05 September 2008

Hanna less than a day from US landfall, Ike looming ominously north of Lesser Antilles, Josephine still battling shear...

Hanna is a 55kt tropical storm, finally able to get better organized now that the vertical shear has decreased to less than 20kts.  It is now east of Daytona Beach FL, but heading NW-N toward the Charleston SC area.  Landfall is expected there early Saturday morning as a tropical storm.  Watches and warnings for the coasts can be found at http://www.nhc.noaa.gov/storm_graphics/AT08/refresh/AL0808R+gif/
It's possible that Hanna could become a minimal hurricane just prior to landfall, given the recent trend in organization.
In the coming days, tropical storm force winds, along with the potential for flash flooding and tornadoes, extend up into new Jersey, New York, and even New England, as Hanna transitions to a potent extratropical storm.

Now on to Ike.  Ike is shaping up to be a serious threat to the Bahamas and the US this weekend into the middle of next week.
Vertical shear is presently moderate, but will be decreasing, and SSTs will be 29-30C in the coming week.  As of 15Z, intensity is 105kts and 954mb, and tracking W at 14kts.  It is entering the expected timeframe of strong vertical shear, and it shows!  The storm is quite lopsided now, with nearly all convection and outflow on the south half.  Ike could weaken to a CAT2 storm before the shear lets up in a couple days.  It's then forecast to regain CAT3 or CAT4 status as it passes directly over Hanna-battered Bahamas, then onto extreme southern Florida by late Tuesday.

Josephine is now nothing more than an exposed low-level swirl.  It is still classified as a 40kt tropical storm, but is barely even that.  In the next few days, shear is forecast to remain strong over the system, but in 4-5 days, could decrease a bit and start allowing Josephine to make a comeback.  Again, it is near no land and no islands, even looking out one week.

As a side note, as of today, we are at the amount of activity in an "average" season, and this one's not even half way over yet.  The activity is defined by the Net Tropical Cyclone index, or NTC, which combines the numbers of storms, their intensities, and their longevities, and compares it to a climatological average of each quantity.

Please visit my tropical Atlantic headquarters.

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