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aperson

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  1. Looks like a bifurcation around day 3. The north group are (almost) all recurving out to sea. Substantial variability in the south group.
  2. Is the dprog/dt trend you're talking about the successive weakening of the ridge that's occurring in these runs? I assume that if this trend continues the system will be steered toward landfall by the low pressure system. https://www.tropicaltidbits.com/analysis/models/?model=gfs&region=us&pkg=z500a&runtime=2017091106&fh=66&xpos=0&ypos=80 https://www.tropicaltidbits.com/analysis/models/?model=gfs&region=us&pkg=z500a&runtime=2017091112&fh=60&xpos=0&ypos=80 https://www.tropicaltidbits.com/analysis/models/?model=gfs&region=us&pkg=z500a&runtime=2017091118&fh=54&xpos=0&ypos=81
  3. This system's extratropical transition is making a very big rain threat to the NE coast of FL into GA. Many flood gauges in JAX at major flood stage now: http://water.weather.gov/ahps2/index.php?wfo=jax
  4. Is the blowup in windfield and precipitation related to the extratropical transition of these systems? Irma is interacting with that cold front while still at a very low pressure.
  5. No idea. I'm way too much of a hobbyist to know to what extent terrain and water buildup effects could contribute to BOE here. My naive opinion is that the pass near Lake Okeechobee helped prevent a more rapid weakening.
  6. Indeed. WV loops show bursts of convection both near the center of circulation and in the huge feeder band that's building: http://weather.cod.edu/satrad/exper/?parms=meso1-13-96-1-10 That feeder band is out over high CAPE (3k+ to 4k+ the whole way) water and is rapidly turning this system into a significant rainfall event for the NE side of FL. I've been keeping my eye on JAX loop and flood levels: https://www.wunderground.com/weather-radar/united-states/fl/jacksonville/jax/?region=pie&MR=1 http://water.weather.gov/ahps2/index.php?wfo=jax&fcst_timeframe=0&current_color=all&current_type=all&fcst_type=obs&conus_map=d_map&center_point_lat=30.609549999999484&center_point_lon=-82.2711189999986&default_zoom=8&marker=false&refresh=true
  7. A met posted on here a few days ago something that really cleared this up for me. The motion path of hurricanes is trochoidal: https://en.wikipedia.org/wiki/Trochoid Think of taking a top that is moving forward and then lightly blowing on one side of it in the same direction as its rotation
  8. Does NAM have any validity whatsoever at tracking the steering of a tropical system? When watching Harvey it seemed useful for synoptics and precipitation behavior, but it constantly missed the track of the system.
  9. What is the minimum time frame where it's feasible to make these "Irma is going X direction" claims? From what I can see, the system seems to have gyroscopic motion like a smaller circle is rotating inside of a larger circle. Given this, you would need to average the motion track out over a longer time. I would love more insight into this motion behavior because I saw similar with Harvey but I'm pretty naive as to the underlying mechanism of action.