turtlehurricane Posted September 8, 2012 Share Posted September 8, 2012 If the science was there, why was this forecast to strengthen and consolidate, and why is it doing the opposite? What am I missing here? We had a long discussion in this thread about how Leslie causing upwelling in the same spot for so long would weaken the storm, and how the models can't really capture that. Writing was on the wall days ago. I recall mentioning how Leslie was likely to intensify as it accelerates northwards and encounters warm SSTs (non-upwelled) and its outflow couples with the mid-latitude jet. That's what's happening now (not quite accelerating yet but the outflow is coupling strongly). Could get interesting quickly once it does move, for the fish. Link to comment Share on other sites More sharing options...
wxmx Posted September 8, 2012 Share Posted September 8, 2012 You're all wrong...Leslie was too close to the tropics, it's now getting away from such bad influence and now that it's reaching 30N, strengthening is expected. Link to comment Share on other sites More sharing options...
OSUmetstud Posted September 8, 2012 Share Posted September 8, 2012 okay...you win Link to comment Share on other sites More sharing options...
phil882 Posted September 8, 2012 Share Posted September 8, 2012 You're all wrong...Leslie was too close to the tropics, it's now getting away from such bad influence and now that it's reaching 30N, strengthening is expected. Link to comment Share on other sites More sharing options...
HurricaneJosh Posted September 8, 2012 Share Posted September 8, 2012 The NHC forecast is almost constantly tied to a dynamical/statistical model mean. Sometimes some of the forecasters like to get more agressive/conservative, but they don't like to stray too far away from the model consensus. Most of the time this is the smart course of action. This particular case, however, is where the models would not have a good handle on the intensity since none of the global dynamical guidance can forecast upwelling since they are not dynamically coupled with the ocean. This is something the mesoscale models (GFDL,HWRF) should have a handle on, but apparently not. Anyone that has taken a basic class in tropical meteorology can deduce that 24.5 degree sea surface temperatures are not favorable for intensification of any pure tropical cyclone, let alone a hurricane. The models however did have a good handle on the extremely slow motion, and on the overall size of the circulation. Slow moving storm + large storm is a winning combination for substancial upwelling. That is why one could make, with reasonable accuracy, that the global models wouldn't handle the intensity of Leslie well. Of course it would take a much more careful analysis of Leslie to deduce this scientifically, but I think there is evidence here that its the models, not the current science of TC dynamics, that have failed in the forecast of Leslie. We had a long discussion in this thread about how Leslie causing upwelling in the same spot for so long would weaken the storm, and how the models can't really capture that. Writing was on the wall days ago. I recall mentioning how Leslie was likely to intensify as it accelerates northwards and encounters warm SSTs (non-upwelled) and its outflow couples with the mid-latitude jet. That's what's happening now (not quite accelerating yet but the outflow is coupling strongly). Could get interesting quickly once it does move, for the fish. But at the end of the day, we have another cyclone that is not performing as forecast. And then there's Michael-- which did the exact opposite and over-performed like crazy. Whether it's upwelling, dry air, shear, SAL, or god knows what combination of these factors or other issues, intensity forecasting remains a crap shoot-- and Leslie is just Exhibit Q. Don't even get me started on the Isaac forecasts. You both expected a major out of it. My point remains. Link to comment Share on other sites More sharing options...
Superstorm93 Posted September 8, 2012 Share Posted September 8, 2012 You're all wrong...Leslie was too close to the tropics, it's now getting away from such bad influence and now that it's reaching 30N, strengthening is expected. This. Link to comment Share on other sites More sharing options...
phil882 Posted September 9, 2012 Share Posted September 9, 2012 But at the end of the day, we have another cyclone that is not performing as forecast. And then there's Michael-- which did the exact opposite and over-performed like crazy. Whether it's upwelling, dry air, shear, SAL, or god knows what combination of these factors or other issues, intensity forecasting remains a crap shoot-- and Leslie is just Exhibit Q. Don't even get me started on the Isaac forecasts. You both expected a major out of it. My point remains. I don't take qualms with your statement that "Intensity forecast remains a crap shoot". What did bug me was the statement indicating that "the science isn't there" which implies not only are these systems difficult to forecast, but there is no scientific basis for why the intensity is changing as we are witnessing. Perhaps I over reacted a bit... I think the science, while not perfect, could have lead a forecaster in the right direction. I don't claim to be perfect ( as evidence of my horrible Isaac forecast). However, I aim to try to understand what went wrong and hopefully point out certain features that can be understood better in the future. TC generated upwelling is a very complicated process that is seldom observed in-situ (although it was in Leslie's case). My aim I tried to present in this thread is to show that models don't need to be followed blindly, especially when there is a key physical process that are a total unknown to the vast majority of the guidance. Link to comment Share on other sites More sharing options...
Amped Posted September 9, 2012 Share Posted September 9, 2012 I don't take qualms with your statement that "Intensity forecast remains a crap shoot". What did bug me was the statement indicating that "the science isn't there" which implies not only are these systems difficult to forecast, but there is no scientific basis for why the intensity is changing as we are witnessing. Perhaps I over reacted a bit... I think the science, while not perfect, could have lead a forecaster in the right direction. I don't claim to be perfect ( as evidence of my horrible Isaac forecast). However, I aim to try to understand what went wrong and hopefully point out certain features that can be understood better in the future. TC generated upwelling is a very complicated process that is seldom observed in-situ (although it was in Leslie's case). My aim I tried to present in this thread is to show that models don't need to be followed blindly, especially when there is a key physical process that are a total unknown to the vast majority of the guidance. If you want to see a nicelooking storm check out Micheal. In the meantime I'm writting leslie off and calling for rapid weaking, because when I do that the storm usually makes a comeback. Link to comment Share on other sites More sharing options...
HurricaneJosh Posted September 9, 2012 Share Posted September 9, 2012 I don't take qualms with your statement that "Intensity forecast remains a crap shoot". What did bug me was the statement indicating that "the science isn't there" which implies not only are these systems difficult to forecast, but there is no scientific basis for why the intensity is changing as we are witnessing. Perhaps I over reacted a bit... I think the science, while not perfect, could have lead a forecaster in the right direction. I don't claim to be perfect ( as evidence of my horrible Isaac forecast). However, I aim to try to understand what went wrong and hopefully point out certain features that can be understood better in the future. TC generated upwelling is a very complicated process that is seldom observed in-situ (although it was in Leslie's case). My aim I tried to present in this thread is to show that models don't need to be followed blindly, especially when there is a key physical process that are a total unknown to the vast majority of the guidance. The science isn't currently there to reliably predict the future intensity of a given tropical cyclone. It just isn't. This isn't a diss on you, the NHC, or any other agency-- it's a statement of reality. That doesn't mean that when a storm fizzles or pulls RI that we can't analyze and understand what happened after the fact-- but for some reason, the effects of the various factors at play cannot be reliably predicted in advance. When a cyclone enters the Gulf, we really have no idea what it's going to be when it approaches land on the other side-- it could be a TS, it could be 120 kt. Track forecasting gets better and better, on the other hand. Link to comment Share on other sites More sharing options...
Ed Lizard Posted September 9, 2012 Share Posted September 9, 2012 You're all wrong...Leslie was too close to the tropics, it's now getting away from such bad influence and now that it's reaching 30N, strengthening is expected. Is that a dig on a famous pro-mets twitter analysis of the 2012 cyclone activity? Same pro-met who thought MDR would be dead, but SE USA and Western Gulf would be at increased risk of close in developments? On the other hand, maybe because of the 30ºN thing, as mentioned in disco about Bermuda radar, huge slop eye is starting to form as seen on vis loops. As Phil has been bragging about, even though intensity forecasting isn't super accurate, he has been predicting underperformance based on slow motion and upwelling. Link to comment Share on other sites More sharing options...
Amped Posted September 9, 2012 Share Posted September 9, 2012 Is that a dig on a famous pro-mets twitter analysis of the 2012 cyclone activity? Same pro-met who thought MDR would be dead, but SE USA and Western Gulf would be at increased risk of close in developments? On the other hand, maybe because of the 30ºN thing, as mentioned in disco about Bermuda radar, huge slop eye is starting to form as seen on vis loops. As Phil has been bragging about, even though intensity forecasting isn't super accurate, he has been predicting underperformance based on slow motion and upwelling. It's accelerating now. And the troff may help to pump out the outflow, or shred the storm, or do one of those for 24hrs then the other. Link to comment Share on other sites More sharing options...
OSUmetstud Posted September 9, 2012 Share Posted September 9, 2012 upwelling shouldn't be messing it up this much at this point. But yet, it can't do a thing with an upper level anticyclone and very low shear over the top lol. Link to comment Share on other sites More sharing options...
thewxmann Posted September 9, 2012 Share Posted September 9, 2012 upwelling shouldn't be messing it up this much at this point. But yet, it can't do a thing with an upper level anticyclone and very low shear over the top lol. Can't really do anything if it's missing an inner core lol.... Link to comment Share on other sites More sharing options...
Superstorm93 Posted September 9, 2012 Share Posted September 9, 2012 It honestly does look a little like a sub-tropical system. I don't know exactly how many days it's been since Leslie has had an inner core, but it does seem to have at least a partially complete one. There has to have been more complicated things at work here to completely kill any intensification and actually induce weakening, when most models were showing Leslie becoming an intense hurricane. I don't quite think we can just chalk it up to upwelling right now. I find it completely astounding that Michael became the strong Hurricane and Leslie became the "crap cane" Link to comment Share on other sites More sharing options...
klw Posted September 10, 2012 Share Posted September 10, 2012 Leslie does have an inner core- it is just displace by 1000 miles and is called Michael. If I had Photoshop skills I would try to combine the two storms. Link to comment Share on other sites More sharing options...
canderson Posted September 10, 2012 Share Posted September 10, 2012 This will wallop PEI pretty well. Link to comment Share on other sites More sharing options...
Alfoman Posted September 10, 2012 Share Posted September 10, 2012 Leslie does have an inner core- it is just displace by 1000 miles and is called Michael. If I had Photoshop skills I would try to combine the two storms. DID IT! I call it Micheslie 2.0! Link to comment Share on other sites More sharing options...
OSUmetstud Posted September 10, 2012 Share Posted September 10, 2012 Can't really do anything if it's missing an inner core lol.... sure it could. Storms redevelop inner cores under favorable conditions, but yet this one isn't. I suspect the dry air entrained into the circulation from the very dry ambient environment and the westerly shear previously is not allowing for convection within the RMW. Link to comment Share on other sites More sharing options...
Amped Posted September 10, 2012 Share Posted September 10, 2012 If there was an inner core it's gone now. The circulation is just to big to focus energy. Link to comment Share on other sites More sharing options...
HurricaneJosh Posted September 10, 2012 Share Posted September 10, 2012 Love that tight core lolz. Link to comment Share on other sites More sharing options...
andyhb Posted September 10, 2012 Share Posted September 10, 2012 I'd say that Leslie has a good chance to be the first MH of the season (if Kirk wasn't already), as you mentioned that acceleration would aid in creating a healthy upper level environment for the storm to work with. Bust, in more ways than one... Link to comment Share on other sites More sharing options...
HurricaneJosh Posted September 10, 2012 Share Posted September 10, 2012 Bust, in more ways than one... Link to comment Share on other sites More sharing options...
HurricaneJosh Posted September 10, 2012 Share Posted September 10, 2012 Maybe there are some 40-kt gusts in that convective cell E of the center. Pathetic storm. Kill it with fire, I say! Link to comment Share on other sites More sharing options...
on_wx Posted September 10, 2012 Share Posted September 10, 2012 WWCN31 CWHX 100551 SEVERE WEATHER BULLETIN ISSUED BY THE CANADIAN HURRICANE CENTRE OF ENVIRONMENT CANADA AT 2:51 AM ADT MONDAY 10 SEPTEMBER 2012. --------------------------------------------------------------------- TROPICAL STORM WATCH FOR: =NEW= TERRA NOVA =NEW= BONAVISTA NORTH =NEW= CONNAIGRE =NEW= BURGEO TO RAMEA. TROPICAL STORM CONDITIONS ARE POSSIBLE ON TUESDAY. A TROPICAL STORM WATCH MEANS THAT A TROPICAL STORM OR AN INCIPIENT TROPICAL STORM CONDITION POSES A POSSIBLE THREAT TO THE SPECIFIED AREAS WITHIN 36 HOURS. HURRICANE WATCH FOR: =NEW= ST. JOHN'S AND VICINITY =NEW= AVALON PENINSULA NORTH =NEW= AVALON PENINSULA SOUTHEAST =NEW= AVALON PENINSULA SOUTHWEST =NEW= CLARENVILLE AND VICINITY =NEW= BONAVISTA PENINSULA =NEW= BURIN PENINSULA. POTENTIAL FOR MARGINAL HURRICANE CONDITIONS ON TUESDAY. A HURRICANE WATCH MEANS THAT A HURRICANE OR AN INCIPIENT HURRICANE CONDITION POSES A POSSIBLE THREAT TO THE SPECIFIED AREAS WITHIN 36 HOURS. --------------------------------------------------------------------- ==DISCUSSION== TROPICAL STORM LESLIE CONTINUES TO ADVANCE TOWARD ATLANTIC CANADA AND WILL INTERACT WITH SLOW-MOVING FRONTAL TROUGH OVER THE MARITIMES. THIS TROUGH WILL ACCELERATE AND STEER LESLIE TOWARD SOUTHEASTERN NEWFOUNDLAND WHERE IT IS EXPECTED TO MAKE LANDFALL AS A MARGINAL HURRICANE OR STRONG TROPICAL STORM LATER TUESDAY MORNING. AS LESLIE INTERACTS WITH THE TROUGH IT WILL ENHANCE THE HEAVY RAINFALL ALREADY OCCURRING WITH THE TROUGH AS WELL AS STRENGTHEN THE WINDS BEHIND IT. HOWEVER THE STRONGEST WINDS ARE MOST LIKELY JUST TO THE RIGHT OF LESLIE'S TRACK AT LAND FALL VERY STRONG AND GUSTY WINDS ARE LIKELY. HURRICANE WATCHES ARE IN EFFECT FOR THE AREAS MOST LIKELY TO SEE THESE RIGHT-OF-TRACK WINDS, TAKING INTO ACCOUNT THE POSSIBILITY OF A SLIGHTLY MORE WESTWARD TRACK, WITH TROPICAL STORM WATCHES IN EFFECT FOR ADJACENT AREAS. PLEASE REFER TO THE LATEST FORECASTS FOR FURTHER DETAILS. END/.. Link to comment Share on other sites More sharing options...
PSUBlizzicane2007 Posted September 10, 2012 Share Posted September 10, 2012 The structure of Leslie reminds me a lot of Isidore-2002 post-Yucatan. Link to comment Share on other sites More sharing options...
Riptide Posted September 10, 2012 Share Posted September 10, 2012 The structure of Leslie reminds me a lot of Isidore-2002 post-Yucatan. Such hostile environmental conditions for anything tropical; that wall of dry air will kill the instability quickly. Link to comment Share on other sites More sharing options...
Superstorm93 Posted September 10, 2012 Share Posted September 10, 2012 Just call it ET so we can finally be done with this pathetic system... Link to comment Share on other sites More sharing options...
HurricaneJosh Posted September 10, 2012 Share Posted September 10, 2012 Lolz!! Link to comment Share on other sites More sharing options...
Superstorm93 Posted September 11, 2012 Share Posted September 11, 2012 Leslie is a hurricane once again according to ATCF AL, 12, 2012091100, , BEST, 0, 411N, 585W, 65, 986, HU Link to comment Share on other sites More sharing options...
GaWx Posted September 11, 2012 Share Posted September 11, 2012 Derecho!, on 31 August 2012 - 07:55 AM, said: The 4-day stall will be astoundingly fun. How many "regular" and "banter" threads will we need? I think it will eventually p*ss more weenies off than anything else when it very likely fails to produce a U.S. threat. They will be wishing it to get out or die. Mark my words. By the way, rainstorm is having fun with this likelihood now at another BB. It is funny. In all fairness, there haven't been that many "get out or die" comments. Link to comment Share on other sites More sharing options...
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