There's some very bad news for the Riviera Maya (Cancún, Cozumel). Instead of brushing the NE Yucatan, Wilma is expected to make a direct hit as a Cat 4 or 5 storm early Friday morning -- the official forecast calls for landfall as a Cat 5.
We're awaiting Wilma's turn to the north and then the northeast. Her turn northward has been postponed by an upper-level ridge over the Gulf which is weakening a bit slower than expected:
500 mb heights (m): 12Z Wed, 12Z Thu
Brownsville: 5900, 5890
Slidell, LA: 5880, 5870
Key West FL: 5880, 5880
Mérida, YUC: 5890, 5860
Low heights indicate a weaker ridge. Note that the weakening over Mérida is greater -- not good news for the Yucatan. (And how I wish some plane could fly over the central Gulf and release a dropsonde!)
Currently, a trough extends south from Kansas to central Texas. The GFS model models shows that trough weakening and another diving southward over the weekend. The GFS also shows Wilma over the Yucatan for two days instead of one -- good news for Florida, less so for the Yucatan.
Looking for steering winds, it appears that, for now, Wilma is generating the steering currents, and other methods must be used to determine her track.
So, for now the National Weather Service is predicting American landfall near Naples, FL late Sunday afternoon and her exit from Ft. Lauderdale before dawn on Monday. From there, the track predicts no American landfall.
Please note that I am merely a student of meteorology; please follow your local authorities' advice and directions.
Take care,
Yamaneko
(P.S. I'm sorry I wasn't able to link images.)