wxmx Posted September 9, 2011 Share Posted September 9, 2011 Nate has actually gained a decent amount of latitude... Much more than the GFS was predicting. Once again it appears the ECWMF is in the drivers seat. Yep, it still needs to gain at least 2 degrees in latitude (I don't really expect it, but would be a nice surprise), to avoid the near coast mountains at 20N, because of the probable WSW motion before LF. Link to comment Share on other sites More sharing options...
wxmx Posted September 9, 2011 Share Posted September 9, 2011 I just saw the 06Z GFS... encouraging, LF at 21N, a bit N of the Euro...with little loss of latitude before LF Link to comment Share on other sites More sharing options...
Ed Lizard Posted September 9, 2011 Share Posted September 9, 2011 The low cu from cool air over warmer water circulating into the backside is almost gone, and early visible, it actually looks like a tropical cyclone now. IMHO. Just a preference that TCs look like TCs and not lows on the tail end of a front, thats all. Link to comment Share on other sites More sharing options...
dan88 Posted September 9, 2011 Share Posted September 9, 2011 Convection really waning now, though probably will refire later. Recon on the way Link to comment Share on other sites More sharing options...
phil882 Posted September 9, 2011 Share Posted September 9, 2011 Wow, the shear over the system is nearly Nil, yet convection still has not been able to fire near the center. All it needs is a semi-big burst of convection to occur to mix out the dry air that has been advected into the circulation, and it can start developing again. However, the convection that has been occurring near the center has not been able to fill up the entire cyclonic circulation, so dry air on the edges of the circulation have been infiltrating the center and preventing development. Given the current trends, I think it might be a good 12-18 hours before this system gets its convection re-established. I think this BOC case is a lot more unique than most other systems in this area because of the magnitude of the dry air that has been in the Gulf of Mexico, which is of record low TPW value for this time of year. Link to comment Share on other sites More sharing options...
Mallow Posted September 9, 2011 Share Posted September 9, 2011 Given the current trends, I think it might be a good 12-18 hours before this system gets its convection re-established. I think this BOC case is a lot more unique than most other systems in this area because of the magnitude of the dry air that has been in the Gulf of Mexico, which is of record low TPW value for this time of year. Agreed, and that's what I was trying to say several days ago... if it can get a well-defined, symmetric, persistent core going, it can fend off the dry air. But given just how dry the air is, it's very tough for the storm to get a foothold. It seems to be part of the reason Nate is so small, but that could end up being a benefit for the system if it can really get going. Link to comment Share on other sites More sharing options...
phil882 Posted September 9, 2011 Share Posted September 9, 2011 Agreed, and that's what I was trying to say several days ago... if it can get a well-defined, symmetric, persistent core going, it can fend off the dry air. But given just how dry the air is, it's very tough for the storm to get a foothold. It seems to be part of the reason Nate is so small, but that could end up being a benefit for the system if it can really get going. I still think its going to get to the stage where the core is moist enough, but its only been in a low enough shear environment for the last 12-18 hours to support this theory. Beforehand, we had easterly shear which actually increased the net inflow from the west side of the circulation, which allowed all this advection of the exceptionally dry air occur beforehand. I think I underestimated its staying power considering how its of record magnitude and would take longer than normal to mix out. Link to comment Share on other sites More sharing options...
Mallow Posted September 9, 2011 Share Posted September 9, 2011 I still think its going to get to the stage where the core is moist enough, but its only been in a low enough shear environment for the last 12-18 hours to support this theory. Beforehand, we had easterly shear which actually increased the net inflow from the west side of the circulation, which allowed all this advection of the exceptionally dry air occur beforehand. I think I underestimated its staying power considering how its of record magnitude and would take longer than normal to mix out. Sounds reasonable to me. Link to comment Share on other sites More sharing options...
phil882 Posted September 9, 2011 Share Posted September 9, 2011 Winds are down to 50mph... pressure is about the same at last time 999mb. Without an inner core, this is going to take some time to get back on track and I think the chances of Nate becoming a major hurricane have taken a major blow. Link to comment Share on other sites More sharing options...
HurricaneJosh Posted September 9, 2011 Author Share Posted September 9, 2011 Weaker and losing latitude... and as dry as a husk on IR. lolz Link to comment Share on other sites More sharing options...
dan88 Posted September 9, 2011 Share Posted September 9, 2011 With the latest recon pass, center was extremely close to the previous pass, so very little movement if not stalled Extrap was down a tad, 999.8mb vs 999.1mb, got 999mb on drop. Link to comment Share on other sites More sharing options...
phil882 Posted September 9, 2011 Share Posted September 9, 2011 Weaker and losing latitude... and as dry as a husk on IR. lolz While I think the chances for major hurricane have decreased, that's mainly just due to the fact its running on limited time. The convection will come back, it just is a matter of how long it will take to mix the dry air from the center. Link to comment Share on other sites More sharing options...
icebreaker5221 Posted September 9, 2011 Share Posted September 9, 2011 Wow, the shear over the system is nearly Nil, yet convection still has not been able to fire near the center. All it needs is a semi-big burst of convection to occur to mix out the dry air that has been advected into the circulation, and it can start developing again. However, the convection that has been occurring near the center has not been able to fill up the entire cyclonic circulation, so dry air on the edges of the circulation have been infiltrating the center and preventing development. Given the current trends, I think it might be a good 12-18 hours before this system gets its convection re-established. I think this BOC case is a lot more unique than most other systems in this area because of the magnitude of the dry air that has been in the Gulf of Mexico, which is of record low TPW value for this time of year. I wouldn't be surprised. That dry air over the Gulf is impressive, especially considering the fact that it is occurring in the absence of some massive continent-sweeping cold front. I'm having trouble finding much positive omega over the N. Gulf, but CIMSS analysis is suggesting that there is some large-scale descent over the region (UL convergence, LL divergence). So adiabatic descent is probably a large culprit. I also wouldn't be surprised if the drought over TX is exacerbating the issue. Persistent northerly wind trajectories the last few days is really bringing in that "drought airmass" (low evapotranspiration + too dry for convection over TX keeps it drier downstream). Link to comment Share on other sites More sharing options...
icebreaker5221 Posted September 9, 2011 Share Posted September 9, 2011 Looks like PWATS in the N. Gulf were between -4 and -5 sigma at yesterday's 00Z analysis (-5.77 sigma over MX!), so a rare occurrence indeed. Link to comment Share on other sites More sharing options...
phil882 Posted September 9, 2011 Share Posted September 9, 2011 Looks like PWATS in the N. Gulf were between -4 and -5 sigma at yesterday's 00Z analysis (-5.77 sigma over MX!), so a rare occurrence indeed. Thanks for the image... do you happen to know where you found that? Certainly seems like this dry air is remarkably anomalous for that region for this particular time of the year. Ultimately, I think Nate will be able to overcome the dry air, but its going to take its sweet time doing so. The convection firing up this afternoon diurnal convective minimum is the first sign its starting to get back on track, and I think we will see convection return in earnest tonight during the diurnal max. Link to comment Share on other sites More sharing options...
icebreaker5221 Posted September 9, 2011 Share Posted September 9, 2011 Thanks for the image... do you happen to know where you found that? Certainly seems like this dry air is remarkably anomalous for that region for this particular time of the year. Ultimately, I think Nate will be able to overcome the dry air, but its going to take its sweet time doing so. The convection firing up this afternoon diurnal convective minimum is the first sign its starting to get back on track, and I think we will see convection return in earnest tonight during the diurnal max. Here: http://eyewall.met.psu.edu/rich/gefs/ Link to comment Share on other sites More sharing options...
phil882 Posted September 9, 2011 Share Posted September 9, 2011 Here: http://eyewall.met.psu.edu/rich/gefs/ Excellent! It looks like progressing forward in time, the severe negative anomaly is expected to modify pretty quickly, in that by 24 hours most of the Bay of Campeche is around average, although this is the SREF so I don't know how accurate it is in that part of the domain. Link to comment Share on other sites More sharing options...
donsutherland1 Posted September 9, 2011 Share Posted September 9, 2011 At 8 pm, Tropical Storm Nate was centered at 20.1N 92.9W with maximum sustained winds of 50 mph. During the course of the day, Nate has moved very little. However, overnight and tomorrow, it should begin to drift, westward and perhaps a little to the north, as well. However, as ridging redevelops, it will likely turn west-southwest and then southwest ahead of landfall. Given its closer proximity to the southern edge of the Bay of Campeche, I have lowered my estimate for its strength at landfall. Nonetheless, I still believe Nate will likely be a Category 1 hurricane when it makes landfall, which is stronger than the model consensus. However, there is a chance that it could make landfall as a strong tropical storm (the model consensus keeps Nate a tropical storm). Nate's Trajectory: 12-Hour Period Ended: 9/9 11 am: 330° 9/9 2 pm: 293° 9/9 5 pm: 279° 9/9 8 pm: 279° 6-Hour Motion: 315° 24-Hour Motion: 296° The models are now in very close agreement concerning Nate's track to landfall. There remain some modest differences, with the GFS perhaps a tad south of the model consensus while the NAM is to the north of the consensus. Overall, my revised track takes Nate ashore near Nautla, Mexico. Estimated Track: 20.2N 94.0W 20.3N 96.0W 20.0N 98.0W 19.4N 100.0W Estimated Point of Landfall: Just south of: 20.2N 96.7W Intensity at Landfall: Maximum sustained winds: 75 mph Link to comment Share on other sites More sharing options...
icebreaker5221 Posted September 10, 2011 Share Posted September 10, 2011 Excellent! It looks like progressing forward in time, the severe negative anomaly is expected to modify pretty quickly, in that by 24 hours most of the Bay of Campeche is around average, although this is the SREF so I don't know how accurate it is in that part of the domain. You can actually change it (drop-down button on the left-hand side) from SREF to GEFS to get the GFS ensemble, with is quite a bit better than the SREF. Link to comment Share on other sites More sharing options...
Amped Posted September 10, 2011 Share Posted September 10, 2011 Symetric with nice outflow. Link to comment Share on other sites More sharing options...
HurricaneJosh Posted September 10, 2011 Author Share Posted September 10, 2011 The cyclone tonight looks nothing like I would have expected 24 hr ago. In place of the tight little core last night, we have this yawning chasm in the middle, framed by a couple of hefty feeder bands. Wtf happened? How did a system with all that hawt microcane potential turn into this stretched-out old hag of a cyclone overnight? Just puzzled. Link to comment Share on other sites More sharing options...
am19psu Posted September 10, 2011 Share Posted September 10, 2011 The cyclone tonight looks nothing like I would have expected 24 hr ago. In place of the tight little core last night, we have this yawning chasm in the middle, framed by a couple of hefty feeder bands. Wtf happened? How did a system with all that hawt microcane potential turn into this stretched-out old hag of a cyclone overnight? Just puzzled. All of these W Gulf systems have been huge disappointments this year... using the climo rapid spin up prior to landfall has been a major bust this year. Link to comment Share on other sites More sharing options...
phil882 Posted September 10, 2011 Share Posted September 10, 2011 All of these W Gulf systems have been huge disappointments this year... using the climo rapid spin up prior to landfall has been a major bust this year. I still think is going to pull some Lorenzo 2007 crap before landfall but yea I'm very surprised is still looks like crap. The upper level wind shear is certainly low and I honestly don't think there has been too much upwelling. I still think the culprit is the super dry air that got into the system yesterday which was 4-5 standard deviations below normal. That obviously has prevented deep convection from forming near the center which has created a "gutted" appearance similar to a system that has upwelled alot of cool water. This is a good lesson learned here with Nate because I don't think I've ever seen such dry air get into a system before. I mean at one point PWATs across areas in the deep south were .2-.3" which is insanely low. You just can't get convection to form in that sort of dry air environment. This air got into Nate when the easterly shear was higher on Wednesday and Thursday. Link to comment Share on other sites More sharing options...
Ed Lizard Posted September 10, 2011 Share Posted September 10, 2011 Nobody has claimed they see an eye as big as Ohio? Link to comment Share on other sites More sharing options...
dan88 Posted September 10, 2011 Share Posted September 10, 2011 Some convection trying to wrap towards the center from the Eastern part of the band, deep convection developing SE of the center. Link to comment Share on other sites More sharing options...
HurricaneJosh Posted September 10, 2011 Author Share Posted September 10, 2011 All of these W Gulf systems have been huge disappointments this year... using the climo rapid spin up prior to landfall has been a major bust this year. Totally. But I still don't get why this thing looks like a horseshoe. I've never seen dry air cause a cyclone to look like a horseshoe. Link to comment Share on other sites More sharing options...
HurricaneJosh Posted September 10, 2011 Author Share Posted September 10, 2011 Convection has deepened a tad and it looks like it's trying to wrap into the center a bit. Could see some improvement today. Link to comment Share on other sites More sharing options...
dan88 Posted September 10, 2011 Share Posted September 10, 2011 Looks to be intensifying, 68kt thus far at flight level (850mb) in the NE quad Edit: pressure up a bit on the other hand, extrap about 1002mb Link to comment Share on other sites More sharing options...
HurricaneJosh Posted September 10, 2011 Author Share Posted September 10, 2011 The new advisory indicates some modest strengthening. Link to comment Share on other sites More sharing options...
dan88 Posted September 10, 2011 Share Posted September 10, 2011 Up to 55kt, Hurricane warnings up. Link to comment Share on other sites More sharing options...
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