NJwx85 Posted September 7, 2017 Author Share Posted September 7, 2017 Where are these shear forecasts coming from? I see very minimal shear on the GFS until Irma has already made LF in FL and even less on the Euro. Link to comment Share on other sites More sharing options...
Random Chaos Posted September 7, 2017 Share Posted September 7, 2017 2 minutes ago, jojo762 said: 153kt SFMR, supported by other ~150kt readings in the NW eye wall. 153 was rain flagged. 149kt was not. Link to comment Share on other sites More sharing options...
Morris Posted September 7, 2017 Share Posted September 7, 2017 2 minutes ago, jojo762 said: 153kt SFMR, supported by other ~150kt readings in the NW eye wall. This is likely why they've held it at 160 kts. They figure it's likely there and either way, they would only lower it by 5 knots, so not worthwhile to change for messaging and other purposes. Link to comment Share on other sites More sharing options...
NJwx85 Posted September 7, 2017 Author Share Posted September 7, 2017 5 minutes ago, wthjnky said: By looking at the Models It appears that if this track holds then the Center of the storm will pass about 30 miles from the coast of Jacksonville. I have some friends there and I was really wondering what the winds would be like that distance from the eye. Expect the models to continue to over correct East and West the next few days. It's way to early to determine the exact track near FL, but I like the official track. Link to comment Share on other sites More sharing options...
CaWx Posted September 7, 2017 Share Posted September 7, 2017 4 minutes ago, SnowGoose69 said: The shear increases pretty significantly after 90 hours and more so after 100. I could see a scenario where if it stayed say 50-100 miles off FL and never made landfall til SC that it could be down to a Cat 2. If it comes straight into MIA though I would be shocked if it was under 125mph at this point...to me thats the low end possibility. I guess I didn't realize the shear was suppose to increase that much. In theory how much shear could Irma take on while sitting over 84F+ temps before it weakens? Link to comment Share on other sites More sharing options...
donsutherland1 Posted September 7, 2017 Share Posted September 7, 2017 CNN reported: French Interior Minister Gérard Collomb said some of the strongest buildings on the island of 75,000 people had been destroyed, boding ill for weaker structures on St. Martin. "In terms of material damage, the four strongest buildings on the island of St. Martin have been destroyed," which meant that weaker structures likely had been damaged or destroyed, he told reporters. http://www.cnn.com/2017/09/06/americas/hurricane-irma-caribbean-islands/index.html This highlights the potential danger Miami faces should Irma make landfall just to the city's west at Category 5 strength. Even the most modern buildings would likely be susceptible to varying degrees of damage. In addition, windows would blow out on a widespread basis from others. Other parts of the city would be flooded by the storm surge. My guess is that Irma will make landfall as a Category 4 storm (and I think LEK's thinking on strength and track is very realistic at this time), but a Category 5 storm still can't be ruled out, as some of the guidance continues to insist on Irma's intensification ahead of possible Florida landfall. Hopefully, Irma will stay offshore to spare Miami and the southeast Florida coastline of the kind of catastrophic damage that is possible from such a powerful storm. Link to comment Share on other sites More sharing options...
Morris Posted September 7, 2017 Share Posted September 7, 2017 2 minutes ago, Random Chaos said: 153 was rain flagged. 149kt was not. How do you see if it's flagged? I used to remember.... Link to comment Share on other sites More sharing options...
Latitudedfb Posted September 7, 2017 Share Posted September 7, 2017 What are opinions on the wind speed if Irma makes landfall in South Florida near Miami and then travels inland up the state? What effects would the "ground friction" have on the winds onshore 10 to 15 miles inland? Link to comment Share on other sites More sharing options...
Random Chaos Posted September 7, 2017 Share Posted September 7, 2017 Just now, Morris said: How do you see if it's flagged? I used to remember.... Last column, 3 , 5 , 6, or 9: http://www.nhc.noaa.gov/abouthdobs_2007.shtml Link to comment Share on other sites More sharing options...
Dcwx Posted September 7, 2017 Share Posted September 7, 2017 FWIW 12z JMA has Irma splitting FL down the middle. Link to comment Share on other sites More sharing options...
Random Chaos Posted September 7, 2017 Share Posted September 7, 2017 1 minute ago, Latitudedfb said: What are opinions on the wind speed if Irma makes landfall in South Florida near Miami and then travels inland up the state? What effects would the "ground friction" have on the winds onshore 10 to 15 miles inland? Florida is very flat, with good moisture sources off both coasts. Hurricanes have been know to cross E-W with minimal impact to intensity. No idea about a S-N route, though. Link to comment Share on other sites More sharing options...
the ghost of leroy Posted September 7, 2017 Share Posted September 7, 2017 1 minute ago, Dcwx said: FWIW 12z JMA has Irma splitting FL down the middle. Do you know where to find verification scores for the JMA? Link to comment Share on other sites More sharing options...
Morris Posted September 7, 2017 Share Posted September 7, 2017 2 minutes ago, Random Chaos said: Last column, 3 , 5 , 6, or 9: http://www.nhc.noaa.gov/abouthdobs_2007.shtml Thanks! Link to comment Share on other sites More sharing options...
otown Posted September 7, 2017 Share Posted September 7, 2017 5 minutes ago, Dcwx said: FWIW 12z JMA has Irma splitting FL down the middle. Earlier JMA models had Irma way out west, wouldn't this just show its beginning to catch up to other trends of an easterly path Link to comment Share on other sites More sharing options...
Bostonseminole Posted September 7, 2017 Share Posted September 7, 2017 2 minutes ago, cmasty1978 said: Do you know where to find verification scores for the JMA? not sure those exist, at least not on the same scale as other models Link to comment Share on other sites More sharing options...
JC-CT Posted September 7, 2017 Share Posted September 7, 2017 Do you know where to find verification scores for the JMA?Cmc has them for North America. Not very good, but I find useful as an ensemble member at long range. Useless for this though.https://weather.gc.ca/verification/monthly_ts_e.html Link to comment Share on other sites More sharing options...
Hoosier Posted September 7, 2017 Share Posted September 7, 2017 3 minutes ago, Latitudedfb said: What are opinions on the wind speed if Irma makes landfall in South Florida near Miami and then travels inland up the state? What effects would the "ground friction" have on the winds onshore 10 to 15 miles inland? Historical cases would suggest gust potential near/over 100 mph well northward, at least into central Florida if not farther, IF it landfalls as a cat 4-5 and takes a track like you suggest. Link to comment Share on other sites More sharing options...
Dcwx Posted September 7, 2017 Share Posted September 7, 2017 3 minutes ago, cmasty1978 said: Do you know where to find verification scores for the JMA? No idea - mostly post the JMA as a joke. It always gets posted in HECS winter storms too. I do recall it verified better than any other model for one of the major 2010 DC snowstorms but that's probably it's claim to fame. Link to comment Share on other sites More sharing options...
bdgwx Posted September 7, 2017 Share Posted September 7, 2017 18 minutes ago, NJwx85 said: Where are these shear forecasts coming from? I see very minimal shear on the GFS until Irma has already made LF in FL and even less on the Euro. The shear will start to increase as Irma begins the turn north while interacting with the trough. I'm looking at 950-800mb across 600-400mb for mid level shear and up to 300-200mb for deep layer shear. The question is...will Irma get a brief boost from being placed favorably in the RER of the upper level jet streak before the shear encroaches too close to the core? I like LEK's position of the lowest pressure. It's about as perfect of a location as I can imagine...between land masses, high SSTs, jet dynamics for increased outflow, but early enough that shear *might* not take hold yet. That last item is a big if though. Link to comment Share on other sites More sharing options...
Random Chaos Posted September 7, 2017 Share Posted September 7, 2017 4 minutes ago, Dcwx said: No idea - mostly post the JMA as a joke. It always gets posted in HECS winter storms too. I do recall it verified better than any other model for one of the major 2010 DC snowstorms but that's probably it's claim to fame. At least no one is posting CRAS - I just checked it - and it makes every outlier model look sane Link to comment Share on other sites More sharing options...
Windspeed Posted September 7, 2017 Share Posted September 7, 2017 Irma's windfield will continue to expand as it nears the southwestern Bahamas and Florida. I would imagine the size of the hurricane combined with a decrease in surface to 500mb level background pressures as it turns into the weakness will weaken the pressure gradient. The ridge will have weakened/backed its position further east. That basically means Irma should not be able to sustain the absurd wind speeds even if it remains a sub 920mb cyclone or goes through another strengthening phase at a much larger size. Unfortunately it just means a much larger swath of major hurricane force winds. Also, the eyewall, if still intense, will be able to produce upper Cat 4 or borderline 5. This is perhaps semantics, but I am just reiterating that you can bring down the winds 20-30 kts. The hurricane still remains catastrophic in winds and surge. But it will technically weaken aside from structural changes just based on its surrounding atmosphere. Link to comment Share on other sites More sharing options...
yoda Posted September 7, 2017 Share Posted September 7, 2017 00z GFS out to 30... Irma in the SE Bahamas Link to comment Share on other sites More sharing options...
Kleimax Posted September 7, 2017 Share Posted September 7, 2017 No big changes on GFS out to 24 hrs Link to comment Share on other sites More sharing options...
donsutherland1 Posted September 7, 2017 Share Posted September 7, 2017 Since 1851, there were 15 major hurricanes that formed in August or prior to September 15 and passed within 100 nautical miles of Irma's 11 pm position (19.4°N, 66.8°W). 60% made U.S. landfall. Areas of Landfall: Florida: 56% North Carolina: 22% South Carolina: 11% Texas: 11% Strength at Landfall: Category 1: 11% Category 2: 22% Category 3: 22% Category 4: 44% Major: 67% The Category 4 Storms were: Great Miami Hurricane (1926): 125 knots Lake Okeechobee Hurricane (1928): 125 knots Donna (1960): 125 knots Hugo (1989): 120 knots The spread of the 12z ECMWF ensembles continues to highlight the Florida-South Carolina area as being at highest risk of U.S. landfall. North Carolina is also a landfall site for some of those ensemble members. None make landfall west of the Florida Panhandle. A few take Irma offshore and avoid landfall. I still think Florida landfall is somewhat more likely than not and probably at similar strength to the three Category 4 hurricanes that made Florida landfall. Second landfall should occur at Georgia or South Carolina. Link to comment Share on other sites More sharing options...
CamSE-Wx Posted September 7, 2017 Share Posted September 7, 2017 GFS further south, speed about the same. More western of a path coming? Link to comment Share on other sites More sharing options...
LovintheWhiteFluff Posted September 7, 2017 Share Posted September 7, 2017 it's slightly SSE...maybe 20 miles or so. Link to comment Share on other sites More sharing options...
olafminesaw Posted September 7, 2017 Share Posted September 7, 2017 Link to comment Share on other sites More sharing options...
Random Chaos Posted September 7, 2017 Share Posted September 7, 2017 On the GFS run, compare the size of the storm at present (hour 0) to two days from now (hour 48) - looks to double in physical size. Link to comment Share on other sites More sharing options...
SACRUS Posted September 7, 2017 Share Posted September 7, 2017 4 minutes ago, donsutherland1 said: Since 1851, there were 15 major hurricanes that formed in August or prior to September 15 and passed within 100 nautical miles of Irma's 11 pm position (19.4°N, 66.8°W). 60% made U.S. landfall. Areas of Landfall: Florida: 56% North Carolina: 22% South Carolina: 11% Texas: 11% Strength at Landfall: Category 1: 11% Category 2: 22% Category 3: 22% Category 4: 44% Major: 67% The Category 4 Storms were: Great Miami Hurricane (1922): 125 knots Lake Okeechobee Hurricane (1928): 125 knots Donna (1960): 125 knots Hugo (1989): 120 knots The spread of the 12z ECMWF ensembles continues to highlight the Florida-South Carolina area as being at highest risk of U.S. landfall. North Carolina is also a landfall site for some of those ensemble members. None make landfall west of the Florida Panhandle. A few take Irma offshore and avoid landfall. I still think Florida landfall is somewhat more likely than not and probably at similar strength to the three Category 4 hurricanes that made Florida landfall. Second landfall should occur at Georgia or South Carolina. Don, excellent summary. One note the Great Miami Hurricane I think you are referring to was n 1926. The others for reference Link to comment Share on other sites More sharing options...
mfgmfg Posted September 7, 2017 Share Posted September 7, 2017 Found a better picture of that cell/radio/microwave tower in Barbuda from earlier: Source @ 13:10 here: Link to comment Share on other sites More sharing options...
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