high risk Posted September 4, 2017 Share Posted September 4, 2017 It's worth remembering that the recent GFS upgrade makes it so that the SST is allowed to warm during the day and then return to the base state at night. Some (but not all) of the largest 6-hr pressure falls are occurring during the day. Link to comment Share on other sites More sharing options...
TriPol Posted September 4, 2017 Share Posted September 4, 2017 1 minute ago, high risk said: It's worth remembering that the recent GFS upgrade makes it so that the SST is allowed to warm during the day and then return to the base state at night. Some (but not all) of the largest 6-hr pressure falls are occurring during the day. Why do we keep picking on the GFS when nearly every single computer model is showing low-pressure readings for Irma that haven't been seen in over a decade? Remember, it's not just the GFS that's predicting pressure readings that would be synonymous to a Category 5 hurricane. Link to comment Share on other sites More sharing options...
ncskywarn Posted September 4, 2017 Share Posted September 4, 2017 Hour 36 just a tad south of 18Z. Link to comment Share on other sites More sharing options...
high risk Posted September 4, 2017 Share Posted September 4, 2017 2 minutes ago, TriPol said: Why do we keep picking on the GFS when nearly every single computer model is showing low-pressure readings for Irma that haven't been seen in over a decade? Remember, it's not just the GFS that's predicting pressure readings that would be synonymous to a Category 5 hurricane. I don't think we're picking on it, per se. It's clearly going to intensify a LOT. We're just trying to understand how a global model is dropping the central pressure into the 880s. Link to comment Share on other sites More sharing options...
Hoosier Posted September 4, 2017 Share Posted September 4, 2017 3 minutes ago, TriPol said: Why do we keep picking on the GFS when nearly every single computer model is showing low-pressure readings for Irma that haven't been seen in over a decade? Remember, it's not just the GFS that's predicting pressure readings that would be synonymous to a Category 5 hurricane. Because the GFS is one of the more obviously egregious models. IF we bottom out at 895 mb or 910 mb it's super impressive but considerably above the GFS. Link to comment Share on other sites More sharing options...
TriPol Posted September 4, 2017 Share Posted September 4, 2017 Out to 42, Irma looks slightly south and west to its 18z location, but that's been the trend on new model initializations for the GFS with Irma as of late. Link to comment Share on other sites More sharing options...
ncskywarn Posted September 4, 2017 Share Posted September 4, 2017 1 minute ago, high risk said: I don't think we're picking on it, per se. It's clearly going to intensify a LOT. We're just trying to understand how a global model is dropping the central pressure into the 880s. Funny thing is if it actually happened we would all be sitting here with our jaws dropped to the floor. Link to comment Share on other sites More sharing options...
Torchageddon Posted September 4, 2017 Share Posted September 4, 2017 I notice the SHIPS intensity forecast gets Irma only to 110 knots and then leaves it there...also that there is complete silence on the SHIPS output. That's another bizarre solution. I think the real question with some models uncoupling the ocean, some of us want to know why it happened on the 18z run but not some other run. Link to comment Share on other sites More sharing options...
TriPol Posted September 4, 2017 Share Posted September 4, 2017 Just now, Hoosier said: Because the GFS is one of the more obviously egregious models. IF we bottom out at 895 mb or 910 mb it's super impressive but considerably above the GFS. Is there any computer model that can accurately predict a tropical system's pressure 7+ days out? I think the trend is that the pressure is going to be extremely low and potentially historic. I think that's what the GFS is screaming to us and other models are saying the same thing, just not as loudly. Do you agree? Link to comment Share on other sites More sharing options...
NJwx85 Posted September 4, 2017 Author Share Posted September 4, 2017 Irma looking good again tonight with a burst of -70c cloud tops near the center. It's still not perfect but I wouldn't be surprised to see the intensity increase overnight. Link to comment Share on other sites More sharing options...
Morris Posted September 4, 2017 Share Posted September 4, 2017 And it moved almost due SW in the past few hours. Link to comment Share on other sites More sharing options...
TriPol Posted September 4, 2017 Share Posted September 4, 2017 Out to 66, looks like it's going to hit PR dead on. Link to comment Share on other sites More sharing options...
Hoosier Posted September 4, 2017 Share Posted September 4, 2017 2 minutes ago, TriPol said: Is there any computer model that can accurately predict a tropical system's pressure 7+ days out? I think the trend is that the pressure is going to be extremely low and potentially historic. I think that's what the GFS is screaming to us and other models are saying the same thing, just not as loudly. Do you agree? Yes, it's fair to think we could see something pretty rare/historic for the given zone that this will be passing through. Link to comment Share on other sites More sharing options...
ncskywarn Posted September 4, 2017 Share Posted September 4, 2017 Definitely a little SW at 66 Link to comment Share on other sites More sharing options...
ineedsnow Posted September 4, 2017 Share Posted September 4, 2017 Just north of pr... Close call Link to comment Share on other sites More sharing options...
Morris Posted September 4, 2017 Share Posted September 4, 2017 Center goes north of PR at 72 Link to comment Share on other sites More sharing options...
weathafella Posted September 4, 2017 Share Posted September 4, 2017 This thread is half reunion of long standing bb members back to WWBB and half weenie roast. Link to comment Share on other sites More sharing options...
LandofLincoln Posted September 4, 2017 Share Posted September 4, 2017 Nothing really sticks out to me as much different through 84. Link to comment Share on other sites More sharing options...
jmg378s Posted September 4, 2017 Share Posted September 4, 2017 25 minutes ago, KPITSnow said: Can someone explain to me what uncoupling is? I'm no expert but my understanding is that this means the model itself isn't fully accounting for the effects, some negative and some positive, that the storm has on the sea and vice versa. For instance, upwelling of cooler water, ocean wave surface drag, and sea spray enthalpy flux, etc. The negative feedbacks being more dominant when not modeled allow the models to overdeepen cyclones under otherwise favorable conditions. I'm guessing increased resolution may then exacerbate the issue... Link to comment Share on other sites More sharing options...
BlunderStorm Posted September 4, 2017 Share Posted September 4, 2017 1 minute ago, ineedsnow said: Just north of pr... Close call With the way things are going the GFS may project a landfall on the Puerto Rico coast by 12z tomorrow. Certainly unlikely but one has to wonder I suppose. Link to comment Share on other sites More sharing options...
Hoosier Posted September 4, 2017 Share Posted September 4, 2017 1 minute ago, BlunderStorm said: With the way things are going the GFS may project a landfall on the Puerto Rico coast by 12z tomorrow. Certainly unlikely but one has to wonder I suppose. All of Puerto Rico is in the cone as of now. Certainly going to be an uncomfortably close pass at least. Link to comment Share on other sites More sharing options...
weathafella Posted September 4, 2017 Share Posted September 4, 2017 Just now, TriPol said: Do you plan on continuing the observations of the Arctic ice extent this year? I am looking forward to reading that. Of course! Thread should start within 2 weeks hopefully. Link to comment Share on other sites More sharing options...
TriPol Posted September 4, 2017 Share Posted September 4, 2017 Out to 96, Irma is over the Windward Islands. Interesting observation that Jose is tailing Irma pretty quickly. I wonder if there will be some form of interaction with Jose that could impact Irma? Link to comment Share on other sites More sharing options...
TPAwx Posted September 4, 2017 Share Posted September 4, 2017 17mb pressure difference output for 12z Friday wrt 18z Link to comment Share on other sites More sharing options...
olafminesaw Posted September 4, 2017 Share Posted September 4, 2017 Link to comment Share on other sites More sharing options...
olafminesaw Posted September 4, 2017 Share Posted September 4, 2017 1 minute ago, TPAwx said: 17mb pressure difference output for 12z Friday wrt 18z Land interaction. Link to comment Share on other sites More sharing options...
ncskywarn Posted September 4, 2017 Share Posted September 4, 2017 120 just North of Eastern Cuba looks like the trough is also moving out quicker. Link to comment Share on other sites More sharing options...
Stebo Posted September 4, 2017 Share Posted September 4, 2017 Just now, ncskywarn said: 120 just North of Eastern Cuba looks like the trough is also moving out quicker. It is moving out much much quicker compared to 12 and 18z. That is a huge change. Link to comment Share on other sites More sharing options...
hawkeye_wx Posted September 4, 2017 Share Posted September 4, 2017 Yep, this run the trough does not get cut off, which enables it to lift out to the northeast more quickly, enabling more ridging to build north of Irma, which sends it even farther south/west than previous runs. Link to comment Share on other sites More sharing options...
hlcater Posted September 4, 2017 Share Posted September 4, 2017 It's so close to Cuba, downsloping off the mountainous terrain in the east could possibly disrupt the storm. Link to comment Share on other sites More sharing options...
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