ATL: TROPICAL DEPRESSION ALEX - DISCUSSION

[srainhoutx]

Hmm..not looking at the low by central america

[Air Force Met]

I don't see the western wave lifting NW unless it deepens - and it's shown absolutely no hint of doing so yet.

If it stays a naked surface swirl, it seems to me it will keep moving west straight into CA.

My take: The wave doesn't have to move NW. The fact is the wave axis is leaning NE and that is where any eventual LLC will form.

If this thing develops...it will probably do so in this manner:
1) Surge of easterlies seen moving through central and eastern CAR. Sea (watch vis loops and notice how fast cu field is moving W-WNW) moves into backside of wave axis...
2) Meanwhile...pressures south of Haiti and Hisp fall due to intense convection (brought on by increasing speed convegence of low level surge)...and wave axis tilts ENE from broad low in response to lowering pressures...broad surface low also stops moving west...
3) intense convection fires along eastside of wave axis during diurnal max...lowering pressures even more...
4) LLC forms NE of broad low...deepens...and eventually becomes the only low.

[tolakram]

How about this loop.

http://wwwghcc.msfc.nasa.gov/cgi-bin/ge ... mframes=16

This is the area I was watching earlier. Speed up the loop and carefully watch the CU clouds west of 75W. See how they seem to be drifting more toward the N/NE with time, rather that drifting NW with the old center? I think the persistent convection here is creating a new area of low pressure ... stealing words from the pro met above, and this is what I'm seeing.

[Aquawind]

Still a naked swirl alright..more pronounced but still entirely naked. I am having a hard time thinking it's going to make any dramatic changes so close to land. It's is going to have to make a pretty dramatic change in direction and at some point convection has to fireup overhead.. It looks like the only player at the LLs so maybe after it weakens another will reform with some convection but, I don't have alot of confidence it that either. Annoying 93L.

http://www.ssd.noaa.gov/goes/flt/t1/flash-rgb.html

[CrazyC83]

16N82W is just off the coast of Honduras. If that is the actual center, it might be inland before it has a chance to develop...

[x-y-no]

I think to many on here are way to quick to dismiss oppr old 93L. I disagree with x-y-no on it running out of time. I think what is happening is a secondary impulse is moving into the backside of the wave and we see that result in the form of the deep convection exploding south of Hisp. There is a surge of low level easterlies pressing into the wave axis and this is the cause of the convection...and why the wave axis is starting to tilt more towards the NE (insted of N-S).

If you look at the hi-res vis loops and watch the actual broad low...you can see that it is slowely becoming less round and more egg shaped...leaning NE-SW. What is happening is the low level cu field is responding to the lowering pressures in the area...

I give this more than a 50/50 chance...more like a 70% chance of forming...probably by tomorrow night. I don't think the trof will catch it...and believe that somewhere along the lower TX coast or N Mexico is the eventual destination. What could also happen is the GFS is more right than I am giving it credit...and future Alex moves into the north or central Gulf...stalls...then heads to the west as the ridge builds in.

There...that's my 2 cents...for what it is worth...

I think we may be saying the same thing in different ways.

The feature I was referring to as "running out of time" is specifically the wave axis which has now passed 81W and is still moving westward with essentially no associated convection.

And like you, I see a secondary impulse (the weak wave analyzed at 71W) approaching the convection south of Hispaniola, and I speculated that could interact with that area to spin something up.

[Brent]

How about this loop.

http://wwwghcc.msfc.nasa.gov/cgi-bin/ge ... mframes=15

This is the area I was watching earlier. Speed up the loop and carefully watch the CU clouds west of 75W. See how they seem to be drifting more toward the N/NE with time, rather that drifting NW with the old center? I think the persistent convection here is creating a new area of low pressure ... stealing words from the pro met above, and this is what I'm seeing.

I agree with that, it looks very interesting to me. I think the only chance this has for significant development anytime soon is to reform further east.

[Stormcenter]

Twins

[KWT]

I don't see the western wave lifting NW unless it deepens - and it's shown absolutely no hint of doing so yet.

If it stays a naked surface swirl, it seems to me it will keep moving west straight into CA.

My take: The wave doesn't have to move NW. The fact is the wave axis is leaning NE and that is where any eventual LLC will form.

If this thing develops...it will probably do so in this manner:
1) Surge of easterlies seen moving through central and eastern CAR. Sea (watch vis loops and notice how fast cu field is moving W-WNW) moves into backside of wave axis...
2) Meanwhile...pressures south of Haiti and Hisp fall due to intense convection (brought on by increasing speed convegence of low level surge)...and wave axis tilts ENE from broad low in response to lowering pressures...broad surface low also stops moving west...
3) intense convection fires along eastside of wave axis during diurnal max...lowering pressures even more...
4) LLC forms NE of broad low...deepens...and eventually becomes the only low.

Yeah I was wondering about that, a tighter LLC forming within the broad low level circulation as the convection increases to the east of the wave, esp as the better conditions aloft catch the wave up.

That being said I'd be very surprised if we get things going in one D-max, think it may take a couple of stabs at it...

[Cdeck81]

Does anyone expect an upgrade at 8?

[x-y-no]

Does anyone expect an upgrade at 8?

Upgrade?

Maybe a slight increase in the probability ...

[HURAKAN]

Does anyone expect an upgrade at 8?

Maybe from Big Mess to Even Bigger Mess

[HURAKAN]

If you add the days of 90L + 91L + 92L + 93L, this is the 20th invest day and we still can't get a depression to form!

No wonder most of us are frustrated!!!

[dixiebreeze]

Does anyone expect an upgrade at 8?

Upgrade?

Maybe a slight increase in the probability ...

Watch 2 a.m. Friday.

[Aquawind]

Does anyone expect an upgrade at 8?

Unlikely..unless come convection is associated with either the existing LL rotation or a with a obvious new forming LLC.. Which I do have more confidence will happen after reading AFM's postings..but it will still take awhile for that to happen..

[Air Force Met]

Does anyone expect an upgrade at 8?

An upgrade in %? Yes...I suspect there will be a small tick up.

[KWT]

16N82W is just off the coast of Honduras. If that is the actual center, it might be inland before it has a chance to develop...

I think what AFM has some merit, plus remember its only a broad low which is quite elongated still, its quite possible the circulation will form on the eastern side of the circulation and the upper trough should cause the system to start lifting NW in the next 24-36hrs...GFDL is pretty much on the money with where the broad low is right now.

Now we have a LLC will probably see it go upto 50%, possibly even 60% if convection looks like its getting closer.

[Aquawind]

Does anyone expect an upgrade at 8?

An upgrade in %? Yes...I suspect there will be a small tick up.

I guess that does figure being I said my confidence was going up after reading your postings..lol 50% would be my guess and it should happen within the 48 hour period..

[Ivanhater]

Interesting discussion from AFM, I just wish we had consistency in models. An awful lot of them take it into the central GOM.

[Cdeck81]

Interesting discussion from AFM, I just wish we had consistency in models. An awful lot of them take it into the central GOM.

I know. We will just have to wait until this actually becomes something (if it ever does) and then there should be some consistency in the models. It's still to early to tell.