LakeEffectKing Posted August 27, 2012 Share Posted August 27, 2012 The period of intensification tonight should be stout. Also of concern is the slowing of the system, which not only prolongs the sensible effects for those along the C. Gulf coast, but would better maximize the frictional tightening of the wind field as the core approaches the quasi-concave coastline. While I feel we most definitely won't have an intensity,nor the size of the beast from 7 years ago, the different angle of approach, the progged slower movement, and the potential for this to be strengthening up to LF, certainly creates a bit of deja vu, wrt the anticipation of something "not-so-good". Link to comment Share on other sites More sharing options...
BeauDodson Posted August 27, 2012 Share Posted August 27, 2012 17:35 vs 20:35 images. It is always interesting to watch these systems try to get their act together - especially after moving over some islands. Seems like when they are lopsided that they struggle and struggle to develop. A year or two ago I remember a long discussion on that topic - in the forum. Seems like we are still quite a few years away from achieving significant skill in forecasting intensity. Track forecasts have certainly improved over the last decade - just need to get the intensity forecasts in better shape. Link to comment Share on other sites More sharing options...
David Reimer Posted August 27, 2012 Share Posted August 27, 2012 Additional towers going up in proximity to the LLC. Link to comment Share on other sites More sharing options...
Superstorm93 Posted August 27, 2012 Share Posted August 27, 2012 Been a while since the last fix. Pretty odd to have no dropsonde or VDM data yet. Link to comment Share on other sites More sharing options...
phil882 Posted August 27, 2012 Share Posted August 27, 2012 Most likely because the sheer size of the storm. Irene was huge too. The pressure drops, but the wind field is very large so it gets more spread out. Not quite as much wind response to pressure drops as a smaller storm like an Andrew. IMO, I am still seeing major dry air issues even with new towers going up. I agree with Phil that the dry air problem should be on its way out in the near future, but I am not sure that there will be enough time left for extreme RI before landfall once that happens. Also the boundary layer concerns me. Even though the waters are warm, the boundary layer is fairly shallow... the slow movement of the storm could cause upwelling which could also help to inhibit any RI. Still don't see this thing going beyond a Cat 2, if that. Cloud tops have warmed over the past 45 minutes. That might temporarily halt or at least slow this strengthening trend. My thinking is that the relaxation in convection close to the core this afternoon and evening might be more related to a diurnal pulse event, which typically results in an outward extension of convection with weakening convection in the core during the afternoon and evening. While there is still substantially dry air to the storm's west and southwest, the shear vector has shifted easterly today. This should prevent a major dry air intrusion into the central core since the total precipitable water from that region is quite moist. Earlier in Isaac's life, the low and mid-level centres were not vertically aligned which made it easy for try air to get into the core. This shouldn't be as drastic this time. Link to comment Share on other sites More sharing options...
OUGrad05 Posted August 27, 2012 Share Posted August 27, 2012 Towers in the core... Should be an interesting night. Man that's a good shot... The period of intensification tonight should be stout. Also of concern is the slowing of the system, which not only prolongs the sensible effects, but would better maximize the frictional tightening of the wind field as the core approaches the quasi-concave coastline. While I feel we most definitely won't have an intensity,nor the size of the beast from 7 years ago, the different angle of approach, the progged slower movement, and the potential for this to be strengthening up to LF, certainly creates a bit of deja vu, wrt anticipation of something "not-so-good". I read a white paper years ago (or some kind of paper from NOAA and NHC I think) that basically said strengthening storms are capable of damage at least one level higher and in many cases significantly more damage. If I remember correctly it basically said that the wind speeds are more steady in a weakening storm as the pressure rises and convection begins to die off. But in a strengthening storm the gusts can be significantly higher, even two levels or more higher. So it's possible a strengthening 2 could leave pockets of high end 3 damage. The paper was basically about Andrew of I remember correctly... I assume this theory still holds true today... Link to comment Share on other sites More sharing options...
dan88 Posted August 27, 2012 Share Posted August 27, 2012 981mb drop with 14kt from NOAA plane. Link to comment Share on other sites More sharing options...
HKY_WX Posted August 27, 2012 Share Posted August 27, 2012 Definitely looks like a solid eyewall forming. My guess is it will take hours to close off. Once that happens the strengthening will probably really start(if these short range model projections are accurate). Link to comment Share on other sites More sharing options...
dan11295 Posted August 27, 2012 Share Posted August 27, 2012 Given how slow the storm will be moving onshore will probably peak before moving on land, although since much of that area is marsh weakening will be slower than normal. Link to comment Share on other sites More sharing options...
Bluescat1 Posted August 27, 2012 Share Posted August 27, 2012 Given how slow the storm will be moving onshore will probably peak before moving on land, although since much of that area is marsh weakening will be slower than normal. The late John Hope used to talk about that. Link to comment Share on other sites More sharing options...
David Reimer Posted August 27, 2012 Share Posted August 27, 2012 Product: NOAA Vortex Message (URNT12 KWBC) Transmitted: 27th day of the month at 21:51Z Aircraft: Lockheed WP-3D Orion (Reg. Num. N42RF) Storm Number & Year: 09L in 2012 Storm Name: Isaac (flight in the North Atlantic basin) Mission Number: 28 Observation Number: 08 A. Time of Center Fix: 27th day of the month at 21:25:41Z B. Center Fix Coordinates: 26°27'N 86°12'W (26.45N 86.2W) B. Center Fix Location: 253 miles (407 km) to the WSW (245°) from Tampa, FL, USA. C. Minimum Height at Standard Level: Not Available D. Estimated (by SFMR or visually) Maximum Surface Wind: 49kts (~ 56.4mph) E. Location of the Estimated Maximum Surface Wind: 19 nautical miles (22 statute miles) to the NE (36°) of center fix F. Maximum Flight Level Wind Inbound: From 120° at 52kts (From the ESE at ~ 59.8mph) G. Location of Maximum Flight Level Wind Inbound: 32 nautical miles (37 statute miles) to the NNE (33°) of center fix H. Minimum Sea Level Pressure: 981mb (28.97 inHg) I. Maximum Flight Level Temp & Pressure Altitude Outside Eye: 16°C (61°F) at a pressure alt. of 2,450m (8,038ft) J. Maximum Flight Level Temp & Pressure Altitude Inside Eye: 20°C (68°F) at a pressure alt. of 2,446m (8,025ft) K. Dewpoint Temp (collected at same location as temp inside eye): 14°C (57°F) K. Sea Surface Temp (collected at same location as temp inside eye): Not Available L. Eye Character: Open in the east M. Eye Shape & Diameter: Circular with a diameter of 25 nautical miles (29 statute miles) N. Fix Determined By: Penetration, Radar, Wind, Pressure and Temperature N. Fix Level: Other - Not surface, 1500ft, 925mb (if vortex is newer than about mid 90's; see note for more), 850mb, 700mb, 500mb, 400mb, 300mb or 200mb O. Fix Determined By / Fix Level (Undecoded): 1 / 1 nm Remarks Section: MAX OUTBOUND FL WIND AND MAX FL WIND 56 KT SW QUAD 21:40:26Z SONDE SFC WIND 15KTS Link to comment Share on other sites More sharing options...
lakeeffectkid383 Posted August 27, 2012 Share Posted August 27, 2012 Product: NOAA Vortex Message (URNT12 KWBC) Transmitted: 27th day of the month at 21:51Z Aircraft: Lockheed WP-3D Orion (Reg. Num. N42RF) Storm Number & Year: 09L in 2012 Storm Name: Isaac (flight in the North Atlantic basin) Mission Number: 28 Observation Number: 08 A. Time of Center Fix: 27th day of the month at 21:25:41Z B. Center Fix Coordinates: 26°27'N 86°12'W (26.45N 86.2W) B. Center Fix Location: 253 miles (407 km) to the WSW (245°) from Tampa, FL, USA. C. Minimum Height at Standard Level: Not Available D. Estimated (by SFMR or visually) Maximum Surface Wind: 49kts (~ 56.4mph) E. Location of the Estimated Maximum Surface Wind: 19 nautical miles (22 statute miles) to the NE (36°) of center fix F. Maximum Flight Level Wind Inbound: From 120° at 52kts (From the ESE at ~ 59.8mph) G. Location of Maximum Flight Level Wind Inbound: 32 nautical miles (37 statute miles) to the NNE (33°) of center fix H. Minimum Sea Level Pressure: 981mb (28.97 inHg) I. Maximum Flight Level Temp & Pressure Altitude Outside Eye: 16°C (61°F) at a pressure alt. of 2,450m (8,038ft) J. Maximum Flight Level Temp & Pressure Altitude Inside Eye: 20°C (68°F) at a pressure alt. of 2,446m (8,025ft) K. Dewpoint Temp (collected at same location as temp inside eye): 14°C (57°F) K. Sea Surface Temp (collected at same location as temp inside eye): Not Available L. Eye Character: Open in the east M. Eye Shape & Diameter: Circular with a diameter of 25 nautical miles (29 statute miles) N. Fix Determined By: Penetration, Radar, Wind, Pressure and Temperature N. Fix Level: Other - Not surface, 1500ft, 925mb (if vortex is newer than about mid 90's; see note for more), 850mb, 700mb, 500mb, 400mb, 300mb or 200mb O. Fix Determined By / Fix Level (Undecoded): 1 / 1 nm Remarks Section: MAX OUTBOUND FL WIND AND MAX FL WIND 56 KT SW QUAD 21:40:26Z SONDE SFC WIND 15KTS So 981 with winds of 15kt so about 980 now or perhaps 979. Link to comment Share on other sites More sharing options...
lakeeffectkid383 Posted August 27, 2012 Share Posted August 27, 2012 Tons of lightning on the W side of the core now. Link to comment Share on other sites More sharing options...
Superstorm93 Posted August 27, 2012 Share Posted August 27, 2012 NE quad should start firing up soon. Link to comment Share on other sites More sharing options...
deltadog03 Posted August 27, 2012 Share Posted August 27, 2012 Looks like its cruising of to the NNW or even closer to N in the short term. Link to comment Share on other sites More sharing options...
PSUBlizzicane2007 Posted August 27, 2012 Share Posted August 27, 2012 18Z GFS looks like a slight further east landfall point near the mouth of the Mississippi River, but a slightly further left track after landfall. Link to comment Share on other sites More sharing options...
Amped Posted August 27, 2012 Share Posted August 27, 2012 Winds have not increased much despite the pressure drop we are seeing an irene p w relationship Link to comment Share on other sites More sharing options...
ZackH Posted August 27, 2012 Share Posted August 27, 2012 Winds have not increased much despite the pressure drop we are seeing an irene p w relationship Most likely because the sheer size of the storm. Irene was huge too. The pressure drops, but the wind field is very large so it gets more spread out. Not quite as much wind response to pressure drops as a smaller storm like an Andrew. IMO, I am still seeing major dry air issues even with new towers going up. I agree with Phil that the dry air problem should be on its way out in the near future, but I am not sure that there will be enough time left for extreme RI before landfall once that happens. Also the boundary layer concerns me. Even though the waters are warm, the boundary layer is fairly shallow... the slow movement of the storm could cause upwelling which could also help to inhibit any RI. Still don't see this thing going beyond a Cat 2, if that. Link to comment Share on other sites More sharing options...
dan11295 Posted August 27, 2012 Share Posted August 27, 2012 Some erosion of convection in the North quad, wonder if some dry air got into the core. If so should halt intensification for now. Link to comment Share on other sites More sharing options...
Superstorm93 Posted August 27, 2012 Share Posted August 27, 2012 Still dry air problems. We'll see what happens tonight. Link to comment Share on other sites More sharing options...
salbers Posted August 27, 2012 Share Posted August 27, 2012 Greetings, This storm surge map from the SLOSH model could be compared with available indundation maps from local emergency management agencies. http://www.nws.noaa....=e50&Th=50&Z=z2 Link to comment Share on other sites More sharing options...
NorEaster27 Posted August 27, 2012 Share Posted August 27, 2012 its clear this is not intensifying as it continues to struggle to wrap convection around the center. Link to comment Share on other sites More sharing options...
LakeEffectKing Posted August 27, 2012 Share Posted August 27, 2012 New HRWF ticked east w/LF (as expected with the 18z GFS ticking east): Link to comment Share on other sites More sharing options...
thewxmann Posted August 27, 2012 Share Posted August 27, 2012 Latest HRRR indicates inner core will still be pretty loose and dry-air infiltrated well into the night and tomorrow morning. This thing will probably not get its act together until frictional convergence contracts the inner core at landfall. Link to comment Share on other sites More sharing options...
BeauDodson Posted August 27, 2012 Share Posted August 27, 2012 Latest HRRR certainly makes every attempt to strengthen Isaac over the next 10-12 hours. Still fighting some dry air on the HRRR - but with that said - HRRR does seem to develop Isaac tonight. It will be interesting to see how the HRRR does tonight - I know a few people earlier in the thread mentioned the subject. Seems like these lopsided storms have a very hard time getting their act together. The big story with Isaac is going to be the flooding. Will be curious to see how the storm surge plays out - especially if it moves extremely slow into the coast. Then the question will be where does the big rainfall totals set up shop. --- Interesting site on possible impacts from Isaac http://w1.weather.go...&threat=coastal Later tonight Link to comment Share on other sites More sharing options...
bluewave Posted August 27, 2012 Share Posted August 27, 2012 Does anyone know if this is near the record lowest pressure for a tropical storm in the Gulf? We have seen interesting wind/pressure relationships in recent years from Alex to Ike and Earl to Irene. Link to comment Share on other sites More sharing options...
Amped Posted August 27, 2012 Share Posted August 27, 2012 Does anyone know if this is near the record lowest pressure for a tropical storm in the Gulf? We have seen interesting wind/pressure relationships in recent years from Alex to Ike and Earl to Irene. I call it annoying not interesting. However this is not uncommon in the wpac so I assume it can happen im our basin. I think isador had a lower pressure Link to comment Share on other sites More sharing options...
wi_fl_wx Posted August 27, 2012 Share Posted August 27, 2012 The SSMIS pass at 23Z actually looks pretty good. I'm surprised. Despite the dry air problems there is a nice ring of rain wrapped around the center. The issues on the northern side appear to be mostly at upper levels. So I think there is still a decent chance of RI overnight into tomorrow. Link to comment Share on other sites More sharing options...
Chaser25973 Posted August 27, 2012 Author Share Posted August 27, 2012 So 981 with winds of 15kt so about 980 now or perhaps 979. I can't remember the last time I've seen sub 980 tropical storm. I think the lowest pressure I've seen in a tropical storm was like 985? 984? I wonder what the record is... Link to comment Share on other sites More sharing options...
bluewave Posted August 27, 2012 Share Posted August 27, 2012 I call it annoying not interesting. However this is not uncommon in the wpac so I assume it can happen im our basin. I think isador had a lower pressure I think we have seen this also with CAT downgrades upon recent reanalysis of older Atlantic storms. Link to comment Share on other sites More sharing options...
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