11 December 2007

Olga forms near Hispaniola...

At 03Z today, the area of disturbed weather that was east of Puerto Rico yesterday was upgraded to Sub-tropical Storm Olga.  Intensity is now estimated at 40kts and 1005mb, and since the strongest winds are still quite far from the center of circulation, it is it classified as purely tropical.  STS Olga is forecast to weaken as it heads W not only over Jamaica, but also into much stronger vertical wind shear.

There's a long radar loop showing Olga's development near Puerto Rico available at:  http://einstein.atmos.colostate.edu/~mcnoldy/tropics/olga07/Olga_10-11Dec07.gif

Please visit my tropical Atlantic headquarters.

10 December 2007

New disturbance near Puerto Rico...

Although the Atlantic hurricane season officially ended ten days ago, the tropical atmosphere still has a little kick in it yet.  A potent yet asymmetric 1010mb Low is presently located just a couple degrees east of Puerto Rico.  It is in weak southwesterly wind shear, and has a window of opportunity of about 24-36 hours to organize before shear increases.  It's over 27.5C water and should remain over that for the next few days as it heads WNW at 10kts.  If this gets named, it would become Olga, the 15th named storm of the season.

You can track the precipitation around this disturbance from the San Juan long-range radar:  http://einstein.atmos.colostate.edu/~mcnoldy/tropics/olga07/Olga_10Dec07.gif

If you recall, the season started off on May 9 with Andrea... three weeks before the official beginning of Atlantic hurricane season.  Should Olga form in December, we'd really have a long tropical season!

Up through this potential storm, and using the currently available "best track" data from NHC (not all storms have been reanalyzed post-season yet), we had 14 tropical storms, 6 of which became hurricanes, and 2 of those became major hurricanes.  Combining these numbers and their respective longevities allows us to compare the season to a "normal" season (net tropical cyclone activity = NTC).  In this comparison, 2007 was 95.1% of normal, or about as average as it gets!  If the current disturbance gets named, let's suppose for a day, that percentage goes up to 97.2.  Furthermore, neither Dean nor Felix have final reports completed yet, and any change in the major hurricanes could change the NTC a bit.

Please visit my tropical Atlantic headquarters.