Daweathablog

Charles E. Roop giving his own forecasts, weather discussions, photos and adventures for the Starkville, MS area, Florida, and beyond.

Monday, October 24, 2011

Hurricane Rina Forms in the Caribbean Sea

I got my slight dose of shock this afternoon as Tropical Storm Rina was upgraded to hurricane status Monday afternoon. I say slight because it just looked really nice on the GOES loops.

Sunday afternoon, a tropical disturbance over the Caribbean Sea that was given invest classification became a tropical depression. Rina was then born by the 11 p.m. ET advisory.

When I viewed the satellite imagery this morning, the tropical cyclone (TC) looked like it was getting its act together quickly. The NHC forecasts had Rina becoming a hurricane a few days out. But the satellite loops showed Rina having good outflow and looking really organized. It wasn't until early this afternoon when USAF Hurricane Hunters found a central pressure of 991 mb and winds of at least 65 knots. This storm's winds increased 30 mph in roughly three hours and dropped 10 mb within the same time frame. At that point, the visible satellite loops were showing what looked like a developing eye.

Currently, the storm is still maintaining 65-kt winds. The pressure has dropped, but only a little (currently 989 mb) and the TC is still dragging west-northwest at 3 mph. Based on infrared satellite imagery, Rina's cloudtops are starting to become taller near the center of circulation (see below).

Source: NOAA
The ridge over southern Texas and northern Mexico is keeping Rina at bay and moving it slowly west. The GFS appears to break down the ridge come Tuesday afternoon as a trough over the western US begins to dig and move eastward. Most of the guidance models track Rina to the north and northeast late in the week. The NHC however, according to their last discussion, are not confident in the future track due to inconstant paths in the previous runs (hence why the "cone of error" is so large).

It may go north over time, but if it does, it may not last very long as a TC. The upper-level environment is very unfavorable to the north of Rina. Current wind shear numbers are 30+ knots. The NHC expects southerly shear to begin impacting the storm within a few days. Dry air is parked to the northwest of the storm. Right now, Rina is doing a good job of shielding itself from this dry air. But once it finds a way in, Rina will start to deteriorate. If, for example, Rina does move towards Florida, it will likely not be a beast of a hurricane because of this. Heck, it'll likely not even be tropical in nature at that point. It depends on how strong it gets. It could be a rain maker, at least.

This storm may take off to the north and northeast over time, but I doubt it will be anything tropical by that point because of the unfavorable environment ahead of it. It's still worth watching. Stay tuned to my Twitter feed for the latest. I might post another blog entry in a day or two, if conditions (and time) warrant.

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