Ed Lizard Posted July 28, 2011 Share Posted July 28, 2011 Natural glass half full optimism, maybe Don is somewhat modifying the hideously dry air around it, or maybe I'm wishcasting what I see on the TPW loop. Link to comment Share on other sites More sharing options...
CUmet Posted July 28, 2011 Share Posted July 28, 2011 Honestly I'm not sure if I believe the dewpoint readings on the HDOBs. It's hard to believe that they flew right through the convection, only to have the 850 mb Tds still in the single digits. Also, all of the global model initializations have the 850 mb Tds in the core being on the order of 15+ C. Link to comment Share on other sites More sharing options...
Ed Lizard Posted July 28, 2011 Share Posted July 28, 2011 Honestly I'm not sure if I believe the dewpoint readings on the HDOBs. It's hard to believe that they flew right through the convection, only to have the 850 mb Tds still in the single digits. Also, all of the global model initializations have the 850 mb Tds in the core being on the order of 15+ C. Yesterdays 12Z MMMD sounding was pretty dry... Edit- today's sounding is better, but Don has passed. Link to comment Share on other sites More sharing options...
LakeEffectKing Posted July 28, 2011 Share Posted July 28, 2011 Honestly I'm not sure if I believe the dewpoint readings on the HDOBs. It's hard to believe that they flew right through the convection, only to have the 850 mb Tds still in the single digits. Also, all of the global model initializations have the 850 mb Tds in the core being on the order of 15+ C. If the convection/system is tilted, you can get all sorts of dry layers, and NOT really have it be part of the system....if you know what I mean. A system can be tilted a bit (and a dropsonde doesn't "follow" the tilt) and still be quite organized and robust along the tilted vertical axis of rotation. Link to comment Share on other sites More sharing options...
CUmet Posted July 28, 2011 Share Posted July 28, 2011 Yesterdays 12Z MMMD sounding was pretty dry... The 850 Td is still 12.4C. I definitely don't doubt the possibility of single-digit 850 mb Tds outside the core, but when you get readings that low within the convection itself, it raises a lot of questions regarding the reliability of the data. Link to comment Share on other sites More sharing options...
Ed Lizard Posted July 28, 2011 Share Posted July 28, 2011 Good news/bad news- looks like a convective tower is trying to go up near/just Northwest of the center. Bad news, I'm pretty sure that is an outflow boundary/arc headed Northeast coming out to the North/Northeast... Link to comment Share on other sites More sharing options...
wxmx Posted July 28, 2011 Share Posted July 28, 2011 12z GFS is further south, even a bit south of CRP.. I don't know what the deal is, but it shows a complete decoupling of the mid and low levels, with the mid level going due west... if that happens, forget about any intensification/significant precipitation. Link to comment Share on other sites More sharing options...
wxmx Posted July 28, 2011 Share Posted July 28, 2011 Good news/bad news- looks like a convective tower is trying to go up near/just Northwest of the center. Bad news, I'm pretty sure that is an outflow boundary/arc headed Northeast coming out to the North/Northeast... It's bad news... my guess is that it's unraveling. Link to comment Share on other sites More sharing options...
tmagan Posted July 28, 2011 Share Posted July 28, 2011 I hate to say this, but at the end of the day, this is a glorified mesoscale convective complex. Link to comment Share on other sites More sharing options...
phil882 Posted July 28, 2011 Share Posted July 28, 2011 It's bad news... my guess is that it's unraveling. Yea the convective trends this morning have been poor at best... this will get nowhere near my forecast intensity yesterday and I'll have to make some revisions this afternoon. Also a more northerly track than I alluded to yesterday is more likely with a weaker system. It seems like the dry air over the Eastern Gulf of Mexico is having a far greater impact than I suspected. Link to comment Share on other sites More sharing options...
Mr Torchey Posted July 28, 2011 Share Posted July 28, 2011 impressive shear from the north and east, lots of dry air, I thought don had a chance but its looking very sick. Link to comment Share on other sites More sharing options...
Sunny and Warm Posted July 28, 2011 Share Posted July 28, 2011 Yea the convective trends this morning have been poor at best... this will get nowhere near my forecast intensity yesterday and I'll have to make some revisions this afternoon. Also a more northerly track than I alluded to yesterday is more likely with a weaker system. It seems like the dry air over the Eastern Gulf of Mexico is having a far greater impact than I suspected. score one for the GFS I guess. Some were saying that the GFS was out to lunch with its suggestion earlier today that Don would go POOF. While I don't think that necessarily happens, Don is taking a beating from the dry air and it could happen as the GFS says. Link to comment Share on other sites More sharing options...
wxmx Posted July 28, 2011 Share Posted July 28, 2011 impressive shear from the north and east, lots of dry air, I thought don had a chance but its looking very sick. The thing is that the shear is not impressive at all... it's probably 10-15kts around the center. Link to comment Share on other sites More sharing options...
Srain Posted July 28, 2011 Share Posted July 28, 2011 Product: Air Force Vortex Message (URNT12 KNHC) Transmitted: 28th day of the month at 16:15Z Aircraft: Air Force Aircraft (Last 3 digits of the tail number are 303) Storm Number & Year: 04L in 2011 Storm Name: Don (flight in the North Atlantic basin) Mission Number: 2 Observation Number: 11 A. Time of Center Fix: 28th day of the month at 15:48:40Z B. Center Fix Coordinates: 24°15'N 90°19'W (24.25N 90.3167W) B. Center Fix Location: 396 miles (638 km) to the S (182°) from New Orleans, LA, USA. C. Minimum Height at Standard Level: 1,458m (4,783ft) at 850mb D. Estimated (by SFMR or visually) Maximum Surface Wind: 45kts (~ 51.8mph) E. Location of the Estimated Maximum Surface Wind: 86 nautical miles (99 statute miles) to the NE (48°) of center fix F. Maximum Flight Level Wind Inbound: From 150° at 52kts (From the SSE at ~ 59.8mph) G. Location of Maximum Flight Level Wind Inbound: 70 nautical miles (81 statute miles) to the NE (48°) of center fix H. Minimum Sea Level Pressure: 1005mb (29.68 inHg) I. Maximum Flight Level Temp & Pressure Altitude Outside Eye: 18°C (64°F) at a pressure alt. of 1,524m (5,000ft) J. Maximum Flight Level Temp & Pressure Altitude Inside Eye: 24°C (75°F) at a pressure alt. of 1,524m (5,000ft) K. Dewpoint Temp (collected at same location as temp inside eye): 9°C (48°F) K. Sea Surface Temp (collected at same location as temp inside eye): Not Available L. Eye Character: Not Available M. Eye Shape: Not Available N. Fix Determined By: Penetration, Wind, Pressure and Temperature N. Fix Level: 850mb O. Navigation Fix Accuracy: 0.02 nautical miles O. Meteorological Accuracy: 1 nautical mile Remarks Section: Maximum Flight Level Wind: 52kts (~ 59.8mph) in the northeast quadrant at 15:26:00Z Link to comment Share on other sites More sharing options...
k*** Posted July 28, 2011 Share Posted July 28, 2011 Link to comment Share on other sites More sharing options...
CUmet Posted July 28, 2011 Share Posted July 28, 2011 The dropsondes have the 850 mb dewpoints in the 17-19C range, which is much more realistic. I think the HDOB dewpoints are totally bogus now. Link to comment Share on other sites More sharing options...
phil882 Posted July 28, 2011 Share Posted July 28, 2011 score one for the GFS I guess. Some were laughing at its suggestion earlier today that Don would go POOF. While I don't think that necessarily happens, Don is taking a beating from the dry air and it could happen as the GFS says. No... the GFS yesterday had it going to Louisiana... I'm not expecting Don to dissipate either which is what the GFS had at 00z. Thus far it has been a joke track and intensity wise, and the ECWMF has had a much more realistic scenario. The thing is that the shear is not impressive at all... it's probably 10-15kts around the center. Yea, the stronger influence here is the dry air being advected in from the east. The air in the West Gulf of Mexico has actually gotten dryer in the last 24 hours and the small Don has struggled with dry air intrusions so far. Link to comment Share on other sites More sharing options...
CUmet Posted July 28, 2011 Share Posted July 28, 2011 The prior two passes have had pretty decent 5-10 m/s storm-relative inflow in the western quad all the way to under 20 km from the center, which is where the bulk of the dry air is according to MIMIC-TPW and global model analyses. My guess is that the downdrafts associated with the persistent convection to the south is transporting this dry air down into the boundary layer, and this low theta-e air is being advected counterclockwise around to the eastern and northern quads and choking off attempts to build convection there. Link to comment Share on other sites More sharing options...
Sunny and Warm Posted July 28, 2011 Share Posted July 28, 2011 No... the GFS yesterday had it going to Louisiana... I'm not expecting Don to dissipate either which is what the GFS had at 00z. Thus far it has been a joke track and intensity wise. Yea, the stronger influence here is the dry air being advected in from the east. The air in the West Gulf of Mexico has actually gotten dryer in the last 24 hours and the small Don has struggled with dry air intrusions so far. maybe trackwise, but what other model had Don suffering like this in the next 48 hrs like the GFS did at 00z? You seem overly dismissive of a model that is currently tracking nicely with events. Again, I agree with you that the GFS is overdone, but why the hate? It isn't such a bad tropical model anymore. Link to comment Share on other sites More sharing options...
phil882 Posted July 28, 2011 Share Posted July 28, 2011 maybe trackwise, but what other model had Don suffering like this in the next 48 hrs like the GFS did at 00z? You seem overly dismissive of a model that is currently tracking nicely with events. Again, I agree with you that the GFS is overdone, but why the hate? It isn't such a bad tropical model anymore. Oh I am certainly not hating on the GFS... its a great global model for tropical cyclones. It just hasn't done well with Don thus far. If you compare the 850mb vorticity in previous runs to what it is in actuality, you can see it has significantly under-predicted Don. Link to comment Share on other sites More sharing options...
hckyplayer8 Posted July 28, 2011 Share Posted July 28, 2011 6z Link to comment Share on other sites More sharing options...
Mallow Posted July 28, 2011 Share Posted July 28, 2011 maybe trackwise, but what other model had Don suffering like this in the next 48 hrs like the GFS did at 00z? You seem overly dismissive of a model that is currently tracking nicely with events. Again, I agree with you that the GFS is overdone, but why the hate? It isn't such a bad tropical model anymore. Most of the global models had a weak Don. So far, the GFS has been too weak, even for as crappy as Don has been. The main difference between the models has been the track, and the euro, for example, has done better there. So I wouldn't be giving kudos to the GFS just yet, personally. Link to comment Share on other sites More sharing options...
weathermanchild Posted July 28, 2011 Share Posted July 28, 2011 Anybody else think the CC is re-developing farther south? I know this is a named system, but is is miniscule and small weak storms can have a jumping center until one takes over. And with the dry air and shear around, that may take a while. However, because it is small, and SSTs are warm, all it would need is a break in the already weak shear and it could develop rapidly. Link to comment Share on other sites More sharing options...
LakeEffectKing Posted July 28, 2011 Share Posted July 28, 2011 Most of the global models had a weak Don. So far, the GFS has been too weak, even for as crappy as Don has been. The main difference between the models has been the track, and the euro, for example, has done better there. So I wouldn't be giving kudos to the GFS just yet, personally. Nor would I give kudos to any of the intensity forecasts yet either....the GFDL and HWRF both indicate a strengthening phase later today into tonight, but then seem to weaken it fairly quickly thereafter. Link to comment Share on other sites More sharing options...
wxmx Posted July 28, 2011 Share Posted July 28, 2011 Anybody else think the CC is re-developing farther south? I know this is a named system, but is is miniscule and small weak storms can have a jumping center until one takes over. And with the dry air and shear around, that may take a while. However, because it is small, and SSTs are warm, all it would need is a break in the already weak shear and it could develop rapidly. Recon is there, no redeveloping is going on. Link to comment Share on other sites More sharing options...
wxmx Posted July 28, 2011 Share Posted July 28, 2011 Hmmm.... recon can't find west winds now. Link to comment Share on other sites More sharing options...
beneficii Posted July 28, 2011 Share Posted July 28, 2011 Is it just me or is Don now moving due west toward the Mexican coast? Link to comment Share on other sites More sharing options...
k*** Posted July 28, 2011 Share Posted July 28, 2011 Hmmm.... recon can't find west winds now. must be turtlehurricane's fault Link to comment Share on other sites More sharing options...
wxmx Posted July 28, 2011 Share Posted July 28, 2011 must be turtlehurricane's fault He must be at the wheel. Link to comment Share on other sites More sharing options...
Ed Lizard Posted July 28, 2011 Share Posted July 28, 2011 Hmmm.... recon can't find west winds now. IIRC, at a low point in then Tropical Storm Andrew's life recon couldn't close the circulation, but based on expected improving conditions and 50 knot winds North of the center, NHC decided not to demote it to a wave, knowing they'd probably have to upgrade again. Of course, this is completely different... Link to comment Share on other sites More sharing options...
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