wxsmwhrms Posted September 8, 2011 Share Posted September 8, 2011 I was kinda surprised that NHC bit off on the 6z GFS based guidance so hard. I'd have thought they would wait to see what the foreign centers came out with at 12z. The problem was I don't think they really had any guidance other than the UK as far left as their previous track. It was left of even the ECMWF, so they probably felt compelled to go farther right. Link to comment Share on other sites More sharing options...
wxmx Posted September 8, 2011 Share Posted September 8, 2011 Excellent discussion, I agree with you except for one thing, I also think the strength of the ridge to the east of the system is playing a key role here. The stronger that ridge gets, the more poleward motion the system can gain in the shorter term. Along with trending the trough weaker, it seems like the positive SOI you and Phil have been discussing is also trending that ridge stronger, potentially resulting in more poleward motion early on. I am 50/50 right now, but that is a trend down from 60/40 on the northward motion yesterday. The main thing that keeps me concerned is the amount of latitude the ECMWF gains in the shorter term. If the models were just showing it staying down in the BOC and eventually guided west, I could buy that pretty easily. The problem is all of them except the UK and NOGAPS show it making nearly 25N, and I think if it gets that far north it is going to be very vulnerable to being picked up, even by a weaker trough. I think it needs to stay S of 23/24N to be sure of staying on the more westward solution. Good observation about the Carib. ridge... whatever transpires, this isn't a done deal yet. Link to comment Share on other sites More sharing options...
wxmx Posted September 8, 2011 Share Posted September 8, 2011 The problem was I don't think they really had any guidance other than the UK as far left as their previous track. It was left of even the ECMWF, so they probably felt compelled to go farther right. Well, the latest part of the Euro was farther left than their previous track... but I know you don't buy that strong SW movement prior to Landfall still Link to comment Share on other sites More sharing options...
wxsmwhrms Posted September 8, 2011 Share Posted September 8, 2011 Well, the latest part of the Euro was farther left than their previous track... but I know you don't buy that strong SW movement prior to Landfall still Yeah, I meant the first 72 hours. Link to comment Share on other sites More sharing options...
wxsmwhrms Posted September 8, 2011 Share Posted September 8, 2011 First 24 hours, GFS is a little west of the 06Z and farther NW than the 00Z. Not big changes, but as wxmx said, subtle changes are all that is needed in this setup. Link to comment Share on other sites More sharing options...
wxsmwhrms Posted September 8, 2011 Share Posted September 8, 2011 Through 48 hours, GFS is still a hair west-northwest of its 06Z run on the track but well NNE of its 00Z run. Troughing looks about the same, maybe just a hair to the west of the 06Z/00Z runs. Link to comment Share on other sites More sharing options...
Ivanhater Posted September 8, 2011 Share Posted September 8, 2011 12z GFS looks like it is getting caught in the trough at 48 hours. Too soon to say, but it is a deeper cyclone this run which may make a difference. Link to comment Share on other sites More sharing options...
wxmx Posted September 8, 2011 Share Posted September 8, 2011 I think it will miss the trough...it's WSW of the 06z run at day 3, it'll probably look like the HWRF, left meandering. Haha, too much speculation Link to comment Share on other sites More sharing options...
wxsmwhrms Posted September 8, 2011 Share Posted September 8, 2011 12z GFS looks like it is getting caught in the trough at 48 hours. Too soon to say, but it is a deeper cyclone this run which may make a difference. Looking at it through 78 hours, it wouldn't surprise me if it ends up being one of these solutions like the EnKF where it gets up to relatively close to the coast and then gets left behind. It's a bit WSW of the 06Z run (although way NNE of the 00Z run). Link to comment Share on other sites More sharing options...
wxsmwhrms Posted September 8, 2011 Share Posted September 8, 2011 I think it will miss the trough...it's WSW of the 06z run at day 3, it'll probably look like the HWRF, left meandering. Haha, too much speculation LOL, great minds!! Link to comment Share on other sites More sharing options...
wxmx Posted September 8, 2011 Share Posted September 8, 2011 LOL, great minds!! What a difference < 100 mi in 3 days do...actually it may come down to the first few panels where it started moving N farther W Link to comment Share on other sites More sharing options...
Ivanhater Posted September 8, 2011 Share Posted September 8, 2011 It gained too much latitude, I think it continues to drift north on this run Link to comment Share on other sites More sharing options...
wxmx Posted September 8, 2011 Share Posted September 8, 2011 As expected, it's left meandering, and it's drifting NW making a beeline towards Houston...but fortunately they will probably be saved by the building ridge </sarcasm> Link to comment Share on other sites More sharing options...
wxsmwhrms Posted September 8, 2011 Share Posted September 8, 2011 What a difference < 100 mi in 3 days do...actually it may come down to the first few panels where it started moving N farther W Yeah, but one thing that it kind of agrees with what I have been tending to think that if the trough misses it, there is not enough ridging to move it west. In fact, at 108 hours it looks like it's pretty much stuck between the ridges to it east and west. That may very well happen, but I will say that it would be unique for systems approaching the Gulf Coast from that direction. Usually, once systems are headed N toward the central Gulf Coast they keep on coming, and if it's as intense as the GFS/EC show, it would not surprise me if it did keep on coming due to more influence from the stronger SW flow aloft. But clearly there are a few exceptions, so what the GFS shows is defintely not impossible. One thing the GFS definitely held serve on is the more N/NNE idea rather than west into Mexico. Link to comment Share on other sites More sharing options...
NaoPos Posted September 8, 2011 Share Posted September 8, 2011 Tell you what. If Texas gets hit with this, it wouldn't be as good as people think. I'd imagine the ground is so dry and hard, that most of what would fall runs off fairly quickly. That would trigger a significant ff event. But that's for sub forum topic I suppose. Can't see Nate getting any stronger the next 48-72hrs with all that dry air on all northern peripherys. Quick question though. With that dry air, any chance Nate becomes a hybrid/extra tropical system? Link to comment Share on other sites More sharing options...
wxmx Posted September 8, 2011 Share Posted September 8, 2011 Yeah, but one thing that it kind of agrees with what I have been tending to think that if the trough misses it, there is not enough ridging to move it west. In fact, at 108 hours it looks like it's pretty much stuck between the ridges to it east and west. That may very well happen, but I will say that it would be unique for systems approaching the Gulf Coast from that direction. Usually, once systems are headed N toward the central Gulf Coast they keep on coming, and if it's as intense as the GFS/EC show, it would not surprise me if it did keep on coming due to more influence from the stronger SW flow aloft. But clearly there are a few exceptions, so what the GFS shows is defintely not impossible. One thing the GFS definitely held serve on is the more N/NNE idea rather than west into Mexico. Once N of 24N, it's a tossup, I can agree with that. Link to comment Share on other sites More sharing options...
Ed Lizard Posted September 8, 2011 Share Posted September 8, 2011 As expected, it's left meandering, and it's drifting NW making a beeline towards Houston...but fortunately they will probably be saved by the building ridge </sarcasm> I see the sarc tag, but ~1400 homes burnt up around Southeast and South-Central Texas, I'd be almost willing to offer the Popo Playa Party Pad as a sacrifice to the rain gods. The 6Z GFDL, worst case track for Houston, just far enough East for little/no rain but solid winds, probably verifies, if I had to guess. Separate topic- I still don't see how the convection over even 30º water can modify not exactly tropical air. Dewpoint at MMVR is lower today than yesterday. Link to comment Share on other sites More sharing options...
wxmx Posted September 8, 2011 Share Posted September 8, 2011 By day 7, the SW drift begins... this thing is dragging it's feet. Link to comment Share on other sites More sharing options...
LithiaWx Posted September 8, 2011 Share Posted September 8, 2011 12Z GFS shows landfall around the Texas/LA border then it gets rapidly pulled NE.. Link to comment Share on other sites More sharing options...
wxmx Posted September 8, 2011 Share Posted September 8, 2011 After teasing TX for 5 days, it gets less than 150mi from Popo's house, and then gets caught in the westerlies, making sure Ed gets some sprinkles and misses TX to the East. Link to comment Share on other sites More sharing options...
valkhorn Posted September 8, 2011 Share Posted September 8, 2011 Tell you what. If Texas gets hit with this, it wouldn't be as good as people think. I'd imagine the ground is so dry and hard, that most of what would fall runs off fairly quickly. That would trigger a significant ff event. But that's for sub forum topic I suppose. Can't see Nate getting any stronger the next 48-72hrs with all that dry air on all northern peripherys. Quick question though. With that dry air, any chance Nate becomes a hybrid/extra tropical system? That depends. With Lee we had some flash flooding, but it was the first rain we had in about 6 weeks and the ground was very dry. If the rain isn't too heavy, it ends up being a soaking rain. It rained all day with about 6", so the average was .25" an hour, which isn't too bad. We probably had some lighter and heavier rains mixed in though. Link to comment Share on other sites More sharing options...
Ed Lizard Posted September 8, 2011 Share Posted September 8, 2011 Tell you what. If Texas gets hit with this, it wouldn't be as good as people think. I'd imagine the ground is so dry and hard, that most of what would fall runs off fairly quickly. That would trigger a significant ff event. But that's for sub forum topic I suppose. Can't see Nate getting any stronger the next 48-72hrs with all that dry air on all northern peripherys. Quick question though. With that dry air, any chance Nate becomes a hybrid/extra tropical system? Ensemble North American 500 mb height loop It would have to thread the finest of needles, getting pulled up then left behind, far enough North that the West to Southwest motion starts far enough North to get this to landfall in Texas, and to help the drought/fire areas, it would need to landfall North of BRO to do much good. Not impossible, I guess, GFS comes close, but it is even more craptastic than the 6Z GFDL for the fires, with a longer period of wind with little/no rain. Link to comment Share on other sites More sharing options...
wxsmwhrms Posted September 8, 2011 Share Posted September 8, 2011 Canadian switches, and after getting it to about 25N, 94W, turns it almost completely around (SW to SSW movement) and has it east of the east central coast of Mexico in 6-7 days. Link to comment Share on other sites More sharing options...
NaoPos Posted September 8, 2011 Share Posted September 8, 2011 That depends. With Lee we had some flash flooding, but it was the first rain we had in about 6 weeks and the ground was very dry. If the rain isn't too heavy, it ends up being a soaking rain. It rained all day with about 6", so the average was .25" an hour, which isn't too bad. We probably had some lighter and heavier rains mixed in though. IM sure the soil/topography of TN is a wee bit different than the barren land of TX after this summer. Surprised he looks this healthy and at the lack of shear ( mostly 5-10kts) in the BOC with the relative proximity to the base of the trough in the eastern conus. Link to comment Share on other sites More sharing options...
wxsmwhrms Posted September 8, 2011 Share Posted September 8, 2011 Maybe I am missing something with the climo, and if so I would appreciate it being pointed out, but I can't really find any storms in the history (at least back to 1900) that have done what any of the models are suggesting. I looked at systems that became hurricanes in the BOC, and hurricanes that moved through a 5x5 degree around 25/95 in September. I found one storm (1944) which did stall around 25/95, but it died. Everything else either did one of two things: moved north and kept moving into the northern Gulf Coast, or moved west or west-northwest into Mexico. This moving north then stalling, or moving north and then turning west and southwest does not seem to have any past historical matches, at least not in September. Of course, that does NOT mean those solutions cannot happen - just interesting. Link to comment Share on other sites More sharing options...
wxsmwhrms Posted September 8, 2011 Share Posted September 8, 2011 The UK never even gets Nate far enough N for it to really show up on the NOAM projection. It also well left on Maria, takes it into MIA. Link to comment Share on other sites More sharing options...
donsutherland1 Posted September 8, 2011 Share Posted September 8, 2011 Maybe I am missing something with the climo, and if so I would appreciate it being pointed out, but I can't really find any storms in the history (at least back to 1900) that have done what any of the models are suggesting. I looked at systems that became hurricanes in the BOC, and hurricanes that moved through a 5x5 degree around 25/95 in September. I found one storm (1944) which did stall around 25/95, but it died. Everything else either did one of two things: moved north and kept moving into the northern Gulf Coast, or moved west or west-northwest into Mexico. This moving north then stalling, or moving north and then turning west and southwest does not seem to have any past historical matches, at least not in September. Of course, that does NOT mean those solutions cannot happen - just interesting. Henri (1979) might be the closest candidate in the general region for a stalling/drifting system. But that's about it. Link to comment Share on other sites More sharing options...
wxsmwhrms Posted September 8, 2011 Share Posted September 8, 2011 After seeing the 12Z EC and UK through 72 hours, and the GFDL and HWRF, I think the 06Z/12Z GFS are outliers. My whole problem with the EC solution was that it had the system getting well up to 25N/94W and then driving it SW without enough ridging north of the system to do it. However, these latest models show the system never getting north of 22.5 or 23N in the first place, and pretty much keep it on a WNW (or even west) heading. The fact that the GFDL and HWRF do that with GFS boundary conditions tell me a lot. I said earlier I was backing down on my thoughts on a southern CONUS landfall even after seeing the 06Z GFS, and feel even more comfortable with that now. As we've said all along, the key was how far north could it get in the shorter term, and it seems like all the models but the GFS and Canadian are capped out far enough S to keep it in the BOC. Link to comment Share on other sites More sharing options...
dan88 Posted September 8, 2011 Share Posted September 8, 2011 Looks like the center has lost some latitude since yesterday, Center looks to be around 19.7N, 92.2W (last observation was just about to the center). Extrap looks to be just above 997mb Link to comment Share on other sites More sharing options...
wxsmwhrms Posted September 8, 2011 Share Posted September 8, 2011 Looks like the center has lost some latitude since yesterday, Center looks to be around 19.7N, 92.2W (last observation was just about to the center). Extrap looks to be just above 997mb It's definitely looking pretty good, and I think as wxmx alluded to earlier, it getting just a little farther S into the BOC could have been death knell for enough short term northerly movement for it to get north out of the BOC. Anyway, as far as intensity, GFDL and HWRF are both quite bullish, looking to have it near cat 3, although the HWRF weakens it some just before LF. Josh may want to think about planning though if he's going to, those models and the EC/UK pretty much have LF in about 72 hours. Link to comment Share on other sites More sharing options...
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