Sep 25, 2011

DAY 117

A rough day for Ophelia, as she was downgraded to a depression. Her minimum central pressure has risen to 1010 mb. It's not a complete shocker that this happened because of the way the wind shear has been picking her apart. All the thunderstorms that fire up, are quickly dispatched by that persistent westerly wind shear. Ophelia's surface circulation is still visible, so I don't think she is in immediate danger of opening up, but if she continues on the course she's on, Ophelia could dissipate in another 24 hours.

(Ophelia Downgraded)

The National Hurricane Center is forecasting Ophelia to dissipate on Monday night or early Tuesday morning. If that actually does happen, she probably wont be able to make a comeback. You can see on the water vapor loop that Ophelia is on a collision course with the tail of an upper trough. As that low moves off to the northwest, it's tail will relax a bit. The only way that Ophelia is going to survive this, is to take an escape route to the north. 

There are two solutions for the future of Ophelia. The NHC death solution, I would say has the higher probability of verifying. But just by a hair. The GFS is the only computer model at this moment that is supporting that solution, but I must remind you that the GFS has been the more reliable model this season. The other solution is for a high pressure break down. Other computer models, like the HWRF, are forecasting the break down of high pressure near Bermuda, which would open the door for Ophelia to escape to the north. Other factors to consider when deciding which way you might forecast, are climatology and NHC past performance. When I say climatology, I'm referring to how the climate has shown for this season already. Emily, Gert, Katia, and Maria took that route before being picked up by sweeping troughs. And the Hurricane Center has been spot on with tracks, but a little off with intensities. They missed Irene, and Maria by quite a bit. Based on all that, I would say that there is still a good chance that Ophelia could make a comeback and head north.

(HWRF model showing High Pressure break down)
Topical Storm Philippe saw some modest strengthening today. His pressure is down to 997 mb and his winds are at 60 mph. Philippe is starting to build his eye wall already. It's visible in the 85GHz microwave image below. It is just on the south side right now, but there are some strong storms developing on the west side as well.

(Tropical Storm Philippe)

The Hurricane Center is still forecasting Philippe to become a hurricane, but only for a brief time. That would make sense, because he is headed into an area that is full of dry air coming off of the Saharan Desert. If he is able to close off an eye wall on that north side over the next 24 hours, that would give Philippe some brief protection from dry air intrusion.

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