Superstorm93 Posted August 27, 2012 Share Posted August 27, 2012 A bit lopsided, but we have around 2/3s of an eyewall. Cat 2 is a high probability, IMO. And that's four hours old. We probably have more of an eyewall now. Link to comment Share on other sites More sharing options...
A-L-E-K Posted August 27, 2012 Share Posted August 27, 2012 A bit lopsided, but we have around 2/3s of an eyewall. Cat 2 is a high probability, IMO. I think so too....I mentioned this morning that I thought Isaac was about 12 hrs away from a period of intesification up to low/med cat 2...with about 6 more hours to go in that window, things are looking on track. Link to comment Share on other sites More sharing options...
dan11295 Posted August 27, 2012 Share Posted August 27, 2012 Those SFMR look to be uncontaminated..Will see if its enough to Upgrade... Link to comment Share on other sites More sharing options...
Baroclinic Zone Posted August 27, 2012 Share Posted August 27, 2012 12z Euro track looks similar to the 12z GGEM and UKMET brining the center inland just E of Slidell and W of Bay St Louis. ~976mb looking at WunderMaps. Link to comment Share on other sites More sharing options...
SnowGoose69 Posted August 27, 2012 Share Posted August 27, 2012 Regardless if this makes it to Cat 2 or not I still think the surge will not catch up in time before it comes ashore, it may have 110 mph winds in what is now my thinking on the worst case sceario but it may only have high end TS or minimal hurricane surge thankfully. I still think because of the lousy sloping of the shelf in the northern GOM it will still do alot of damage but I don't see anything resembling Katrina right now Link to comment Share on other sites More sharing options...
phil882 Posted August 27, 2012 Share Posted August 27, 2012 Funny thing is, I was thinking the exact opposite. Most of the coldest cloud tops on IR/WV are left of shear, which is what you would expect from a sheared system. However, the radar returns from the Tampa radar are pretty symmetric about the center, and high-resolution visible imagery suggest this as well (although much tougher to tell). Something that does bode well for strengthening is the fact that recon had pretty substantial SFMR rain rates pretty close to the center, suggesting that there is quite a bit of diabatic heating in the inertially stable region inside the RMW. But as we all know, intensity forecasting is extremely difficult, so we'll have to wait and see how this plays out. The recon pass through right now indicates that the wind field is responding to this. The RMW has now contracted to 20 km as a new inner wind maximum has sprouted up. We *could* be looking at the beginnings of an accelerated intensification, with the caveat that these things are always difficult to diagnose/predict. Edit: RMW in the SW quad is bit further out at 40-50 km, but the point still remains valid: an inner wind maximum has sprouted up when before it didn't exist. Agree with this. The shear has actually decreased over the system today (as expected) but the resultant dry air that was ingested yesterday is still trying to be mixed out. It will probably be another 12 hour or so till this is not as much of an issue. It does appear that the core RMW is decreasing, which bodes well for intensification down the road. A bit lopsided, but we have around 2/3s of an eyewall. Cat 2 is a high probability, IMO. We are in agreement. Link to comment Share on other sites More sharing options...
40/70 Benchmark Posted August 27, 2012 Share Posted August 27, 2012 Regardless if this makes it to Cat 2 or not I still think the surge will not catch up in time before it comes ashore, it may have 110 mph winds in what is now my thinking on the worst case sceario but it may only have high end TS or minimal hurricane surge thankfully. I still think because of the lousy sloping of the shelf in the northern GOM it will still do alot of damage but I don't see anything resembling Katrina right now That is the thing....you want winds intensifying upon LF to maximize impact, but conversely with regard to surge, you want it to have had time to build it....ie, Katrina did not maximize wind damage because it was decaying, but it had had days at cat 5 strength to amass that lethal surge....this one will not. This system may transport wind energy more efficiently from aloft to the surface at LF than Katrina did, but the surge will be minimized. Great point. Link to comment Share on other sites More sharing options...
David Reimer Posted August 27, 2012 Share Posted August 27, 2012 roduct: Air Force Vortex Message (URNT12 KNHC) Transmitted: 27th day of the month at 18:26Z Aircraft: Air Force Aircraft (Last 3 digits of the tail number are 306) Storm Number & Year: 09L in 2012 Storm Name: Isaac (flight in the North Atlantic basin) Mission Number: 27 Observation Number: 06 A. Time of Center Fix: 27th day of the month at 17:52:10Z B. Center Fix Coordinates: 26°07'N 85°59'W (26.1167N 85.9833W) B. Center Fix Location: 252 miles (405 km) to the WSW (239°) from Tampa, FL, USA. C. Minimum Height at Standard Level: 1,296m (4,252ft) at 850mb D. Estimated (by SFMR or visually) Maximum Surface Wind: 64kts (~ 73.6mph) E. Location of the Estimated Maximum Surface Wind: 40 nautical miles (46 statute miles) to the NW (318°) of center fix F. Maximum Flight Level Wind Inbound: From 57° at 54kts (From the ENE at ~ 62.1mph) G. Location of Maximum Flight Level Wind Inbound: 37 nautical miles (43 statute miles) to the NW (319°) of center fix H. Minimum Sea Level Pressure: 985mb (29.09 inHg) I. Maximum Flight Level Temp & Pressure Altitude Outside Eye: 18°C (64°F) at a pressure alt. of 1,538m (5,046ft) J. Maximum Flight Level Temp & Pressure Altitude Inside Eye: 22°C (72°F) at a pressure alt. of 1,544m (5,066ft) K. Dewpoint Temp & 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, Radar, Wind, Pressure and Temperature N. Fix Level: 850mb O. Navigation Fix Accuracy: 0.02 nautical miles O. Meteorological Accuracy: 0.5 nautical miles Remarks Section: Maximum Flight Level Wind: 54kts (~ 62.1mph) in the northwest quadrant at 17:39:00Z Link to comment Share on other sites More sharing options...
phil882 Posted August 27, 2012 Share Posted August 27, 2012 Regardless if this makes it to Cat 2 or not I still think the surge will not catch up in time before it comes ashore, it may have 110 mph winds in what is now my thinking on the worst case sceario but it may only have high end TS or minimal hurricane surge thankfully. I still think because of the lousy sloping of the shelf in the northern GOM it will still do alot of damage but I don't see anything resembling Katrina right now That is the thing....you want winds intensifying upon LF to maximize impact, but conversely with regard to surge, you want it to have had time to build it....ie, Katrina did not maximize wind damage because it was decaying, but it had had days at cat 5 strength to amass that lethal surge....this one will not. This system may transport wind energy more efficiently from aloft to the surface at LF than Katrina did, but the surge will be minimized. Great point. This was debunked yesterday by CUMet The storm surge is much more a function of storm size, particularly the RMW and the extent of gale-hurricane force winds than it is of previous 24 hour maximum intensity. The concept of the storm surge having a "memory" of the max intensity, or there being some sort of lag was popularized immediately following the 2005 Gulf hurricanes, but the papers I've read about the topic since then suggest that the effect, if any, is small. For example, Charley had a small surge mostly because its wind field was small and the angle of approach may not have been optimal, not because it underwent RI just prior to landfall. Link to comment Share on other sites More sharing options...
phil882 Posted August 27, 2012 Share Posted August 27, 2012 One model that has been preforming remarkably well with Isaac is actually the HRRR. Last night I watched a few runs and it indeed showed the progression of the shear vector from southerly to more easterly today corresponding to a shifting the reflectivity swath. More recently, its finally showing signs of developing in eye in the 5-6 hour range. It was not developing an eye on reflectivity in the model runs last night. For todays 16z animation go here Link to comment Share on other sites More sharing options...
David Reimer Posted August 27, 2012 Share Posted August 27, 2012 AL, 09, 2012082718, , BEST, 0, 261N, 859W, 60, 984, TS, 34, NEQ, 180, 150, 80, 180, 1007, 230, 30, 0, 0, L, 0, , 0, 0, ISAAC, D, Link to comment Share on other sites More sharing options...
40/70 Benchmark Posted August 27, 2012 Share Posted August 27, 2012 This was debunked yesterday by CUMet Thank you. Link to comment Share on other sites More sharing options...
LakeEffectKing Posted August 27, 2012 Share Posted August 27, 2012 Delta T's in/outside the COC are at a modest 4C.....let's see how that changes over the next few hours of recon....The new inner wind max only adds to the intensification potential this evening into tomorrow morning. Link to comment Share on other sites More sharing options...
PSUBlizzicane2007 Posted August 27, 2012 Share Posted August 27, 2012 About the storm surge... other than CU having the correct viewpoint on this, keep in mind that one of the most prominent drivers in this area for surge... as with Katrina's surge... is the geography of the coastline acting as an almost perfect funnel for high surge. If Katrina had made landfall at the same intensity with the same duration as a cat 5 in, say, Pensacola for example... the surge would not have neared 30 feet at all, but instead it may have been more on the order of 17-20 feet. Link to comment Share on other sites More sharing options...
Nikolai Posted August 27, 2012 Share Posted August 27, 2012 About the storm surge... other than CU having the correct viewpoint on this, keep in mind that one of the most prominent drivers in this area for surge... as with Katrina's surge... is the geography of the coastline acting as an almost perfect funnel for high surge. If Katrina had made landfall at the same intensity with the same duration as a cat 5 in, say, Pensacola for example... the surge would not have neared 30 feet at all, but instead it may have been more on the order of 17-20 feet. Indeed. Another major thing people forget is that the surge can actually pile up East of the Mississippi River much more effectively than it can West of the river, which is illustrated on storm surge maps for the region, and is quite simple to explain-- Besides the shallow shelf, the levees that protect New Orleans and the greater region from flooding are actually higher on the Mississippi side versus Lake Pontchartrain. This actually keeps the water on the eastern side of the levees from spilling over, which actually makes the storm surge even worse, as it simply keeps building up. Link to comment Share on other sites More sharing options...
Superstorm93 Posted August 27, 2012 Share Posted August 27, 2012 IF conditions remain favorable, this could technically be strengthening right up until landfall with that kind of OHC. Link to comment Share on other sites More sharing options...
David Reimer Posted August 27, 2012 Share Posted August 27, 2012 Link to comment Share on other sites More sharing options...
thewxmann Posted August 27, 2012 Share Posted August 27, 2012 If you ask me, it looks as if the low-level and the mid-level centers are still not well-aligned. Very Gustav-ish in appearance, and probably won't strengthen appreciably for another 12 hr. Link to comment Share on other sites More sharing options...
Superstorm93 Posted August 27, 2012 Share Posted August 27, 2012 0120827 1745 26.4 86.0 T4.0/4.0 09L ISAAC Link to comment Share on other sites More sharing options...
wxmeddler Posted August 27, 2012 Share Posted August 27, 2012 If you ask me, it looks as if the low-level and the mid-level centers are still not well-aligned. Very Gustav-ish in appearance, and probably won't strengthen appreciably for another 12 hr. It's stacked from at least 850 down with the Hurricane Hunter "eye" dropsonde. I know that's not 500mb down but if you get less than 8 kts from 850 down with chaotic wind direction. That means at least something. Link to comment Share on other sites More sharing options...
David Reimer Posted August 27, 2012 Share Posted August 27, 2012 Recon heading back into the center from the NE Quad now. Link to comment Share on other sites More sharing options...
lakeeffectkid383 Posted August 27, 2012 Share Posted August 27, 2012 Its definitly still having a hard time mixing the dry air out according to WV. Hopefully this thing can get its act together tonight with D Min because I think its truly the last chance this thing has to get organized before LF. Link to comment Share on other sites More sharing options...
Superstorm93 Posted August 27, 2012 Share Posted August 27, 2012 Really tightening up the core on the latest visible images. Link to comment Share on other sites More sharing options...
N. OF PIKE Posted August 27, 2012 Share Posted August 27, 2012 not yet 192200 2640N 08546W 8411 01435 //// +196 //// 104044 046 039 004 01 192230 2638N 08547W 8415 01429 //// +195 //// 104045 046 040 004 01 192300 2637N 08548W 8411 01429 //// +196 //// 102045 046 041 004 01 192330 2635N 08548W 8412 01424 //// +198 //// 098047 048 041 001 01 192400 2634N 08549W 8412 01417 //// +196 //// 099052 054 042 004 01 192430 2632N 08550W 8412 01415 //// +176 //// 100052 054 043 009 01 192500 2631N 08551W 8404 01418 //// +166 //// 099049 051 042 008 01 192530 2629N 08552W 8417 01399 //// +176 //// 102048 050 042 008 01 192600 2628N 08552W 8410 01406 //// +176 //// 105041 045 041 009 01 192630 2626N 08553W 8410 01399 //// +179 //// 107036 040 043 008 01 192700 2625N 08554W 8409 01397 //// +182 //// 101035 037 043 009 01 Link to comment Share on other sites More sharing options...
CUmet Posted August 27, 2012 Share Posted August 27, 2012 Pressure at Buoy 42003 is slightly falling or hovering at 985-986 mb, despite strong southerly winds and Isaac moving away from the site. Link to comment Share on other sites More sharing options...
Superstorm93 Posted August 27, 2012 Share Posted August 27, 2012 Center looks to have moved NNE from the last VDM... Link to comment Share on other sites More sharing options...
wxmeddler Posted August 27, 2012 Share Posted August 27, 2012 It looks as though the center is still moving/ "dancing" around a bit under the MLC as the latest recon fix was NE of the last fix. Link to comment Share on other sites More sharing options...
CoastalWx Posted August 27, 2012 Share Posted August 27, 2012 Looks like even on IR, the center appears to be somewhere in that convection. Link to comment Share on other sites More sharing options...
LakeEffectKing Posted August 27, 2012 Share Posted August 27, 2012 No real changes with LF position with latest GFS/EnKF tracks: Link to comment Share on other sites More sharing options...
PSUBlizzicane2007 Posted August 27, 2012 Share Posted August 27, 2012 No real changes with LF position with latest GFS/EnKF tracks: I hate how the EnKF forecasts are 6 hours behind. I anxiously await the 12Z run of it since the 12Z operational GFS shifted east a tad. Link to comment Share on other sites More sharing options...
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