#54 Postby jhamps10 » Thu Sep 20, 2007 11:31 pm
this from pro met over on eastern, nickname wxsmwhrms.
OK, I took my first semi-serious look at this system, and I have to admit I am pretty interested. The GFS at first looked very squirrelly with this thing, bringing it across a strong upper jet and just flying it northward. But now, it seems to be settling down, and looking a bit more concerning. The forward speed has slown down, now not getting to the coast until Sunday night, and I am guessing it will continue to get a bit slower with time. Secondly, the upper pattern it is forecasting looks pretty favorable for development. The system starts out under an upper level anticyclone in good diffluence, and then seems to ride up the east side of a 200 mb jet. The actual flow it is in is only about 15-25kt, which given a pretty good forward motion implies not much shear, but good divergence in a RRQ of a jetmax to aid outflow. Finally, it looks to be in a pretty well-defined steering flow between the old mid level low/remnants of possibly Jerry and a good ridge to the east which would almost certainly result in it being guided toward the central Gulf coast. And, of course, it helps that there is already great looking intense convection in the area where the GFS develops this thing.
A couple of modeling notes, first the GFS is very compact with this thing - maybe due to some sort of convective/grid-scale feedback, or maybe because it is trying to model a compact system as we have seen with some intense tropical cyclones before. Secondly, I am almost sure that this is happening in the timeframe the ECWMF was showing about a week ago when it had it major 'cane shooting the Yucatan Channel and heading for New Orleans, and the Euro has still been periodically hinting at something coming out of this area the last few days.
Something to watch for sure.
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