29 September 2011

Ophelia nearly a hurricane

The easterly wave that exited the African coast on September 16 became TS Ophelia on Sep 21, then on the 25th was so weak that it wasn't even classified as a Depression.  A couple days later, it regained Depression status, then yesterday it regained TS status, and today, after this tremendous comeback, it is almost the season's 4th hurricane!  The images on this page allow you to easily track the appearance of this system over the past week: http://einstein.atmos.colostate.edu/~mcnoldy/tropics/hovmoller/epac_carib1/

At 15Z this morning, Ophelia is a 60kt TS with 991mb central pressure.  The microwave image below shows quite clearly that the storm has formed an eyewall, though the eye hasn't cleared out yet in infrared imagery.

The forecast is for some additional strengthening over the next couple of days as it heads north toward Bermuda.  Then as it comes under the influence of a mid-latitude trough, the shear will increase, and as it enters the north-central Atlantic, the SSTs will decrease.  Together, these effects will transform Ophelia into an extratropical cyclone within 4-5 days.

Moving on to Philippe... not much has changed.  The storm is still embedded in a strong vertical shear environment, so the deep convection associated with the Low is displaced completely to the northeast of the surface circulation.  At 15Z, the intensity estimate is 40kts and 1005mb... located about 1240 miles west of the Cape Verde islands.
The forecast is looking more interesting with time.  A large-scale ridge is expected to move back over the central Atlantic, which would steer eastern Atlantic systems more to the west (the current trough in place has been pulling everything north).  So despite the shear remaining fairly high during the period, the SSTs will at least be warm, and Philippe should be several degrees north of the Leeward Islands by the middle of next week.

Please visit my tropical Atlantic headquarters.

No comments:

Post a Comment