TD 9 an Open Wave?

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wxman57
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TD 9 an Open Wave?

#1 Postby wxman57 » Fri Aug 22, 2003 8:10 am

Well, I can't find any evidence of a LLC this morning. I DO have one ship report about 50 miles south of the "center" that has a 20 knot wind from the EAST, and this ship is in the clear. There's an evident mid-level circulation on radar/satellite, however. I think the NHC jumped the gun yesterday in upgrading it. Question is, what do they do when this morning's recon finds no LLC?

Also, take a look at WV loops - you'll see the western side of the depression running into increasing SW shear and flattening-out. Probably no Fabian in the next 24 hrs.
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#2 Postby Anonymous » Fri Aug 22, 2003 8:15 am

Happy Birthday Wxman57. Have a great one! :new-bday:
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#3 Postby Air Force Met » Fri Aug 22, 2003 9:09 am

That's what I wrote in the IWIC forecast discussion on the thing. I think it is an open wave and unless some deep convection starts firing over the center, recon will find an open wave when they get there. Bottom line...I doubt the NHC would pull the trigger today on a td if they did not do it yesterday.
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#4 Postby Thunder44 » Fri Aug 22, 2003 9:24 am

Did you read the first discussion yesterday? Well, yesterday it had an LLC cuz a ship reported a west wind. That isn't consistent with a open wave. I don't think they jumped the gun then. And I also suspect the NHC has more info this storm that we can't find like yesterday. However recon will probably provide the best info on this system.
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#5 Postby Air Force Met » Fri Aug 22, 2003 9:43 am

I think you misread. We were not saying it was an open wave yesterday...but opened up over the night and is one now. What I said is if that ship had not been there yesterday...and they had not classified it yesterday...they certainly would not do so this morning based on what they were seeing.

So...it probably did have an LLC yesterday but today it looks as if it has opened up. I also just checked QuikSCAT and there is not even a hint of a circulation.

http://manati.wwb.noaa.gov/storm_at_ima ... _at_0.html
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#6 Postby Steve H. » Fri Aug 22, 2003 9:54 am

Well that might be academic, since an Lcc is clearly visible now, but in fact it might have been open earlier.
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#7 Postby Air Force Met » Fri Aug 22, 2003 10:02 am

I don't think it is clear now. I see the MLC. BUt I also see westward moving low level cloud elements less than 60 miles west of the LLC. If there is an LLc...it is very very weak. It may be there but it certainly is not evident on the vis pics I have. The MLC is certainly. Maybe an LLC...but again the problem is those westward moving clouds. What thay means is the LLC is embedded in a cusp type feature. Not classic by any stretch of the imagination.
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#8 Postby Thunder44 » Fri Aug 22, 2003 10:17 am

wxman57 wrote:
Well, I can't find any evidence of a LLC this morning. I DO have one ship report about 50 miles south of the "center" that has a 20 knot wind from the EAST, and this ship is in the clear. There's an evident mid-level circulation on radar/satellite, however. I think the NHC jumped the gun yesterday in upgrading it. Question is, what do they do when this morning's recon finds no LLC?


Air Force Met, you didn't say it but wxman57 said it or at least that's the way I understood it. I was responding more to wxman57 then you. Although I disagree with you that there is an open wave now. QS didn't detect a LLC yesterday either.
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#9 Postby Air Force Met » Fri Aug 22, 2003 10:39 am

One west wind from a ship is suspect. I did not see any low clouds moving west yesterday. I did see the ship report. Being a long time weatehr observer...I am always leary of those reports seeing how they are cargo ships from monrovia or something like that;) You also may have gotten a t-storm wind or something like that. There were some in that area. So...all we are saying is the evidence was circumstantial...not rick solid. QuikSCAT is not going to be that wrong. the west wind from the ship was fairly far south of where the LLC was. Matter of fact, it was 100 miles south of the LLC. So...that means that quikscat would have to have missed 100 miles of west winds...and that the vis sat imagery which also did not show any low cloud elements moving east in that whole area...but yet had west winds there also.

How do you explain that? 100 miles? No east moving low clouds...no easterly quickscat winds...and one report 100 miles to the south. Do you have a meteorological answer for this one? You have to remember, WXman and I are professional mets. We ahve to make these decisions (not the upgrading...but the forecasting of and all sorts of other stuff) based on emperical data we observe. When we see a piece of evidence like a west ship wind...we have to fit that into other things. When that west wind doesn't fit into the cloud elements and QuikSCAT...we have to ask ourselves...does that fit or is there another explaination?

If I am missing something please help out...but please explain how you have a west wind in a circulation 100 miles away...yet it doesn't show in quikscat and vis loops. I can give many probabilities for the explaination of a west wind: bad ob, t-storm, local eddy, drunk observer ;) please tell me meteorologically how it can fit given the other evidence.

ALso...they MAy have jumped the gun. I have seen much more info available to them without them pulling the trigger. This is one ob 100 miles away with no other supporting data (ship did not report again). So...who knows.
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#10 Postby rob8303 » Fri Aug 22, 2003 10:45 am

Honestly, I don't think the NHC is a bunch of fools. Are you saying that they would upgrade a TD just based on one ship captain's report? That's all they upgraded it on? If they did, they should all be fired. I thought td classificiations were only made after a variety of factors were considered, not just one ship reporting in. I HIGHLY doubt that's the only reason TD 9 was upgraded.
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#11 Postby Air Force Met » Fri Aug 22, 2003 11:00 am

All I am saying is based on the low lcoud elements and the quikscat...that west wind did not fit. One thing is certain...a def. LLC yesterday was NOT a slam dunk. I think they upgraded it because they had some evidence and it looked good on sat. It looked as if it was about to go to town...at least that is what I thought. I did not say they were a bunch of fools. I do think it was more a preventive measure than anything though. Given the choice of upgrading a system based on some weak data...or letting it sit there a while and get some explosive development so close to land...you upgrade it.

Ask yourself this question: If that system was at 15N and 40W...given all the details...do you think it would have been upgraded? Nope. I was upgraded because it looked ready to roll (which it didn't) and it was semi-close to land.
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#12 Postby Derek Ortt » Fri Aug 22, 2003 11:09 am

I see the report of an east wind as well. This is not becoming better organized and recon may very well find an open wave
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#13 Postby Air Force Met » Fri Aug 22, 2003 11:12 am

I wish I could draw what I think is there. If there is a LLC...it is embedded in a cusp at the end of a wave and is very small in area...maybe 30 miles across. To the west aer those low clouds moving away. Definitely not a healthy LLC by any stretch of the imagination. If that MLC can go down...and some deep convection can get going...all will be fine...until it hits Hispaniola ;)
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#14 Postby mitchell » Fri Aug 22, 2003 11:13 am

Air Force Met wrote:I think they upgraded it because they had some evidence and it looked good on sat. It looked as if it was about to go to town...at least that is what I thought. I did not say they were a bunch of fools


Agree...a bit of healthy skepticism is not a bad thing and it looked to me like once the convective ball dissipated this a.m. the structure of the storm was exposed for what it is...primarily a mid level circ.
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#15 Postby Air Force Met » Fri Aug 22, 2003 11:17 am

Given what I saw yesterday...I would have said "better safe than sorry" if I was the NHC as well. All we are doing today is analyzing data in the hindsite mode. Why? To learn for tomorrow.

All the more need for recon and more quicksat sats.
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#16 Postby Thunder44 » Fri Aug 22, 2003 11:46 am

I'm not a "professional met" but the people at NHC are. I'm sure they investigated the ship report as well, and they probably know more about the ship and it whearabouts at the time that you are so skeptical of as well, then you, Air Force Met. I'm sure other factors were considered well. But we'll see what the recon finds when they go there this afternoon.

Where is this ship report by the way, some of you have that this morning?
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#17 Postby Scott_inVA » Fri Aug 22, 2003 11:49 am

Air Force Met wrote:All I am saying is based on the low lcoud elements and the quikscat...that west wind did not fit. One thing is certain...a def. LLC yesterday was NOT a slam dunk. I think they upgraded it because they had some evidence and it looked good on sat. It looked as if it was about to go to town...at least that is what I thought. I did not say they were a bunch of fools. I do think it was more a preventive measure than anything though. Given the choice of upgrading a system based on some weak data...or letting it sit there a while and get some explosive development so close to land...you upgrade it.

Ask yourself this question: If that system was at 15N and 40W...given all the details...do you think it would have been upgraded? Nope. I was upgraded because it looked ready to roll (which it didn't) and it was semi-close to land.


These are valid comments and fit into TPC's "Path of Least Regret" philosophy. I looked over everything after pulsing down for the night and believe there was nothing closed off at the SFC. While TPC performs on data and not looks, going from nothing to Fabian is not a good thing...pragmatically or politically. Still don't think there was much there (code: loosely defined center"), the right call was likely made Thursday afternoon.

Scott
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#18 Postby Air Force Met » Fri Aug 22, 2003 12:05 pm

Agreed Scott...and I think that is what they were thinking. I wrote that yesterday. While there wasn't a lot of data to show a closed LLC...there was an impressive sig in the IR that hinted a Fabian. IN order to avoid yet another jump...they pulled the trigger.

Looking at the GHCC vis now...the LLC should be near 16.7/68.9...extraping the feature they used at 10. 30 miles to the west...at 16.5/69.3 there are some westward moving low clouds. If there is a LLC...these should be moving SE. So...we either have an open wave...or an LLC that is less than 30 miles across.

Not good and def. not better organized (IMO) than yesterday, since yesterday there was a west wind 100 miles away from the center (assuming it was part of the circulation). SO...yesterday west winds 100 miles south...today east winds 30 miles west. I think it has to be a little weaker. If the MLC can work down with some convection...it should go pretty quickly since the east winds aren't real strong...so the flow is weak and can be turned around easily.
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