eurojosh Posted August 30, 2011 Share Posted August 30, 2011 4) Therefore, despite the low lat. of TD #12, I feel comfortable maintaining a high (say ~90%) chance that TD #12/Katia will not hit the CONUS, especially considering that the GFS/Euro still show/suggest a recurve due to a lack of sig. high pressure over the W Atl. If the lat. had not been so low, I may have already gone with ~95% chance of no hit. I will update my %’s over the days to come. Thanks, this is not only well argued, but also entirely credible at this point. Link to comment Share on other sites More sharing options...
Ed Lizard Posted August 30, 2011 Share Posted August 30, 2011 nearly 300 miles wide already Still splitting the goal posts, apparently, but look at previous Euro runs, it is coming closer to bouncing off the left upright that is New England. Fish still most likely optionn, but not a done deal. Link to comment Share on other sites More sharing options...
free_man Posted August 30, 2011 Share Posted August 30, 2011 Fish still most likely optionn, but not a done deal. Still a week away from having a reasonably accurate track , be it away from the U.S., or away from land period - or not. That is a long, long time. One thing the models do have is a very consistent track north of the islands/PR. That should at least keep people more interested than usual, along with Irenes history (which was very anomalous obviously). I wouldn't begin to rule anything out, from SE coast to Maritimes, or even Bermuda I guess. Link to comment Share on other sites More sharing options...
GaWx Posted August 30, 2011 Share Posted August 30, 2011 Wrong...looks like they are weighted this way...but when DT is doing your heavy lifting I guess you don't need to know anything The weightings on current location, intensity, and time of year in the current routine are as follows: Location: 0.025 point for every km away from current location Intensity: 0.5 point for every kt away from current intensity Time of year: 0.075 point for every day away from current date I like the general idea of them weighting a variety of factors to determine the best analogs. However, regarding the factors on which they based their analogs and considering the study I posted here last night, I feel that they should also include a difference in heading factor and weigh it the most heavily with difference in location (latitude) being 2nd most heavily weighted. Because they don't consider heading, I feel this is overstating the CONUS threat by Katia. I also feel that difference in the speed of movement should be introduced but as a lighter input vs. the heading and latitude. Also, strength difference seems reasonable to have albeit perhaps at a little lighter weighting than speed of movement. Having distance from date is tricky because I feel that distance away from current date isn't all that symmetrical a factor at this time of year. Why? Because a TC from one month prior (7/30) would probably behave more similarly than one from one month later (9/30). Of course, there will be very few that far east that late in the season and not all that many near 7/30 for that matter since that is still a bit early. Link to comment Share on other sites More sharing options...
IsentropicLift Posted August 30, 2011 Share Posted August 30, 2011 12z Early guidance, looks like a number of models shifted west towards the coast, overall its still screaming recurve Link to comment Share on other sites More sharing options...
am19psu Posted August 30, 2011 Share Posted August 30, 2011 12z Early guidance, looks like a number of models shifted west towards the coast You need to stop wishcasting. There has been very little shifting of the models over the last few sets of runs. The clusters have been just south of 20N at 55W and almost everything is showing a recurve. This is your warning. Link to comment Share on other sites More sharing options...
Ellinwood Posted August 30, 2011 Share Posted August 30, 2011 12z Early guidance, looks like a number of models shifted west towards the coast, overall its still screaming recurve How can it be "screaming" recurve if it's trending west? Wouldn't that be "indicating fish, but it's getting closer to the US?" You need to stop wishcasting. There has been very little shifting of the models over the last few sets of runs. And this. Link to comment Share on other sites More sharing options...
IsentropicLift Posted August 30, 2011 Share Posted August 30, 2011 How can it be "screaming" recurve if it's trending west? Wouldn't that be "indicating fish, but it's getting closer to the US?" And this. to me, it looked like it trended west, its not a wishcast. I went 36 hours without power and my town is devistated by flooding, the last thing I want is another hit up this way. and I was just stating how most of the members are still showing recurve by a large majority. Link to comment Share on other sites More sharing options...
PSUBlizzicane2007 Posted August 30, 2011 Share Posted August 30, 2011 I'm really intrigued by the idea of a narrow ridge forming to turn Katia back to the west near the end of the period... and it seems to have some support... but at the moment, I feel quite tepid towards the idea of such a ridge being able to bring Katia towards the US. Link to comment Share on other sites More sharing options...
OKpowdah Posted August 30, 2011 Share Posted August 30, 2011 You need to stop wishcasting. There has been very little shifting of the models over the last few sets of runs. The clusters have been just south of 20N at 55W and almost everything is showing a recurve. This is your warning. To be honest, that sounded like a pretty unbiased post that you just jumped all over. And also, there HAS been a trend to the SW in the 3-5 day period. Link to comment Share on other sites More sharing options...
am19psu Posted August 30, 2011 Share Posted August 30, 2011 To be honest, that sounded like a pretty unbiased post that you just jumped all over. And also, there HAS been a trend to the SW in the 3-5 day period. Sure, over the last 3-5 days. But not from 12z yesterday to 12z today or any time in between. His post implied that the trend occurred at 12z today. Link to comment Share on other sites More sharing options...
eurojosh Posted August 30, 2011 Share Posted August 30, 2011 1100 NHC advisory is out... LATER IN THE FORECASTPERIOD...THE TROPICAL CYCLONE IS EXPECTED TO BE APPROACHING A WEAKNESS IN THE RIDGE CREATED BY A TROUGH OVER THE WESTERN ATLANTIC. THIS SHOULD CAUSE KATIA TO BEGIN TO TURN TOWARD THE NORTHWEST WITH A DECREASE IN FORWARD SPEED. Link to comment Share on other sites More sharing options...
OKpowdah Posted August 30, 2011 Share Posted August 30, 2011 Sure, over the last 3-5 days. But not from 12z yesterday to 12z today or any time in between. His post implied that the trend occurred at 12z today. Sorry, I was talking about the 3-5 day forecast period. The trend has been run-to-run Link to comment Share on other sites More sharing options...
am19psu Posted August 30, 2011 Share Posted August 30, 2011 Sorry, I was talking about the 3-5 day forecast period. The trend has been run-to-run Which models are you using? I just went and checked the 12z GFS/0z GFS and the 12z Euro/0z Euro and there was no trend in the positions comparing 108 at 12z to 96 at 0z. Link to comment Share on other sites More sharing options...
jconsor Posted August 30, 2011 Share Posted August 30, 2011 There is definitely a faster and more west trend if you compare the 120 hour position from today's 0z Euro vs. yesterday's 144 hour position on the 0z Euro, and the same for today's 0z GFS vs. yesterday's 0z GFS. The same trend is evident if you compare the 120 hour position on Monday's 12z Euro with the 144 hour position on Sunday's 12z Euro, and for Monday's 12z GFS compared to Sunday's. Which models are you using? I just went and checked the 12z GFS/0z GFS and the 12z Euro/0z Euro and there was no trend in the positions comparing 108 at 12z to 96 at 0z. Link to comment Share on other sites More sharing options...
Bob Chill Posted August 30, 2011 Share Posted August 30, 2011 There is definitely a faster and more west trend if you compare the 120 hour position from today's 0z Euro vs. yesterday's 144 hour position on the 0z Euro, and the same for today's 0z GFS vs. yesterday's 0z GFS. Being this far out I've been only concentrating on the trend with the st ridge and not the 5+ day projected tracks. I feel this is the most important feature irt the potential for any possibility of a us landfall. Should I be focused on other features as well? From what I can tell, the odds of the US being affected by Katia appear quite low and nothing is indicating that this is going to change too much. Link to comment Share on other sites More sharing options...
boulderrr Posted August 30, 2011 Share Posted August 30, 2011 Historical probability has dropped to 29% chance of U.S. landfall at any intensity based on its current position. 24% chance as a hurricane. 14% chance as a major hurricane. The first two were above 30% yesterday. Link to comment Share on other sites More sharing options...
SnowlieSnowstormson Posted August 30, 2011 Share Posted August 30, 2011 Incoming trof late in the period is going to boot that thing all the way to England... Link to comment Share on other sites More sharing options...
CooL Posted August 30, 2011 Share Posted August 30, 2011 12z GFS: positive PNA over the west with a pretty deep trough over the east. Its gonna recurve with that pattern unless this all changes. Link to comment Share on other sites More sharing options...
Typhoon Tip Posted August 30, 2011 Share Posted August 30, 2011 Some of my own thoughts on this today: The teleconnectors are argumentative. The PNA from the CDC calculations shows a huge +PNA signal erupting starting smartly on the 31st of August …right out to the 10th or so of September. The thing is, the CPC’s mean is less emphatic, showing a respectable negative that nadirs in about 4 days, then any rise thereafter is a bit more mop-ended among the members as far as how much. One thing to note: The PNA becomes more correlated on the flow around September 1 each year – accordance with CDC findings. Prior to this time, JJA, correlation matrix doesn’t even derive the values per their source. In other words, no skill.. What all that means is that a should a CDC value be more indicative (and there really isn’t any way to know for sure at this point in time) then the progressivity in the flow would tend to reduce in that time in keeping with a +PNA correlation being a western ridge, eastern trough. Also, the interpretation that a trough in the east is an automatic seaward result is poor. +PNA means the flow is becoming less longitudinal and more latitudinally oriented, mean just as well more opportunity for S steering level along the EC. That can draw these in... The other thing is that the NAO, which doesn’t have much of any temporal reduction in correlation, is weakly positive and averaged to persist so for the foreseeable future. It is not overwhelmingly so by any stretch …but, enough so to wonder if a better fit is stronger subtropical ridge tendency (the teleconnector domain overlaps the PNA by a small amount over E North America. That complicates matters a little, but it could also mean a stronger subtropical ridging N of Katia, while troughing emerges around the OV/MA. I wouldn’t use that to predict a direct threat to the U.S., but I don’t necessarily agree with the linear correlation of x,y,z storms do this however % of the time; that kind of statistical analysis completely falls apart when looking at patterns per reanalysis. They shimmer like coincidences, when it is far more accurate to say that given 4,000 nautical miles of open ocean, there are too many plausible permutations to disrupt an unperturbed westerly motion. Kind of like being shot at by a single round or two and dodging those, versus having a machine gun’s worth of bullets and having to dodge all of them. Don’t get me wrong; the linear stuff has a lot of use – very good use – in the sense that it establishes a canvas. But the deeper analysis is what paints the picture. This time, the teleconnectors do offer some plausibility to a westward adjustment here. Just something to keep in mind. No prediction of a strike here. Link to comment Share on other sites More sharing options...
negative-nao Posted August 30, 2011 Share Posted August 30, 2011 12z GFS: positive PNA over the west with a pretty deep trough over the east. Its gonna recurve with that pattern unless this all changes. Notice the low presure of the coast of texas. It just hangs out there. Might give them copious amounts of well needed rainfall Link to comment Share on other sites More sharing options...
Cheeznado Posted August 30, 2011 Share Posted August 30, 2011 I agree with the fish scenario. The Euro ensembles are a tad farther west than the operationals but with the double whammy of climo and the pattern of western ridge/eastern trough, I feel very confident that the only question here is will the storm hit: Bermuda and/or Nova Scotia and/or Newfoundland. Link to comment Share on other sites More sharing options...
k*** Posted August 30, 2011 Share Posted August 30, 2011 Is the euro still trending west? Link to comment Share on other sites More sharing options...
thewxmann Posted August 30, 2011 Share Posted August 30, 2011 12Z Euro goes east... near or east of Bermuda in fact. <div><br></div><div>EDIT: also much weaker with the Gulf entity.</div> Link to comment Share on other sites More sharing options...
OKpowdah Posted August 30, 2011 Share Posted August 30, 2011 Which models are you using? I just went and checked the 12z GFS/0z GFS and the 12z Euro/0z Euro and there was no trend in the positions comparing 108 at 12z to 96 at 0z. Link to comment Share on other sites More sharing options...
k*** Posted August 30, 2011 Share Posted August 30, 2011 That GFDN trend is sick Link to comment Share on other sites More sharing options...
Ed Lizard Posted August 30, 2011 Share Posted August 30, 2011 That GFDN trend is sick IIRC, that is an earlier model of the GFDL with one less nested grid and initialized and bounded by the NoGaps. Of course its sick. Link to comment Share on other sites More sharing options...
donsutherland1 Posted August 30, 2011 Share Posted August 30, 2011 Some quick thoughts: 1. Yesterday, I noted that the stronger storms that developed in the region in which Katia formed had less chance of recurvature than the weaker ones, noting that none of the storms that failed to recurve were tropical storms. The 12z Euro is depicting a markedly weaker storm. Not too surprisingly, it turns the storm much more quickly than the 0z run did (around 64°W vs.71°W on the earlier run). 2. Given the better agreement between the GFS and ECMWF, I have added confidence in Katia's recurvature (probably > 60% chance). Right now, if I had to venture a guess, Katia would probably get as far west as 65°W-70°W. 3. In addition, Katia's faster forward motion as increased prospects that it will find the weakness in the ridging before the ridging can rebuild. 4. After Katia, if there is another formative tropical cyclone in the Atlantic basin, that storm might have a better chance at making it farther west, perhaps threatening eventually the Caribbean or Southeast, given the pattern that appears to be evolving on the most recent run of the GFS ensembles. Link to comment Share on other sites More sharing options...
PSUBlizzicane2007 Posted August 30, 2011 Share Posted August 30, 2011 The TVCN, GFDL, GFDN, HWRF, and NOGAPS are the only ones to support your observations. Not exactly the Hall of Fame for Hurricane Modeling, there. Link to comment Share on other sites More sharing options...
am19psu Posted August 30, 2011 Share Posted August 30, 2011 4. After Katia, if there is another formative tropical cyclone in the Atlantic basin, that storm might have a better chance at making it farther west, perhaps threatening eventually the Caribbean or Southeast, given the pattern that appears to be evolving on the most recent run of the GFS ensembles. Agree with this, Don. It looks like that one will be slower to develop, as well, increasing the chances it stays farther south longer. Link to comment Share on other sites More sharing options...
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