the shallow nature of the ridge will prompt it to have less influence on Fay if the system deepens.

On the third point, I notice the West Coast sea breeze front on the ADAS Mesonet. It seems to me that this boundary may have eroded some of the near-surface ridging (?).

- Jay

Your points are pretty much on target. What is to be taken from this is that is you were to start computing mean layer winds steering winds, you'd get SW-NE for any layer that you picked. This begs the question just how far north between central and south Florida the ridge north of Fay extends. Check out Key West...

http://www.rap.ucar.edu/weather/upper/eyw.gif

The low to mid level ridge is pretty stout there...and the axis is to the north. Now Miami...

http://www.rap.ucar.edu/weather/upper/mfl.gif

A tad weaker above 500MB but still strong below. There's a pretty pronounced shift in the flow pattern once you get to central Florida. Just where between 26N and 28N this occurs is crucial to the specific track and eventual landfall. And of course, do the models have a good feel for what the evolution of the ridge and trough to the north will be.

agreed... I believe the possiblilty of weak steering currents over the 2 days is going to axagerate the forcast track of fay especially once it enters the gulf. a sooner than expected NE turn could happen making landfall along the lines of the GFDL more probable.. allthough we could also see a prolonged wnw motion because of the lack of and well defined steering which may lead to a slightly farther west track more along the lines of the NHC. it reamains to be seen as you said what the evolution of the "weakening" ridge will play a role in with the eventual landfall.

[AJC3]

While Fay seems to have slowed to reorganize, she's still moving W-NW or NW - on track with the NHC. This discussion about stalling is really irritating since one cannot discern the LLC from IR and you need RECON for fixes to establish that. The storm has always been progged to slow as it rounds the edge of the ridge. I don't see anything in the recent guidance to change the NHC's track signifiantly. By the way, the axis of that northern GOM trough is already near Mobile and will be lifting out the next 24 hrs with Atlantic high pressure building in from the east.

True. One point that needs to be made, however, is that model guidance has been consistently overdoing the extent of deep layer ridging across Forida - and I mean all summer long (locally there has been quite a bit of talk about the lack of prevailing easterlies across central Florida this summer). There was deep layer west to southwest flow in place all last week...long before this short wave trough came into the picture.

Like I said earlier...do the models have the right idea about how much the ridge will build westward? I have some doubts. But we'll find out one way or the other over the next couple of days.

[Scorpion]

Looks like we will be getting the sloppy side of Fay. Should be an interesting day tomorrow.

[KWT]

I've noticed that as well Jay alot of the landfalls tend to be further east then the models progged, the ultimate example being Charley of course.

I think our friend Sanibel may get a visit from Fay.

Edit---also LLC seems to have jumped eastwards a touch compared to last recon mission if thats the core starting to wrap around on the microwave imagery.

[sweetpea]

Clear as mud, eh?

LMAO

My husband was like what the heck is that!!

[tgenius]

It seems like a wet and windy birthday for me tomm in miami

:#Birthday: To you and me both! I turn 32 tomorrow Guess Fay wants to come by and say happy birthday too LOL

Yep I turn the big 30.. my wife threw me a surprise 30th Bday party for family and friends.. a GATOR themed party no less.. lots of fun.

[ExBailbonds]

scary looking

[Bocadude85]

For some reason I can not copy the link but go to key west long range radar.. is that the northern part of the center showing up on radar... matches with where the center should be.. seems to be heading more north if that is the northern extent of the storm.

[lbvbl]

I think PBC schools should be closed. Dont wanna take any risks

[wxman57]

Only two of the entire group have any kind of easterly component to them at the end of their runs... obviously they expect this trough to be of no significant at the end of their run.. or they are all wrong... models... only ones I like show up in sports illustrated...

And 11 of those plotted models are about worthless for hurricanes. The 11 moving it to the FL Panhandle.

That's a pretty bold statement for a Pro Met. Why would the NHC use them at all? Calling them worthless means you know something the NHC doesn't?

Just because a model is run by someone (not the NHC) doesn't mean the NHC will use it. For example, the BAM models should not be used out of the deep tropics as they don't take into account a changing environment in the path of a TC. There are several versions of the NAM plotted on that spaghetti plot, a model that has never proven any good for TCs. Then there are other experimental models made up by who knows who which seem to always take storms in strange directions. And you have the LBAR on there.

The NHC doesn't look at such models for guidance. They're just plotted. The best models are the consensus models like the CONU, TVCC, TCCN, TVCN, GUNS, CGUN, GUNA, HWRF, GFDL, and the FSU Superensemble. Those are the models closely followed because they have a proven track record.