Tuesday, October 25, 2011

Good evening/morning,
Rina had a very good day development wise. The storm had a burst of convection with an eye wall formation early in the day then intensified into a strong category two hurricane with sustained winds of 95 knots...109 mph...and gusts to near 115 knots...132 mph. The motion of the storm is still in question with the aircraft projecting a westward motion at 3 knots which is so slow that this could just be drifting. With the storm meandering expect that a concise model solution will be very difficult. With that in mind believe that the latest NHC Official forecast track is as good as its going to get unless the storm decides to start moving.

Some of the dynamical and ensemble member forecasts are shown in the image above from CIMSS. These tracks are shifting slightly with each run of the models with the official track sitting about dead center. The intensity forecast is most in question as the storm is not moving and is over some deep water. this long lived storm over nearly the same location for the past 3 days has to be inducing up-welling and mixing of surface water and exchanging it with the cooler water below 10 meters. The shear is slightly lower tonight than the past few days but still substantial to the north of the system. The satellite presentation of the system tonight has shown some stretching of the storm along an axis oriented from southwest to northeast. There are two dry slots set along the northwest and southeast sectors of the system which appear to be knocking down the outflow channel a bit as well. What this could be is the shear is taking effect on the storm, while the cutting off of the outflow would be an indication of some filling in of the pressure field...rising pressures in the storm environment. Both of these are detrimental to the future of Rina. The only caveat to this is that this could also be just a part of the diurnal cycle of convection in an intensifying storm. We will know by sunrise as the convection will usually burst up over night. The good news is that the storm should remain south of the Keys and be a tropical storm at best by day 5. The bad news is that NHC has issued warnings from Cancun to Punta Gruesa on the eastern coast of the Yucatan Peninsula, with tropical storm warnings from Punta Gruesa to Chetumal, with a tropical storm watch from Chetumal to Belize City.

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