Max Posted August 31, 2012 Share Posted August 31, 2012 Is Leslie's short term motion SW or WSW? Because by looking at sat lately it looks like it. I don't know for sure maybe I'm seeing things, but anybody else have input on this motion? Based on vorticity maps, seems like Leslie's vorticity is south of where the NHC center? Maybe the center is re-aligning towards the deeper convection giving the look of moving south of due west? Link to comment Share on other sites More sharing options...
MJO812 Posted September 1, 2012 Share Posted September 1, 2012 The 18z GFS is further east than the 12z run. The trough that is coming to the east will be the main player for this storm. Link to comment Share on other sites More sharing options...
Riptide Posted September 1, 2012 Share Posted September 1, 2012 The 18z GFS is further east than the 12z run. The trough that is coming to the east will be the main player for this storm. I think the shortwave over the central atlantic is also very important, the 12z and 18z GFS keep creating phantom lows south of Greenland which allows Leslie to lose too much longitude in order to affect the continental United States. It may or may not be realistic because this area of the world is very divergent and the thermal gradient quickly spins up lows on stationary cold fronts. The main issue all along has been how much longitude Leslie gains before coming north and stalling, imo. The trough can be very deep but if Leslie is east of 60W; she will cause the trough to go positive tilt and easily recurve away from the conus. Link to comment Share on other sites More sharing options...
stormspotterlive Posted September 1, 2012 Share Posted September 1, 2012 Looks like the center of Leslie may have relocated and it is now moving more west? Correct me if I am wrong though certinly looks a bit off the forecasted track right now. Link to comment Share on other sites More sharing options...
cyclogent Posted September 1, 2012 Share Posted September 1, 2012 Looks like the center of Leslie may have relocated and it is now moving more west? Correct me if I am wrong though certinly looks a bit off the forecasted track right now. Seeing the same thing. Leslie will miss the 6z forecast point by about 90 miles to the south. Not exactly a good forecast for a 12 hour period lol, so needless to say I think the 5 day forecast is bunk. Couple weeks ago, the models had Isaac forecast as a fish east of Bermuda,,,ended up in Louisiana. Oops Link to comment Share on other sites More sharing options...
ChrisM Posted September 1, 2012 Share Posted September 1, 2012 Seeing the same thing. Leslie will miss the 6z forecast point by about 90 miles to the south. Not exactly a good forecast for a 12 hour period lol, so needless to say I think the 5 day forecast is bunk. Couple weeks ago, the models had Isaac forecast as a fish east of Bermuda,,,ended up in Louisiana. Oops Unless I was a pro forecaster who had to do it contractually I wouldn't even look at this thing until sometime next week. Link to comment Share on other sites More sharing options...
Sunny and Warm Posted September 1, 2012 Share Posted September 1, 2012 Seeing the same thing. Leslie will miss the 6z forecast point by about 90 miles to the south. Not exactly a good forecast for a 12 hour period lol, so needless to say I think the 5 day forecast is bunk. Couple weeks ago, the models had Isaac forecast as a fish east of Bermuda,,,ended up in Louisiana. Oops As I recall, this is completely untrue. Link to comment Share on other sites More sharing options...
Derecho! Posted September 1, 2012 Share Posted September 1, 2012 As I recall, this is completely untrue. No, before advisories started, Isaac indeed was depicted on the models as recurving before entering the Carribean; check the first Isaac thread. Link to comment Share on other sites More sharing options...
dan88 Posted September 1, 2012 Share Posted September 1, 2012 Recent microwave Link to comment Share on other sites More sharing options...
Max Posted September 1, 2012 Share Posted September 1, 2012 I guess the mid- and low-level circulations are displaced. Story of this season. Guess no upgrade at 11pm. Link to comment Share on other sites More sharing options...
Superstorm93 Posted September 1, 2012 Share Posted September 1, 2012 As I recall, this is completely untrue. I followed the damn thing since it was over Africa (which I greatly regret) and I can verify that the statement is true. All the globals had Isaac as a big fish storm when It was still developing. Sent from Tapatalk Imagine if this was cruising due west? Link to comment Share on other sites More sharing options...
Juliancolton Posted September 1, 2012 Share Posted September 1, 2012 I highly doubt the 17.4N center position is where the center is. How can NHC base a forecast off a microwave image 3+ hours old? Worst forecasting I've seen by the NHC this year in a long time. They need to review and revise some of their policies because I really am starting to not even look at the discussions anymore. There's nothing good to see from them. Does it really matter right now? If there are really huge errors (I haven't checked into them), they can correct them all post-season. Leslie is like a week away from any potential impacts on society. Link to comment Share on other sites More sharing options...
Minnesota Meso Posted September 1, 2012 Share Posted September 1, 2012 I actually do think Leslie could be a threat in 7+ days, at least to NEw England. if you are interested I explain a little more in-depth here. http://www.examiner....s-to-be-watched In short, I think the Carolinas north should watch it, particularly Bermuda, New England and into the Maritimes. I agree completely with this, the trough coming in to the CONUS needs to do one of two things to allow the Atlantic ridge to build east a little bit. Either slow down by about 24 hrs or come in less amplified than the models are showing, creating a weakness along the east cost of the US. Chances of that happening while not zero, seem to be small according to current guidance. So I give that a 2 in 10 chance of happening, meaning she needs to be watched. Right now I don't see this as a fish storm as it could impact Bermuda and the Canadian Maritimes (sp) Link to comment Share on other sites More sharing options...
Typhoon Tip Posted September 1, 2012 Share Posted September 1, 2012 Actually during Isaac's formation phases the bulk of the guidance types either recurved Isaac early and/or impacted the eastern seaboard. The operational Euro, as well as few tropical model, and Global numerical models ensemble members began indicating a conserved westward motion. These were the exceptions to the rule. Over time, all the models collapsed to the west positions. That was the general model bias behavior during Isaac's life cycle. I do not believe it is a very good idea to assume those biases should be used as a correction measure for Leslie. Sometimes that can work, but at a risk. We have to look at each system individually, balancing governing synoptics as unique; regardless of any similarities "air" apparent. I do not currently see any reason why NHC is off with their position and subsequent reasoning. The models are tightly clustered, and they "seem" to fit with what is observable of the surrounding influences; not just modeled, but vapor imagery shows a strong steering level trough diving S around 70 W axis. The natural "mind's eye" conclusion is that the southern end of this trough would tend to sever, perhaps creating a strong TUTT- like gyre somewhere E of the Bahamas. I don't see Leslie careening through any such feature. And it thus also physically makes sense that Leslie would be influenced by that; a few models, including the operational Euro, indicate a severed gyre. That would lend to N motion out in time. That said, I see some philosophies that cannot yet be discounted. One would be a N drift/slow motion/virtual stall, after which a resumed motion is unknown, because by D6 the actual synoptics and the modeled synoptics have increased potential of parting company. Another quite naturally would include the chance that a N motion would leave Leslie eventually vulnerable to the westerlies and see you later. I do find it interesting that the recent 2 to 3 cycles of the GFS have indicated a less aggressive polarward position by the late middle range periods - if nothing else, that indicates uncertainty with handling the steering fields out in time (go wonder). Yet a 3rd possibility, how ever unlikely, is that Leslie briefly goes N, stalls, then resumes a west motion, as said TUTT-like feature moves WSW and ridging reforms near Bermuda. None of these possibilities - or any left out - can be discounted with certainty as we are talking a minimum of 5 days before the truth takes place. As far as Leslie is now, I also believe NHC is spot on with their 11pm status of things. There is observed NE shear impacting/tilting the vortex SW, exposing the low level vortex. This is evident by microwave imagery, clearly. It is important to remember that TCs are powered by the sea; that is a partially atmospheric-oceanic coupled physics. In some cases, a strong UVM associated with a 700 mb vortex can excite a center jump as the intense UVM draws in new lower level convergence. However, that usually takes place with TCs weaker than 55kt wind fields; however, not always. Very impressive colorful CDO like features have duped people in the past. In understanding all this, there is no eye just yet. Link to comment Share on other sites More sharing options...
Minnesota Meso Posted September 1, 2012 Share Posted September 1, 2012 the 09/0z run of the GFS shows a even more amplified trough, it may take her east of Bermuda and missing the North America coast entirely. Link to comment Share on other sites More sharing options...
Eyewall2005 Posted September 1, 2012 Share Posted September 1, 2012 There just isnt anything do drive leslie any futher westward past 60w. If i were in bermuda i'd be watching this one rather closely. Link to comment Share on other sites More sharing options...
Ed Lizard Posted September 1, 2012 Share Posted September 1, 2012 If 0Z GFS at 192 is right, it is already entering the Westerlies North of 30º and the game is over. Looks nice, cyclone al the way to 250 mb and nice anticyclone at 200 mb. I think this will be a major. ETA Big surf maker if GFS is right, just crawls, approaching Canadian Maritimes almost 2 weeks out beyond resolution chop ETA 2: Depending on how long NHC holds this as a tropical system, and they just might hold it a while if it is threatening Canadian territory, this could easily be the ACE winner of the year, and make this season a darned respectable ACE season.. Link to comment Share on other sites More sharing options...
Eyewall2005 Posted September 1, 2012 Share Posted September 1, 2012 I followed the damn thing since it was over Africa (which I greatly regret) and I can verify that the statement is true. All the globals had Isaac as a big fish storm when It was still developing. Sent from Tapatalk Imagine if this was cruising due west? Its been a long while since we have has a formidable tc heading w-wnw across the basin threatening the southeast. Its been all about recurve the past few seasons. Link to comment Share on other sites More sharing options...
PSUBlizzicane2007 Posted September 1, 2012 Share Posted September 1, 2012 Weenies need to settle down. This is not going into the Caribbean/Bahamas/Florida/Carolinas. Link to comment Share on other sites More sharing options...
Minnesota Meso Posted September 1, 2012 Share Posted September 1, 2012 Weenies need to settle down. This is not going into the Caribbean/Bahamas/Florida/Carolinas. Agreed, this could be a major disruption for the shipping lanes if this run of the GFS verifies. Of course this could give major headaches to individual companies that relay on ocean transport, between North America and Europe. On a side note: up here in the northern latitudes of the US, the Blue moon is amazing Link to comment Share on other sites More sharing options...
OSUmetstud Posted September 1, 2012 Share Posted September 1, 2012 If Leslie can't make hurricane status within the next 24 to 48 hours, which is certainly reasonable, it probably won't make hurricane status until day 4 to 5. NWerly shear looks pretty rough until an upper level anticyclone builds in day 5 onward... Link to comment Share on other sites More sharing options...
Superstorm93 Posted September 1, 2012 Share Posted September 1, 2012 Pretty decent comeback. Outflow has expanded to the north and the convection is right on the verge of taking in the circulation. http://www.ghcc.msfc.nasa.gov/GOES/GOES05452012245kJhdWK.jpg Link to comment Share on other sites More sharing options...
phil882 Posted September 1, 2012 Share Posted September 1, 2012 Pretty impressive comeback. Outflow has expanded to the north and the convection is right on the verge of taking in the circulation. Not really... Leslie continues to be highly decoupled from its mid-level vortex. The NHC mentions this in their discussion. One look at the microwave imagery shows this system has a long way to go to become better organized and it is possible its actually weaker than its given intensity by the NHC. Link to comment Share on other sites More sharing options...
Superstorm93 Posted September 1, 2012 Share Posted September 1, 2012 Not really... Leslie continues to be highly decoupled from its mid-level vortex. The NHC mentions this in their discussion. One look at the microwave imagery shows this system has a long way to go to become better organized and it is possible its actually weaker than its given intensity by the NHC. Well that pass is about six hours old, so it may have become a bit better organized since then. We'll have to wait until morning to find out, unless we get another MW pass. Still screams partially exposed, but it could improve during the next 12 hours. Regardless, this storm is probably going to be sticking around for a while and could become a decent hurricane if conditions permit. Link to comment Share on other sites More sharing options...
Minnesota Meso Posted September 1, 2012 Share Posted September 1, 2012 Shear is increasing to it's NW quad. Doesn't look good for RI to me Link to comment Share on other sites More sharing options...
CoastalWx Posted September 1, 2012 Share Posted September 1, 2012 I don't really see this posing a threat right now to the EC. Link to comment Share on other sites More sharing options...
free_man Posted September 1, 2012 Share Posted September 1, 2012 Wrong-Way Leslie? It's a little early for a recurve at that lat, no? Link to comment Share on other sites More sharing options...
Sunny and Warm Posted September 1, 2012 Share Posted September 1, 2012 I followed the damn thing since it was over Africa (which I greatly regret) and I can verify that the statement is true. All the globals had Isaac as a big fish storm when It was still developing. I stand corrected then. I must have tried to blank that from my memory bank. Link to comment Share on other sites More sharing options...
U_Thant Posted September 1, 2012 Share Posted September 1, 2012 Pretty much looks like complete crap now. In about 36 hours, the shear vector has gone from E to NE to N and now looks like it's gone to NW. Link to comment Share on other sites More sharing options...
OSUmetstud Posted September 1, 2012 Share Posted September 1, 2012 00z euro has a much weaker storm at days 5 to 8 than previous runs...I don't think it's modeling a hurricane at that time. Link to comment Share on other sites More sharing options...
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