Here's an overview of water vapor imagery and upper-level pattern across the US and Atlantic basin this evening, including its potential evolution and how it relates to Emily's future path. ' remnants are caught in the middle of the broad upper-level ridge (with the surface reflection being the subtropical high) across the east coast of the US. Just offshore -- and including the remnants of Cindy in its midst somewhere -- is a broad trough of low pressure that doesn't appear to be moving a lot. This may be because of what is just to its east -- an upper level ridge with an upper-level low caught in its midst, a blocking scenario.
The coupling of the broad trough plus an upper-level low in the SW Caribbean is creating strong SW flow across the Lesser Antilles at this time, a scenario more akin to what we see this time of year. In the short-term, this isn't going away. In a few days, however, I believe we'll see what we call trough fracture, where the broad trough will become "fractured" along the west side of the ridge in the central Atlantic and begin to lift up and around it. As the western Caribbean feature moves west along the southern edge of the upper ridge across the eastern US, this will weaken the southwesterly flow across the central Atlantic and allow the ridge to build eastward, keeping the storm in a favorable upper-level environment. This should allow for Emily to strengthen and to keep it from recurving out to sea in the long haul. The biggest question then becomes where it will track with respect to the Greater Antilles -- Puerto Rico, Hispaniola, and Cuba. If it tracks north of the islands, the storm could get quite a bit stronger in the deep warm waters near the Bahamas; if it tracks over them, it could lose quite a bit of its punch due to interaction with mountainous terrain; if it tracks south of them, upwelling from may serve to play a role in limiting intensity -- but it's too early to make a call on that.
Needless to say, any US impact (if any) is a week away at least, with an impact for the islands about 3 days away. At this time, I don't see any particular reason to deviate strongly from the current forecast path, which takes it very near Puerto Rico and Hispaniola in 4 days, except perhaps trend just on the northern end of things by the smallest of margins. This could prove important to the intensity forecast, but again -- it's too early to call. The did an excellent job with the overall track of and, given tightly clustered model guidance, I see no reason to deviate from that at this time.
Conditions are marginal for the wave behind it to develop, even more marginal if Emily becomes stronger faster, but it has a chance of slow development over the next few days. Since it is at a rather low latitude to begin with, a more southerly course into the Caribbean is more likely, no matter whether or not it develops. Stay tuned for more as the storm progresses through the basin in what is shaping up to be a season to remember.
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